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Bulletin of the Global Volcanism Network

All reports of volcanic activity published by the Smithsonian since 1968 are available through a monthly table of contents or by searching for a specific volcano. Until 1975, reports were issued for individual volcanoes as information became available; these have been organized by month for convenience. Later publications were done in a monthly newsletter format. Links go to the profile page for each volcano with the Bulletin tab open.

Information is preliminary at time of publication and subject to change.


Recently Published Bulletin Reports

Ubinas (Peru) Intermittent ash explosions in June-August 2019

Santa Maria (Guatemala) Persistent explosions with local ashfall, March-August 2019; frequent lahars during June; increased explosions in early July

Stromboli (Italy) Major explosions on 3 July and 28 August 2019; hiker killed by ejecta

Ol Doinyo Lengai (Tanzania) Multiple lava flows within the summit crater, September 2018-August 2019

Ulawun (Papua New Guinea) Explosions on 26 June and 3 August 2019 send plumes above 19 km altitude

Sarychev Peak (Russia) Ash plume on 11 August; thermal anomalies from late May to early October 2019

Asamayama (Japan) Ashfall from phreatic eruptions on 7 and 25 August 2019

Villarrica (Chile) Strombolian activity continued during March-August 2019 with an increase in July

Reventador (Ecuador) Daily ash emissions and incandescent block avalanches continue, February-July 2019

Raikoke (Russia) Short-lived series of large explosions 21-23 June 2019; first recorded activity in 95 years

Sinabung (Indonesia) Large ash explosions on 25 May and 9 June 2019

Semisopochnoi (United States) Small explosions detected between 16 July and 24 August 2019



Ubinas (Peru) — September 2019 Citation iconCite this Report

Ubinas

Peru

16.355°S, 70.903°W; summit elev. 5672 m

All times are local (unless otherwise noted)


Intermittent ash explosions in June-August 2019

Prior to renewed activity in June 2019, the most recent eruptive episode at Ubinas occurred between 13 September 2016 and 2 March 2017, with ash explosions that generated plumes that rose up to 1.5-2 km above the summit crater (BGVN 42:10). The volcano remained relatively quiet between April 2017 and May 2019. This report discusses an eruption that began in June 2019 and continued through at least August 2019. Most of the Information was provided by the Instituto Geofísico del Perú (IGP), Observatoria Vulcanologico del Sur (IGP-OVS), the Observatorio Volcanológico del INGEMMET (Instituto Geológical Minero y Metalúrgico) (OVI-INGEMMET), and the Buenos Aires Volcanic Ash Advisory Center (VAAC).

Activity during June 2019. According to IGP, seismic activity increased suddenly on 18 June 2019 with signals indicating rock fracturing. During 21-24 June, signals indicating fluid movement emerged and, beginning at 0700 on 24 June, webcams recorded ash, gas, and steam plumes rising from the crater. Plumes were visible in satellite images rising to an altitude of 6.1 km and drifting N, NE, and E.

IGP and INGEMMET reported that seismic activity remained elevated during 24-30 June; volcano-tectonic (VT) events averaged 200 per day and signals indicating fluid movement averaged 38 events per day. Emissions of gas, water vapor, and ash rose from the crater and drifted N and NE, based on webcam views and corroborated with satellite data. According to a news article, a plume rose 400 m above the crater rim and drifted 10 km NE. Weather clouds often obscured views of the volcano, but an ash plume was visible in satellite imagery on 24 June 2019 (figure 49). On 27 June the Alert Level was raised to Yellow (second lowest on a 4-level scale).

Figure (see Caption) Figure 49. Sentinel-2 satellite image in natural color showing an ash plume blowing north from Ubinas on 24 June 2019. Courtesy of Sentinel Hub Playground.

Activity during July 2019. IGP reported that seismic activity remained elevated during 1-15 July; VT events averaged 279 per day and long-period (LP) events (indicating fluid movement) averaged 116 events per day. Minor bluish emissions (magmatic gas) rose from the crater. Infrared imagery obtained by Sentinel-2 first showed a hotspot in the summit crater on 4 July.

According to IGP, during 17-19 July, gas-and-ash emissions occasionally rose from Ubinas's summit crater and drifted N, E, and SE. Beginning at 0227 on 19 July, as many as three explosions (two were recorded at 0227 and 0235) generated ash plumes that rose to 5.8 km above the crater rim. The Buenos Aires VAAC reported that, based on satellite images, ash plumes rose to an altitude as high as 12 km. The Alert Level was raised to Orange and the public were warned to stay beyond a 15-km radius. Ash plumes drifted as far as 250 km E and SE, reaching Bolivia. Ashfall was reported in areas downwind, including the towns of Ubinas (6.5 km SSE), Escacha, Anascapa (11 km SE), Tonohaya (7 km SSE), Sacohaya, San Miguel (10 km SE), Huarina, and Matalaque, causing some families to evacuate. The Buenos Aires VAAC reported that during 20-23 July ash plumes rose to an altitude of 7.3-9.5 km and drifted E, ESE, and SE.

IGP reported that activity remained elevated after the 19 July explosions. A total of 1,522 earthquakes, all with magnitudes under 2.2, were recorded during 20-24 July. Explosions were detected at 0718 and 2325 on 22 July, the last ones until 3 September. The Buenos Aires VAAC reported that an ash plume rising to an altitude of 9.4 km. and drifting SE was identified in satellite data at 0040 on 22 July (figure 50). Continuous steam-and-gas emissions with sporadic pulses of ash were visible in webcam views during the rest of the day. Ash emissions near the summit crater were periodically visible on 24 July though often partially hidden by weather clouds. Ash plumes were visible in satellite images rising to an altitude of 7 km. Diffuse ash emissions near the crater were visible on 25 July, and a thermal anomaly was identified in satellite images. During 26-28 July, there were 503 people evacuated from areas affected by ashfall.

Figure (see Caption) Figure 50. Image of ash streaming from the summit of Ubinas on 22 July 2019 captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite. Courtesy of NASA's Earth Observatory (Joshua Stevens and Kathryn Hansen).

Activity during August 2019. IGP reported that during 13-19 August blue-colored gas plumes rose to heights of less than 1.5 km above the base of the crater. The number of seismic events was 1,716 (all under M 2.4), a decrease from the total recorded the previous week.

According to IGP, blue-colored gas plumes rose above the crater and eight thermal anomalies were recorded by the MIROVA system during 20-26 August. The number of seismic events was 1,736 (all under M 2.4), and there was an increase in the magnitude and number of hybrid and LP events. Around 1030 on 26 August an ash emission rose less than 2 km above the crater rim. Continuous ash emissions on 27 August were recorded by satellite and webcam images drifting S and SW.

IGP reported that during the week of 27 August, gas-and-water-vapor plumes rose to heights less than 1 km above the summit. The number of seismic events was 2,828 (all under M 2.3), with VT signals being the most numerous. There was a slight increase in the number of LP, hybrid, and VT events compared to the previous week. The Alert Level remained at Orange.

Thermal anomalies. The MIROVA (Middle InfraRed Observation of Volcanic Activity) system detected a large concentration of anomalies between 19 July until almost the end of August 2019, all of which were of low radiative power (figure 51). Infrared satellite imagery (figure 52) also showed the strong thermal anomaly associated with the explosive activity on 19 July and then the continuing hot spot inside the crater through the end of August.

Figure (see Caption) Figure 51. Log radiative power MIROVA plot of MODIS thermal anomalies at Ubinas for the year ending on 4 October 2019. Thermal activity began in the second half of July. Courtesy of MIROVA.
Figure (see Caption) Figure 52. Sentinel-2 satellite images (Atmospheric penetration rendering, bands 12, 11, 8A) showing thermal anomalies during the eruption on 19 July (left) and inside the summit crater on 29 July 2019 (right). A hot spot inside the crater persisted through the end of August. Courtesy of Sentinel Hub Playground.

Geologic Background. A small, 1.4-km-wide caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Perú. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3700 years ago extend 10 km from the volcano. Widespread plinian pumice-fall deposits include one of Holocene age about 1000 years ago. Holocene lava flows are visible on the flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.

Information Contacts: Instituto Geofisico del Peru (IGP), Observatoria Vulcanologico del Sur (IGP-OVS), Arequipa Regional Office, Urb La Marina B-19, Cayma, Arequipa, Peru (URL: http://ovs.igp.gob.pe/); Observatorio Volcanologico del INGEMMET (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa (URL: http://ovi.ingemmet.gob.pe); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php?lang=es); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Instituto Nacional de Defensa Civil Perú (INDECI) (URL: https://www.indeci.gob.pe/); Gobierno Regional de Moquegua (URL: http://www.regionmoquegua.gob.pe/web13/); La Republica (URL: https://larepublica.pe/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/).


Santa Maria (Guatemala) — September 2019 Citation iconCite this Report

Santa Maria

Guatemala

14.757°N, 91.552°W; summit elev. 3745 m

All times are local (unless otherwise noted)


Persistent explosions with local ashfall, March-August 2019; frequent lahars during June; increased explosions in early July

The dacitic Santiaguito lava-dome complex on the W flank of Guatemala's Santa María volcano has been growing and actively erupting since 1922. The youngest of the four vents in the complex, Caliente, has been erupting with ash explosions, pyroclastic, and lava flows for more than 40 years. A lava dome that appeared within the summit crater of Caliente in October 2016 has continued to grow, producing frequent block avalanches down the flanks. Daily explosions of steam and ash also continued during March-August 2019, the period covered in this report, with information primarily from Guatemala's INSIVUMEH (Instituto Nacional de Sismologia, Vulcanologia, Meterologia e Hidrologia) and the Washington VAAC (Volcanic Ash Advisory Center).

Activity at Santa Maria continued with little variation from previous months during March-August 2019, except for a short-lived increase in the frequency and intensity of explosions during early July that produced minor pyroclastic flows. Plumes of steam with minor magmatic gases rose continuously from both the S rim of the Caliente crater and from the summit of the growing dome throughout the period. They usually rose 100-700 m above the summit, generally drifting W or SW, and occasionally SE, before dissipating. In addition, daily explosions with varying amounts of ash rose to altitudes of around 2.8-3.5 km and usually extended no more than 25 km before dissipating. Most of the plumes drifted SW or SE; minor ashfall occurred in the adjacent hills almost daily and was reported at the fincas located within 10 km in those directions several times each month. Continued growth of the Caliente lava dome resulted in daily block avalanches descending its flanks to the base of the dome. The MIROVA plot of thermal energy during this time shows a consistent level of heat from early December 2018 through April 2019, very little activity during May and June, and a short-lived spike in activity from late June through early July that coincides with the increase in explosion rate and intensity. Activity decreased later in July and into August (figure 95).

Figure (see Caption) Figure 95. Thermal activity at Santa Maria from 8 December 2018 through August 2019 was similar to previous months. A noticeable decrease in activity occurred during May and early June 2019 with a short-lived spike during late June and early July that corresponded to an increase in explosion rate and intensity during that brief interval. Courtesy of MIROVA.

Explosive activity increased slightly during March 2019 to 474 events from 409 events during February, averaging about 15 per day; the majority of explosions were weak to moderate in strength. The moderate explosions generated small block avalanches daily that sent debris 300 m down the flanks of Caliente dome; the explosions contained low levels of ash and large quantities of steam. Daily activity consisted mostly of degassing around the southern rim of the crater and within the central dome, with plumes rising about 100 m from the S rim, and pulsating between 100-400 m above the central dome, usually white and sometimes blue with gases; steam plumes drifted as far as 10 km. The weak ash emissions resulted in ashfall close to the volcano, primarily to the W and SW in the mountainous areas of El Faro, Patzulín, La Florida, and Monte Bello farms. During mid-March, residents of the villages of Las Marías and El Viejo Palmar, located S of the dome, reported the smell of sulfur. The seismic station STG3 registered 8-23 explosions daily that produced ash plumes which rose to altitudes between 2.7 and 3.3 km altitude. Explosions from the S rim were usually steam rich, while reddish oxidized ash was more common from the NE edge of the growing dome in the summit crater (figure 96). The constant block avalanches were generated by viscous lava slowly emerging from the growing summit dome, and also from the explosive activity. On the steep S flank of Santa Maria, blocks up to 3 m in diameter often produce small plumes of ash and debris as they fall.

Figure (see Caption) Figure 96. Mostly steam rose from the S rim of the Caliente dome at Santa Maria throughout March-August 2019. On 1 March 2019, oxidized reddish ash from the growing dome was also part of the emissions (left). The dome continued to grow, essentially filling the inside of the summit crater of Caliente. Courtesy of INSIVUMEH (INFORME MENSUAL DE ACTIVIDAD VOLCÁNICA MARZO 2019, VOLCÁN SANTIAGUITO).

Late on 4 March 2019 an explosion was heard 10 km away that generated incandescence 100 m above the crater and block avalanches that descended to the base of the Caliente dome; it also resulted in ashfall around the perimeter of the volcano. Powerful block avalanches were reported in Santa María creek on 8 March. Ashfall was reported in the villages of San Marcos and Loma Linda Palajunoj on 14 March. Ash plumes on 18 March drifted W and caused ashfall in the villages of Santa María de Jesús and Calaguache. A small amount of ashfall was reported on 26 March around San Marcos Palajunoj. The Washington VAAC reported volcanic ash drifting W from the summit on 8 March at 4.6 km altitude. A small ash plume was visible in satellite imagery moving WSW on 11 March at 4.6 km altitude. On 20 March a plume was detected drifting SW at 3.9 km altitude for a short time before dissipating.

Explosion rates of 10-14 per day were typical for April 2019. Ash plumes rose to 2.7-3.2 km altitude. Block avalanches reached the base of the Caliente dome each day. Steam and gas plumes pulsated 100-400 m above the S rim of the crater (figure 97). Ashfall in the immediate vicinity of the volcano, generally on the W and SW flanks was also a daily feature. The Washington VAAC reported multiple small ash emissions on 2 April moving W and dissipating quickly at 4.9 km altitude. An ash plume from two emissions drifted WSW at 4.3 km altitude on 10 April, and on 22 April two small discrete emissions were observed in satellite images moving SE at 4.6 km altitude. Ashfall was reported on 13 and 14 April in the nearby mountains and areas around Finca San José to the SE. On 15 and 23 April, ash plumes drifted W and ashfall was reported in the area of San Marcos and Loma Lina Palajunoj.

Figure (see Caption) Figure 97. Degassing from the Caliente dome at Santa Maria on 3 April (left, infrared image) and 13 April 2019 (right) produced steam-rich plumes with minor quantities of ash. Courtesy of INSIVUMEH (Reporte Semanal de Monitoreo:, Volcán Santiaguito, Semana del 30 de marzo al 05 de abril de 2019).

Constant degassing continued from the S rim of the crater during May 2019 while pulses of steam and gas rose 100-500 m from the dome at the center of the summit crater. Weak to moderate explosions continued at a rate of 8-12 per day. White and gray plumes of steam and ash rose 300-700 m above the crater daily. A moderate-size lahar on 16 May descended the Rio San Isisdro; it was 20 m wide and carried blocks 2 m in diameter. Ashfall was reported on the W flank around the area of San Marcos and Loma Lina Palajunoj on 21 and 24 May. INSIVIUMEH reported on 29 and 30 May that seismic station STG8 recorded moderate lahars descending the Rio San Isidro (a drainage to the Rio Tambor). The thick, pasty lahars transported blocks 1-3 m in diameter, branches, and tree trunks. They were 20 m wide and 1.5-2 m deep.

Weak to moderate explosions continued during June 2019 at a rate of 9-12 per day, producing plumes of ash and steam that rose 300-700 m above the Caliente crater. On 1 June explosions produced ashfall to the E over the areas of Calaguache, Las Marías and other nearby communities. Ash plumes commonly reached 3.0-3.3 km altitude and drifted W and SW, and block avalanches constantly descended the E and SE flanks from the dome at the top of Caliente. Ashfall was reported at the Santa María de Jesús community on 7 June. Ashfall to the W in San Marcos and Loma Linda Palajunoj was reported on 10, 15, 18, 20, and 22 June. Ashfall to the SE in Fincas Monte Claro and El Patrocinio was reported on 26 June. A few of the explosions on 28 June were heard up to 10 km away. On 29 June ash dispersed to the W again over the farms of San Marcos, Monte Claro, and El Patrocinio in the area of Palajunoj; the next day, ash was reported in Loma Linda and finca Monte Bello to the SW. The Washington VAAC reported ash emissions on 29 June that rose to 4.3 km and drifted W; two ash clouds were observed, one was 35 km from Santa Maria and the second drifted 55 km before dissipating.

With the onset of the rainy season, eight lahars were reported during June. The Rio Cabello de Ángel, a tributary of Río Nimá I (which flows into Rio Samalá) on the SE flank experienced lahars on 3, 5, 11, 12, 21, and 30 June (figure 98). The lahars were 15-20 m wide, 1-2 m deep, and carried branches, tree trunks and blocks 1-3 m in diameter. On 12 and 15 June, lahars descended the Río San Isidro on the SW flank. They were 1.5 m deep, 15-20 m wide and carried tree trunks and blocks up to 2 m in diameter.

Figure (see Caption) Figure 98. Activity at Santa Maria on 12 June 2019 included explosions with abundant ash and lahars. This lahar is in the Rio Nimá I, and started in the Rio Cabello de Ángel. Courtesy of INSIVUMEH (Reporte Semanal de Monitoreo: Volcán Santiaguito, Semana del 08 al 14 de junio de 2019).

An increase in the frequency and intensity of seismic events was noted beginning on 28 June that lasted through 6 July 2019. Explosions occurred at a rate of 5-6 per hour, reaching 40-45 events per day instead of the 12-15 typical of previous months. Ash plumes rose to 3.5-3.8 km altitude and drifted W, SW, and S as far as 10 km, and ashfall was reported in San Marcos Palajunoj, Loma Linda villages, Monte Bello farms, El Faro, La Mosqueta, La Florida, and Monte Claro. Activity decreased after 7 July back to similar levels of the previous months. As a result of the increased activity during the first week of July, several small pyroclastic flows (also known as pyroclastic density currents or PDC's) were generated that traveled up to 1 km down the S, SE, and E flanks during 2-5 and 13 July, in addition to the constant block avalanches from the dome extrusion and explosions (figure 99). As activity levels decreased after 6 July, the ash plume heights lowered to 3.3 km altitude, while pulsating degassing continued from the summit dome, rising 100-500 m.

Figure (see Caption) Figure 99. An increase in explosive activity at Santa Maria during the first week of July 2019 resulted in several small pyroclastic flows descending the flanks, including one on 3 July 2019 (left). An ash emission on 19 July 2019 rose above the nearby summit of Santa Maria (right). Courtesy of INSIVUME (INFORME MENSUAL DE ACTIVIDAD VOLCÁNICA JULIO 2019, VOLCÁN SANTIAGUITO).

The Washington VAAC reported an ash plume on 2 July from a series of emissions that rose to 3.9 km altitude and drifted W. Satellite imagery on 4 July showed a puff of ash moving W from the summit at 4.3 km altitude. The next day an ash emission was observed in satellite imagery moving W at 4.9 km altitude. A plume on 11 July drifted W at 4.3 km for several hours before dissipating. Ashfall was reported on 2 July at the San Marcos farm and in the villages of Monte Claro and El Patrocinio in the Palajunoj area. On 4 and 6 July ash fell to the SW and W in San Marcos and Loma Linda Palajunoj. On 5 July there were reports of ashfall in Monte Claro and areas around San Marcos Palajunoj and some explosions were heard 5 km away. In Monte Claro to the SW ash fell on 7 July and sounds were heard 5 km away every three minutes. Incandescence was observed in the early morning on the SE and NE flanks of the dome. During 8 and 9 July, four to eight weak explosions per hour were noted and ash dispersed SW, especially over Monte Claro; pulsating degassing noises were heard every two minutes. Monte Bello and Loma Linda reported ashfall on 12, 16, 17, 19, and 20 July. On 15, 22, 26, and 29 July ash was reported in San Marcos and Loma Linda Palajunoj; 33 explosions occurred on 25 July. Two lahars were reported on 8 July. A strong one in the Rio San Isidro was more than 2 m deep, and 20-25 m wide with blocks as large as 3 m in diameter. A more moderate lahar affected Rio Cabello de Angel and was also 2 m deep. It was 15-20 m wide and had blocks 1-2 m in diameter.

Activity declined further during August 2019. Constant degassing continued from the S rim of the crater, but only occasional pulses of steam and gas rose from the central dome. Weak to moderate explosions occurred at a rate of 15-20 per day. White and gray plumes with small amounts of ash rose 300-800 m above the summit daily. Block avalanches descended to the base of the dome and sent fine ash particles down the SE and S flanks. Ashfall was common within 5 km of the summit, generally on the SW flank, near Monte Bello farm, Loma Linda village and San Marcos Palajunoj. Explosions rates decreased to 10-11 per day during the last week of the month. Degassing and ash plumes rose to 2.9-3.2 km altitude throughout the month.

On 1 August ash plumes drifted 10-15 km SW, causing ashfall in that direction. On 3 and 27 August ashfall occurred at Monte Claro and El Patrocinio in the Palajunoj area to the SW. On 7 and 31 August ashfall was reported in Monte Claro. San Marcos and Loma Linda Palajunoj reported ash on 11, 16, 19, and 23 August. On 21 August ashfall was reported to the SE around Finca San José. The Washington VAAC reported an ash plume visible in satellite imagery on 10 August 2019 drifting W at 4.3 km altitude a few kilometers from the summit which dissipated quickly. On 27 August a plume was observed 25 km W of the summit at 3.9 km altitude, dissipating rapidly. On 3 August a moderate lahar descended the Rio Cabello de Ángel that was 1 m deep, 15 m wide and carried blocks up to 1 m in diameter along with branches and tree trunks. A large lahar on 20 August descended Río Cabello de Ángel; it was 2-3 m high, 15 m wide and carried blocks 1-2 m diameter, causing erosion along the flanks of the drainage (figure 100).

Figure (see Caption) Figure 100. A substantial lahar at Santa Maria on 20 August 2019 sent debris down the Río Cabello de Ángel in the vicinity of El Viejo Palmar (left), the spectrogram of the seismic signal lasted for 2 hours and 16 minutes (top right), and the seismograph was saturated with the lahar signal in red (bottom right). Courtesy of INSIVUMEH (Reporte Semanal de Monitoreo: Volcán Santiaguito, Semana del 17 al 23 de agosto de 2019).

Geologic Background. Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing W towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html).


Stromboli (Italy) — September 2019 Citation iconCite this Report

Stromboli

Italy

38.789°N, 15.213°E; summit elev. 924 m

All times are local (unless otherwise noted)


Major explosions on 3 July and 28 August 2019; hiker killed by ejecta

Near-constant fountains of lava at Stromboli have served as a natural beacon in the Tyrrhenian Sea for at least 2,000 years. Eruptive activity at the summit consistently occurs from multiple vents at both a north crater area (N area) and a southern crater group (CS area) on the Terrazza Craterica at the head of the Sciara del Fuoco, a large scarp that runs from the summit down the NW side of the volcano-island. Periodic lava flows emerge from the vents and flow down the scarp, sometimes reaching the sea; occasional large explosions produce ash plumes and pyroclastic flows. Thermal and visual cameras that monitor activity at the vents are located on the nearby Pizzo Sopra La Fossa, above the Terrazza Craterica, and at multiple locations on the flanks of the volcano. Detailed information for Stromboli is provided by Italy's Istituto Nazionale di Geofisica e Vulcanologia (INGV) as well as other satellite sources of data; March-August 2019 is covered in this report.

Typical eruptive activity recorded at Stromboli by INGV during March-June 2019 was similar to activity of the past few years (table 6); two major explosions occurred in July and August with a fatality during the 3 July event. In the north crater area, both vents N1 and N2 emitted fine (ash) ejecta, occasionally mixed with coarser lapilli and bombs; most explosions rose less than 80 m above the vents, some reached 150 m. Average explosion rates ranged from 1 to 12 per hour. In the CS crater area continuous degassing and occasional intense spattering were typical at vent C, vent S1 was a low-intensity incandescent jet throughout the period. Explosions from vent S2 produced 80-150 m high ejecta of ash, lapilli, and bombs at average rates of 2-17 per hour.

After a high-energy explosion and lava flow on 25 June, a major explosion with an ash plume and pyroclastic flow occurred on 3 July 2019; ejecta was responsible for the death of a hiker lower down on the flank and destroyed monitoring equipment near the summit. After the explosion on 3 July, coarse ejecta and multiple lava flows and spatter cones emerged from the N area, and explosion rates increased to 4-19 per hour. At the CS area, lava flows emerged from all the vents and spatter cones formed. Explosion intensity ranged from low to very high with the finer ash ejecta rising over 250 m from the vents and causing ashfall in multiple places on the island. This was followed by about 7 weeks of heightened unrest and lava flows from multiple vents. A second major explosion with an ash plume and pyroclastic flow on 28 August reshaped the summit area yet again and scattered pyroclastic debris over the communities on the SW flank near the ocean.

Table 6. Summary of activity levels at Stromboli, March-August 2019. Low-intensity activity indicates ejecta rising less than 80 m, medium-intensity is ejecta rising less than 150 m, and high-intensity is ejecta rising over 200 m above the vent. Data courtesy of INGV.

Month North (N) Area Activity Central-South (CS) Area Activity
Mar 2019 Low- to medium-intensity explosions at both N1 and N2. Coarse-grained ejecta (lapilli and bombs) from N1, fine-grained ash mixed with coarse material from N2. Explosion rates of 3-12 per hour. Medium-intensity explosions from both S area vents, lapilli and bombs mixed with ash, 2-9 explosions per hour.
Apr 2019 Low- to medium-intensity explosions at both N1 and N2. Coarse-grained ejecta (lapilli and bombs) from N1, fine-grained ash from N2. Explosion rates of 5-12 per hour. Continuous degassing from C, low-intensity incandescent jets form S1, up to 4 emission points from S2, mostly fine-grained ejecta, 4-15 explosions per hour.
May 2019 Low- to medium-intensity explosions at both N1 and N2. Mostly fine-grained ejecta, occasionally mixed with coarser material. Explosion rates of 2-8 per hour. Continuous degassing from C, low-intensity incandescent jets form S1, low- to medium-intensity explosions from C, S1, and S2. Mostly fine-grained ejecta, occasionally mixed with coarser material. Explosion rates of 5-16 per hour.
June 2019 Low- to medium-intensity explosions at both N1 and N2. Mostly fine-grained ejecta, occasionally mixed with coarser material. Explosion rates of 1-12 per hour. Continuous degassing at C and sporadic short duration spattering events, low- to medium-intensity incandescent jets at S1, multiple emission points from S2. Ejecta of larger lapilli and bombs mixed with ash. Explosion rates of 2-17 per hour. High-energy explosion on 25 June.
Jul 2019 Low- to medium-intensity explosions at both N1 and N2. Coarse ejecta after major explosion on 3 July. Intermittent intense spattering. Explosions rates of 4-19 per hour. Lava flows from all vents. Major explosion and pyroclastic flow, 3 July, with fatality from falling ejecta. Lava flows from all vents. Continuous degassing and variable intensity explosions from low to very high (over 200 m). Coarse ejecta until 20 July; followed by mostly ash.
Aug 2019 Low- to medium-intensity explosions from the N area, coarse ejecta and occasional intense spattering. Explosion rates of 7-17 per hour. Lava flows. Low- to high-intensity explosions; ash ejecta over 200 m; ashfall during week 1 in S. Bartolo area, Scari, and Piscità. Major explosion on 28 August, with 4-km-high ash plume and pyroclastic flow; lava flows. Explosion rates of 4-16 per hour.

Thermal activity was low from March through early June 2019 as recorded in the MIROVA Log Radiative Power data from MODIS infrared satellite information. A sharp increase in thermal energy coincided with a large explosion and the emergence of numerous lava flows from the summit beginning in late June (figure 144). High heat-flow continued through the end of August and dropped back down at the beginning of September 2019 after the major 28 August explosion.

Figure (see Caption) Figure 144. Thermal activity at Stromboli was low and intermittent from 12 November 2018 through early June 2019, based on this MIROVA plot of thermal activity through August 2019. A spike in thermal energy in late June coincided with a major explosion on 3 July and the emergence of lava from the summit area. Heightened activity continued from 3 July through 28 August with multiple lava flows emerging from both crater areas. Courtesy of MIROVA.

Activity during March-June 2019. Activity was low during March 2019. Low- to medium-intensity explosions occurred at both vents N1 and N2 in the north area. Ejecta was mostly coarse grained (lapilli and bombs) from N1 and fine-grained ash mixed with some coarse material from N2. Intense spattering activity was reported from N2 on 29 March. Explosion rates were reported at 5-12 per hour. At the CS area, medium-intensity explosions from both south area vents produced lapilli and bombs mixed with ash at a rate of 2-9 explosions per hour.

During a visit to the Terrazza Craterica on 2 April 2019, degassing was visible from vents N1, N2, C, and S2; activity continued at similar levels to March throughout the month. Low- and medium-intensity explosions with coarse ejecta, averaging 3-12 per hour, were typical at vent N1 while low-intensity explosions with fine-grained (ash) ejecta occurred at a similar rate from N2. Continuous degassing was observed at the C vent, and low-intensity incandescent jets were present at S1 throughout the month. Multiple emission points from S2 (as many as 4) produced low- to medium-intensity explosions at rates of 4-14 explosions per hour; the ejecta was mostly fine-grained mixed with some coarse material. Frequent explosions on 19 April produced abundant pyroclastic material in the summit area.

Low to medium levels of explosive activity at all of the vents continued during May 2019. Emissions consisted mostly of ash occasionally mixed with coarser material (lapilli and bombs). Rates of explosion were 2-8 per hour in the north area, and 5-16 per hour in the CS Area. Explosions of low-intensity continued from all the vents during the first part of June at rates averaging 2-12 per hour, although brief periods of high-frequency explosions (more than 21 events per hour) were reported during the week of 10 June. Strong degassing was observed from crater C during an inspection on 12 June (figure 145); by the third week, continuous degassing was interrupted at C by sporadic short-duration spattering events.

Figure (see Caption) Figure 145. The Terrazza Craterica as seen from the Pizzo sopra la Fossa (above, near the summit) at Stromboli on 12 June 2019. In red are the two craters (N1 and N2) of the N crater area, in green is the CS crater area with 2 vents (C1 and C2) in the central crater and S2, the largest and deepest crater in the CS area, also with at least two vents. S1 is hidden by the degassing of crater C. Photograph by Giuseppe Salerno, courtesy of INGV (Report 25/2019, Stromboli, Bollettino Settimanale, 10/06/2019-16/06/2019).

Late on 25 June 2019, a high-energy explosion that lasted for 28 seconds affected vent C in the CS area. The ejecta covered a large part of the Terrazza Craterica, with abundant material landing in the Valle della Luna. An ash plume rose over 250 m after the explosion and drifted S. After that, explosion frequency varied from medium-high (17/hour) on 25 June to high (25/hour) on 28 June. On 29 June researchers inspected the summit and noted changes from the explosive events. Thermal imagery indicated that the magma level at N1 was almost at the crater rim. The magma level at N2 was lower and explosive activity was less intense. At vent C, near-constant Strombolian activity with sporadic, more intense explosions produced black ash around the enlarged vent. At vent S2, a pyroclastic cone at the center of the crater produced vertical jets of gas, lapilli, and bombs that exceeded 100 m in height (figure 146).

Figure (see Caption) Figure 146. A high-energy explosion at Stromboli late on 25 June 2019 affected vent C in the CS Area (top row). The ejecta covered a large part of the Terrazza Craterica. An ash plume rose over 250 m after the explosion and drifted S. On 29 June (bottom row) thermal imagery indicated that the magma level at N1 was almost at the crater rim. At vent C, near-constant Strombolian activity was interrupted with sporadic, more intense explosions. At vent S2, a pyroclastic cone at the center of the crater produced vertical jets of gas, lapilli, and bombs that exceeded 100 m in height. Photo 2f by L. Lodato, courtesy of INGV (Rep 27/2019, Stromboli, Bollettino Settimanale, 24/06/2019-30/06/2019).

Activity during July 2019. A large explosion accompanied by lava and pyroclastic flows affected the summit and western flank of Stromboli on 3 July 2019. Around 1400 local time an explosion from the CS area generated a lava flow that spilled onto the upper part of the Sciara del Fuoco. Just under an hour later several events took place: lava flows emerged from the C vent and headed E, from the N1 and N2 vents and flowed N towards Bastimento, and from vent S2 (figure 147). The emergence of the flows was followed a minute later by two lateral blasts from the CS area, and a major explosion that involved the entire Terrazza Craterica lasted for about one minute (figure 148). Within seconds, the pyroclastic debris had engulfed and destroyed the thermal camera located above the Terrazza Craterica on the Pizzo Sopra La Fossa and sent a plume of debris across the W flank of the island (figure 149). Two seismic stations were also destroyed in the event. The Toulouse VAAC reported a plume composed mostly of SO2 at 9.1 km altitude shortly after the explosion. They noted that ash was present in the vicinity of the volcano, but no significant ashfall was expected. INGV scientists observed the ash plume at 4 km above the summit.

Figure (see Caption) Figure 147. A major eruptive event at Stromboli on 3 July 2019 began with an explosion from the CS area that generated a lava flow at 1359 (left). About 45 minutes later (at 1443:40), lava flows emerged from all of the summit vents (right), followed closely by a major explosion. Courtesy of INGV (Eruzione Stromboli. Comunicato straordinario del 4 luglio 2019).
Figure (see Caption) Figure 148. A major explosion at Stromboli beginning at 1445 on 3 July 2019 was preceded by lava flows from all the summit vents in the previous 60 seconds (top row). This thermal camera (SPT) and other monitoring equipment on the Pizzo Sopra La Fossa above the vents were destroyed in the explosion (bottom row). Courtesy of INGV (Il parossismo dello Stromboli del 3 luglio 2019 e l'attività nei giorni successivi: il punto della situazione al 13 luglio 2019).
Figure (see Caption) Figure 149. The monitoring equipment at Stromboli on the Pizzo Sopra La Fossa above the summit was destroyed in the major explosion of 3 July 2019 (left, photo by F. Ciancitto). Most of the W half of the island was affected by pyroclastic debris after the explosion, including the town of Ginostra (right). Courtesy of INGV (Report 28/2019, Stromboli, Bollettino Settimanale, 01/07/2019 - 07/07/2019).

Two pyroclastic flows were produced as a result of the explosions; they traveled down the Sciara and across the water for about 1 km before collapsing into the sea (figure 150). A hiker from Sicily was killed in the eruption and a Brazilian friend who was with him was badly injured, according to a Sicilian news source, ANSA, and the New York Post. They were hit by flying ejecta while hiking in the Punta dei Corvi area, due W of the summit and slightly N of Ginostra, about 100 m above sea level according to INGV. Most of the ejecta from the explosion dispersed to the WSW of the summit. Fallout also ignited vegetation on the slopes which narrowly missed destroying structures in the town. Ejecta blocks and bombs tens of centimeters to meters in diameter were scattered over a large area around the Pizzo Sopra La Fossa and the Valle della Luna in the direction of Ginostra. Smaller material landed in Ginostra and was composed largely of blonde pumice, that floated in the bay (figure 151). The breccia front of the lava flows produced incandescent blocks that reached the coastline. High on the SE flank, the abundant spatter of hot pyroclastic ejecta coalesced into a flow that moved 200-300 m down the flank before cooling, crossing the path normally used by visitors to the summit (figure 152).

Figure (see Caption) Figure 150. At the time of the major explosion of Stromboli on 3 July 2019 people on a German ship located about 2 km off the northern coast captured several images of the event. (a) Two pyroclastic flows traveled down the Sciara del Fuoco and spread over the sea up to about 1 km from the coast. (b) The eruption column was observed rising several kilometers above the summit as debris descended the Sciara del Fuoco. (c) Fires on the NW flank were started by incandescent pyroclastic debris. The photos were taken by Egon Karcher and used with permission of the author by INGV. Courtesy of INGV (Il parossismo dello Stromboli del 3 luglio 2019 e l'attività nei giorni successivi: il punto della situazione al 13 luglio 2019).
Figure (see Caption) Figure 151. Pumice filled the harbor on 4 July 2019 (left) and was still on roofs (right) on 7 July 2019 in the small port of Ginostra on the SW flank of Stromboli after the large explosion on 3 July 2019. Photos by Gianfilippo De Astis, courtesy of INGV (Il parossismo dello Stromboli del 3 luglio 2019 e l'attività nei giorni successivi: il punto della situazione al 13 luglio 2019).
Figure (see Caption) Figure 152. A small lava flow high on the SE flank of Stromboli formed during the 3 July 2019 event from abundant spatter of hot pyroclastic ejecta that coalesced into a flow and moved 200-300 m down the flank before cooling, crossing the path normally used by visitors to the summit. Photo by Boris Behncke taken on 9 July 2019, courtesy of INGV (Il parossismo dello Stromboli del 3 luglio 2019 e l'attività nei giorni successivi: il punto della situazione al 13 luglio 2019).

INGV scientists inspected the summit on 4 and 5 July 2019 and noted that the rim of the Terrazza Craterica facing the Sciara del Fuoco in both the S and N areas had been destroyed, but the crater edge near the central area was not affected. In addition, the N area appeared significantly enlarged and deepened, forming a single crater where the former N1 and N2 vents had been located; an incandescent jet was active in the CS area (figure 153). Explosive activity declined significantly after the major explosions, although moderate overflows of lava continued from multiple vents, especially the CS area where the flows traveled about halfway down the southern part of the Sciara del Fuoco; lava also flowed E towards Rina Grande (about 0.5 km E of the summit). The main lava flows active between 3 and 4 July produced a small lava field along the Sciara del Fuoco which flowed down to an elevation of 210 m in four flows along the S edge of the scarp (figure 154). Additional block avalanches rolled to the coastline.

Figure (see Caption) Figure 153. The summit craters of Stromboli were significantly altered during the explosive event of 3 July 2019. The rim of the Terrazza Craterica facing the Sciara del Fuoco in both the CS and N areas was destroyed, but the crater edge near the CS area was not affected. In addition, the N area was significantly enlarged and deepened, forming a single crater where the former N1 and N2 vents had been located; an incandescent jet was active in the CS area. Courtesy of INGV (Report 28/2019, Stromboli, Bollettino Settimanale, 01/07/2019 - 07/07/2019).
Figure (see Caption) Figure 154. The main lava flows active between 3 and 4 July at Stromboli after the major explosion on 3 July 2019 produced a small lava field along the Sciara del Fuoco. Left: Aerial photo taken by Stefano Branca (INGV-OE) on 5 July; the yellow arrow shows a small overflow from the N crater area, the red arrow shows the largest overflow from the CS crater area. Right: Flows from the CS area traveled down to an elevation of 210 m in four flows along the S edge of the scarp. Additional block avalanches rolled to the coastline. Right photo by Francesco Ciancitto taken on 5 July 2019. Courtesy of INGV (Il parossismo dello Stromboli del 3 luglio 2019 e l'attività nei giorni successivi: il punto della situazione al 13 luglio 2019).

During the second week of July lava flows continued; on 8 July volcanologists reported two small lava flows from the CS area flowing towards the Sciara del Fuoco. A third flow was noted the following day. The farthest flow front was at about 500 m elevation on 10 July, and the flow at the center of the Sciara del Fuoco was at about 680 m. An overflow from the N area during the evening of 12 July produced two small flows that remained high on the N side of the scarp; lava continued flowing from the CS area into the next day. A new flow from the N area late on 14 July traveled down the N part of the scarp (figure 155).

Figure (see Caption) Figure 155. During the second week of July 2019 lava flows at Stromboli continued from both crater areas. Top left: Lava flows from the CS area flowed down the Sciara on 9 July while Strombolian activity continued at the summit, photo by P. Anghemo, mountain guide. Bottom left: A lava flow from the CS area at Stromboli is viewed from Punta dei Corvi during the night of 12-13 July 2019. Photo by Francesco Ciancitto. Right: The active flows on 10 July (in red) were much closer to the summit crater than they had been during 3-4 July (in yellow). Courtesy of INGV, top left and right photos published in Report 29/2019, Stromboli, Bollettino Settimanale, 08/07/2019 - 14/07/2019; bottom left photo published in 'Il parossismo dello Stromboli del 3 luglio 2019 e l'attività nei giorni successivi: il punto della situazione al 13 luglio 2019'.

A new video station with a thermal camera was installed at Punta dei Corvi, a short distance N of Ginostra on the SW coast, during 17-20 July 2019. During the third week of July lava continued to flow from the CS crater area onto the southern part of the Sciara del Fuoco, but the active flow area remained on the upper part of the scarp; block avalanches continuously rolled down to the coastline (figure 156). During visits to the summit area on 26 July and 1 August activity at the Terrazza Craterica was observed by INGV scientists. There were at least six active vents in the N area, including a scoria cone and an intensely spattering hornito; the other vents were ejecting coarse material in jets of Strombolian activity. In the CS area, a large scoria cone was clearly visible from the Pizzo, with two active vents generating medium- to high-intensity explosions rich in volcanic ash mixed with coarse ejecta (figures 157 and 158). Some of the finer-grained material in the jets reached 200 m above the vents. A second smaller cone in the CS area faced the southernmost part of the Sciara del Fuoco and produced sporadic low-intensity "bubble explosions." Effusive activity decreased during the last week of July; the active lava front was located at about 600 m elevation. Blocks continued to roll down the scarp, mostly from the explosive activity, and were visible from Punta dei Corvi.

Figure (see Caption) Figure 156. Lava continued to flow from the CS area at Stromboli during the third week of July 2019, although the active flow area remained near the top of the scarp. Block avalanches continued to travel down the scarp. Image taken by di Francesco Ciancitto from Punta dei Corvi on 19 July 2019. Courtesy of INGV (Report 30/2019, Stromboli, Bollettino Settimanale, 15/07/2019 - 21/07/2019).
Figure (see Caption) Figure 157. Thermal and visible images of Terrazza Craterica at the summit of Stromboli from the Pizzo Sopra La Fossa on 1 August 2019 showed significant changes since the major explosion on 3 July 2019. A large scoria cone was present in the CS area (left) and at least six vents from multiple cones were active in the N area (right). The active lava flow 'Trabocco Lavico' emerged from the southernmost part of the CS area (far left). Courtesy if INGV (Report 32/2019, Stromboli, Bollettino Settimanale, 29/07/2019 - 04/08/2019.
Figure (see Caption) Figure 158. At the summit of Stromboli on 1 August 2019 two active vents inside a large cone in the CS area generated medium- to high-intensity explosions rich in volcanic ash mixed with coarse ejecta (left). There were at least six active vents in the N area (right), including a scoria cone and an intensely spattering hornito; the other vents were ejecting coarse material in jets of Strombolian activity. Courtesy of INGV (Report 32/2019, Stromboli, Bollettino Settimanale, 29/07/2019 - 04/08/2019).

Activity during August 2019. A small overflow of lava on 4 August 2019 from the N area lasted for about 20 minutes and formed a flow that went a few hundred meters down the Sciara del Fuoco. Observations made at the summit on 7 and 8 August 2019 indicated that nine vents were active in the N crater area, three of which had scoria cones built around them (figure 159). They all produced low- to medium-intensity Strombolian activity. In the CS area, a large scoria cone was visible from the summit that generated medium- to high-intensity explosions rich in volcanic ash, which sometimes rose more than 200 m above the vent. Lava overflowing from the CS area on 8 August was confined to the upper part of the Sciara del Fuoco, at an elevation between 500 and 600 m (figure 160). Occasional block avalanches from the active lava fronts traveled down the scarp. Ashfall was reported in the S. Bartolo area, Scari, and Piscità during the first week of August.

Figure (see Caption) Figure 159. Nine vents were active in the N crater area of Stromboli on 7 August 2019, three of which had scoria cones built around them. They all produced low- to medium-intensity Strombolian activity (top). In the CS area (bottom), a large scoria cone was visible from the summit that generated medium- to high-intensity explosions rich in volcanic ash, which sometimes rose more than 200 m above the vent. Visible images taken by S. Consoli, thermal images taken by S. Branca. Courtesy of INGV (Report 33/2019, Stromboli, Bollettino Settimanale, 05/08/2019 - 11/08/2019).
Figure (see Caption) Figure 160. Multiple Lava flows were still active on the Sciara del Fuoco at Stromboli on 7 August 2019. Top images by INGV personnel S Branca and S. Consoli, lower images by A. Di Pietro volcanological guide. Courtesy of INGV (Report 33/2019, Stromboli, Bollettino Settimanale, 05/08/2019 - 11/08/2019).

Drone surveys on 13 and 14 August 2019 confirmed that sustained Strombolian activity continued both in the N area and the CS area. Lava flows continued from two vents in the CS area; they ceased briefly on 16 and 17 August but resumed on the 18th, with the lava fronts reaching 500-600 m elevation (figure 161). A fracture field located in the southern part of the Sciara del Fuoco was first identified in drone imagery on 9 July. Repeated surveys through mid-August indicated that about ten fractures were identifiable trending approximately N-S and ranged in length from 2.5 to 21 m; they did not change significantly during the period. An overflight on 23 August identified the main areas of activity at the summit. A NE-SW alignment of 13 vents within the N area was located along the crater edge that overlooks the Sciara del Fuoco. At the CS area, the large scoria cone had two active vents, there was a pit crater, and two smaller scoria cones. A 50-m-long lava tube emerged from one of the smaller lava cones and fed two small flows that emerged at the top of the Sciara del Fuoco (figure 162).

Figure (see Caption) Figure 161. Detail of a vent at Stromboli on 14 August 2019 located in the SW part of the Sciara del Fuoco at an elevation of 730 m. Flow is tens of meters long. Courtesy of INGV (COMUNICATO DI DETTAGLIO STROMBOLI del 20190816 ORE 17:05 LT).
Figure (see Caption) Figure 162. Thermal and visual imagery of the summit of Stromboli on 23 August 2019 revealed a NE-SW alignment of 13 vents within the N area located along the crater edge that overlooks the Sciara del Fuoco. At the CS area, the large scoria cone had two active vents (1 and 2), there was a pit crater (3), and two smaller scoria cones (4). A 50-m-long lava tube formed from one of the smaller lava cones (5) and fed two small flows that emerged at the top of the Sciara del Fuoco. Photos by L. Lodato and S. Branca, courtesy of INGV (Report 35/2019, Stromboli, Bollettino Settimanale, 19/08/2019 - 25/08/2019).

INGV reported a strong explosion from the CS area at 1217 (local time) on 28 August 2019. Ejecta covered the Terrazza Craterica and sent debris rolling down the Sciara del Fuoco to the coastline. A strong seismic signal was recorded, and a large ash plume rose more than 2 km above the summit (figure 163). The Toulouse VAAC reported the ash plume at 3.7-4.6 km altitude, moving E and rapidly dissipating, shortly after the event. Once again, a pyroclastic flow traveled down the Sciara and several hundred meters out to sea (figures 164). The entire summit was covered with debris. The complex of small scoria cones within the N area that had formed since the 3 July explosion was destroyed; part of the N area crater rim was also destroyed allowing lava to flow down the Sciara where it reached the coastline by early evening.

Figure (see Caption) Figure 163. A major explosion at Stromboli on 28 August 2019 produced a high ash plume and a pyroclastic flow. The seismic trace from the STR4 station (top left) indicated a major event. The ash plume from the explosion was reported to be more than 2 km high (right). The thermal camera located at Stromboli's Punta dei Corvi on the southern edge of the Sciara del Fuoco captured both the pyroclastic flow and the ash plume produced in the explosion (bottom left). Seismogram and thermal image courtesy of INGV (INGVvulcani blog, 30 AGOSTO 2019INGVVULCANI, Nuovo parossismo a Stromboli, 28 agosto 2019). Photo by Teresa Grillo (University of Rome) Courtesy of AIV - Associazione Italiana di Vulcanologia.
Figure (see Caption) Figure 164. A pyroclastic flow at Stromboli traveled across the sea off the W flank for several hundred meters on 28 August 2019 after a major explosion at the summit. Photo by Alberto Lunardi, courtesy of INGV (5 SETTEMBRE 2019INGVVULCANI, Quando un flusso piroclastico scorre sul mare: esempi a Stromboli e altri vulcani).

At 1923 UTC on 29 August a lava flow was reported emerging from the N area onto the upper part of the Sciara del Fuoco; it stopped at mid-elevation on the slope. About 90 minutes later, an explosive sequence from the CS area resulted in the fallout of pyroclastic debris around Ginostra. Shortly after midnight, a lava flow from the CS area traveled down the scarp and reached the coast by dawn, but the lava entry into the sea only lasted for a short time (figure 165).

Figure (see Caption) Figure 165. Lava flows continued for a few days after the major explosion of 28 August 2019 at Stromboli. Left: A lava flow emerged from the N crater area on 29 August 2019 and traveled a short distance down the Sciara del Fuoco. Incandescent blocks from the flow front reached the ocean. Photo by A. DiPietro. Right: A lava flow that emerged from the CS crater area around midnight on 30 August 2019 made it to the ocean around dawn, as seen from the N ridge of the Sciara del Fuoco at an altitude of 400 m. Photo by Alessandro La Spina. Both courtesy of INGV. Left image from 'COMUNICATO DI ATTIVITA' VULCANICA del 2019-08-29 22:20:06(UTC) – STROMBOLI', right image from INGVvulcani blog, 30 AGOSTO 2019 INGVVULCANI, 'Nuovo parossismo a Stromboli, 28 agosto 2019'.

An overflight on 30 August 2019 revealed that after the explosions of 28-29 August the N area had collapsed and now contained an explosive vent producing Strombolian activity and two smaller vents with low-intensity explosive activity. In the CS area, Strombolian activity occurred at a single large crater (figure 166). INGV reported an explosion frequency of about 32 events per hour during 31 August-1 September. The TROPOMI instrument on the Sentinel-5P satellite captured small but distinct SO2 plumes from Stromboli during 28 August-1 September, even though they were challenging to distinguish from the larger signal originating at Etna (figure 167).

Figure (see Caption) Figure 166. A 30 August 2019 overflight of Stromboli revealed that after the explosions of 28-29 August the N area had collapsed and now contained a single explosive vent producing Strombolian activity and two smaller vents with low intensity explosive activity. In the CS area, a single large crater remained with moderate Strombolian activity. No new lava flows appeared on the Sciara del Fuoco, only cooling from the existing flows was evident. Courtesy of INGV (Report 35.6/2019, Stromboli, Daily Bulletin of 08/31/2019).
Figure (see Caption) Figure 167. Small but distinct SO2 signals were recorded from Stromboli during 28 August through 1 September 2019; they were sometimes difficult to discern from the larger signal originating at nearby Etna. Courtesy of NASA Goddard Space Flight Center.

Geologic Background. Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5,000 years ago due to a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium.

Information Contacts: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy, (URL: http://www.ct.ingv.it/en/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Toulouse Volcanic Ash Advisory Center (VAAC), Météo-France, 42 Avenue Gaspard Coriolis, F-31057 Toulouse cedex, France (URL: http://www.meteo.fr/aeroweb/info/vaac/); AIV, Associazione Italiana di Vulcanologia (URL: https://www.facebook.com/aivulc/photos/a.459897477519939/1267357436773935; ANSA.it, (URL: http://www.ansa.it/sicilia/notizie/2019/07/03/-stromboli-esplosioni-da-cratere-turisti-in-mare); The New York Post, (URL: https://nypost.com/2019/07/03/dozens-of-people-dive-into-sea-to-escape-stromboli-volcano-eruption-in-italy/).


Ol Doinyo Lengai (Tanzania) — September 2019 Citation iconCite this Report

Ol Doinyo Lengai

Tanzania

2.764°S, 35.914°E; summit elev. 2962 m

All times are local (unless otherwise noted)


Multiple lava flows within the summit crater, September 2018-August 2019

Frequent historical eruptions from Tanzania's Ol Doinyo Lengai have been recorded since the late 19th century. Located near the southern end of the East African Rift in the Gregory Rift Valley, the unique low-temperature carbonatitic lavas have been the focus of numerous volcanological studies; the volcano has also long been a cultural icon central to the Maasai people who live in the region. Following explosive eruptions in the mid-1960s and early 1980s the volcano entered a phase of effusive activity with the effusion of small, fluid, natrocarbonatitic lava flows within its active north summit crater. From 1983 to early 2007 the summit crater was the site of numerous often-changing hornitos (or spatter cones) and lava flows that slowly filled the crater. Lava began overflowing various flanks of the crater in 1993; by 2007 most flanks had been exposed to flows from the crater.

Seismic and effusive activity increased in mid-2007, and a new phase of explosive activity resumed in September of that year. The explosive activity formed a new pyroclastic cone inside the crater; repeated ash emissions reached altitudes greater than 10 km during March 2008, causing relocation of several thousand nearby villagers. Explosive activity diminished by mid-April 2008; by September new hornitos with small lava flows were again forming on the crater floor. Periodic eruptions of lava from fissures, spatter cones, and hornitos within the crater were witnessed throughout the next decade by scientists and others occasionally visiting the summit. Beginning in 2017, satellite imagery has become a valuable data source, providing information about both the thermal activity and the lava flows in the form of infrared imagery and the color contrast of black fresh lava and whiter cooled lava that is detectable in visible imagery (BGVN 43:10). The latest expeditions in 2018 and 2019 have added drone technology to the research tools. This report covers activity from September 2018 through August 2019 with data and images provided from satellite information and from researchers and visitors to the volcano.

Summary and data from satellite imagery. Throughout September 2018 to August 2019, evidence for repeated small lava flows was recorded in thermal data, satellite imagery, and from a few visits to or overflights of the summit crater by researchers. Intermittent low-level pulses of thermal activity appeared in MIROVA data a few times during the period (figure 187). Most months, Sentinel-2 satellite imagery generated six images with varying numbers of days that had a clear view of the summit and showed black and white color contrasts from fresh and cooled lava and/or thermal anomalies (table 27, figures 188-191). Lava flows came from multiple source vents within the crater, produced linear flows, and covered large areas of the crater floor. Thermal anomalies were located in different areas of the crater; multiple anomalies from different source vents were visible many months.

Figure (see Caption) Figure 187. Intermittent low-level pulses of thermal activity were recorded in the MIROVA thermal data a few times between 21 October 2018 and the end of August 2019. Courtesy of MIROVA.

Table 27. The number of days each month with Sentinel-2 images of Ol Doinyo Lengai, days with clear views of the summit showing detectable color contrasts between black and white lava, and days with detectable thermal anomalies within the summit crater. A clear summit means more than half the summit visible or features identifiable through diffuse cloud cover. Information courtesy of Sentinel Hub Playground.

Month Sentinel-2 Images Clear Summit with Lava Color Contrasts Thermal anomalies
Sep 2018 6 5 5
Oct 2018 7 4 3
Nov 2018 6 2 0
Dec 2018 5 1 1
Jan 2019 6 5 3
Feb 2019 6 5 6
Mar 2019 6 5 5
Apr 2019 6 1 0
May 2019 6 3 2
Jun 2019 6 3 3
Jul 2019 6 5 5
Aug 2019 6 5 3
Figure (see Caption) Figure 188. Sentinel-2 imagery of Ol Doinyo Lengai from September 2018 showed examples of the changing color contrasts of fresh black lava which quickly cools to whitish-brown (top row) and varying intensities and numbers of thermal anomalies on the same days (bottom row). It is clear that the color and thermal patterns change several times during the month even with only a few days of available imagery. Dates of images from left to right are 11, 16, and 21 September. The summit crater is 300 m across and 100 m deep. The top row is with Natural color rendering (bands 4, 3, 2) and the bottom row is with Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 189. Contrasting patterns of dark and light lava flows within the summit crater of Ol Doinyo Lengai on 1 (left) and 11 (right) October 2018 show how quickly new dark flows cool to a lighter color. The flow on 1 October appears to originate in the E part of the crater; the flow in the crater on 11 October has a source in the N part of the crater. These Sentinel-2 images use Natural color rendering (bands 4,3,2). Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 190. A large flow at Ol Doinyo Lengai on 3 February 2019 filled most of the summit crater with lobes of black lava (top left) and generated one of the strongest thermal signatures of the period (top right) in these Sentinel-2 satellite images. On 20 March 2019, a small dark area of fresh material contrasted sharply with the surrounding light-colored material (bottom left); the thermal image of the same data shows a small anomaly near the dark spot (bottom right). The left column is with Natural color rendering (bands 4, 3, 2) and the right column is with Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 191. The dark lava spots at Ol Doinyo Lengai on 18 June 2019 (top left) and 28 July 2019 (top center) produced matching thermal anomalies in the Sentinal-2 imagery (bottom left and center). On days when the summit was partly obscured by clouds such as 27 August (top right), the strong thermal signal from the summit still confirmed fresh flow activity (bottom right). The top row is with Natural color rendering (bands 4, 3, 2) and the bottom row is with Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

Information from site visits and overflights. Minor steam and gas emissions were visible from the summit crater during an overflight on 29 September 2018. Geologist Cin-Ty Lee captured excellent images of the W flank on 20 October 2018 (figure 192). The large circular crater at the base of the flank is the 'Oldoinyo' Maar (Graettinger, 2018a and 2018b). A view into the crater from an overflight that day (figure 193) showed clear evidence of at least five areas of dark, fresh lava. An effusive eruption was visible on the crater floor on 2 March 2019 (figure 194).

Figure (see Caption) Figure 192. A large maar stands out at the base of the SW flank of Ol Doinyo Lengai on 20 October 2018. Courtesy of Cin-Ty Lee (Rice University).
Figure (see Caption) Figure 193. A view into the summit crater of Ol Doinyo Lengai on 20 October 2018 shows clear evidence of recent flow activity in the form of multiple dark spots of fresh lava that has recently emerged from hornitos and fissures. The lava cools to a pale color very quickly, forming the contrasting background to the fresh flows. The summit crater is 300 m across and 100 m deep. Courtesy of Cin-Ty Lee (Rice University).
Figure (see Caption) Figure 194. A view into the crater floor at Ol Doinyo Lengai on 2 March 2019 showed a vent with both fresh (dark brown) and cooled (gray-white) carbonatite lavas and hornitos on the floor of the crater. The darkest material on the crater floor is from recent flows. Courtesy of Aman Laizer, Tanzania.

Research expedition in July-August 2019. In late July and early August 2019 an expedition, sponsored by the Deep Carbon Observatory (DCO) and led by researchers Kate Laxton and Emma Liu (University College London), made gas measurements, collected lava samples for the first time in 12 years, and deployed drones to gather data and images. The Ol Doinyo Lengai sampling team included Papkinye Lemolo, Boni Kicha, Ignas Mtui, Boni Mawe, Amedeus Mtui, Emma Liu, Arno Van Zyl, Kate Laxton, and their driver, Baraka. They collected samples by lowering devices via ropes and pulleys into the crater and photographed numerous active flows emerging from vents and hornitos on the crater floor (figure 195). By analyzing the composition of the first lava samples collected since the volcano's latest explosive activity in 2007, they hope to learn about recent changes to its underground plumbing system. A comparison of the satellite image taken on 28 July with a drone image of the summit crater taken by them the next day (figure 196) confirms the effectiveness of both the satellite imagery in identifying new flow features on the crater floor, and the drone imagery in providing outstanding details of activity.

Figure (see Caption) Figure 195. Researchers Kate Laxton and Emma Liu collected gas and lava samples at the summit of Ol Doinyo Lengai during their 26 July-4 August 2019 expedition. They sent gas sampling devices (small white "hamster ball" in center of left image) and lava sampling devices (right) down into the crater via ropes and pulleys. The crater is 300 m across and 100 m deep. Courtesy of Kate Laxton (University College London).
Figure (see Caption) Figure 196. A clear view by drone straight down into the crater at Ol Doinyo Lengai on 29 July 2019 provides valuable information about ongoing activity at the remote volcano. N is to the top. The summit crater is 300 m across and 100 m deep. The same configuration of fresh and cooled lava can be seen in Sentinel-2 imagery taken on 28 July 2019 (inset, N to the top). Courtesy of Emma Liu (University College London) and Sentinel Hub Playground.

With the drone technology, they were able to make close-up observations of features on the north crater floor such as the large hornito on the inner W wall of the crater (figure 197), an active lava pond near the center of the crater (figure 198), and several flows resurfacing the floor of the crater while they were there (figure 199). A large crack that rings the base of the N cone had enlarged significantly since last measured in 2014 (figure 200).

Figure (see Caption) Figure 197. A closeup view of the large hornito in the W wall of the Ol Doinyo Lengai summit crater on 26 July 2019 shows recent activity from the vent (dark material). See figure 197 for location of hornito against W wall. View is to the NW. Courtesy of Emma Liu (University College London).
Figure (see Caption) Figure 198. Incandescence from the lava pond in the center of the crater was still visible at 0627 on 29 July 2019 at Ol Doinyo Lengai; incandescence from the large hornito in the NW quadrant (behind the lava pond) had been visible when the researchers arrived at the summit at about 0500 that morning. The crater floor is continually resurfaced by ultra-low viscosity natrocarbonatite lava flows. The lava hydrates on contact with air within hours, changing color from black to grey/white in a very short time. View towards the N. Courtesy of Kate Laxton (University College London).
Figure (see Caption) Figure 199. On 30 July 2019 a lava flow from a hornito cluster resurfaced the NE quadrant of the crater floor at Ol Doinyo Lengai. The initial outbreak occurred at 0819, was vigorous, and ended by 0823. Lava continued to flow out of the hornito cluster at intervals throughout the day. Image facing NE, courtesy of Kate Laxton (University College London).
Figure (see Caption) Figure 200. The circumferential crack near the base of the N cone of Ol Doinyo Lengai is seen here being inspected by Emma Liu on 30 July 2019 where it intersects the Western Summit Trail. View is to the S. Significant widening of the crack is seen when compared with a similar image of the same crack from March 2014 (figure 172, BGVN 39:07). Local observers reported that the crack continued to widen after July 2019. Courtesy of Kate Laxton (University College London).

The color of the flows on the crater floor changed from grays and browns to blues and greens after a night of rainfall on 31 July 2019 (figure 201). Much of the lava pond surface was crusted over that day, but the large hornito in the NW quadrant was still active (figure 202), and both the pond and another hornito produced flows that merged onto the crater floor (figure 203).

Figure (see Caption) Figure 201. The active crater at Ol Doinyo Lengai is on the north side of and slightly below the topographic summit of the mountain (in the background). After overnight rain, lava flows on the crater floor turned various shades of greys, whites, blues, and greens on 31 July 2019. View to the SW, drone image. Courtesy of Emma Liu (University College London).
Figure (see Caption) Figure 202. A closeup view to the NW of the Ol Doinyo Lengai north crater on 31 July 2019 shows the blue and green tones of the hydrated lavas after the previous night's rains. The lava pond is at high-stand with much of the surface crusted over. The adjacent hornito is still active and breached to the NE. Courtesy of Emma Liu (University College London).
Figure (see Caption) Figure 203. Two fresh lava flows merge over the hydrated crater floor of the north crater at Ol Doinyo Lengai on 31 July 2019. One comes from a small hornito just out of view to the SW (lower right) and the other from the overflowing lava pond (left), merging in the SE quadrant. The colors of the two flows differ; the pond lava appears jet black, and the hornito lava is a lighter shade of brown. View to the SE, courtesy of Emma Liu (University College London).

On 1 August 2019 much of the crater floor was resurfaced by a brown lava that flowed from a hornito E of the lava pond (figure 204). Images of unusual, ephemeral features such as "spatter pots," "frozen jets," and "frothy flows" (figure 205) help to characterize the unusual magmatic activity at this unique volcano (figure 206).

Figure (see Caption) Figure 204. On 1 August 2019 at Ol Doinyo Lengai brown lava flowed from a hornito directly E of the lava pond (above the pond in figure 203) and resurfaced much of the S portion of the crater floor. At the far left of the image, the white (hydrated) lava jet aimed away from the hornito was solidified in mid-flow. View to the SE, courtesy of Emma Liu (University College London).
Figure (see Caption) Figure 205. Frothy pale-brown lava flowed across the SE quadrant of the crater floor (right) at Ol Doinyo Lengai on 4 August 2019 from an uncertain source between the adjacent hornito and lava pond which appears nearly crusted over. Spattering from a "spatter pot" (inset) and a small flow also headed NE from the hornito cluster E of the pond (behind pond). Courtesy of Kate Laxton (University College London).
Figure (see Caption) Figure 206. A view from the summit peak of Ol Doinyo Lengai on 4 August 2019 looking at the entire N cone and the swale between it and the peak. The crack shown in figure 201 rings the base of cone; the main summit trail intersects the crack near the bottom center of the cone. The researcher's campsite on the W flank (left) shows the scale of the cone. The East African Rift wall and Lake Natron are visible in the background on the left and right, respectively. Courtesy of Kate Laxton (University College London).

References: Graettinger, A. H., 2018a, MaarVLS database version 1, (URL: https://vhub.org/resources/4365).

Graettinger, A. H., 2018b, Trends in maar crater size and shape using the global Maar Volcano Location and Shape (MaarVLS) database. Journal of Volcanology and Geothermal Research, v. 357, p. 1-13. https://doi.org/10.1016/j.jvolgeores.2018.04.002.

Geologic Background. The symmetrical Ol Doinyo Lengai is the only volcano known to have erupted carbonatite tephras and lavas in historical time. The prominent stratovolcano, known to the Maasai as "The Mountain of God," rises abruptly above the broad plain south of Lake Natron in the Gregory Rift Valley. The cone-building stage ended about 15,000 years ago and was followed by periodic ejection of natrocarbonatitic and nephelinite tephra during the Holocene. Historical eruptions have consisted of smaller tephra ejections and emission of numerous natrocarbonatitic lava flows on the floor of the summit crater and occasionally down the upper flanks. The depth and morphology of the northern crater have changed dramatically during the course of historical eruptions, ranging from steep crater walls about 200 m deep in the mid-20th century to shallow platforms mostly filling the crater. Long-term lava effusion in the summit crater beginning in 1983 had by the turn of the century mostly filled the northern crater; by late 1998 lava had begun overflowing the crater rim.

Information Contacts: Cin-Ty Lee, Department of Earth, Environmental and Planetary Sciences, Rice University, 6100 Main St., Houston, TX 77005-1827, USA (URL: https://twitter.com/CinTyLee1, images at https://twitter.com/CinTyLee1/status/1054337204577812480, https://earthscience.rice.edu/directory/user/106/); Emma Liu, University College London, UCL Hazards Centre (Volcanology), Gower Street, London, WC1E 6BT, United Kingdom (URL: https://twitter.com/EmmaLiu31, https://www.ucl.ac.uk/earth-sciences/people/academic/dr-emma-liu); Kate Laxton, University College London, UCL Earth Sciences, Gower Street, London, WC1E 6BT, United Kingdom (URL: https://twitter.com/KateLaxton, https://www.ucl.ac.uk/earth-sciences/people/research-students/kate-laxton); Deep Carbon Observatory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, DC 20015-1305, USA (URL: https://deepcarbon.net/field-report-ol-doinyo-lengai-volcano-tanzania); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Aman Laizer, Volcanologist, Arusha, Tanzania (URL: https://twitter.com/amanlaizerr, image at https://twitter.com/amanlaizerr/status/1102483717384216576).


Ulawun (Papua New Guinea) — September 2019 Citation iconCite this Report

Ulawun

Papua New Guinea

5.05°S, 151.33°E; summit elev. 2334 m

All times are local (unless otherwise noted)


Explosions on 26 June and 3 August 2019 send plumes above 19 km altitude

Typical activity at Ulawun consists of occasional weak explosions with ash plumes. During 2018 explosions occurred on 8 June, 21 September, and 5 October (BGVN 43:11). The volcano is monitored primarily by the Rabaul Volcano Observatory (RVO) and Darwin Volcanic Ash Advisory Centre (VAAC). This report describes activity from November 2018 through August 2019; no volcanism was noted during this period until late June 2019.

Activity during June-July 2019. RVO reported that Real-time Seismic-Amplitude Measurement (RSAM) values steadily increased during 24-25 June, and then sharply increased at around 0330 on 26 June. The RSAM values reflect an increase in seismicity dominated by volcanic tremor. An eruption began in the morning hours of 26 June with emissions of gray ash (figure 17) that over time became darker and more energetic. The plumes rose 1 km and caused minor ashfall to the NW and SW. Local residents heard roaring and rumbling during 0600-0800.

Figure (see Caption) Figure 17. Photograph of a small ash plume rising from the summit crater of Ulawun taken by a helicopter pilot at 1030 local time on 26 June 2019. According to the pilot, the amount of ash observed was not unusual. Image has been color adjusted from original. Courtesy of Craig Powell.

The Darwin VAAC issued several notices about ash plumes visible in satellite data. These stated that during 1130-1155 ash plumes rose to altitudes of 6.7-8.5 km and drifted W, while ash plumes that rose to 12.8-13.4 km drifted S and SW. A new pulse of activity (figures 17 and 18) generated ash plumes that by 1512 rose to an altitude of 16.8 km and drifted S and SE. By 1730 the ash plume had risen to 19.2 km and spread over 90 km in all directions. Ash from earlier ejections continued to drift S at an altitude of 13.4 km and W at an altitude of 8.5 km. RVO stated that RSAM values peaked at about 2,500 units during 1330-1600, and then dropped to 1,600 units as the eruption subsided.

Figure (see Caption) Figure 18. Photograph of Ulawun taken by a helicopter pilot at 1310 local time on 26 June 2019 showing a tall ash plume rising from the summit crater. Image has been color adjusted from original. Courtesy of Craig Powell.
Figure (see Caption) Figure 19. Photograph of Ulawun taken by a helicopter pilot at 1350 local time on 26 June 2019 showing a close-up view of the ash plume rising from the summit crater along with an area of incandescent ejecta. According to the pilot, this was the most active phase. Image has been color adjusted from original. Courtesy of Craig Powell.

According to RVO, parts of the ash plume at lower altitudes drifted W, causing variable amounts of ashfall in areas to the NW and SW. A pyroclastic flow descended the N flank. Residents evacuated to areas to the NE and W; a news article (Radio New Zealand) noted that around 3,000 people had gathered at a local church. According to another news source (phys.org), an observer in a helicopter reported a column of incandescent material rising from the crater, residents noted that the sky had turned black, and a main road in the N part of the island was blocked by volcanic material. Residents also reported a lava flow near Noau village and Eana Valley. RVO reported that the eruption ceased between 1800 and 1900. Incandescence visible on the N flank was from either a lava flow or pyroclastic flow deposits.

On 27 June diffuse white plumes were reported by RVO as rising from the summit crater and incandescence was visible from pyroclastic or lava flow deposits on the N flank from the activity the day before. The seismic station 11 km NW of the volcano recorded low RSAM values of between 2 and 50. According to the Darwin VAAC a strong thermal anomaly was visible in satellite images, though not after 1200. Ash from 26 June explosions continued to disperse and became difficult to discern in satellite images by 1300, though a sulfur dioxide signal persisted. Ash at an altitude of 13.7 km drifted SW to SE and dissipated by 1620, and ash at 16.8 km drifted NW to NE and dissipated by 1857. RVO noted that at 1300 on 27 June satellite images captured an ash explosion not reported by ground-based observers, likely due to cloudy weather conditions. The Alert Level was lowered to Stage 1 (the lowest level on a four-stage scale).

RSAM values slightly increased at 0600 on 28 June and fluctuated between 80 to 150 units afterwards. During 28-29 June diffuse white plumes continued to rise from the crater (figure 20) and from the North Valley vent. On 29 June a ReliefWeb update stated that around 11,000 evacuated people remained in shelters.

Figure (see Caption) Figure 20. Photograph of the steaming summit crater at Ulawun taken by a helicopter pilot at 0730 local time on 29 June 2019. Image has been color adjusted from original. Courtesy of Craig Powell.

According to RVO, diffuse white plumes rose from Ulawun's summit crater and the North Valley vent during 1-4 July and from the summit only during 5-9 July. The seismic station located 11 km NW of the volcano recorded three volcanic earthquakes and some sporadic, short-duration, volcanic tremors during 1-3 July. The seismic station 2.9 km W of the volcano was restored on 4 July and recorded small sub-continuous tremors. Some discrete high-frequency volcanic earthquakes were also recorded on most days. Sulfur dioxide emissions were 100 tonnes per day on 4 July. According to the United Nations in Papua New Guinea, 7,318 people remained displaced within seven sites because of the 26 June eruption.

Activity during August 2019. During 1-2 August RVO reported that white-to-gray vapor plumes rose from the summit crater and drifted NW. Incandescence from the summit crater was visible at night and jetting noises were audible for a short interval. RSAM values fluctuated but peaked at high levels. During the night of 2-3 August crater incandescence strengthened and roaring noises became louder around 0400. An explosion began between 0430 and 0500 on 3 August; booming noises commenced around 0445. By 0600 dense light-gray ash emissions were drifting NW, causing ashfall in areas downwind, including Ulamona Mission (10 km NW). Ash emissions continued through the day and changed from light to dark gray with time.

The eruption intensified at 1900 and a lava fountain rose more than 100 m above the crater rim. A Plinian ash plume rose 19 km and drifted W and SW, causing ashfall in areas downwind such as Navo and Kabaya, and as far as Kimbe Town (142 km SW). The Darwin VAAC reported that the ash plume expanded radially and reached the stratosphere, rising to an altitude of 19.2 km. The plume then detached and drifted S and then SE.

The Alert Level was raised to Stage 3. The areas most affected by ash and scoria fall were between Navo (W) and Saltamana Estate (NW). Two classrooms at the Navo Primary School and a church in Navo collapsed from the weight of the ash and scoria; one of the classroom roofs had already partially collapsed during the 26 June eruption. Evacuees in tents because of the 26 June explosion reported damage. Rabaul town (132 km NE) also reported ashfall. Seismicity declined rapidly within two hours of the event, though continued to fluctuate at moderate levels. According to a news source (Radio New Zealand, flights in and out of Hoskins airport in Port Moresby were cancelled on 4 August due to tephra fall. The Alert Level was lowered to Stage 1. Small amounts of white and gray vapor were emitted from the summit crater during 4-6 August. RVO reported that during 7-8 August minor emissions of white vapor rose from the summit crater.

Additional observations. Seismicity was dominated by low-level volcanic tremor and remained at low-to-moderate levels. RSAM values fluctuated between 400 and 550 units; peaks did not go above 700. Instruments aboard NASA satellites detected high levels of sulfur dioxide near or directly above the volcano on 26-29 June and 4-6 August 2019.

Thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were observed at Ulawun only on 26 June 2019 (8 pixels by the Terra satellite, 4 pixels by the Aqua satellite). The MIROVA (Middle InfraRed Observation of Volcanic Activity) system detected three anomalies during the reporting period, one during the last week of June 2019 and two during the first week of August, all three within 3 km of the volcano and of low to moderate energy.

Geologic Background. The symmetrical basaltic-to-andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. The volcano, also known as the Father, rises above the N coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. The upper 1,000 m is unvegetated. A prominent E-W escarpment on the south may be the result of large-scale slumping. Satellitic cones occupy the NW and E flanks. A steep-walled valley cuts the NW side, and a flank lava-flow complex lies to the south of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.

Information Contacts: Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it); ReliefWeb (URL: https://reliefweb.int/); Radio New Zealand (URL: https://www.rnz.co.nz); phys.org (URL: https://phys.org); United Nations in Papua New Guinea (URL: http://pg.one.un.org/content/unct/papua_new_guinea/en/home.html).


Sarychev Peak (Russia) — November 2019 Citation iconCite this Report

Sarychev Peak

Russia

48.092°N, 153.2°E; summit elev. 1496 m

All times are local (unless otherwise noted)


Ash plume on 11 August; thermal anomalies from late May to early October 2019

Sarychev Peak, located on Matua Island in the central Kurile Islands of Russia, has had eruptions reported since 1765. Renewed activity began in October 2017, followed by a major eruption in June 2009 that included pyroclastic flows and ash plumes (BGVN 43:11 and 34:06). Thermal anomalies, explosions, and ash plumes took place between September and October 2018. A single ash explosion occurred in May 2019. Another ash plume was seen on 11 August, and small thermal anomalies were present in infrared imagery during June-October 2019. Information is provided by the Sakhalin Volcanic Eruption Response Team (SVERT) and the Tokyo Volcanic Ash Advisory Center (VAAC), with satellite imagery from Sentinel-2.

Satellite images from Sentinel-2 showed small white plumes from Sarychev Peak during clear weather on 4 and 14 August 2019 (figure 27); similar plumes were observed on a total of nine clear weather days between late June and October 2019. According to SVERT and the Tokyo VAAC, satellite data from HIMAWARI-8 showed an ash plume rising to an altitude of 2.7 km and drifting 50 km SE on 11 August. It was visible for a few days before dissipating. No further volcanism was detected by SVERT, and no activity was evident in a 17 August Sentinel-2 image (figure 27).

Figure (see Caption) Figure 27. Small white plumes were visible at Sarychev Peak in Sentinel-2 satellite images on 4 and 14 August 2019 (left and center). No activity was seen on 17 August (right). All three Sentinel-2 images use the "Natural Color" (bands 4, 3, 2) rendering; courtesy of Sentinel Hub Playground.

Intermittent weak thermal anomalies were detected by the MIROVA system using MODIS data from late May through 7 October 2019 (figure 28). Sentinel-2 satellite imagery from 28 June, 13 and 23 July, 9 August, and 21 October showed a very small thermal anomaly, but on 28 September a pronounced thermal anomaly was visible (figure 29). No additional thermal anomalies were identified from any source after 7 October through the end of the month.

Figure (see Caption) Figure 28. Thermal anomalies detected at Sarychev Peak by the MIROVA system (Log Radiative Power) using MODIS data for the year ending on 9 October 2019. Courtesy of MIROVA.
Figure (see Caption) Figure 29. Sentinel-2 satellite images of Sarychev Peak on 23 June and 28 September 2019. A small thermal anomaly is visible on the eastern side of the crater on 23 June (left, indicated by arrow), while the thermal anomaly is more pronounced and visible in the middle of the crater on 28 September (right). Both Sentinel-2 satellite images use the "False Color (Urban)" (bands 12, 11, 4) rendering; courtesy of Sentinel Hub Playground.

Geologic Background. Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5-km-wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows, prior to activity in 2009, had descended in all directions, often forming capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760s and include both quiet lava effusion and violent explosions. Large eruptions in 1946 and 2009 produced pyroclastic flows that reached the sea.

Information Contacts: Sakhalin Volcanic Eruption Response Team (SVERT), Institute of Marine Geology and Geophysics, Far Eastern Branch, Russian Academy of Science, Nauki st., 1B, Yuzhno-Sakhalinsk, Russia, 693022 (URL: http://www.imgg.ru/en/, http://www.imgg.ru/ru/svert/reports); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Asamayama (Japan) — September 2019 Citation iconCite this Report

Asamayama

Japan

36.406°N, 138.523°E; summit elev. 2568 m

All times are local (unless otherwise noted)


Ashfall from phreatic eruptions on 7 and 25 August 2019

Asamayama (also known as Asama), located in the Kanto-Chubu Region of Japan, previously erupted in June 2015. Activity included increased volcanic seismicity, small eruptions which occasionally resulted in ashfall, and SO2 gas emissions (BGVN 41:10). This report covers activity through August 2019, which describes small phreatic eruptions, volcanic seismicity, faint incandescence and commonly white gas plumes, and fluctuating SO2 emissions. The primary source of information for this report is provided by the Japan Meteorological Agency (JMA).

Activity during October 2016-May 2019. From October 2016 through December 2017, a high-sensitivity camera captured faint incandescence at night accompanied by white gas plumes rising above the crater to an altitude ranging 100-800 m (figure 44). A thermal anomaly and faint incandescence accompanied by a white plume near the summit was observed at night on 6-7 and 21 January 2017. These thermal anomalies were recorded near the central part of the crater bottom in January, February, and November 2017, and in May 2019. After December 2017 the faint incandescence was not observed, with an exception on 18 July 2018.

Figure (see Caption) Figure 44. A surveillance camera observed faint incandescence at Asamayama in February 2017. Left: Onimushi surveillance camera taken at 0145 on 5 February 2017. Right: Kurokayama surveillance camera taken at 0510 on 1 February 2017. Courtesy of JMA (Monthly Report for February 2017).

Field surveys on 6, 16, and 28 December 2016 reported an increased amount of SO2 gas emissions from November 2016 (100-600 tons/day) to March 2017 (1,300-3,200 tons/day). In April 2017 the SO2 emissions decreased (600-1,500 tons/day). Low-frequency shallow volcanic tremors decreased in December 2016; none were observed in January 2017. From February 2017 through June 2018 volcanic tremors occurred more intermittently. According to the monthly JMA Reports on February 2017 and December 2018 and data from the Geographical Survey Institute's Global Navigation Satellite Systems (GNSS), a slight inflation between the north and south baseline was recorded starting in fall 2016 through December 2018. This growth become stagnant at some of the baselines in October 2017.

Activity during August 2019. On 7 August 2019 a small phreatic eruption occurred at the summit crater and continued for about 20 minutes, resulting in an ash plume that rose to a maximum altitude of 1.8 km, drifting N and an associated earthquake and volcanic tremor (figure 45). According to the Tokyo Volcanic Ash Advisory (VAAC), this plume rose 4.6 km, based on satellite data from HIMAWARI-8. A surveillance camera observed a large volcanic block was ejected roughly 200 m from the crater. According to an ashfall survey conducted by the Mobile Observation Team on 8 August, slight ashfall occurred in the Tsumagoi Village (12 km N) and Naganohara Town (19 km NE), Gunma Prefecture (figure 46 and 47). About 2 g/m2 of ash deposit was measured by the Tokyo Institute of Technology. Immediately after the eruption on 7 August, seismicity, volcanism, and SO2 emissions temporarily increased and then decreased that same day.

Figure (see Caption) Figure 45. Surveillance camera images of Asamayama showing the small eruption at the summit crater on 7 August 2019, resulting in incandescence and a plume rising 1.8 km altitude. Both photos were taken on 7 August 2019.Courtesy of JMA (Monthly Report for August 2019).
Figure (see Caption) Figure 46. A photomicrograph of fragmented ejecta (250-500 µm) from Asamayama deposited roughly 5 km from the crater as a result of the eruption on 7 August 2019. Courtesy of JMA (Monthly Report for August 2019).
Figure (see Caption) Figure 47. Photos of ashfall in a nearby town NNE of Asamayama due to the 7 August 2019 eruption. Courtesy of JMA (Daily Report for 8 August 2019).

Another eruption at the summit crater on 25 August 2019 was smaller than the one on 7 August. JMA reported the resulting ash plume rose to an altitude of 600 m and drifted E. However, the Tokyo VAAC reported that the altitude of the plume up to 3.4 km, according to satellite data from HIMAWARI-8. A small amount of ashfall occurred in Karuizawa-machi, Nagano (4 km E), according to interview surveys and the Tokyo Institute of Technology.

Geologic Background. Asamayama, Honshu's most active volcano, overlooks the resort town of Karuizawa, 140 km NW of Tokyo. The volcano is located at the junction of the Izu-Marianas and NE Japan volcanic arcs. The modern Maekake cone forms the summit and is situated east of the horseshoe-shaped remnant of an older andesitic volcano, Kurofuyama, which was destroyed by a late-Pleistocene landslide about 20,000 years before present (BP). Growth of a dacitic shield volcano was accompanied by pumiceous pyroclastic flows, the largest of which occurred about 14,000-11,000 BP, and by growth of the Ko-Asama-yama lava dome on the east flank. Maekake, capped by the Kamayama pyroclastic cone that forms the present summit, is probably only a few thousand years old and has an historical record dating back at least to the 11th century CE. Maekake has had several major plinian eruptions, the last two of which occurred in 1108 (Asamayama's largest Holocene eruption) and 1783 CE.

Information Contacts: Japan Meteorological Agency (JMA), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).


Villarrica (Chile) — September 2019 Citation iconCite this Report

Villarrica

Chile

39.42°S, 71.93°W; summit elev. 2847 m

All times are local (unless otherwise noted)


Strombolian activity continued during March-August 2019 with an increase in July

Villarrica is a frequently active volcano in Chile with an active lava lake in the deep summit crater. It has been producing intermittent Strombolian activity since February 2015, soon after the latest reactivation of the lava lake; similar activity continued into 2019. This report summarizes activity during March-August 2019 and is based on reports from the Southern Andes Volcano Observatory (Observatorio Volcanológico de Los Andes del Sur, OVDAS), part of Chile's National Service of Geology and Mining (Servicio Nacional de Geología y Minería, SERNAGEOMIN), Projecto Observación Villarrica Internet (POVI), part of the Fundacion Volcanes de Chile research group, and satellite data.

OVDAS-SERNAGEOMIN reported that degassing continued through March with a plume reaching 150 m above the crater with visible incandescence through the nights. The lava lake activity continued to fluctuate and deformation was also recorded. POVI reported sporadic Strombolian activity throughout the month with incandescent ejecta reaching around 25 m above the crater on 17 and 24 March, and nearly 50 m above the crater on the 20th (figure 76).

Figure (see Caption) Figure 76. A webcam image of Villarrica at 0441 on 20 March 2019 shows Strombolian activity and incandescent ejecta reaching nearly 50 m above the crater. People are shown for scale in the white box to the left in the blue background image that was taken on 27 March. Photos taken about 6 km away from the volcano, courtesy of POVI.

There was a slight increase in Strombolian activity reported on 7-8 April, with incandescent ballistic ejecta reaching around 50 m above the crater (figure 77). Although seismicity was low during 14-15 April, Strombolian activity produced lava fountains up to 70 m above the crater over those two days (figure 78). Activity continued into May with approximately 12 Strombolian explosions recorded on the night of 5-6 May erupting incandescent ejecta up to 50 m above the crater rim. Another lava fountaining episode was observed reaching around 70 m above the crater on 14 May (figure 79). POVI also noted that while this was one of the largest events since 2015, no significant changes in activity had been observed over the last five months. Throughout May, OVDAS-SERNAGEOMIN reported that the gas plume height did not exceed 170 m above the crater and incandescence was sporadically observed when weather allowed. SWIR (short-wave infrared) thermal data showed an increase in energy towards the end of May (figure 80).

Figure (see Caption) Figure 77. Strombolian activity at Villarrica on 7-8 April 2019 producing incandescent ballistic ejecta reaching around 50 m above the crater. Courtesy of POVI.
Figure (see Caption) Figure 78. Images of Villarrica on 15 April show a lava fountain that reached about 70 m above the crater. Courtesy of POVI.
Figure (see Caption) Figure 79. These images of Villarrica taken at 0311 and 2220 on 14 May 2019 show lava fountaining reaching 70-73 m above the crater. Courtesy of POVI.
Figure (see Caption) Figure 80. This graph shows the variation in short-wave infrared (SWIR) energy with the vertical scale indicating the number of pixels displaying high temperatures between 23 June 2018 and 29 May 2019. Courtesy of POVI.

Ballistic ejecta were observed above the crater rim on 17 and 20 June 2019 (figure 81), and activity was heard on 20 and 21 June. Activity throughout the month remained similar to previous months, with a fluctuating lava lake and minor explosions. On 15 July a thermal camera imaged a ballistic bomb landing over 300 m from the crater and disintegrating upon impact. Incandescent material was sporadically observed on 16 July. Strombolian activity increased on 22 July with the highest intensity activity in four years continuing through the 25th (figure 82).

Figure (see Caption) Figure 81. Ballistic ejecta is visible above the Villarrica crater in this infrared camera (IR940 nm) image taken on 17 June 2019. Courtesy of POVI.
Figure (see Caption) Figure 82. Strombolian activity at Villarrica on 22, 23, and 24 July with incandescent ballistic ejecta seen here above the summit crater. Courtesy of POVI.

On 6 August the Alert Level was raised by SERNAGEOMIN from Green to Yellow (on a scale of Green, Yellow, Orange, and Red indicating the greatest level of activity) due to activity being above the usual background level, including ejecta confirmed out to 200 m from the crater with velocities on the order of 100 km/hour (figure 83). The temperature of the lava lake was measured at a maximum of 1,000°C on 25 July. POVI reported the collapse of a segment of the eastern crater rim, possibly due to snow weight, between 9 and 12 August. The MIROVA system showed an increase in thermal energy in August (figure 84) and there was one MODVOLC thermal alert on 24 July.

Figure (see Caption) Figure 83. Observations during an overflight of Villarrica on 25 July 2019 showed that ballistic ejecta up to 50 cm in diameter had impacted out to 200 m from the crater. The velocities of these ejecta were likely on the order of 100 km/hour. The maximum temperature of the lava lake measured was 1,000°C, and 500°C was measured around the crater. Courtesy of SERNAGEOMIN.
Figure (see Caption) Figure 84. Thermal activity at Villarrica detected by the MIROVA system shows an increase in detected energy in August 2019. Courtesy of MIROVA.

Geologic Background. Glacier-clad Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km-wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Historical eruptions, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks.

Information Contacts: Proyecto Observación Villarrica Internet (POVI) (URL: http://www.povi.cl/); Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).


Reventador (Ecuador) — August 2019 Citation iconCite this Report

Reventador

Ecuador

0.077°S, 77.656°W; summit elev. 3562 m

All times are local (unless otherwise noted)


Daily ash emissions and incandescent block avalanches continue, February-July 2019

The andesitic Volcán El Reventador lies east of the main volcanic axis of the Cordillera Real in Ecuador and has historical eruptions with numerous lava flows and explosive events going back to the 16th century. An eruption in November 2002 generated a 17-km-high eruption cloud, pyroclastic flows that traveled 8 km, and several lava flows. Eruptive activity has been continuous since 2008. Daily explosions with ash emissions and ejecta of incandescent blocks rolling hundreds of meters down the flanks have been typical for many years. Alameida et al. (2019) provide an excellent summary of recent activity (2016-2018) and monitoring. Activity continued during February-July 2019, the period covered in this report, with information provided by Ecuador's Instituto Geofisico (IG-EPN), the Washington Volcano Ash Advisory Center (VAAC), and infrared satellite data.

Persistent thermal activity accompanied daily ash emissions and incandescent block avalanches during February-July 2019 (figure 111). Ash plumes generally rose 600-1,200 m above the summit crater and drifted W or NW; incandescent blocks descended up to 800 m down all the flanks. On 25 February an ash plume reached 9.1 km altitude and drifted SE, causing ashfall in nearby communities. Pyroclastic flows were reported on 18 April and 19 May traveling 500 m down the flanks. Small but distinct SO2 emissions were detectible by satellite instruments a few times during the period (figure 112).

Figure (see Caption) Figure 111. The thermal energy at Reventador persisted throughout 4 November 2018 through July 2019, but was highest in April and May. Courtesy of MIROVA.
Figure (see Caption) Figure 112. Small SO2 plumes were released from Reventador and detected by satellite instruments only a few times during February-July 2019. Columbia's Nevada del Ruiz produced a much larger SO2 signal during each of the days shown here as well. Top left: 26 February; top right: 27 February; bottom left: 3 April; bottom right: 4 April. Courtesy of NASA Goddard Space Flight Center.

The Washington VAAC issued multiple daily ash advisories on all but two days during February 2019. IGEPN reported daily ash emissions rising from 400 to over 1,000 m above the summit crater. Incandescent block avalanches rolled 400-800 m down the flanks on most nights (figure 113). Late on 8 February the Washington VAAC reported an ash plume moving W at 5.8 km altitude extending 10 km from the summit. Plumes rising more than 1,000 m above the summit were reported on 9, 13, 16, 18, 19, and 25 February. On 25 February the Washington VAAC reported an ash plume visible in satellite imagery drifting SE from the summit at 9.1 km altitude that dissipated quickly, and drifted SSE. It was followed by new ash clouds at 7.6 km altitude that drifted S. Ashfall was reported in San Luis in the Parish of Gonzalo Díaz de Pineda by UMEVA Orellana and the Chaco Fire Department.

Figure (see Caption) Figure 113. Emission of ash from Reventador and incandescent blocks rolling down the cone occurred daily during February 2019, and were captured by the COPETE webcam located on the S rim of the caldera. On 1 February (top left) incandescent blocks rolled 600 m down the flanks. On 13 February (top right) ash plumes rose 800 m and drifted W. On 16 February (bottom left) ash rose to 1,000 m and drifted W. On 18 February (bottom right) the highest emission exceeded 1,000 m above the crater and was clearly visible in spite of meteoric clouds obscuring the volcano. Courtesy of IGEPN (Daily reports 2019-32, 44, 47, and 49).

Ash plumes exceeded 1,000 m in height above the summit almost every day during March 2019 and generally drifted W or NW. The Washington VAAC reported an ash plume visible above the cloud deck at 6.7 km altitude extending 25 km NW early on 3 March; there were no reports of ashfall nearby. Incandescent block avalanches rolled 800 m down all the flanks the previous night; they were visible moving 300-800 m down the flanks most nights throughout the month (figure 114).

Figure (see Caption) Figure 114. Ash plumes and incandescent block avalanches occurred daily at Reventador during March 2019 and were captured by the COPETE webcam on the S rim of the caldera. On 3 March (top left) a possible pyroclastic flow traveled down the E flank in the early morning. Ash plumes on 17 and 18 March (top right, bottom left) rose 900-1,000 m above the summit and drifted W. On 23 March (bottom right) ash plumes rose to 1,000 m and drifted N while incandescent blocks rolled 600 m down the flanks. Courtesy of IGEPN (Daily reports 2019 62, 76, 77, and 82).

During April 2019 ash plume heights ranged from 600 to over 1,000 m above the summit each day, drifting either W or NW. Incandescent avalanche blocks rolled down all the flanks for hundreds of meters daily; the largest explosions sent blocks 800 m from the summit (figure 115). On 18 April IGEPN reported that a pyroclastic flow the previous afternoon had traveled 500 m down the NE flank.

Figure (see Caption) Figure 115. Ash plumes and incandescent block avalanches occurred daily at Reventador during April 2019. On 3 April, ash emissions were reported drifting W and NW at 1,000 m above the summit (top left). On 14 April ash plumes rose over 600 m above the summit crater (top right). The 3 and 14 April images were taken from the LAVCAM webcam on the SE flank. Incandescent block avalanches descended 800 m down all the flanks on 15 April along with ash plumes rising over 1,000 m above the summit (bottom left), both visible in this image from the COPETE webcam on the S rim of the caldera. A pyroclastic flow descended 500 m down the NE flank on 17 April and was captured in the thermal REBECA webcam (bottom right) located on the N rim of the caldera. Courtesy of IGEPN (Daily reports 2019-93, 104, 105, and 108).

On most days during May 2019, incandescent block avalanches were observed traveling 700-800 m down all the flanks. Ash plume heights ranged from 600 to 1,200 m above the crater each day of the month (figure 116) they were visible. A pyroclastic flow was reported during the afternoon of 19 May that moved 500 m down the N flank.

Figure (see Caption) Figure 116. Even on days with thick meteoric clouds, ash plumes can be observed at Reventador. The ash plumes reached 1,000 m above the crater on 8 May 2019 (top left). The infrared webcam REBECA on the N rim of the caldera captured a pyroclastic flow on the N flank on the afternoon of 19 May (top right). Strong explosions on 23 May sent incandescent blocks and possible pyroclastic flows at least 800 m down all the flanks (bottom left). Ash plumes reached 1,000 m above the summit on 27 May and drifted W (bottom right). Images on 8, 23, and 27 May taken from the COPETE webcam on the S rim of the caldera. Courtesy of IGEPN (Daily Reports 2019-128, 140, 143, and 147).

Activity diminished somewhat during June 2019. Ash plumes reached 1,200 m above the summit early in June but decreased to 600 m or less for the second half of the month. Meteoric clouds prevented observation for most of the third week of June; VAAC reports indicated ash emissions rose to 5.2 km altitude on 19 June and again on 26 June (about 2 km above the crater). Incandescent blocks were reported traveling down all of the flanks, generally 500-800 m, during about half of the days the mountain was visible (figure 117). Multiple VAAC reports were also issued daily during July 2019. Ash plumes were reported by IGEPN rising over 600 m above the crater every day it was visible and incandescent blocks traveled 400-800 m down the flanks (figure 118). The Darwin VAAC reported an ash emission on 9 July that rose to 4.9 km altitude as multiple puffs that drifted W, extending about 35 km from the summit.

Figure (see Caption) Figure 117. Activity diminished slightly at Reventador during June 2019. Incandescent material was visible on the N flank from infrared webcam REBECA on the N rim of the caldera on 6 June (top left). On 7 June ash rose over 1,000 m above the summit and drifted N and W (top right) as seen from the COPETE webcam on the S rim of the caldera. Incandescent block avalanches rolled 600 m down all the flanks on 8 June (bottom left) and were photographed by the LAVCAM webcam located on the SE flank. An ash plume rose to 1,000 m on 25 June and was photographed from the San Rafael waterfall (bottom right). Courtesy of IGEPN (Daily Reports 2019-157, 158, 159, and 176).
Figure (see Caption) Figure 118. Daily explosive activity was reported at Reventador during July 2019. On 9 and 10 July ash plumes rose over 600 m and drifted W and incandescent blocks descended 800 m down all the flanks (top row), as seen from the LAVCAM webcam on the SE flank. On 27 July many of the large incandescent blocks appeared to be several m in diameter as they descended the flanks (bottom left, LAVCAM). On 1 August, a small steam plume was visible on a clear morning from the CORTESIA webcam located N of the volcano. Courtesy of IGEPN Daily reports (2019-190, 191, 208, and 213).

References: Almeida M, Gaunt H E, and Ramón P, 2019, Ecuador's El Reventador volcano continually remakes itself, Eos, 100, https://doi.org/10.1029/2019EO117105. Published on 18 March 2019.

Geologic Background. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

Information Contacts: Instituto Geofísico (IG-EPN), Escuela Politécnica Nacional, Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec ); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).


Raikoke (Russia) — August 2019 Citation iconCite this Report

Raikoke

Russia

48.292°N, 153.25°E; summit elev. 551 m

All times are local (unless otherwise noted)


Short-lived series of large explosions 21-23 June 2019; first recorded activity in 95 years

Raikoke in the central Kuril Islands lies 400 km SW of the southern tip of Russia's Kamchatcka Peninsula. Two significant eruptive events in historical times, including fatalities, have been recorded. In 1778 an eruption killed 15 people "under the hail of bombs" who were under the command of Captain Chernyi, returning from Matua to Kamchatka. This prompted the Russian military to order the first investigation of the volcanic character of the island two years later (Gorshkov, 1970). Tanakadate (1925) reported that travelers on a steamer witnessed an ash plume rising from the island on 15 February 1924, observed that the island was already covered in ash from recent activity, and noted that a dense steam plume was visible for a week rising from the summit crater. The latest eruptive event in June 2019 produced a very large ash plume that covered the island with ash and dispersed ash and gases more than 10 km high into the atmosphere. The volcano is monitored by the Sakhalin Volcanic Eruption Response Team, (SVERT) part of the Institute of Marine Geology and Geophysics, Far Eastern Branch of the Russian Academy of Sciences (IMGG FEB RAS) and the Kamchatka Volcanic Eruption Response Team (KVERT) which is part of the Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences (IVS FEB RAS).

A brief but intense eruption beginning on 21 June 2019 sent major ash and sulfur dioxide plumes into the stratosphere (figures 1 and 2); the plumes rapidly drifted over 1,000 km from the volcano. Strong explosions with dense ash plumes lasted for less than 48 hours, minor emissions continued for a few more days; the SO2, however, continued to circulate over far eastern Russia and the Bering Sea for more than three weeks after the initial explosion. The eruption covered the island with centimeters to meters of ash and enlarged the summit crater. By the end of July 2019 only minor intermittent steam emissions were observed in satellite imagery.

Figure (see Caption) Figure 1. On the morning of 22 June 2019, astronauts on the International Space Station captured this image of a large ash plume rising from Raikoke in the Kuril Islands. The plume reached altitudes of 10-13 km and drifted E during the volcano's first known explosion in 95 years. Courtesy of NASA Earth Observatory.
Figure (see Caption) Figure 2. A large and very dense SO2 plume (measuring over 900 Dobson Units (DU)) drifted E from Raikoke in the Kuril Islands on 22 June 2019, about 8 hours after the first known explosion in 95 years. Courtesy of NASA Goddard Space Flight Center.

Summary of 2019 activity. A powerful eruption at Raikoke began at 1805 on 21 June 2019 (UTC). Volcano Observatory Notices for Aviation (VONA's) issued by KVERT described the large ash plume that rapidly rose to 10-13 km altitude and extended for 370 km NE within the first two hours (figure 3). After eight hours, the plume extended 605 km ENE; it had reached 1,160 km E by 13 hours after the first explosion (figure 4). The last strong explosive event, according to KVERT, producing an ash column as high as 10-11 km, occurred at 0540 UTC on 22 June. SVERT reported a series of nine explosions during the eruption. Over 440 lightning events within the ash plume were detected in the first 24 hours by weather-monitoring equipment. The Japanese Ministry of Transportation reported that almost 40 planes were diverted because of the ash plume (figure 5).

Figure (see Caption) Figure 3. A dense ash plume drifted E from Raikoke on 22 June 2019 from a series of large explosions that lasted for less than 24 hours, as seen in this Terra satellite image. The plume was detected in the atmosphere for several days after the end of the eruptive activity. Courtesy of NASA Earth Observatory.
Figure (see Caption) Figure 4. The ash plume from Raikoke volcano that erupted on 21 June 2019 drifted over 1,000 km E by late in the day on 22 June, as seen in this oblique, composite view based on data from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite. Courtesy of NASA Earth Observatory.
Figure (see Caption) Figure 5. Numerous airplanes were traveling on flight paths near the Raikoke ash plume (black streak at center) early on 22 June 2019. The Japanese Ministry of Transportation reported that almost 40 planes were diverted because of the plume. Courtesy of Flightradar24 and Volcano Discovery.

On 23 June (local time) the cruise ship Athena approached the island; expedition member Nikolai Pavlov provided an eyewitness account and took remarkable drone photographs of the end of the eruption. The ship approached the W flank of the island in the late afternoon and they were able to launch a drone and photograph the shore and the summit. They noted that the entire surface of the island was covered with a thick layer of light-colored ash up to several tens of centimeters thick (figure 6). Fresh debris up to several meters thick fanned out from the base of the slopes (figure 7). The water had a yellowish-greenish tint and was darker brown closer to the shore. Dark-brown steam explosions occurred when waves flowed over hot areas along the shoreline, now blanketed in pale ash with bands of steam and gas rising from it (figure 8). A dense brown ash plume drifted W from the crater, rising about 1.5 km above the summit (figure 9).

Figure (see Caption) Figure 6. The entire surface of the island of Raikoke was covered with a thick layer of light-colored ash up to several tens of centimeters thick on 23 June 2019 when photographed by drone from the cruise ship Athena about 36 hours after the explosions began. View is of the W flank. Photo by Nik Pavlov; courtesy of IVS FEB RAS.
Figure (see Caption) Figure 7. Fresh ash and volcanic debris up to several meters thick coated the flanks of Raikoke on 23 June 2019 after the large explosive eruption two days earlier. View is by drone of the W flank. Photo by Nik Pavlov; courtesy of IVS FEB RAS.
Figure (see Caption) Figure 8. The 21 June 2019 eruption of Raikoke covered the island in volcanic debris. The formerly vegetated areas (left, before eruption) were blanketed in pale ash with bands of steam and gas rising all along the shoreline (right, on 23 June 2019) less than two days after the explosions began. The open water area between the sea stack and the island was filled with tephra. Photos by Nik Pavlov; courtesy of IVS FEB RAS.
Figure (see Caption) Figure 9. At the summit of Raikoke on 23 June 2019, a dense brown ash plume drifted W from the crater, rising about 1.5 km, two days after a large explosive eruption. Drone photo by Nik Pavlov; courtesy of IVS FEB RAS.

Early on 23 June, the large ash cloud continued to drift E and then NE at an altitude of 10-13 km. At that altitude, the leading edge of the ash cloud became entrained in a large low pressure system and began rotating from SE to NW, centered in the area of the Komandorskiye Islands, 1,200 km NE of Raikoke. By then the farthest edge of ash plume was located about 2,000 km ENE of the volcano. Meanwhile, at the summit and immediately above, the ash plume was drifting NW on 23 June (figures 9 and 10). Ashfall was reported (via Twitter) from a ship in the Pacific Ocean 40 km from Raikoke on 23 June. Weak ashfall was also reported in Paramushir, over 300 km NE the same day. KVERT reported that satellite data from 25 June indicated that a steam and gas plume, possibly with some ash, extended for 60 km NW. They also noted that the high-altitude "aerosol cloud" continued to drift to the N and W, reaching a distance of 1,700 km NW (see SO2 discussion below). By 27 June KVERT reported that the eruption had ended, but the aerosols continued to drift to the NW and E. They lowered the Aviation Alert Level to Green the following day.

Figure (see Caption) Figure 10. The brown ash plume from Raikoke was drifting NW on 23 June 2019 (left), while the remnants of the ash from the earlier explosions continued to be observed over a large area to the NE on 25 June (right). The plume in the 23 June image extends about 30 km NW; the plume in the 25 June image extends a similar distance NE. Natural color rendering (bands 4, 3, 2) of Sentinel-2 imagery, courtesy of Sentinel Hub Playground.

Tokyo and Anchorage VAAC Reports. The Tokyo VAAC first observed the ash plume in satellite imagery at 10.4 km altitude at 1850 on 21 June 209, just under an hour after the explosion was first reported by KVERT. About four hours later they updated the altitude to 13.1 km based on satellite data and a pilot report. By the evening of 22 June the high-level ash plume was still drifting ESE at about 13 km altitude while a secondary plume at 4.6 km altitude drifted SE for a few more hours before dissipating. The direction of the high-altitude plume began to shift to the NNW by 0300 on 23 June. By 0900 it had dropped slightly to 12.2 km and was drifting NE. The Anchorage VAAC reported at 2030 that the ash plume was becoming obscured by meteorological clouds around a large and deep low-pressure system in the western Bering Sea. Ash and SO2 signals in satellite imagery remained strong over the region S and W of the Pribilof Islands as well as over the far western Bering Sea adjacent to Russia. By early on 24 June the plume drifted NNW for a few hours before rotating back again to a NE drift direction. By the afternoon of 24 June, the altitude had dropped slightly to 11.6 km as it continued to drift NNE.

The ash plume was still clearly visible in satellite imagery late on 24 June. An aircraft reported SO2 at 14.3 km altitude above the area of the ash plume. The plume then began to move in multiple directions; the northern part moved E, while the southern part moved N. The remainder was essentially stationary, circulating around a closed low-pressure zone in the western Bering Sea. The ash plume remained stationary and slowly dissipated as it circulated around the low through 25 June before beginning to push S (figure 11). By early on 26 June the main area of the ash plume was between 325 km WSW of St. Matthew Island and 500 km NNW of St. Lawrence Island, and moving slowly NW. The Anchorage VAAC could no longer detect the plume in satellite imagery shortly after midnight (UTC) on 27 June, although they noted that areas of aerosol haze and SO2 likely persisted over the western Bering Sea and far eastern Russia.

Figure (see Caption) Figure 11. This RGB image created from a variety of spectral channels from the GOES-17 (GOES-West) satellite shows the ash and gas plume from Raikoke on 25 June 2019. The brighter yellows highlight features that are high in SO2 concentration. Highlighted along the bottom of the image is the pilot report over the far southern Bering Sea; the aircraft was flying at an altitude of 11 km (36,000 feet), and the pilot remarked that there were multiple layers seen below that altitude which had a greyish appearance (likely volcanic ash). Courtesy of NOAA and Scott Bachmeier.

Sulfur dioxide emissions. A very large SO2 plume was released during the eruption. Preliminary total SO2 mass estimates by Simon Carn taken from both UV and IR sensors suggested around 1.4-1.5 Tg (1 Teragram = 109 Kg) that included SO2 columns within the ash plume with values as high as 1,000 Dobson Units (DU) (figure 12). As the plume drifted on 23 and 24 June, similar to the ash plume as described by the Tokyo VAAC, it moved in a circular flow pattern as a result of being entrained in a low-pressure system in the western Bering Sea (figure 13). By 25 June the NW edge of the SO2 had reached far eastern Russia, 1,700 km from the volcano (as described by KVERT), while the eastern edges reached across Alaska and the Gulf of Alaska to the S. Two days later streams of SO2 from Raikoke were present over far northern Siberia and northern Canada (figure 14). For the following three weeks high levels of SO2 persisted over far eastern Russia and the Bering Sea, demonstrating the close relationship between the prevailing weather patterns and the aerosol concentrations from the volcano (figure 15).

Figure (see Caption) Figure 12. A contour map showing the mass and density of SO2 released into the atmosphere from Raikoke on 22 June 2019. Courtesy of Simon Carn.
Figure (see Caption) Figure 13. Streams of SO2 from Raikoke drifted around a complex flow pattern in the Bering Sea on 23 and 24 June 2019. Data from TROPOMI instrument on the Sentinel-5P satellite, courtesy of NASA Goddard Space Flight Center and Simon Carn.
Figure (see Caption) Figure 14. SO2 plumes from Raikoke dispersed over a large area of the northern hemisphere in late June 2019. By 25 June (top) the SO2 plumes had dispersed to far eastern Russia, 1,700 km from the volcano, while the eastern edges reached across Alaska and the Gulf of Alaska to the S. By 27 June (bottom) streams of SO2 were present over far northern Siberia and northern Canada, and also continued to circulate in a denser mass over far eastern Russia. Data from TROPOMI instrument on the Sentinel-5P satellite, courtesy of NASA Goddard Space Flight Center and Simon Carn.
Figure (see Caption) Figure 15. For the first two weeks of July 2019, high levels of SO2 from the 21 June 2019 eruption of Raikoke persisted over far eastern Russia and the Bering Sea entrained in a slow moving low-pressure system, demonstrating the close relationship between the prevailing weather patterns and the aerosol concentrations from the volcano. Data from TROPOMI instrument on the Sentinel-5P satellite, courtesy of NASA Goddard Space Flight Center.

Changes to the island. Since no known activity had occurred at Raikoke for 95 years, the island was well vegetated on most of its slopes and the inner walls of the summit crater before the explosion (figure 16). The first clear satellite image after the explosion, on 30 June 2019, revealed a modest steam plume rising from the summit crater, pale-colored ash surrounding the entire island, and new deposits of debris fans extending out from the NE, SW, and S flanks. Part of a newly enlarged crater was visible at the N edge of the old crater. Two weeks later only a small steam plume was present at the summit, making the outline of the enlarged crater more visible; the extensive shoreline deposits of fresh volcanic material remained. A clear view into the summit crater on 23 July revealed the size and shape of the newly enlarged summit crater (figure 17).

Figure (see Caption) Figure 16. Changes at Raikoke before and after the 21 June 2019 eruption were clear in Sentinel-2 satellite imagery. The island was heavily vegetated on most of its slopes and the inner walls of the summit crater before the explosion (top left, 3 June 2019). The first clear satellite image after the explosion, on 30 June 2019 revealed a steam plume rising from the summit crater, pale-colored ash surrounding the entire island, and new deposits of debris fans extending out from the NE, SW, and S flanks (top right). Part of a newly enlarged crater was visible at the N edge of the old crater. Two weeks later only a small steam plume was present at the summit, making the outline of the enlarged crater more visible; the extensive shoreline deposits of fresh volcanic material remained (bottom right, 13 July 2019). A clear view into the summit crater on 23 July revealed the new size and shape of the summit crater (bottom left). Natural Color rendering (bands 4, 3, 2), courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 17. Sentinel-2 satellite imagery of the summit crater of Raikoke before (left) and after (right) the explosions that began on 21 June 2019. The old crater rim is outlined in red in both images. The new crater rim is outlined in yellow in the 23 July image. Natural Color rendering (bands 4, 3, 2), courtesy of Sentinel Hub Playground.

References: Gorshkov G S, 1970, Volcanism and the Upper Mantle; Investigations in the Kurile Island Arc, New York: Plenum Publishing Corp, 385 p.

Tanakadate H, 1925, The volcanic activity in Japan during 1914-1924, Bull Volc. v. 1, no. 3.

Geologic Background. A low truncated volcano forms the small barren Raikoke Island, which lies 16 km across the Golovnin Strait from Matua Island in the central Kuriles. The oval-shaped basaltic island is only 2 x 2.5 km wide and rises above a submarine terrace. An eruption in 1778, during which the upper third of the island was said to have been destroyed, prompted the first volcanological investigation in the Kuril Islands two years later. Incorrect reports of eruptions in 1777 and 1780 were due to misprints and errors in descriptions of the 1778 event (Gorshkov, 1970). Another powerful eruption in 1924 greatly deepened the crater and changed the outline of the island. Prior to a 2019 eruption, the steep-walled crater, highest on the SE side, was 700 m wide and 200 m deep. Lava flows mantle the eastern side of the island.

Information Contacts: Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Sakhalin Volcanic Eruption Response Team (SVERT), Institute of Marine Geology and Geophysics, Far Eastern Branch, Russian Academy of Science, Nauki st., 1B, Yuzhno-Sakhalinsk, Russia, 693022 (URL: http://www.imgg.ru/en/, http://www.imgg.ru/ru/svert/reports); Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); NOAA, Cooperative Institute for Meteorological Satellite Studies (CIMSS), Space Science and Engineering Center (SSEC), University of Wisconsin-Madison, 1225 W. Dayton St. Madison, WI 53706, (URL: http://cimss.ssec.wisc.edu/); Simon Carn, Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA (URL: http://www.volcarno.com/, Twitter: @simoncarn); Scott Bachmeier, Cooperative Institute for Meteorological Satellite Studies (CIMSS), Space Science and Engineering Center (SSEC), University of Wisconsin-Madison, 1225 W. Dayton St. Madison, WI 53706; Flightradar24 (URL: https://www.flightradar24.com/51,-2/6); Volcano Discovery (URL: http://www.volcanodiscovery.com/).


Sinabung (Indonesia) — August 2019 Citation iconCite this Report

Sinabung

Indonesia

3.17°N, 98.392°E; summit elev. 2460 m

All times are local (unless otherwise noted)


Large ash explosions on 25 May and 9 June 2019

Indonesia's Sinabung volcano in north Sumatra has been highly active since its first confirmed Holocene eruption during August and September 2010. It remained quiet after the initial eruption until September 2013, when a new eruptive phase began that continued uninterrupted through June 2018. Ash plumes often rose several kilometers, avalanche blocks fell kilometers down the flanks, and deadly pyroclastic flows traveled more than 4 km repeatedly during the eruption. After a pause in eruptive activity from July 2018 through April 2019, explosions took place again during May and June 2019. This report covers activity from July 2018 through July 2019 with information provided by Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), referred to by some agencies as CVGHM or the Indonesian Center of Volcanology and Geological Hazard Mitigation, the Darwin Volcanic Ash Advisory Centre (VAAC), and the Badan Nacional Penanggulangan Bencana (National Disaster Management Authority, BNPB). Additional information comes from satellite instruments and local news reports.

After the last ash emission observed on 5 July 2018, activity diminished significantly. Occasional thermal anomalies were observed in satellite images in August 2018, and February-March 2019. Seismic evidence of lahars was recorded almost every month from July 2018 through July 2019. Renewed explosions with ash plumes began in early May; two large events, on 24 May and 9 June, produced ash plumes observed in satellite data at altitudes greater than 15 km (table 9).

Table 9. Summary of activity at Sinabung during July 2018-July 2019. Steam plume heights from PVMBG daily reports. VONA reports issued by Sinabung Volcano Observatory, part of PVMBG. Satellite imagery from Sentinel-2. Lahar seismicity from PVMBG daily and weekly reports. Ash plume heights from VAAC reports. Pyroclastic flows from VONA reports.

Month Steam Plume Heights (m) Dates of VONA reports Satellite Thermal Anomalies (date) Seismicity indicating Lahars (date) Ash Plume Altitude (date and distance) Pyroclastic flows
Jul 2018 100-700 -- -- -- -- --
Aug 2018 50-700 -- 30 1, 20 -- --
Sep 2018 100-500 -- -- 1st week, 12, 29 -- --
Oct 2018 50-1,000 -- -- 1 -- --
Nov 2018 50-350 -- -- 14 -- --
Dec 2018 50-500 -- -- 30 -- --
Jan 2019 50-350 -- -- -- -- --
Feb 2019 100-400 -- 6, 21 -- -- --
Mar 2019 50-300 -- 3, 8 27 -- --
Apr 2019 50-400 -- -- 2, 4, 11 -- --
May 2019 200-700 7, 11, 12, 24, 26, 27 (2) -- 4, 14 7 (4.6 km), 24 (15.2 km), 25 (6.1 km) --
June 2019 50-600 9, 10 -- -- 9 (16.8 km), 10 (3.0 km) 9-3.5 km SE, 3.0 km S
July 2019 100-700 -- -- 10, 12, 14, 16, 4th week -- --

No eruptive activity was reported after 5 July 2018 for several months, however Sentinel-2 thermal imagery on 30 August indicated a hot spot at the summit suggestive of eruptive activity. The next distinct thermal signal appeared on 6 February 2019, with a few more in late February and early March (figure 66, see table 9).

Figure (see Caption) Figure 66. Sentinel-2 satellite imagery on 30 August 2018, 6 February, and 8 March 2019 showed distinct thermal anomalies suggestive of eruptive activity at Sinabung, although no activity was reported by PVMBG. Images rendered with Atmospheric Penetration, bands 12, 11, and 8A. Courtesy of Sentinel Hub Playground.

PVMBG reported the first ash emission in 11 months early on 7 May 2019. They noted that an ash plume rose 2 km above the summit and drifted ESE. The Sinabung Volcano Observatory (SVO) issued a VONA (Volcano Observatory Notice for Aviation) that described an eruptive event lasting for a little over 40 minutes. Ashfall was reported in several villages. The Jakarta Post reported that Karo Disaster Mitigation Agency (BPDB) head Martin Sitepu said four districts were affected by the eruption, namely Simpang Empat (7 km SE), Namanteran (5 km NE), Kabanjahe (14 km SE), and Berastadi (12 km E). The Darwin VAAC reported the ash plume at 4.6 km altitude and noted that it dissipated about six hours later (figure 67). The TROPOMI SO2 instrument detected an SO2 plume shortly after the event (figure 68).

Figure (see Caption) Figure 67. Images from the explosion at Sinabung on 7 May 2019. Left and bottom right photos by Kopi Cimbang and Kalak Karo Kerina, courtesy of David de Zabedrosky. Top right photo courtesy of Sutopo Purwo Nugroho, BNPB.
Figure (see Caption) Figure 68. The TROPOMI instrument on the Sentinel-5P satellite captured an SO2 emission from Sinabung shortly after the eruption on 7 May 2019. Courtesy of NASA Goddard Space Flight Center.

On 11 May 2019 SVO issued a VONA reporting a seismic eruption event with a 9 mm amplitude that lasted for about 30 minutes; clouds and fog prevented visual confirmation. Another VONA issued the following day reported an ash emission that lasted for 28 minutes but again was not observed due to fog. The Darwin VAAC did not observe the ash plumes reported on 11 or 12 May; they did report incandescent material observed in the webcam on 11 May. Sutopo Purwo Nugroho of BNPB reported that the 12 May eruption was accompanied by incandescent lava and ash, and the explosion was heard in Rendang (figure 69). The Alert Level had been at Level IV since 2 June 2015. Based on decreased seismicity, a decrease in visual activity (figure 70), stability of deformation data, and a decrease in SO2 flux during the previous 11 months, PVMBG lowered the Alert Level from IV to III on 20 May 2019.

Figure (see Caption) Figure 69. Incandescent lava and ash were captured by a webcam at Sinabung on 12 May 2019. Courtesy of Sutopo Purwo Nugroho, BNPB.
Figure (see Caption) Figure 70. The summit of Sinabung emitted only steam and gas on 18 May 2019, shortly before PVMBG lowered the Alert Level from IV to III. Courtesy of PVMBG (Decreased G. Sinabung activity level from Level IV (Beware) to Level III (Standby), May 20, 2019).

A large explosion was reported by the Darwin VAAC on 24 May 2019 (UTC) that produced a high-altitude ash plume visible in satellite imagery at 15.2 km altitude moving W; the plume was not visible from the ground due to fog. The Sinabung Volcano Observatory reported that the brief explosion lasted for only 7 minutes (figure 71), but the plume detached and drifted NW for about 12 hours before dissipating. The substantial SO2 plume associated with the event was recorded by satellite instruments a few hours later (figure 72, left). Another six-minute explosion late on 26 May (UTC) produced an ash plume that was reported by a ground observer at 4.9 km altitude drifting S (figure 72, right). About an hour after the event, the Darwin VAAC observed the plume drifting S at 6.1 km altitude; it had dissipated four hours later. Sumbul Sembiring, a resident of Kabanjahe, told news outlet Tempo.com that ash had fallen at the settlements. Two more explosions were reported on 27 May; the first lasted for a little over 12 minutes, the second (about 90 minutes later, 28 May local time) lasted for about 2.5 minutes. No ash plumes were visible from the ground or satellite imagery for either event.

Figure (see Caption) Figure 71. A brief but powerful explosion at Sinabung in the early hours of 25 May 2019 (local time) produced a seven-minute-long seismic signal and a 15.2-km-altitude ash plume. Courtesy of MAGMA Indonesia and Volcano Discovery.
Figure (see Caption) Figure 72. Two closely spaced eruptive events occurred at Sinabung on 24 and 26 May UTC (25 and 27 May local time). The 24 May event produced a significant SO2 plume recorded by the TROPOMI instrument a few hours afterwards (left), and a 15.2-km-altitude ash plume only recorded in satellite imagery. The event on 26 May produced a visible ash plume that was reported at 6.1 km altitude and was faintly visible from the ground (right). SO2 courtesy of NASA Goddard Space Flight Center, photograph courtesy of PVMBG and Øystein Lund Andersen.

An explosion on 9 June 2019 produced an ash plume, estimated from the ground as rising to 9.5 km altitude, that drifted S and E; pyroclastic flows traveled 3.5 km SE and 3 km S down the flanks (figure 73). The explosion was heard at the Sinabung Observatory. The Darwin VAAC reported that the eruption was visible in Himawari-8 satellite imagery, and reported by pilots, at 16.8 km altitude drifting W; about an hour later the VAAC noted that the detached plume continued drifting SW but lower plumes were still present at 9.1 km altitude drifting W and below 4.3 km drifting SE. They also noted that pyroclastic flows moving SSE were sending ash to 4.3 km altitude. Three hours later they reported that both upper level plumes had detached and were moving SW and W. After six hours, the lower altitude plumes at 4.3 and 9.1 km altitudes had dissipated; the higher plume continued moving SW at 12.2 km altitude until it dissipated within the next eight hours. Instruments on the Sentinel-5P satellite captured an SO2 plume from the explosion drifting W across the southern Indian Ocean (figure 74).

Figure (see Caption) Figure 73. A large explosion at Sinabung on 9 June 2019 produced an ash plume that rose to 16.8 km altitude and also generated pyroclastic flows (foreground) that traveled down the S and SE flanks. Left image courtesy of Sutopo Purwo Nugroho, Head of the BNPB Information and Public Relations Data Center. Right image photo source PVMBG/Mbah Rono/ Berastagi Nachelle Homestay, courtesy of Jaime Sincioco.
Figure (see Caption) Figure 74. An SO2 plume from the 9 June 2019 explosion at Sinabung drifted more than a thousand kilometers W across the southern Indian Ocean. Courtesy of Sentinel Hub and Annamaria Luongo.

The SVO reported continuous ash and gas emissions at 3.0 km altitude moving ESE early on 10 June; it was obscured in satellite imagery by meteoric clouds. There were no additional VONA's or VAAC reports issued for the remainder of June or July 2019. An image on social media from 20 June 2019 shows incandescent blocks near the summit (figure 75). PVMBG reported that emissions on 25 June were white to brownish and rose 200 m above the summit and drifted E and SE.

Figure (see Caption) Figure 75. Incandescent blocks at the summit of Sinabung were visible in this 20 June 2019 image taken from a rooftop terrace in Berastagi, 13 km E. Photo by Nachelle Homestay, courtesy of Jaime Sincioco.

PVMBG detected seismic signals from lahars several times during the second week of July 2019. News outlets reported lahars damaging villages in the Karo district on 11 and 13 July (figure 76). Detik.com reported that lahars cut off the main access road to Perbaji Village (4 km SW), Kutambaru Village (14 km S), and the Tiganderket connecting road to Kutabuluh (17 km WNW). In addition, Puskesmas Kutambaru was submerged in mud. Images from iNews Malam showed large boulders and rafts of trees in thick layers of mud covering homes and roads. No casualties were reported.

Figure (see Caption) Figure 76. Lahars on 11 and 13 July 2019 caused damage in numerous villages around Sinabung, filling homes and roadways with mud, tree trunks, and debris. No casualties were reported. Courtesy of iNews Malam.

Geologic Background. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. The youngest deposit is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at 740-880 CE. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); The Jakarta Post (URL: https://www.thejakartapost.com/news/2019/05/07/mount-sinabung-erupts-again.html); Detikcom (URL: https://news.detik.com/berita/d-4619253/hujan-deras-sejumlah-desa-di-sekitar-gunung-sinabung-banjir-lahar-dingin); iNews Malam (URL: https://tv.inews.id/, https://www.youtube.com/watch?v=uAI4CpSb41k); Tempo.com (URL:https://en.tempo.co/read/1209667/mount-sinabung-erupts-on-monday-morning); David de Zabedrosky, Calera de Tango, Chile (Twitter: @deZabedrosky, URL: https://twitter.com/deZabedrosky/status/1125814504867160065/photo/1, https://twitter.com/deZabedrosky/status/1125814504867160065/photo/2); Sutopo Purwo Nugroho, BNPB (Twitter: @Sutopo_PN, URL: https://twitter.com/Sutopo_PN); Tom Pfeiffer, Volcano Discovery (URL: http://www.volcanodiscovery.com/); Øystein Lund Andersen? (Twitter: @OysteinLAnderse, URL: https://twitter.com/OysteinLAnderse, URL: http://www.oysteinlundandersen.com image at https://twitter.com/OysteinLAnderse/status/1132849458142572544); Jaime Sincioco, Phillipines (Twitter: @jaimessincioca, URL: https://twitter.com/jaimessincioco); Annamaria Luongo, University of Padua, Venice, Italy (Twitter: @annamaria_84, URL:https://twitter.com/annamaria_84).


Semisopochnoi (United States) — September 2019 Citation iconCite this Report

Semisopochnoi

United States

51.93°N, 179.58°E; summit elev. 1221 m

All times are local (unless otherwise noted)


Small explosions detected between 16 July and 24 August 2019

The remote island of Semisopochnoi in the western Aleutians is dominated by a caldera measuring 8 km in diameter that contains a small lake (Fenner Lake) and a number of post-caldera cones and craters. A small (100 m diameter) crater lake in the N cone of Semisopochnoi's Cerberus three-cone cluster has persisted since January 2019. An eruption at Sugarloaf Peak in 1987 included an ash plume (SEAN 12:04). Activity during September-October 2018 included increased seismicity and small explosions (BGVN 44:02). The primary source of information for this reporting period of July-August 2019 comes from the Alaska Volcano Observatory (AVO), when there were two low-level eruptions.

Seismicity rose above background levels on 5 July 2019. AVO reported that data from local seismic and infrasound sensors likely detected a small explosion on 16 July. A strong tremor on 17 July generated airwaves that were detected on an infrasound array 260 km E on Adak Island. In addition to this, a small plume extended 18 km WSW from the Cerberus vent, but no ash signals were detected in satellite data. Seismicity decreased abruptly on 18 July after a short-lived eruption. Seismicity increased slightly on 23 July and remained elevated through August.

On 24 July 2019 AVO reported that satellite data showed that the crater lake was gone and a new, shallow inner crater measuring 80 m in diameter had formed on the crater floor, though no lava was identified. Satellite imagery indicated that the crater of the Cerberus N cone had been replaced by a smooth, featureless area of either tephra or water at a level several meters below the previous floor. Satellite imagery detected faint steam plumes rising to 5-10 km altitude and minor SO2 emissions on 27 July. Satellite data showed a steam plume rising from Semisopochnoi on 18 August and SO2 emissions on 21-22 August. Ground-coupled airwaves identified in seismic data on 23-24 August was indicative of additional explosive activity.

Geologic Background. Semisopochnoi, the largest subaerial volcano of the western Aleutians, is 20 km wide at sea level and contains an 8-km-wide caldera. It formed as a result of collapse of a low-angle, dominantly basaltic volcano following the eruption of a large volume of dacitic pumice. The high point of the island is 1221-m-high Anvil Peak, a double-peaked late-Pleistocene cone that forms much of the island's northern part. The three-peaked 774-m-high Mount Cerberus volcano was constructed during the Holocene within the caldera. Each of the peaks contains a summit crater; lava flows on the northern flank of Cerberus appear younger than those on the southern side. Other post-caldera volcanoes include the symmetrical 855-m-high Sugarloaf Peak SSE of the caldera and Lakeshore Cone, a small cinder cone at the edge of Fenner Lake in the NE part of the caldera. Most documented historical eruptions have originated from Cerberus, although Coats (1950) considered that both Sugarloaf and Lakeshore Cone within the caldera could have been active during historical time.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: https://avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://dggs.alaska.gov/).

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Bulletin of the Global Volcanism Network - Volume 38, Number 04 (April 2013)

Managing Editor: Richard Wunderman

Colima (Mexico)

Microearthquakes leading to January 2013 explosions ending 18 month calm

Kilimanjaro (Tanzania)

2006 rockfall takes climbers' lives; 165 my minimum age; glacial retreat; economic value

Kizimen (Russia)

Active lava flows and ash emissions during October 2011-May 2013

Mayon (Philippines)

Mainly calm during 2009-2013; 7 May 2013 explosion kills five climbers

Seulawah Agam (Indonesia)

Alert Level raised due to increased seismicity in January 2013

Sheveluch (Russia)

Dome growth and volcanic activity continues

Sinabung (Indonesia)

Two simultaneous ash plumes from adjacent vents on 30 August 2010

Suwanosejima (Japan)

Near continuous tremor between July 2012 and March 2013

Zubair Group (Yemen)

Eruption on new island continues into January 2012



Colima (Mexico) — April 2013 Citation iconCite this Report

Colima

Mexico

19.514°N, 103.62°W; summit elev. 3850 m

All times are local (unless otherwise noted)


Microearthquakes leading to January 2013 explosions ending 18 month calm

One and a half years of calm at Colima volcano ended after explosive events starting on 6 January 2013. A sequence of January explosions cored out the previous dome and generated pyroclastic flows that reached 2.8 km W of the dome. As discussed in our previous report (BGVN 36:03) the 1998-2011 effusive-to-explosive eruption at Colima ended in June 2011, leaving in the crater an andesitic lava dome constructed during 2007-2011 extrusions stage (eg., figure 97 of BGVN 36:03). During the subsequent 1.5 years of calm, seismicity dropped and all visible signs of dome growth ceased.

We begin with an abstract that describes the end date of the previous eruptive 2007-2011 interval: 21 June 2011. Next we present a synthesis of a new series of eruption that started in 2013, sent to us in a report from the Colima Volcano Observatory, a report emphasizing both morphologic changes to the dome as a result of the January 2013 explosions and the seismic record associated with those explosions. We follow that submission with information from other sources including news coverage. Colima was the centerpiece at the recent Cities on Volcanoes meeting held in the city of Colima, Mexico in November 2012. At that stage the volcano still remained quiet.

2011 eruption's end date. The missing ingredient in many assessments of eruptions with declining, drawn out waning stages is often the last date of eruption prior to repose. Precise start dates are common, but end dates are not, restricting the precision of eruptive duration. Fortunately, increasing numbers of instrument- and satellite-aided techniques have emerged to help document eruption end dates. Salzer and others (2013) used satellite InSar deformation data coupled with a web camera to assess 21 June 2011 as Colima's final eruption in the 2007-2011 dome extrusion episode. They noted that "measuring deformation in the region of the crater is important to determine the rate of the ongoing eruption and the stability of the dome. The latter part of their abstract follows.

"The activity in the summit region has been recorded by a video monitoring system installed by the University of Colima volcano observatory. We have analysed the optical camera data obtained between February and June 2011 using spatial digital image correlation techniques. We show that the velocity of dome extrusion varies strongly on a daily basis, reaching up to 3m/day, and then systematically decreased over the following months. Deformation was barely above the detection threshold of 30cm/day in the weeks prior to June 21st, when a significant explosion occurred, removing part of the dome. Camera data recorded after this event does not show any displacements, possibly due to the low spatial resolution of the camera data.

"In order to analyse slower deformation processes, we have acquired TerraSAR-X data in spotlight mode for ascending and descending tracks over Colima, obtaining a high spatial resolution of up to 2 m, and a temporal resolution of up to 11 days. In combination with a high resolution digital elevation model, the InSAR data allow the detection of modifications of the dome at a resolution that is two orders of magnitude below the detection threshold of the cameras. The different temporal and spatial scales of deformation detectable by camera and radar monitoring (metre to centimetre, respectively), highlight the benefit of combining these methods to observe the full range of activites at Colima. The results reveal that explosions may occur suddenly after a period of declined dome growth."

Eruptions resume in January 2013. Figure 99(A) shows the dome as seen on 9 March 2012 in the midst of the year and a half interval of quiet when all visible and available geophysical signs of dome growth remained absent. In contrast, figure 99(B) shows the scene after eruptions resumed, starting with explosions on 6 January 2013. There developed both a depression in the dome's summit and some large ejecta perched near that crater's rim. The photo was taken on 31 January after a sequence of explosive events on 6, 13, and 29 January.

Figure (see Caption) Figure 99. (a) The lava dome that was formed in the crater of Colima volcano during the 2007-2011 activity, as seen from the air on 9 March 2012. Few if any documented changes were seen here during June 2011 and prior to the 6 January 2013 explosion. (b) A photograph taken on 31 January 2013 from a perspective somewhat similar to the adjacent photo. The dome had resumed eruption by this time, resulting in a restructuring of the upper part of the dome's surface morphology and a more pronounced circular crater at the dome's crown. Large blocks prominent on the inner rim are from the new activity. Photos from (a) Facultad de Ciencias, Universitad de Colima, and (b) taken during a flight by the Civil Protection of Jalisco State and acquired by the Colima Volcano Observatory.

The January explosions cored out and partly destroyed the 2007-2011 lava dome. Figure 99(B) shows the new crater that was formed within this old lava dome. The volume of this new crater was estimated at about 250,000 m3. During the explosions, a new lava dome began to grow in the new crater with an initial eruption of ˜0.14 m3/s. The January eruptions generated pyroclastic flows that reached 2.8 km W of the dome.

No precursory volcano-tectonic earthquakes or deformation signals were recorded prior to the January sequences. On the other hand, sequences of numerous microearthquakes (pulgas) occurred preceding the largest explosive events. This is shown in the 6 January seismic data presented in figure 100.

Figure (see Caption) Figure 100. A seismogram containing the 24 hour interval of 6 January 2013 record from a short period instrument located 1.9 km from Colima's crater (vertical lines show 1 min time intervals; horizontal lines correspond to local time zone at left and UTC at right). Note the abundance of microearthquakes of many sizes prior to the explosion. After that explosion, microearthquakes in this amplitude range essentially ceased during the rest of the day. Courtesy of Colima Volcano Observatory.

Figure 101 shows the 29 January explosion as viewed from video station Nevado installed 5.3 km N of Colima's crater.

Figure (see Caption) Figure 101. Image made during the explosion of 29 January 2013 from Nevado station N of the crater. Incandescent material has splashed over much of the visible dome surfaces. A dark cauliflower-shaped cloud rose above the summit. Courtesy of Colima Volcano Observatory.

Seismic comparisons. The largest of the explosions in the January eruptive sequence can be compared from seismic records. As noted above, the associated eruptions generated small pyroclastic flows.

Table 19 shows the energy associated with each of the eruptive pulses (6, 13, and 29 January). These results were estimated from the broadband seismic record measured at a distance of 4 km from the crater using the methods described in (Zobin and others, 2009, 2010).

Table 19. Energy of Colima's three largest explosions during January 2013. Courtesy of Colima Volcano Observatory.

Date Energy, J
06 Jan 2013 7.2 x 1010
13 Jan 2013 2.3 x 1010
29 Jan 2013 1.5 x 1011

Figure 102 provides another look at Colima seismic data during January 2013. On the upper two of the three plots (A and B), dates of the three explosions (on the 6th, 13th, and 29th) are indicated as black downward pointing arrows and the key to the seismic signals is shown. Figure 102(A) shows the number of microearthquakes, with in all three cases numbers of events increasing with approach to the explosions. For the first two eruptions, the peaks in microearthquakes coincided with the eruption. For the third microearthquake, on the 29th, counts rose rapidly and peaked prior to the eruption. The counts decreased after the eruption (figure 102(B)).

Figure (see Caption) Figure 102. Plots of seismicity and energy associated with Colima's explosive sequence of January 2013. (A and B) Variations with time in the number of events recorded by a highly sensitive broadband station 1.9 km from the crater. Arrows in A and B show the appearance of three large explosions. (A) Microearthquakes plotted here resulted from processing, where the seismic records were filtered between 1 and 50 Hz to better see seismic events of high frequency and small amplitude. (B) The number of seismic signals indicative of small explosions, rock falls, and pyroclastic density currents. Several peaks occurred-some coincident and others not coincident with the three marked explosions. (C) A plot of log number of events versus log energy to compare the energy of the three largest explosions of the January 2013 sequence (colored, up-pointing arrows) with the computed energy distributions of the small and large explosive events recorded during the 2005 explosive stage. Courtesy of Colima Volcano Observatory.

Figure 102(B) indicates that there were multiple seismically inferred explosions, on the three noted days, as well as on other days. For example, starting at left on Figure 102(B) one sees a progression from the 6th, 1 explosion; to the 10th and 11th, 1 and 2 explosions respectively. The largest number shown was associated with the arrow indicating the explosion on the 29th, 5 explosions, in a sequence escalating to 7 on the 31st (last data on the plot).

Figure 102(C) plots the energy of the three largest explosions of the January 2013 sequence (at the tips of the colored arrows aiming upwards). The two other fields on the plot show the energy distributions of small and large explosive events recorded during 2005 at Colima (Zobin and others, 2010). Thus, figure 101(C) shows that, for events assessed at Colima and in terms of seismically detected energy, the 2013 events may be considered as small to intermediate in size.

News reports. According to news articles, a scientific advisory committee reported the 6 January 2013 eruption from Colima, saying that it ejected tephra and an ash plume that rose ˜2 km above the crater. Ash fell on residents near Ciudad Guzmán, tens of kilometers NE of the volcano. Visitors were evacuated from the Nevado de Colima national park, which contains both Nevado de Colima and the active Volcan de Colima.

During the explosion of 29 January, residents up to 20 km away reported a loud noise, shaking ground, and rattling windows. Colima ejected incandescent material. According to the Washington Volcanic Ash Advisory Center (VAAC), on the 29th an ash plume rose ˜2.5 km above the crater. Based on analyses of satellite imagery, the VAAC reported that the ash plume drifted 55 km NE at an uncertain altitude to a distance of 150 km from the volcano.

References: Salzer , J, Walter , T, Legrand , D, Breton , M, and Reyes , G, 2013, Multiscale deformation monitoring at Colima Volcano using TerraSAR-X interferometry and camera observations, EGU General Assembly Conference Abstracts (2013), vol. 15, pp. 9290.

Zobin, VM, Reyes, GA, Guevara, E, 2, and Bretón, M, 2009, Scaling relationship for Vulcanian explosions derived from broadband seismic signals, J. Geophys. Res., vol. 114, B3, March 2009. DOI: 10.1029/2008JB005983.

Zobin, VM, Melnik, O E, González, M, Macedo, O and Bretón, M, 2010, Swarms of microearthquakes associated with the 2005 Vulcanian explosion sequence at Volcán de Colima, México. Geophysical Journal International, vol. 182, issue 2, pp. 808-828. doi: 10.1111/j.1365-246X.2010.04647.

Geologic Background. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4320 m high point of the complex) on the north and the 3850-m-high historically active Volcán de Colima at the south. A group of cinder cones of late-Pleistocene age is located on the floor of the Colima graben west and east of the Colima complex. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the south, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.

Information Contacts: Observatorio Vulcanologico de la Universidad de Colima (Colima Volcanological Observatory), Calle Manuel Payno, 209 Colima, Col., 28045 Mexico (URL: http://www.ucol.mex/volc/);Facultad de Ciencias, Universidad de Colima; Washington Volcanic Ash Advisory Center (VAAC), NOAA Science Center Room 401, 5200 Auth road, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/).


Kilimanjaro (Tanzania) — April 2013 Citation iconCite this Report

Kilimanjaro

Tanzania

3.07°S, 37.35°E; summit elev. 5881 m

All times are local (unless otherwise noted)


2006 rockfall takes climbers' lives; 165 my minimum age; glacial retreat; economic value

We offer our first Bulletin report on Mount Kilimanjaro, which remains a dormant volcano. We first discuss its economic value and setting. We next mention a few of the many studies of seismically detected rockfalls at volcanoes. We next discuss a 4 January 2006 rockfall that took three climbers' lives and injured five others (Kikoti and others, 2006). An investigation looked into the accident's location and cause, improvements to the route to minimize rockfall risk, as well as further recommendations and implementation to make this approach to the summit safer. Although accidents due to rockfalls and mass wasting are common in mountainous areas, volcanoes included, this subject has not typically been a major focus of Bulletin reporting. This unusually well-documented case illustrates several approaches to mitigating similar hazards at more than just this volcano.

The next section of this report notes diminishing glacial ice on Kilimanjaro, 85% gone since 1912. The youngest age date of volcanic material on the volcano is 165,000 +/- 5,000 ybp. No evidence of younger eruptions was found in studies of glacial ice on the volcano (Kimberly Casey, personal communication, June 2013).

There were several reports discussing the rockfall incident and future steps that might make the route safer. The report by Kikoti and others (2006) was issued after inspection of the Arrow Glacier area looking at various alternative routes, challenges, and recommendations and implementation.

World Heritage site and economic importance. Kilimanjaro was designated a World Heritage site in 1987. UNESCO cited Kilimanjaro as "an outstanding example of a superlative natural phenomenon" with many endangered species. Guides are required for tours and costs can range to $5,000 per person for an expedition to the summit (Py-Lieberman, 2008). Income from Kilimanjaro ecotourism is a principal source of foreign exchange for Tanzania. Income from tourism overall has grown from US $65 million in 1990 to US $725 million in 2001, and then represented roughly 10% of Tanzania's gross domestic product (World Bank/MIGA, 2002). It ranks among the world's favorite volcanoes to climb (Sigurdsson and Lopes-Gautier, 2000).

Rockfalls at volcanoes. Rockfalls represent a special kind of mass movement (mass wasting smaller than landslides) in which one or more rocks become dislodged, enters free fall, and bounces down the ground surface. The rockfalls discussed here were unusually well documented (Kikoti and others, 2006), spurring this report on a phenomena so common as to often elude mention. Rockfalls are a source of noise in seismic monitoring, sometimes masking small earthquakes at depth. Rockfall signals are often counted and reported along with various types of seismic events. Rockfall signals contribute to the average absolute amplitude of seismic signals (eg., RSAM measurements) since those measurements incorporate all the various types of seismic events, rockfall signals, and noise (Endo and Murray, 1991; Voight and others, 1998).

Rockfalls have long been thought of as a possible means of detecting larger impending mass movements and for eruption forecasting, although problems such as glaciers, seasonal melting cycles, precipitation, other noise sources, etc. complicate interpretations. Rockfalls may also be triggered by earthquakes. Regarding rockfall seismic signals at Augustine stratovolcano, DeRoin and McNutt (2012) state that "The high rate of rockfalls in 2005 constitutes a new class of precursory signal that needs to be incorporated into long-term monitoring strategies at Augustine and elsewhere." Hibert and others (2011) carried out a detailed study of rockfalls detected seismically at Piton de la Fournaise, a large shield volcano with rockfalls down steep sided caldera walls. Bulletin editors are currently unaware of past or current seismic monitoring at Kilimanjaro, short- or long-term, and if those records exist, whether rockfalls were important. The rockfall case under discussion at Kilimanjaro, release of glacial deposits down a steep slope, is very unlikely to reflect a pre-eruptive event.

Setting and area of fatal rockfalls. Kilimanjaro sits on the East African rift, a N-trending structure spanning from Mozambique at the S to the Afar and Red Sea region at the N, a distance of 3,000-4,000 km. Kilimanjaro resides in a region where the rift has branched into Eastern and Western rift segments, with Kilimanjaro on the Eastern segment (figure 1). That branching can be seen on figure 1 traversing around Lake Victoria (Lake Nyanza).

Figure (see Caption) Figure 1. (Top) Overview maps showing Eastern Africa, major features of the East African rift (the planet's largest active continental rift), and the location of Kilimanjaro (green dot). (Middle) Annotated satellite image (SRTM) of Kilimanjaro, where colors refer to elevation; this 90 m resolution image shows the main morphologic features. The top map was found online (credit to Google and NASA Tera metrics); the subsequent map and satellite image were taken from Nonnotte and others (2008). (bottom) shows a simplified map labeling key features at Kilimanjaro. Note the volcano's elongate morphology and the summit area (Kibu and crater of the same name) and E of the saddle, the Mawenzi peak. Figure 2 shows two contour maps. The accident's location was at the Western Breach, a spot just W of the summit crater and a low point on the crater's rim (yellow circle on. Figures 3 and 4 show photos of the area where the accident occurred, a spot just below the r-shaped glacier and above Arrow Glacier camp.
Figure (see Caption) Figure 2. Two contour maps showing Kilimanjaro. Note the Kibo and Mawenzi highs. Kilimanjaro's summit resides on Kibo's rim at Uhuru Peak (5,895 m elevation). Mawenzi is the peak to the W of Kibo (16,900 foot summit elevation). The Western Breach (Great West breach) lies on Kibo's SW face, the area where the fatal 4 January 2006 rockfall occurred (lower map, yellow ring). That spot on the upper map is approximately under the right digits of the label "19340" (the summit elevation expressed in feet). Note the large glacier and snow fields; the glacier has since receded (see below). Upper map found online without credit to source; lower map taken from Kikoti and others (2006).
Figure (see Caption) Figure 3. A photo taken with Arrow Glacier camp in the foreground and a yellow dashed line indicating the climbers' route into Kibu's crater. Note the zone of reddish rocks along the ascent as well as the two-pronged glacier at upper left ("r-shaped glacier"). [More details: Camp is at 03°04.580' S, 037°20.357' E; 4,871 m elevation. Location of point of entry onto Crater: 03°04.396' S, 037°21.105' E; 5,726 m elevation; mean gradient of slope, 38.0°; mean gradient of route, 26.0°; linear distance from Arrow Glacier camp to Crater: 1.39 km; route distance from Arrow Glacier camp to Crater: 1.95 km.] Image and details taken from Kikoti and others (2006).
Figure (see Caption) Figure 4. Zooming in on the rockfall accident scene, which occurred slightly below Kilimanjaro's r-shaped glacier (upper left). An annotated image appears below in another figure. Taken from Kikoti and others (2006).

Causes of the Accident. Extensive talus resides at the intersection between the left and right arms of the r-shaped glacier (figures 5-6). Part of this unstable talus collapsed. Kikoti and others (2006) said that the dislodged material traveled 150 m down the slope, reaching a group of people at an estimated speed of ˜40 m/sec (144 km per hour) at the point where the climbers were struck (B, figure 4).

Kikoti and others (2006) thought the talus dislodged because of (a) melting ice freeing the loose material and destabilizing it on the steep slopes, and (b) strong downhill winds measured at 177 km/h. The wind speed was measured by guide George Lyimo on the morning of the accident, using a wind speed gauge wrist unit.

Lyimo survived, having left camp ˜3 hours before the accident. Based on the known conditions at the summit, the climbers would only have had on the order of 5 seconds to escape the avalanche. Besides the strong winds, the climbers also confronted snowfall and poor visibility.

Kikoti and others (2008) examined a conspicuous cavity where the recent fallen rocks were believed to have been dislodged. They estimated that 39 tons of rocks dislodged from the cavity.

Figure (see Caption) Figure 5. View from Kilimanjaro's r-shaped glacier looking downward over angular boulders of talus. Source of deadly rockfall indicated (A) as well as the point where climbers were struck (B). The distance from point A to point B was estimated at 150 m. Taken from Kikoti and others (2006).
Figure (see Caption) Figure 6. At Kilimanjaro, the scene at the rockfall's source area. Rocks here remained unstable after the accident, an ongoing concern (see Recommendations and implementation). Note person for scale. Taken from Kikoti and others (2006).

Current Status of Route. The old route (figure 3) was judged unsafe due to concern over two risk zones (A and B, figure 7). Zone A hosts residual glacial deposit at the intersection of the right and left arms of the r-shaped glacier resulting in exposure to rockfall from above. Zone B includes the crater wall and rock tower, which could shed debris from above. Above this area, the remainder of the route is judged to be subject to no specific identifiable imminent threats.

Figure (see Caption) Figure 7. Annotated photo of the route to Kibu crater. The location of the January 2006 accident delineated with a red "X." Risk zones A and B shown as shaded areas with the likely sources of risk indicated. One part of a proposed alternate route appears as a yellow dotted line. Courtesy of Kikoti and others (2006).

Recommendations and implementation. Kikoti and others (2006) made principal recommendations, some of which follow. As partly seen on figure 7 (yellow dotted line), the proposed new route traverses the rock feature known as the 'Stone Train' largely avoiding indicated hazardous zones. The route would proceed to a handrail up the left hand edge of the Stone Train to join the rock spur adjoining the base of the crater wall at ˜5,400 m.

Many of these recommendations were adopted and a October 2008 posting on the Mt. Kilimanjaro Travel Guide (Baxter, 2008) discussed implementation, obligations of tour operators, climbers, guides and the Park to make the route safer. These ranged from immediate steps such as asking all climbing parties to depart Arrow Glacier camp no later than 5 a.m. to mid-term steps such as the issuance by tour companies of radio handsets for guides to communicate with Kilimanjaro National Park Authority (KINAPA) rescue teams. As a result, the Park was directed to take immediate steps such as erecting signboards warning visitors of rockfall dangers and put in place a rockfall protocol and ensure that all their rescue staffs are trained on how to effectively use it.

Baxter (2008) recommended investigations by further specialists (seismologists, glaciologists, geologists, meteorologists, etc.) to assess the long term future risks associated with climate change and Kilimanjaro's altering geology and glaciology. A safety patrol team was also tasked with visiting the mountain monthly or bi-monthly to survey and identify possible future risk areas in the light of the rapidly changing situation on Kilimanjaro.

Receding glaciers. Cullen and others (2013) discuss the time series of glacial retreat at Kilimanjaro during 1912 to 2011. They concluded that 85 per cent of the glacier had disappeared. Figures 8 and 9 contain satellite imagery and land-based photos presented on a NASA Earth Observatory article (Allen and others, 2012) that describes the state of summit glaciers at Kilimanjaro on 26 October 2012. Melting ice and subsequent melt-water runoff reduce confining pressure on the magmatic system. There is evidence that such reduced pressure or loading might promote the onset of volcanism (e.g., Bay and others, 2004; Pagli and Sigmundsson, 2008; Sigvaldason and others, 1992).

Figure (see Caption) Figure 8. (Left) The Advanced Land Imager on NASA's Earth Observing-1 (EO-1 Ali) satellite acquired the top images. Green lowlands are seen to the S, including rainforest leading upslope to alpine desert. The summit area lacks vegetation. Note thick cloud cover to the N. Glacial ice is clearly absent in much of the circular crater. (Right) A portion of the previous image centered over Kilimanjaro's summit emphasizes the lack of ice fields on 26 October 2012. Labels show both northern and southern icefields and a "new rift" discussed in text, where the ice had recently melted. Bulletin editors have added to the original Earth Observatory figure, inserting the location of the r-shaped glacier ("r."). Courtesy of NASA Earth Observatory.
Figure (see Caption) Figure 9.Lateral views of the Northern (top) and Southern (bottom) icefields in photos taken on 25 and 27 September 2012, respectively. Tents (barely visible at far left) help define scale for the shot of the Northern icefield. Courtesy of Kimberly Casey. 

According to Allen and others (2012), during a 2012 expedition, scientists found that the northern ice field, which had been developing since the 1970s then had a hole wide enough to ride a bicycle through. They also were able to walk on land directly through the rift (labeled on figure 8, right).

Cullen and others (2013) said that despite Mount Kilimanjaro's location in the tropics, the dry and cold air at the top of the mountain has sustained large quantities of ice for more than 10,000 years. At points, ice has completely surrounded the crater. Studies of ice core samples show that Kilimanjaro's ice has persisted through multiple warm spells, droughts, and periods of abrupt climate change.

Fumarolic activity occurs on the volcano, particularly in Kibu crater. Tour operator Eddie Frank (Tusker Trail) has agreed to keep a log of observed changes of color and smell at fumaroles.

Age dates of eruptive products. Nonnotte and others (2008) discussed the youngest K-Ar age date for Kilimanjaro. Samples associated with the latest parasitic phase (05KI41B and 03TZ42B) yield ages of 165 +/- 5 ka and 195 +/- 5 ka, respectively. "The last volcanicity, around 200-150 ka, is marked by the formation of the present summit crater in Kibo and the development of linear parasitic volcanic belts, constituted by numerous Strombolian-type isolated cones on the NW and SE slopes of Kilimanjaro. These belts are likely to occur above deep-seated fractures that have guided the magma ascent, and the changes in their directions with time might be related to the rotation of recent local stress field," Nonnotte and others wrote (2008).

References: Allen, J, Simmon, R, Voiland, A., and Casey, K, 2012, Kilimanjaro's Shrinking Ice Fields, NASA Earth Observatory-Image of the day (URL: http://earthobservatory.nasa.gov/) Posted 8 November 2012; Accesssed 14 June 2013.

Baxter, P., 2008, TANAPA Western Breach Protocol—Tanzania National Parks, Obligations and Actions Regarding the Re-opening of Western Breach Route (Arrow Glacier), Mt. Kilimanjaro Travel Guide [posted 21 October 2008] (URL: http://www.mtkilimanjarologue.com/tanapa-western-breach-protocol).

Bay, RC, Bramall, N, and P Buford Price, 2004, Bipolar correlation of volcanism with millennial climate change, Proc Natl Acad Sci U S A. 2004 April 27; 101(17): 6341-6345. Published online 2004 April 19. doi: 10.1073/pnas.0400323101 PMCID: PMC404046

Cullen, N. J., Sirguey, P., Mölg, T. Kaser, G. Winkler, M. and Fitzsimons, S. J. , 2013.A century of ice retreat on Kilimanjaro: the mapping reloaded, The Cryosphere Discuss., 6, 4233-4265, doi:10.5194/tcd-6-4233-2012, 2012.

DeRoin N. and S.R. McNutt, 2012, Rockfalls at Augustine Volcano, Alaska: The Influence of Eruption Precursors and Seasonal Factors on Occurrence Patterns 1997-2009. J . Volcanol. Geotherm. Res., v. 211-212, p. 61-75

Endo, E.T. and Murray, T., 1991, Real-time seismic amplitude measurement (RSAM): a volcano monitoring and prediction tool. Bulletin of Volcanology 53.7 (1991): 533-545.

Hibert, C., A. Mangeney, G. Grandjean, and N. M. Shapiro, 2011, Slope instabilities in Dolomieu crater, Réunion Island: From seismic signals to rockfall characteristics, J. Geophys. Res., 116, F04032, doi:10.1029/2011JF002038

Kikoti, I., Nchereri, J.P., Mlay, A., Lyimo, G., Msemo, E., and Rees-Evans, J., 2006, Kilimanjaro Safety Patrol Reconnaissance Expedition, 25th-27th January 2006, An investigation to determine the cause of the Western Breach accident of 4th January 2006 and to offer recommendations for the way forward for this route [Report completed June 2006 and posted online at (URL: http://www.yumpu.com/en/document/view/7812851/western-breach-investigation-digital-copy)

Nonnotte, P, Guilloub, H, Le Guillou, B, Benoit, M, Cotten, J, Scaillet, S, 2008, Jour. of Volc. and Geoth. Res., Volume 173, Issues 1-2, 1 June 2008, pp. 99-112

Pagli, C., and Sigmundsson, F. (2008). Will present day glacier retreat increase volcanic activity? Stress induced by recent glacier retreat and its effect on magmatism at the Vatnajökull ice cap, Iceland. Geophysical Research Letters, 35(9), L09304.

Py-Lieberman, B, 2008, Life lists, Hiking Mount Kilimanjaro, A trek up the world's tallest freestanding mountain takes you through five different ecosystems and offers a stunning 19,340-foot view, Smithsonian magazine, January 2008 [online version, URL: http://www.smithsonianmag.com/specialsections/lifelists/lifelist-kilimanjaro.html]

Sigurdsson S., and Lopes-Gautier, R. 2000, Volcanoes and Tourism; Encyclopedia of Volcanoes, Academic Press, pp. 1283-1299.

Sigvaldason, G.E., Annertz, K., and Nilsson, M., 1992, Effect of glacier loading/deloading on volcanism: postglacial volcanic production rate of the Dyngjufjöll area, central Iceland. Bulletin of Volcanology 54, no. 5 (1992): 385-392.

UNESCO, date uncertain, Kilimanjaro National Park, UNESCO (URL:whc.unesco.org/en/list/403)

Geologic Background. Massive Kilimanjaro, Africa's highest mountain, consists of three large stratovolcanoes constructed along a NW-SE trend. The ice-capped summit towers 5,200 m above the surrounding plains. Activity at the older Shira cone, which forms the broad WNW shoulder, began during the Pliocene. The extensively dissected Pleistocene Mawenzi forms a prominent, sharp-topped peak on the upper ESE flank, dominated by a densely packed radial dike swarm. More than 250 satellitic cones occupy a rift zone to the NW and SE of Kibo, the central stratovolcano. A 2.4 x 3.6 km caldera gives the summit of Kibo an elongated, broad profile. Most of Kilimanjaro was constructed during the Pleistocene, but fumarolic activity is present within a group of youthful-looking nested summit craters. Widespread statements that the "most recent activity was about 200 years ago," sometimes referencing the central "ash pit" formation, are of unknown origin with no supporting evidence in geological or anthropological literature. Nonnotte et al. (2008) K-Ar dated caldera rim group lavas in the 170-274 ka range, and placed the most recent volcanism (formation of both the present summit crater, Inner Crater group lavas, and parasitic flank cones) around 150-200 ka.

Information Contacts: Eddie Frank, Tusker Trail, 924 Incline Way Suite H Incline Village, Nevada 89451-9423 USA (URL: http://www.Tusker.com); and Kimberly Casey, NASA Goddard Space Flight Center, Cryospheric Sciences Lab, Code 615, Greenbelt, MD 20771 USA (URL: http://neptune.gsfc.nasa.gov/csb/personnel/?kcasey).


Kizimen (Russia) — April 2013 Citation iconCite this Report

Kizimen

Russia

55.131°N, 160.32°E; summit elev. 2334 m

All times are local (unless otherwise noted)


Active lava flows and ash emissions during October 2011-May 2013

Significant eruptions began at Kizimen in December 2010 (BGVN 36:10) and continued through May 2013. Our previous report highlighted frequent ash explosions, the development of a ˜2.3 km lava flow, and elevated seismicity through September 2011. In this report we continue to present data based on the monitoring efforts of the Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS) and the Kamchatka Volcanic Eruptions Response Team (KVERT).

Developments in data analysis based on Kizimen's 2010 eruption. The onset of activity in late 2010 provided opportunities for new methods of data analysis. Ji and others (2013) and Senyukov (2013) highlighted distinctive precursory activity that could successfully forecast volcanic behavior. Both investigative groups also mentioned the challenge of limited datasets for a volcanic system that recently became active without past records of geophysical data (in particular, deformation or seismic data during a time of elevated activity). The last eruption from Kizimen occurred during 1927-1928 (Siebert and others, 2010), before satellite or seismic monitoring (instrumentation was available in 1961) had begun.

The remote sensing investigation by Ji and others (2013) concluded that InSAR datasets from 2008 and 2010 measured > 6 cm of progressive surface displacement in the satellite's line-of-sight before the eruption began. While "InSAR has been demonstrated to be an important tool for investigating volcanic deformation and understanding magma supply dynamics at many of the world's volcanoes," this was the first significant deformation observed at a Kamchatka volcanic site.

The seismic study by Senyukov (2013) detailed a new method for short-term forecasting explosive eruptions. Development for this technique began with Bezymianny datasets and was followed by a successful application to the 2010 eruption of Kizimen using the correlation between height of ash emissions and the integral of absolute velocity as recorded by local seismic stations.

Elevated alert status continued through May 2013.From October 2011 through May 2013, Kamchatkan authorities maintained elevated an alert status (most frequently an Aviation Color Code of Orange) except for a few days during April-December 2012 and one day in March 2013 (figure 14). A Red level, indicating that an "eruption is underway with significant emission of ash into the atmosphere" was announced and maintained for one day in December 2011. There were several days of unassigned status during July-September 2012 primarily the result of station outages and meteorological conditions that inhibited observations which are based on satellite remote sensing, a video camera, and field visits.

Figure (see Caption) Figure 14. This plot of earthquakes per day at Kizimen has been annotated with Aviation Alert Levels during the time period of October 2011 to May 2013. Blue and maroon colors alternate to distinguish each month; green indicates approximate values that are based on the following scheme: background levels = 10 events/day, slightly above background levels = 20 events/day, and above background levels = 50 events/day. Note that during this time period, the Aviation Color Code varied between Orange and Yellow except where noted otherwise. Data from Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS).

Observations during October 2011-May 2013. KVERT reported in regular notifications to aviation authorities (Volcano Observatory Notification to Aviation, VONA), that lava continued to extrude from the summit of Kizimen from October 2011 through May 2012. New notices of visual confirmation of lava extrusion and ash plumes were released starting on 25 October 2012 and until the time of this report in May 2013 (figure 15).

Figure (see Caption) Figure 15. This natural-color NASA EO-1 ALI (Advanced Land Imager) image of Kizimen was acquired on 25 May 2013. A white plume drifted E from the summit, in high contrast with the ash-covered slopes which appeared gray-brown. Outlined in a dashed yellow line is the lake that had formed in late 2011, now mostly obscurred by snow and ash (see BGVN 36:10 for a comparison). Courtesy of NASA Earth Observatory).

Volcano Observatory Notification to Aviation (VONA) reports were released regularly on the KVERT website covering daily and weekly activity for Kizimen and other Kamchatka volcanoes. This reporting style was adopted by the International Civil Aviation Organization (ICAO) in 2004 "as the international warning system for volcanic ash, becoming the first 'global standardized' VALS [Volcano Alert Level Systems]. In 2006, the USGS adopted two standardized VALS, one for ground-based hazards and the other for aviation ash hazards, replacing extant VALS that had been locally developed at each observatory" (Fearnley and others, 2012; Gardner and Guffanti, 2006). At the time of this report, KVERT notifications were focused on aviation ash hazards with no additional ground-based notification system (figure 16).

Figure (see Caption) Figure 16. This Kizimen VONA from 27 December 2011 highlighted observed gas-and-steam plumes, visible effusive lava flows, and thermal anomalies. A forecast is also included as well as contact information for additional notices and KVERT representatives. Courtesy of KVERT.

Thermal anomalies from the summit. Satellite remote sensing frequently detected elevated temperatures from Kizimen during 2011-2013 (figure 17) and a local monitoring camera maintained by KB GS RAS detected nighttime incandescence during clear viewing conditions (figure 18).

Figure (see Caption) Figure 17. MODIS/MODVOLC detected thermal anomalies from the summit area of Kizimen during October 2011-May 2013. Note that months without anomalies may include time periods when viewing conditions did not allow detection of elevated temperatures. Courtesy of HIGP.
Figure (see Caption) Figure 18. Summit emissions and incandescence from the active flow front was visible at night on 2 March 2012 from Kizimen's E flank. Courtesy of A. Sokorenko of the Institute of Volcanology and Seismology (FED RAS) and KVERT.

Volcanic and seismic activity peaked in December 2011 and Red Aviation Color Code was announced on 13 December when more than 220 earthquakes were detected (figure 14). The next day, seismicity doubled and video observations showed hot avalanches from the E flank lava flow and occasional large pyroclastic flows. During 0620-0810 a large pyroclastic flow with co-ignimbrite clouds was observed. According to the Tokyo Volcanic Ash Advisory Center (VAAC), ash plumes rose 6.1-7.6 km a.s.l. Activity during 13-14 December generated an ash plume that extended ˜150 km E.

FED RAS scientists conducted an aerial survey on 23 December 2011 and determined Kizimen's range of surface temperatures (figure 19). During the overflight, temperatures were as high as 140°C, and a strong steam-and-gas plume was rising from the summit.

Figure (see Caption) Figure 19. Aerial photos of Kizimen on 23 December 2011 captured the active lava flow located on the E flank. (left image) This aerial image of Kizimen shows a lobate flow extending several kilometers from the summit. (right image) This thermal image depicts the active margins of effusive lava flows where elevated temperatures were concentrated; maximum temperatures were ˜140°C. Courtesy of Sergey Chirkov of the Institute of Volcanology and Seismology (FED RAS) and KVERT.

Seismicity during October 2011-May 2013. After peaking with ˜870 earthquakes on 2 October 2011, seismicity peaked again on 20 February 2012 (651 earthquakes/day) before beginning a long period of decline until June 2012 (figure 14). Possible avalanche signals were typical during this time period and explosion events frequently occurred. Seismicity also included spasmodic volcanic tremor, at times continuous, but more frequently intermittent episodes; tremor became less dominant in April and was absent in May.

During May-June 2012, seismicity rarely exceeded background levels (approximately 10 earthquakes/day). Spasmodic tremor was intermittent and rarely occurred during June-July, although an increase in tremor was detected during 24-30 July. Due to technical problems, there were data outages in July, the majority of August, and part of September. Tremor, explosions, and possible avalanche events were detected intermittently by the seismic network in August and September.

The seismic network detected intermittent explosive and rockfall events from October 2012 through December of that year. From October 2012 through May 2013, seismicity rarely exceeded 100 earthquakes/day. Several peaks in activity occurred in late December 2012 (a maximum of 422 earthquakes/day) and January 2013 (a maximum of 322 earthquakes/day). Tremor, explosions, and rockfall events became more frequent in January 2013 and February. After that, tremor became increasingly rare and was absent in May although explosion signatures were frequently-occurring throughout that time period. By May 2013, seismicity had decreased to an average of 62 earthquakes per day.

References:Fearnley, C.J., McGuire, W.J., Davies, G., and Twigg, J., 2012, Standardisation of the USGS Volcano Alert Level System (VALS): analysis and ramifications, Bulletin of Volcanology, 74: 2023-2036.

Gardner, C.A. and Guffanti, M.C., 2006, U.S. Geological Survey's Alert Notification System for Volcanic Activity. In: Fact Sheet 2006-3139. U.S. Geological Survey.

Ji, L., Lu, Z., Dzurisin, D., Senyukov, S., 2013, Pre-eruption deformation caused by dike intrusion beneath Kizimen volcano, Kamchatka, Russia, observed by InSAR, Journal of Volcanology and Geothermal Research, 256, 87-95.

Senyukov, S.L., 2013, Monitoring and Prediction of Volcanic Activity in Kamchatka from Seismological Data: 2000-2010, Journal of Volcanology and Seismology, vol. 7, no 1, 86-97.

Siebert, L., Simkin, T., Kimberly, P., 2010, Volcanoes of the World, 3rd edn. University of California Press, Berkeley.

USGS Volcano Hazards Program: Volcano Observatory Notices for Aviation (VONA), 8 June 2013, (http://volcanoes.usgs.gov/activity/vonainfo.php). Accessed 13 June 2013.

Geologic Background. Kizimen is an isolated, conical stratovolcano that is morphologically similar to St. Helens prior to its 1980 eruption. The summit consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2334-m-high edifice was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2000-3500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of long-term lava dome growth have occurred. The latest eruptive cycle began about 3000 years ago with a large explosion and was followed by intermittent lava dome growth lasting about 1000 years. An explosive eruption about 1100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. Prior to 2010, only a single explosive eruption, during 1927-28, had been recorded in historical time.

Information Contacts: Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia; Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanology and Seismology, Russian Academy of Sciences, Far East Division, 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); MODVOLC, Hawai`i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai`i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sergey Senukov, Kamchatka Branch of the Geophysical Service, Russian Academy of Sciences (KB GS RAS, Russia (URL: http://www.emsd.ru/); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/).


Mayon (Philippines) — April 2013 Citation iconCite this Report

Mayon

Philippines

13.257°N, 123.685°E; summit elev. 2462 m

All times are local (unless otherwise noted)


Mainly calm during 2009-2013; 7 May 2013 explosion kills five climbers

Mayon's emissions, often small, gas-driven, ash-bearing, and without visible magmatic components, were generally minor during 2009 through early June 2013. The summit crater released a sudden minor phreatic eruption on 7 May 2013 that would have been harmless except for the ejection of some large blocks and the presence of dozens of climbers on the nearby upper slopes. Five died.

As previously reported, after erupting in late 2009, Mayon seismicity generally declined to baseline levels through 23 September 2011 (BGVN 36:09). This report summarizes seismic activity from the end of the last report into early June 2013.

According to the Philippine Institute of Volcanology and Seismology (PHIVOLCS), small ground and tilt deformations observed since 2 March 2010 were probably due to regional faulting and not magmatic intrusion. A report published by PHIVOLCS on 27 November 2012 noted that precise leveling surveys found slight inflation of the lower N and E slopes; ground tilt changes were not fully consistent with volcanic ground deformation, but rather with incremental motion along a nearby segment of the Philippine fault zone.

That November 2013 report also noted that steaming had waned significantly by 27 November 2012. Steaming from the crater varied, but was, by November 2012, weak and occasionally wispy. The report indicated that crater incandescence had ceased since March 2012. Sulfur dioxide emissions had decreased to below baseline levels of 500 metric tons/day. As a result of diminished activity, PHIVOLCS decreased the Alert Level to 0 on 27 November 2012; however, the public was reminded not to enter the 6-km-radius Permanent Danger Zone.

The next available report on Mayon indicated that a small phreatic eruption occurred on 7 May 2013 lasting in the range of 73-146 seconds. PHIVOLCS observed that a gray-to-brown ash cloud rose 500 m above the crater and drifted WSW. Traces of ash fell in areas WNW, affecting communities up to 19 km away. The seismic network detected a single associated rockfall event. Seismicity and gas emissions remained within background levels and indicated no increase in activity. The Alert Level remained at 0.

Gas-driven explosion and fatalities on 7 May. PHIVOLCS posted a photo of the eruption taken at distance (figure 21). According to news reports, that 7 May event was fatal to climbers who had ventured to half a kilometer of the summit, a point well within the 6-km-radius Permanent Danger Zone.

Figure (see Caption) Figure 21. Photo taken at 0800 on 7 May 2013 of a phreatic eruption at Mayon. Dense billowy plume is largely white with areas of brown to gray. News reports said eruptions like this were, according to PHIVOLCS, a regular occurrence. PHIVOLCS reported this plume as 500 m tall. According to news reports, rocks discharged by this eruption at 0800 killed five climbers and injured at least seven others in a region close to the summit and well within an exclusionary zone. Courtesy of PHIVOLCS.

Multiple news articles (including those in Interaksyon, The Philippine Star, Associated Press, Sunstar, and GMA Network) noted that the 7 May 2013 phreatic eruption at 0800 ejected large rocks towards climbers, killing five and injuring at least seven. A climber was quoted as saying that their team was resting when they heard a loud rumbling and then saw falling rocks "as big as a living room." A local tour operator said "It rained like hell with stones. It was sudden and there was no warning."

One of the more detailed news reports, a 7 May article by Andrei Medina and Amanda Fernandez in GMA News, said that at least two groups of climbers were on the volcano at the time of the explosion. One of those groups, 20 climbers, incurred all five fatalities. Those fatalities included 4 foreigners [Europeans] and one Filipino tour guide.

The article said that (according to Bernardo Rafaelito Alejandro, head of the Office of Civil Defense in Bicol) the foreign nationals and their guide were about half a kilometer from the crater when the 0800 explosion occurred. Another group, consisting of about seven climbers on another trail suffered three injuries (all Indonesians). Other articles raised sometimes inconsistent details about the number, composure, and locations of the various groups on the volcano.

Although authorities had set the Alert Level at the lowest risk (0, at a scale reaching up to 6) at the time of the eruption, and it remained so immediately thereafter, they had previously established the Permanent Danger Zone. In accord with this information, the article said that Albay Governor Joey Salceda said that the mountain climbing activities of the two groups affected were unauthorized. He added the tourist guides also failed to secure a permit from the Albay Public Safety and Emergency Management Office (APSEMO) and the Department of Tourism." The article went further to say that Bernardo Rafaelito Alejandro, head of the Office of Civil Defense in Bicol, said there was no need to evacuate the residents near the volcano, adding such eruptions are expected from an active volcano, and evacuation only occurs during an Alert Level 3.

An 11 May article by Cet Dematera and Celso Amo in The Philippine Star noted that the bodies of the four foreign nationals had been retrieved from Mayon's slopes. Another climber on Mayon during the 7 May eruption, Boonchai Jattupornpong, had lost contact with fellow Thai climbers, but had survived for 4 days by gathering rainwater. He was found, carried out, and brought to a hospital suffering burns, cuts, and a fractured arm. The composite disaster team involved in the search, rescue, and retrieval operations after the 7 May disaster was recommended for awards and commendation, including a possible Bronze Cross medal award or equivalent, for bravery and heroism by the Albay Provincial Governments.

Rockfalls, degassing, and incandescence. On 8 May 2013, PHIVOLCS reported that two rockfalls at Mayon had been detected within the previous 24 hours. Seismicity remained within background levels and indicated no increase in overall volcanic activity.

On 31 May 2013, PHIVOLCS raised the Alert Level to 1 as a precaution because, during the previous 36-hours, a visible but weak and short-lived hydrogen sulfide (H2S) emission was observed, along with a persistent incandescence. PHIVOLCS was concerned that the incandescence might reflect a steady emission of magmatic gas. However, PHIVOLCS also noted that seismicity remained markedly low and sulfur dioxide (SO2) measurements remained below the normal level. A ground deformation survey indicated slight edifice inflation compared to a 13 February 2013 survey.

According to PHIVOLCS, white to off-white steam plumes drifted in various directions during 5-10 June. Occasionally, bluish fumes were noted. During most evenings during this period, PHIVOLCS observed incandescence from the crater, although cloud cover sometimes obscured the volcano. The seismic network recorded one volcanic earthquake during 5-6 June and another one during 9-10 June. During 6-7 June, a single rockfall signal was detected.

Geologic Background. Beautifully symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the Philippines' most active volcano. The structurally simple edifice has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions date back to 1616 and range from Strombolian to basaltic Plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS) (URL: http://www.phivolcs.dost.gov.ph); InterAksyon (URL: http://www.interaksyon.com); The Philippine Star (URL: http://www.philstar.com/); Sunstar (URL: http://www.sunstar.com.ph/).


Seulawah Agam (Indonesia) — April 2013 Citation iconCite this Report

Seulawah Agam

Indonesia

5.448°N, 95.658°E; summit elev. 1810 m

All times are local (unless otherwise noted)


Alert Level raised due to increased seismicity in January 2013

Seulawah Agam (also known as Seuleuwah Agam) volcano, one of three active stratovolcanoes in the Aceh province (>5 million inhabitants), is located at the NW tip of Sumatra. Seulawah Agam has two craters, van Heutsz (Heszt), the most active crater at an elevation of 714 m on the N flank, and Simpago on the S flank. The Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM) reported that activity at Seulawah Agam is generally characterized by white plumes rising ˜1 m from the crater. Seulawah Agam has remained non-eruptive through at least 2 January 2013.

Historical data indicated that Seulawah Agam volcano last erupted 12-13 January 1839 on its NNE flank (van Heutsz crater). Prior to that, an eruption occurred in 1510 (˜10 years), also on its NNE flank.

During April to August 2010, the seismic data suggested increased activity overall, with marginal fluctuation. On 1 September 2010, CVGHM raised the Alert Level from I to II and restricted visitors from approaching the crater within a 3-km radius. [The 4-level Indonesian Alert Level Scale is as follows: I - Normal (green); II - Waspada or Alert (yellow); III - Siaga or Standby (orange); and IV - Awas or Aware (red).]

During October 2010-July 2011 overall activity at Seulawah Agam decreased; seismicity, water temperature, and magmatic gas emissions decreased, but pH measurements were stable and no significant changes at the surface were observed. The volcano was often shrouded in fog during this period. On 11 July 2011 the Alert Level was lowered from II to I.

Beginning on 27 December 2012 (table 3), there was an increase in deep volcanic seismicity over the course of the following week. Visual observations were often prevented due to fog, although on 2 January 2013 scientists observed a new solfatara (a natural volcanic steam vent in which sulfur gases are the dominant constituent, along with hot water vapor) that produced roaring noises and emissions which drifted ˜20 m out from van Heutsz Crater. On 3 January 2013 the Alert Level was raised from I to II; then, on 11 May 2013, the Level was lowered to I.

Table 3. Daily numbers of earthquakes measured at Seulawah Agam volcano from the week 27 Dec 2012-2 January 2013. Courtesy of CVGHM.

Date Deep volcanic (VA) Shallow volcanic (VB) Local tectonic (TL) Long-distance tectonic (TJ)
27 Dec 2012 4 1 3 --
28 Dec 2012 8 -- -- 3
29 Dec 2012 5 -- 2 1
30 Dec 2012 2 -- -- 1
31 Dec 2012 14 -- 3 3
01 Jan 2013 14 -- 6 3
02 Jan 2013 8 -- 5 4

Geologic Background. Seulawah Agam at the NW tip of Sumatra is an extensively forested volcano of Pleistocene-Holocene age constructed within the large Pleistocene Lam Teuba caldera. A smaller 8 x 6 km caldera lies within Lam Teuba caldera. The summit contains a forested, 400-m-wide crater. The active van Heutsz crater, located at 650 m on the NNE flank of Suelawah Agam, is one of several areas containing active fumarole fields. Sapper (1927) and the Catalog of Active Volcanoes of the World (CAVW) reported an explosive eruption in the early 16th century, and the CAVW also listed an eruption from the van Heutsz crater in 1839. Rock et al. (1982) found no evidence for historical eruptions. However the Volcanological Survey of Indonesia noted that although no historical eruptions have occurred from the main cone, the reported NNE-flank explosive activity may have been hydrothermal and not have involved new magmatic activity.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://proxy.vsi.esdm.go.id/index.php).


Sheveluch (Russia) — April 2013 Citation iconCite this Report

Sheveluch

Russia

56.653°N, 161.36°E; summit elev. 3283 m

All times are local (unless otherwise noted)


Dome growth and volcanic activity continues

Background. A summary of Shiveluch volcano was included in a paper by Van Manen and others (2012). It noted that the activity of Shiveluch was predominantly characterized by dome formation accompanied by strong explosions (as described by Belousov and others, 1999). After 14 years of intense fumarolic activity, Shiveluch fed a Plinian eruption accompanied by large-scale edifice failure on 11 November 1964 (Gorshkov and Dubik, 1970). Since 1964, at least 0.27 km3 of magma had been discharged from Shiveluch during three main phases: (1) 1980-1981, (2) 1993-1995 and (3) 2001-2004 (Dirksen and others, 2006). An additional phase of dome extrusion, accompanied by minor explosive activity that commenced in 2006, continued at least to January 2012. Each of these phases was associated with andesite dome growth punctuated by explosions.

A website by KVERT (Kamchatka Volcanic Eruption Response Team) (2013) shows several years of primarily ground-based photographs of plumes from Shiveluch volcano.

The Institute of Volcanology and Seismology website (2013) reported that Shiveluch is noted for its unusual rocks, close to adakites, likely indicating its position over the northern edge of the subducting Pacific plate, warmed by mantle flow (Volynets et al. 2000; Yogodzinski et al. 2001). It is one of the most prolific explosive centers of Kamchatka, with a magma discharge of ˜36x106 tons per year, an order of magnitude higher than that typical of island arc volcanoes (Melekestsev et al. 1991).

March 2011-May 2013. Our last issue on Shiveluch covered up to March 2011 (BGVN 36:04). Based on visual observations and analyses of satellite data, KVERT reported that from March 2011 through at least May 2013, explosive-extrusive-effusive eruption of the volcano continued. A viscous lava flow effused on the NW to E flanks of the lava dome, accompanied by hot avalanches, incandescence, and fumarolic activity. Satellite imagery showed a daily thermal anomaly on the lava dome when not obscured by clouds. The Aviation Color Code remained at Orange except for a few days in October 2011.

In Table 11 we include several representative cases where possible plumes (steam and/or ash) of larger sizes were documented during the last 2 years. Measurements were made by ground observers or from satellite images; in many cases, cloud cover over several weeks or months presumably excluded observations. In addition, the KVERT reports contain many unexplained time gaps for description of the plume.

Table 11. Representative cases of occurrence of reported possible plume altitude in excess of 8 km and/or plume drift greater than 100 km during the period March 2011-June 2013; "nr" = not reported. It should be noted that the distances based on observations are probably accurate to no more than ˜1-2 km. International flights were rerouted on 28-31 August 2011. The Aviation Color code was raised to Red, then lowered to Orange during 3-8 October 2011. Courtesy of KVERT and Tokyo Volcanic Ash Advisory Center (VAAC).

Date(s) Plume altitude Plume drift (km)/direction Comments
11-18 Mar 11 3.8-8 km 312 km/W and NW --
18-20 Mar 11 5.8 km 373 km/SE and N --
1-5 Apr 11 7.5 km 187 km --
22-27 Apr 11 6.7 km 153 km/N; 400 km/SE --
1 May 11 4.5 km 124 km/NE --
5-7 May 11 3-7.5 km 196 km/N --
29-31 May 11 7.6-10 km 1,000 km/S-SW --
4-6 Jun 11 6.1-9.1 km 734 km/SE --
15 Jun 11 10 km 26 km/NW --
19-21 Jun 11 10 km 176 km/nr --
23 Aug 11 8.2 km nr/nr --
28-31 Aug 11 6.1-8.6 km nr/E and NE International flights rerouted
11 Sep 11 10.3 km nr/nr --
3-8 Oct 11 6-9 km 160 km/NE Aviation Color Code raised to Red, then lowered to Orange
13-18 Oct 11 8-10.5 km 75 km/E --
21-25 Oct 11 7.1-10.6 km 170 km/SE --
25-28 Mar 12 7 km 192 km/E and SE --
29 Mar-3 Apr 12 6.6 km 114 km/W,E, and NE --
14-18 Apr 12 4-7.5 km 120 km/N, NE, and E --
24 Apr 12 10 km 396 km/NE --
1 May 12 5 km 270 km/NE --
5 May 12 10 km 800 km/SE --
12 May 12 8 km 800 km/E --
19-20 May 12 9.1-9.5 km 410 km/SW --
25-30 May 12 9 km 555 km/SW, SE, and E --
2 Jun 12 9.1 km 250 km/S --
5-6 Jun 12 8-8.2 km nr/nr --
15 Jun 12 8.2 km nr/nr --
24 Jun 12 5.2-9.8 km nr/nr --
27 Jul 12 10.1 km nr/nr --
6-11 Apr 12 7.7 km 210 km/SW and SE --
18-20 Sep 12 8 km 2,000 km/SE --
4-6 Oct 12 6-7 km 360 km/SE --
4-6 Mar 13 7-9 km 200 km/SE --
10 Jun 13 7-8 km nr/nr --

As shown on the table, on 5 October 2011, KVERT reported that the current Aviation Color Code for Shiveluch was Red. Activity of the volcano began to increase from 3 October. Ash plumes rose up to 6.0-9.0 km on 3-5 October. According to visual data, a bright incandesce of the lava dome was observed over several hours. Satellite data showed a large thermal anomaly over the lava dome, and strong explosive events could occur in near time. On 6 October 2011, the Aviation Color Code was reduced to Orange. Explosive-extrusive eruption of the volcano continued. New lava extruded at the lava dome after strong explosions on 3-5 October, and moderate seismic activity of the volcano continued. On 5-6 October, ash plumes rose up to 4.5-5.0 km. Ash plumes drifted to the NE from the volcano. Satellite images showed that the large thermal anomaly continued over the lava dome.

A rather interesting pair of satellite images were collected on 6 October 2012 (figure 35). The first image image captured Shiveluch just before an exuption; the second, 2 hours later, showed an eruption plume drifting away from the volcano. The MODVOLC Hot Spots web site showing Modis satellite thermal alerts measured no alert during this 6 October event.

Figure (see Caption) Figure 35. When NASA's Terra satellite passed over Russia's Kamchatka Peninsula at noon local time (0000 UTC) on 6 October 2012, Shilveluch Volcano was quiet (top image). By the time NASA's Aqua satellite passed over the area two hours later (bottom image), the volcano had erupted and sent a plume of ash over the Kamchatskiy Zaliv. The plume traveled about 90 kilometers toward the SSE, where a change in wind direction began pushing the plume toward the E. On 6 October, the Kamchatka Volcanic Emergency Response Team (KVERT) reported that the ash plume from Shiveluch reached an altitude of 3 kilometers above sea level, and had traveled some 220 kilometers from the volcano summit. This was not the first time that MODIS observed a Shiveluch eruption shortly after it started. In 2007, MODIS captured an image within minutes of the eruption's start, before winds could blow the ash away from the summit. NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott.

On 4 March 2013, a single explosion ejected an ash plume up to 7 km. Strong collapses of hot avalanches from the lava dome occurred on 6 March, and resulting ash plumes rose up to 5 km and extended about 200 km SE of the volcano. An explosion on 5 April observed by video generated an ash plume that rose to altitudes of 5.5-6 km (figure 36).

Figure (see Caption) Figure 36. (Left) Quiet winds on 3 April 2013 allowed a plume of gas and ash to remain above and near Shiveluch. This false-color (near infrared, red, and green) image was collected by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite. Looking at the land surface, snow is white; ash, light brown, and volcanic debris, dark brown. (Right) A broader view on the same day of Shiveluch (upper right) and some adjacent volcanoes, including Bezymianny, Tolbachik, and Kizimen, all seen in eruption on high resolution versions of this image. A fourth volcano, Klyuchevskaya (synynom of Klinchevoskoi) emitted a small plume. Image courtesy of NASA Earth Observatory with credit to Jesse Allen and Robert Simmon (who used data from the NASA/GSFC/METI/ERSDAC/JAROS and the U.S./Japan ASTER Science Team).

References: Belousov, A.B., 1995, The Shiveluch volcanic eruption of 12 November 1964-explosive eruption provoked by failure of the edifice, Journal of Volcanology and Geothermal Research, v. 66, pp. 357-365.

Belousov, A., Belousova, M., and Voight, B., 1999, Multiple edifice failures, debris avalanches and associated eruptions in the Holocene history of Shiveluch volcano, Kamchatka, Russia, Bulletin of Volcanology, v. 61, no. 5, pp. 324-342.

Dirksen, O., Humphreys, M.C.S., Pletchov, P., Melnik, O., Demyanchuk, Y., Sparks, R.S.J., and Mahony, S., 2006, The 2001-2004 dome-forming eruption of Shiveluch volcano, Kamchatka: observation, petrological investigation and numerical modelling, Journal of Volcanology and Geothermal Research, v. 155, issue 3-4, pp. 201-226.

Gorshkov, G.S. and Dubik, Y.M., 1970, Gigantic directed blast as Shiveluch volcano (Kamchatka), Bulletin of Volcanology, v. 34, no. 1, pp. 261-288.

Institute of Volcanology and Seismology, 2013, Holocene Kamchatka volcanoes - Shiveluch, Global Volcanism Program number 1000-27, Kamchatka, Russia (URL: http://www.kscnet.ru/ivs/volcanoes/holocene/main/textpage/shiveluch.htm ).

KVERT, 2013, Current activity of the volcanoes, (URL: http://www.kscnet.ru/ivs/kvert/current_eng.php?pageNum_img=1&name=Sheveluch ).

Melekestsev, I.V., Volynets, O.N., Ermakov, V.A., Kirsanova, T.P., and Masurenkov, Yu.P., 1991, Shiveluch volcano. In: Fedotov, S.A., and Masurenkov, Yu.P. (eds) Active volcanoes of Kamchatka. V. 1. Nauka, Moscow, pp 84-92 [in Russian, summary in English].

Ponomareva, V.V., Pevzne,r M.M., and Melekestsev, I.V., 1998, Large debris avalanches and associated eruptions in the Holocene eruptive history of Shiveluch volcano, Kamchatka, Russia. Bulletin of Volcanology, v. 59, no. 7, pp. 490-505.

van Manen, S.M., Blake, S., and Dehn, J., 2012, Satellite thermal infrared data of Shiveluch, Kliuchevskoi, and Karymsky, 1993-2008: effusion, explosions and the potential to forecast ash plumes, Bulletin of Volcanology, v. 74, pp. 1313-1335 (DOI 10.1007/s00445-012-0599-8).

Volynets, O.N., Babanskii, A.D., and Gol'tsman, Y.V., 2000, Variations in isotopic and trace-element composition of lavas from volcanoes of the Northern group, Kamchatka, in relation to specific features of subduction, Geochemistry International. v. 38, no. 10, pp. 974-989.

Yogodzinski, G.M., Lees, J.M., Churikova, T.G., Dorendorf, F., Woerner, G., and Volynets, O.N., 2001, Geochemical evidence for the melting of subducting oceanic lithosphere at plate edges, Nature, v. 409, 25 January, pp. 500-504.

Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Information Contacts: Kamchatkan Volcanic Eruption Response Team (KVERT) (URL: http://www.kscnet.ru/ivs/kvert/index_eng.php); Tokyo Volcanic Ash Advisory Center (VAAC); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=80830).


Sinabung (Indonesia) — April 2013 Citation iconCite this Report

Sinabung

Indonesia

3.17°N, 98.392°E; summit elev. 2460 m

All times are local (unless otherwise noted)


Two simultaneous ash plumes from adjacent vents on 30 August 2010

Our previous report on Sinabung (BGVN 36:03) discussed the decreased activity following the 27 August-September 2010 eruption (BGVN 35:07). That was Sinabung's first confirmed Holocene eruption (although there was an unconfirmed eruption in 1881). The decrease in activity since that event prompted Center of Volcanology and Geological Hazard Mitigation (CVGHM) to lower the Alert Level to 3 (on a scale of 1-4) on 23 September, where it remained through at least mid-March 2011. Sinabung is the highest mountain in North Sumatra and sits 80 km NNW of the Toba caldera.

This report includes a more recently available post eruption photo (figure 3). That photo was taken from an aircraft on 13 May 2011 and posted by Johnny Siahaan on Flickr (Siahaan, 2010).

Figure (see Caption) Figure 3. Aerial photo taken 13 May 2011 showing summit area craters and deeply incised upper flanks at Sinabung, as seen in the aftermath of the late 2010 eruption. A thin white plume rises from the summit area. Photo posted by Johnny Siahaan.

This report also includes aspects of the eruption (Siahaan, 2010) during August-September 2010 (BGVN 35:07), including video of the Mt. Sinabung. Johnny Siahaan's video of 30 August 2010 shows a scene with two separate ash plumes rising together (figure 4). The larger plume emitted laterally (almost horizontally) but convection of the hot ash and gasses bent it into the vertical well out over the flank of the volcano. The other plume was initially smaller, escaping from an adjacent but distinct area of the summit, and rising nearly vertically. The two plumes appear to merge at altitude and then bend in the wind. What looks like an older plume in the distance near the beginning of the video rose and was strongly sheared in the wind. The "look direction" of the video was not stated.

Figure (see Caption) Figure 4. Two separate ash plumes rising from two vents at Sinabung. Photo courtesy of Johnny Siahaan's Youtube video, 30 August 2010.

References: Siahaan, J, Image 1414, Sinabung Flickr (URL: http://www.flickr.com/photos/johnnysiahaan/5735509397/)

Siahaan, J, 30 August 2010, Mount Sinabung Eruption, YouTube video (URL: http://www.youtube.com/watch?v=dMSkvYRxLwA )

Siahaan, J, 30 August 2010, Gunung Sinabung Meletus, YouTube video (URL: http://www.youtube.com/watch?v=dMSkvYRxLwA )

Geologic Background. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. The youngest deposit is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at 740-880 CE. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://vsi.esdm.go.id/).


Suwanosejima (Japan) — April 2013 Citation iconCite this Report

Suwanosejima

Japan

29.638°N, 129.714°E; summit elev. 796 m

All times are local (unless otherwise noted)


Near continuous tremor between July 2012 and March 2013

This report discusses Suwanose-jima (figure 16) during July 2012 through April 2013, an interval with generally abundant tremor, low numbers of earthquakes, weak plumes (less than 0.7 km above the crater rim), and occasional intermittent eruptions. Our previous report on Suwanose-jima discussed seismicity through June 2012 that included volcanic earthquakes and tremor, minor explosions, and plumes which occasionally deposited ash [in the residential area ~4 km SSW of the active crater, administratively part of the multi-island Toshima Village,] as late as June 2012 (BGVN 37:08).

Figure (see Caption) Figure 16. Satellite image showing the location of Suwanose-jima. Courtesy of Google Earth.

Recent monthly reports of volcanic activity from the Japan Meteorological Agency (JMA) translated into English resumed in October 2010. Since June 2012, English-translated JMA reports on Suwanose-jima were available online every month through March 2013.

According to JMA, seismic activity at Suwanose-jima remained at low levels between July 2012 and March 2013. Although explosive eruptions have occurred repeatedly in the past, no such eruption occurred during the reporting period. However, JMA reported infrequent tiny eruptions. Volcanic tremor occurred almost continually between 28 September 2012 and March 2013. A high-sensitivity camera often detected a weak night glow during every month. No unusual ground deformation was seen in GPS observation data. Table 11 summarizes tremor activity and other information reported by JMA.

Table 11. A compilation of data on Suwanose-jima between July 2012 and March 2013. '--' indicates data not reported. A-type earthquakes are generally considered to have shallow focal depths; B-type earthquakes, deeper focal depths. An asterisk "*" in the earthquake column indicates that the number of events reported for a specific month conflicts with the number reported for that same month in the sequential monthly JMA report. Data courtesy of JMA.

Month Earthquakes Tremor duration (hours:minutes) Max plume height (m above crater rim) Comments
Jul 2012 29 A-type events, 123 B-type events 38:5 400 Eruption.
Aug 2012 17 A-type events, 39 B-type events (or 60 events)* 0:0 (or 0:1)* 300 No eruption. Plume on 19 Aug only.
Sep 2012 37 A-type events, 86 B-type events (or 74 events)* 0:1 (or 67:52)* 300-400 No eruption. White plumes. 11 Sep aerial observation spotted white plume above Otake crater.
Oct 2012 22 A-type events, 78 B-type events. 705:19 700 Tiny intermittent eruptions at Otake crater. According to Tokyo VAAC, an ash plume on 3 Oct drifted SW at altitude of 3 km (i.e. 1.5 km higher than the JMA reported). Ashfall [in the village], 4 km SSW of Otake, on 2 and 5 Oct.
Nov 2012 -- 720:0 500-600 Tiny intermittent eruptions. Tiny amount of ashfall [in the village] on 25 Nov.
Dec 2012 -- 622:23 500 Tiny intermittent eruptions on 26th, red hot mass seen.
Jan 2013 -- 744:0 500 White plumes.
Feb 2013 -- 672:0 500 M 3.6 earthquake on 19 Feb with aftershocks. Tiny intermittent eruption on 3 Feb. Tiny amount of ashfall [in the village] on 3 Feb.
Mar 2013 -- -- 500 Tremor data unavailable.
Apr 2013 -- -- 700 Small eruption on 13 April. Tremor data unavailable.

On 8 November 2012, a field survey at Bunka crater revealed no remarkable change in the crater's shape. Infrared images showed no significant change in the crater's temperature distribution. On 26 December 2012, an aerial observation revealed a red-hot lava mass inside Otake crater. This phenomenon has occasionally been observed in past observations.

On 19 February 2013, a M 3.6 earthquake occurred (apparently at Suwanose-jima). The earthquake's maximum seismic intensity on JMA's scale was 3 (felt indoors by most or all people, objects rattle and fall off tables, houses shake strongly and may receive slight damage). In addition, a swarm of ten earthquakes (aftershocks?) with seismic intensities of 1 or greater on JMA's scale were recorded. These earthquakes caused no significant changes in surface phenomena or tiltmeter data. Seismicity remained at low levels, with hypocenters located just beneath the Otake crater.

Geologic Background. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).


Zubair Group (Yemen) — April 2013 Citation iconCite this Report

Zubair Group

Yemen

15.05°N, 42.18°E; summit elev. 191 m

All times are local (unless otherwise noted)


Eruption on new island continues into January 2012

In BGVN 36:11 we reported on an ongoing submarine eruption in the N portion of Yemen's Zubair group of islands in the Red Sea that [produced visible activity on 18 December 2011]. A new island emerged in this vicinity and was large enough to resolve in satellite imagery by 23 December 2011. The latitude and longitude given in the header for this report is for the volcanic island of Jebel Zubair (15.05°N, 42.18°E), the largest island of the Zubair Group (figure 5). The new island emerged approximately 15.158°N, 42.101°E, or ˜10 km NW off the NW coast of Jebel Zabair. A bathymetric sketch map made in 1973 indicated a water depth of about 100 m in that area. The S end of the new island is about 500 m NNW of Rugged Island.

Figure (see Caption) Figure 5. Map and index map of the 10 islands of the Zubair Group (Yemen) showing the site of the new eruption and its associated emergent island. Islands are represented by gray shading; other features are identified by the legend at left. The cross section at the bottom is along line A-B through the S portion of the group. Modified from Gass and others (1973); index map modified from MapsOf.net.

By 7 January 2012, the island had grown to about 530 x 710 m, and a gas-and-steam plume containing ash rose from a distinct cone (figure 6). A video from a Yemeni miliary helicopter uploaded on YouTube on 2 January 2012 showed violent explosions typical of shallow submarine eruptions. The satellite image in figure 6 shows that a new island in the Zubair Group is the source of the volcanic plume.

Figure (see Caption) Figure 6. This satellite image, acquired 7 January 2012, shows that the island had risen above water. A plume of steam, other volcanic gases, and ash rises from a distinct cone. The land surrounding the vent had grown, and was about 530 by 710 m in dimension. Once above water, past eruptions in the Zubair Islands were primarily effusive, with low viscosity lava forming thin lava flows. This natural-color image was acquired by the Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite. Courtesy of NASA Earth Observatory web site; image by Robert Simmon, using ALI data from the EO-1 Team; caption by Robert Simmon.

Natural-color images from the Enhanced Thematic Mapper Plus (ETM+) on Landsat-7 on 15 January and 15 February 2012 show the new island, but no plume rising from it or any other indication of eruption continuing.

MODVOLC, using MODIS data from the Aqua satellite, measured a 2-pixel thermal anomaly at 2235 UTC, 11 January 2012, at latitude 15.16°N, longitude 42.10°E, just S of Haycock Island. This was the only thermal alert measured in the area during the December 2011-January 2012 time period.

References: Gass, I.G., Mallick, D.I.J., and Cox, K.G., 1973, Volcanic islands of the Red Sea. Journal of the Geological Society of London, v. 129, no. 3, pp. 275-309.

Vervaeck, A., 2012 (17 January), Surtseyan eruption along the coast of Yemen forms a new island - January 15 new ALI satellite image, Earthquake newsreport web site (URL: http://earthquake-report.com/2011/12/29/surtseyan-eruption-along-the-coast-of-yemen-forms-a-new-island-today-eruption-cloud-stain); accessed 21 May 2013.

YouTube video uploaded by Naif8989889 on 2 January 2012, (http://www.youtube.com/watch?v=YoMLNEJC-Nk&feature=gu&context=G2d0c74aFUAAAAAAAAAA).

Geologic Background. The 5-km-long Jebel Zubair Island is the largest of a group of small islands and submerged shoals that rise from a shallow platform in the Red Sea rift. The platform and eruptive vents forming the islands and shoals are oriented NNW-SSE, parallel to the rift. An early explosive phase was followed by a brief period of marine erosion, then by renewed explosive activity accompanied by the extrusion of basaltic pahoehoe lava flows. This latest phase of activity occurred on the morphologically youngest islands of Zubair, Centre Peak, Saba, and Haycock. Historical explosive activity was reported from Saddle Island in the 19th century. Spatter cones and pyroclastic cones were erupted along fissures that form the low spine of Zubair Island. Eruptions that began in late 2011 built two new islands, increasing the total number in the group to 12.

Information Contacts: NASA Earth Observatory (URL: http://www.earthobservatory.gov).

Atmospheric Effects

The enormous aerosol cloud from the March-April 1982 eruption of Mexico's El Chichón persisted for years in the stratosphere, and led to the Atmospheric Effects section becoming a regular feature of the Bulletin. Descriptions of the initial dispersal of major eruption clouds remain with the individual eruption reports, but observations of long-term stratospheric aerosol loading will be found in this section.

Atmospheric Effects (1980-1989)  Atmospheric Effects (1995-2001)

Special Announcements

Special announcements of various kinds and obituaries.

Special Announcements

Additional Reports

Reports are sometimes published that are not related to a Holocene volcano. These might include observations of a Pleistocene volcano, earthquake swarms, or floating pumice. Reports are also sometimes published in which the source of the activity is unknown or the report is determined to be false. All of these types of additional reports are listed below by subregion and subject.

Kermadec Islands


Floating Pumice (Kermadec Islands)

1986 Submarine Explosion


Tonga Islands


Floating Pumice (Tonga)


Fiji Islands


Floating Pumice (Fiji)


Andaman Islands


False Report of Andaman Islands Eruptions


Sangihe Islands


1968 Northern Celebes Earthquake


Southeast Asia


Pumice Raft (South China Sea)

Land Subsidence near Ham Rong


Ryukyu Islands and Kyushu


Pumice Rafts (Ryukyu Islands)


Izu, Volcano, and Mariana Islands


Acoustic Signals in 1996 from Unknown Source

Acoustic Signals in 1999-2000 from Unknown Source


Kuril Islands


Possible 1988 Eruption Plume


Aleutian Islands


Possible 1986 Eruption Plume


Mexico


False Report of New Volcano


Nicaragua


Apoyo


Colombia


La Lorenza Mud Volcano


Pacific Ocean (Chilean Islands)


False Report of Submarine Volcanism


Central Chile and Argentina


Estero de Parraguirre


West Indies


Mid-Cayman Spreading Center


Atlantic Ocean (northern)


Northern Reykjanes Ridge


Azores


Azores-Gibraltar Fracture Zone


Antarctica and South Sandwich Islands


Jun Jaegyu

East Scotia Ridge


Additional Reports (database)

08/1997 (BGVN 22:08) False Report of Mount Pinokis Eruption

False report of volcanism intended to exclude would-be gold miners

12/1997 (BGVN 22:12) False Report of Somalia Eruption

Press reports of Somalia's first historical eruption were likely in error

11/1999 (BGVN 24:11) False Report of Sea of Marmara Eruption

UFO adherent claims new volcano in Sea of Marmara

05/2003 (BGVN 28:05) Har-Togoo

Fumaroles and minor seismicity since October 2002

12/2005 (BGVN 30:12) Elgon

False report of activity; confusion caused by burning dung in a lava tube



False Report of Mount Pinokis Eruption (Philippines) — August 1997

False Report of Mount Pinokis Eruption

Philippines

7.975°N, 123.23°E; summit elev. 1510 m

All times are local (unless otherwise noted)


False report of volcanism intended to exclude would-be gold miners

In discussing the week ending on 12 September, "Earthweek" (Newman, 1997) incorrectly claimed that a volcano named "Mount Pinukis" had erupted. Widely read in the US, the dramatic Earthweek report described terrified farmers and a black mushroom cloud that resembled a nuclear explosion. The mountain's location was given as "200 km E of Zamboanga City," a spot well into the sea. The purported eruption had received mention in a Manila Bulletin newspaper report nine days earlier, on 4 September. Their comparatively understated report said that a local police director had disclosed that residents had seen a dormant volcano showing signs of activity.

In response to these news reports Emmanuel Ramos of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) sent a reply on 17 September. PHIVOLCS staff had initially heard that there were some 12 alleged families who fled the mountain and sought shelter in the lowlands. A PHIVOLCS investigation team later found that the reported "families" were actually individuals seeking respite from some politically motivated harassment. The story seems to have stemmed from a local gold rush and an influential politician who wanted to use volcanism as a ploy to exclude residents. PHIVOLCS concluded that no volcanic activity had occurred. They also added that this finding disappointed local politicians but was much welcomed by the residents.

PHIVOLCS spelled the mountain's name as "Pinokis" and from their report it seems that it might be an inactive volcano. There is no known Holocene volcano with a similar name (Simkin and Siebert, 1994). No similar names (Pinokis, Pinukis, Pinakis, etc.) were found listed in the National Imagery and Mapping Agency GEOnet Names Server (http://geonames.nga.mil/gns/html/index.html), a searchable database of 3.3 million non-US geographic-feature names.

The Manila Bulletin report suggested that Pinokis resides on the Zamboanga Peninsula. The Peninsula lies on Mindanao Island's extreme W side where it bounds the Moro Gulf, an arm of the Celebes Sea. The mountainous Peninsula trends NNE-SSW and contains peaks with summit elevations near 1,300 m. Zamboanga City sits at the extreme end of the Peninsula and operates both a major seaport and an international airport.

[Later investigation found that Mt. Pinokis is located in the Lison Valley on the Zamboanga Peninsula, about 170 km NE of Zamboanga City and 30 km NW of Pagadian City. It is adjacent to the two peaks of the Susong Dalaga (Maiden's Breast) and near Mt. Sugarloaf.]

References. Newman, S., 1997, Earthweek, a diary of the planet (week ending 12 September): syndicated newspaper column (URL: http://www.earthweek.com/).

Manila Bulletin, 4 Sept. 1997, Dante's Peak (URL: http://www.mb.com.ph/).

Simkin, T., and Siebert, L., 1994, Volcanoes of the world, 2nd edition: Geoscience Press in association with the Smithsonian Institution Global Volcanism Program, Tucson AZ, 368 p.

Information Contacts: Emmanuel G. Ramos, Deputy Director, Philippine Institute of Volcanology and Seismology, Department of Science and Technology, PHIVOLCS Building, C. P. Garcia Ave., University of the Philippines, Diliman campus, Quezon City, Philippines.


False Report of Somalia Eruption (Somalia) — December 1997

False Report of Somalia Eruption

Somalia

3.25°N, 41.667°E; summit elev. 500 m

All times are local (unless otherwise noted)


Press reports of Somalia's first historical eruption were likely in error

Xinhua News Agency filed a news report on 27 February under the headline "Volcano erupts in Somalia" but the veracity of the story now appears doubtful. The report disclosed the volcano's location as on the W side of the Gedo region, an area along the Ethiopian border just NE of Kenya. The report had relied on the commissioner of the town of Bohol Garas (a settlement described as 40 km NE of the main Al-Itihad headquarters of Luq town) and some or all of the information was relayed by journalists through VHF radio. The report claimed the disaster "wounded six herdsmen" and "claimed the lives of 290 goats grazing near the mountain when the incident took place." Further descriptions included such statements as "the volcano which erupted two days ago [25 February] has melted down the rocks and sand and spread . . . ."

Giday WoldeGabriel returned from three weeks of geological fieldwork in SW Ethiopia, near the Kenyan border, on 25 August. During his time there he inquired of many people, including geologists, if they had heard of a Somalian eruption in the Gedo area; no one had heard of the event. WoldeGabriel stated that he felt the news report could have described an old mine or bomb exploding. Heavy fighting took place in the Gedo region during the Ethio-Somalian war of 1977. Somalia lacks an embassy in Washington DC; when asked during late August, Ayalaw Yiman, an Ethiopian embassy staff member in Washington DC also lacked any knowledge of a Somalian eruption.

A Somalian eruption would be significant since the closest known Holocene volcanoes occur in the central Ethiopian segment of the East African rift system S of Addis Ababa, ~500 km NW of the Gedo area. These Ethiopian rift volcanoes include volcanic fields, shield volcanoes, cinder cones, and stratovolcanoes.

Information Contacts: Xinhua News Agency, 5 Sharp Street West, Wanchai, Hong Kong; Giday WoldeGabriel, EES-1/MS D462, Geology-Geochemistry Group, Los Alamos National Laboratory, Los Alamos, NM 87545; Ayalaw Yiman, Ethiopian Embassy, 2134 Kalorama Rd. NW, Washington DC 20008.


False Report of Sea of Marmara Eruption (Turkey) — November 1999

False Report of Sea of Marmara Eruption

Turkey

40.683°N, 29.1°E; summit elev. 0 m

All times are local (unless otherwise noted)


UFO adherent claims new volcano in Sea of Marmara

Following the Ms 7.8 earthquake in Turkey on 17 August (BGVN 24:08) an Email message originating in Turkey was circulated, claiming that volcanic activity was observed coincident with the earthquake and suggesting a new (magmatic) volcano in the Sea of Marmara. For reasons outlined below, and in the absence of further evidence, editors of the Bulletin consider this a false report.

The report stated that fishermen near the village of Cinarcik, at the E end of the Sea of Marmara "saw the sea turned red with fireballs" shortly after the onset of the earthquake. They later found dead fish that appeared "fried." Their nets were "burned" while under water and contained samples of rocks alleged to look "magmatic."

No samples of the fish were preserved. A tectonic scientist in Istanbul speculated that hot water released by the earthquake from the many hot springs along the coast in that area may have killed some fish (although they would be boiled rather than fried).

The phenomenon called earthquake lights could explain the "fireballs" reportedly seen by the fishermen. Such effects have been reasonably established associated with large earthquakes, although their origin remains poorly understood. In addition to deformation-triggered piezoelectric effects, earthquake lights have sometimes been explained as due to the release of methane gas in areas of mass wasting (even under water). Omlin and others (1999), for example, found gas hydrate and methane releases associated with mud volcanoes in coastal submarine environments.

The astronomer and author Thomas Gold (Gold, 1998) has a website (Gold, 2000) where he presents a series of alleged quotes from witnesses of earthquakes. We include three such quotes here (along with Gold's dates, attributions, and other comments):

(A) Lima, 30 March 1828. "Water in the bay 'hissed as if hot iron was immersed in it,' bubbles and dead fish rose to the surface, and the anchor chain of HMS Volage was partially fused while lying in the mud on the bottom." (Attributed to Bagnold, 1829; the anchor chain is reported to be on display in the London Navy Museum.)

(B) Romania, 10 November 1940. ". . . a thick layer like a translucid gas above the surface of the soil . . . irregular gas fires . . . flames in rhythm with the movements of the soil . . . flashes like lightning from the floor to the summit of Mt Tampa . . . flames issuing from rocks, which crumbled, with flashes also issuing from non-wooded mountainsides." (Phrases used in eyewitness accounts collected by Demetrescu and Petrescu, 1941).

(C) Sungpan-Pingwu (China), 16, 22, and 23 August 1976. "From March of 1976, various large anomalies were observed over a broad region. . . . At the Wanchia commune of Chungching County, outbursts of natural gas from rock fissures ignited and were difficult to extinguish even by dumping dirt over the fissures. . . . Chu Chieh Cho, of the Provincial Seismological Bureau, related personally seeing a fireball 75 km from the epicenter on the night of 21 July while in the company of three professional seismologists."

Yalciner and others (1999) made a study of coastal areas along the Sea of Marmara after the Izmet earthquake. They found evidence for one or more tsunamis with maximum runups of 2.0-2.5 m. Preliminary modeling of the earthquake's response failed to reproduce the observed runups; the areas of maximum runup instead appeared to correspond most closely with several local mass-failure events. This observation together with the magnitude of the earthquake, and bottom soundings from marine geophysical teams, suggested mass wasting may have been fairly common on the floor of the Sea of Marmara.

Despite a wide range of poorly understood, dramatic processes associated with earthquakes (Izmet 1999 apparently included), there remains little evidence for volcanism around the time of the earthquake. The nearest Holocene volcano lies ~200 km SW of the report location. Neither Turkish geologists nor scientists from other countries in Turkey to study the 17 August earthquake reported any volcanism. The report said the fisherman found "magmatic" rocks; it is unlikely they would be familiar with this term.

The motivation and credibility of the report's originator, Erol Erkmen, are unknown. Certainly, the difficulty in translating from Turkish to English may have caused some problems in understanding. Erkmen is associated with a website devoted to reporting UFO activity in Turkey. Photographs of a "magmatic rock" sample were sent to the Bulletin, but they only showed dark rocks photographed devoid of a scale on a featureless background. The rocks shown did not appear to be vesicular or glassy. What was most significant to Bulletin editors was the report author's progressive reluctance to provide samples or encourage follow-up investigation with local scientists. Without the collaboration of trained scientists on the scene this report cannot be validated.

References. Omlin, A, Damm, E., Mienert, J., and Lukas, D., 1999, In-situ detection of methane releases adjacent to gas hydrate fields on the Norwegian margin: (Abstract) Fall AGU meeting 1999, Eos, American Geophysical Union.

Yalciner, A.C., Borrero, J., Kukano, U., Watts, P., Synolakis, C. E., and Imamura, F., 1999, Field survey of 1999 Izmit tsunami and modeling effort of new tsunami generation mechanism: (Abstract) Fall AGU meeting 1999, Eos, American Geophysical Union.

Gold, T., 1998, The deep hot biosphere: Springer Verlag, 256 p., ISBN: 0387985468.

Gold, T., 2000, Eye-witness accounts of several major earthquakes (URL: http://www.people.cornell.edu/ pages/tg21/eyewit.html).

Information Contacts: Erol Erkmen, Tuvpo Project Alp.


Har-Togoo (Mongolia) — May 2003

Har-Togoo

Mongolia

48.831°N, 101.626°E; summit elev. 1675 m

All times are local (unless otherwise noted)


Fumaroles and minor seismicity since October 2002

In December 2002 information appeared in Mongolian and Russian newspapers and on national TV that a volcano in Central Mongolia, the Har-Togoo volcano, was producing white vapors and constant acoustic noise. Because of the potential hazard posed to two nearby settlements, mainly with regard to potential blocking of rivers, the Director of the Research Center of Astronomy and Geophysics of the Mongolian Academy of Sciences, Dr. Bekhtur, organized a scientific expedition to the volcano on 19-20 March 2003. The scientific team also included M. Ulziibat, seismologist from the same Research Center, M. Ganzorig, the Director of the Institute of Informatics, and A. Ivanov from the Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences.

Geological setting. The Miocene Har-Togoo shield volcano is situated on top of a vast volcanic plateau (figure 1). The 5,000-year-old Khorog (Horog) cone in the Taryatu-Chulutu volcanic field is located 135 km SW and the Quaternary Urun-Dush cone in the Khanuy Gol (Hanuy Gol) volcanic field is 95 km ENE. Pliocene and Quaternary volcanic rocks are also abundant in the vicinity of the Holocene volcanoes (Devyatkin and Smelov, 1979; Logatchev and others, 1982). Analysis of seismic activity recorded by a network of seismic stations across Mongolia shows that earthquakes of magnitude 2-3.5 are scattered around the Har-Togoo volcano at a distance of 10-15 km.

Figure (see Caption) Figure 1. Photograph of the Har-Togoo volcano viewed from west, March 2003. Courtesy of Alexei Ivanov.

Observations during March 2003. The name of the volcano in the Mongolian language means "black-pot" and through questioning of the local inhabitants, it was learned that there is a local myth that a dragon lived in the volcano. The local inhabitants also mentioned that marmots, previously abundant in the area, began to migrate westwards five years ago; they are now practically absent from the area.

Acoustic noise and venting of colorless warm gas from a small hole near the summit were noticed in October 2002 by local residents. In December 2002, while snow lay on the ground, the hole was clearly visible to local visitors, and a second hole could be seen a few meters away; it is unclear whether or not white vapors were noticed on this occasion. During the inspection in March 2003 a third hole was seen. The second hole is located within a 3 x 3 m outcrop of cinder and pumice (figure 2) whereas the first and the third holes are located within massive basalts. When close to the holes, constant noise resembled a rapid river heard from afar. The second hole was covered with plastic sheeting fixed at the margins, but the plastic was blown off within 2-3 seconds. Gas from the second hole was sampled in a mechanically pumped glass sampler. Analysis by gas chromatography, performed a week later at the Institute of the Earth's Crust, showed that nitrogen and atmospheric air were the major constituents.

Figure (see Caption) Figure 2. Photograph of the second hole sampled at Har-Togoo, with hammer for scale, March 2003. Courtesy of Alexei Ivanov.

The temperature of the gas at the first, second, and third holes was +1.1, +1.4, and +2.7°C, respectively, while air temperature was -4.6 to -4.7°C (measured on 19 March 2003). Repeated measurements of the temperatures on the next day gave values of +1.1, +0.8, and -6.0°C at the first, second, and third holes, respectively. Air temperature was -9.4°C. To avoid bias due to direct heating from sunlight the measurements were performed under shadow. All measurements were done with Chechtemp2 digital thermometer with precision of ± 0.1°C and accuracy ± 0.3°C.

Inside the mouth of the first hole was 4-10-cm-thick ice with suspended gas bubbles (figure 5). The ice and snow were sampled in plastic bottles, melted, and tested for pH and Eh with digital meters. The pH-meter was calibrated by Horiba Ltd (Kyoto, Japan) standard solutions 4 and 7. Water from melted ice appeared to be slightly acidic (pH 6.52) in comparison to water of melted snow (pH 7.04). Both pH values were within neutral solution values. No prominent difference in Eh (108 and 117 for ice and snow, respectively) was revealed.

Two digital short-period three-component stations were installed on top of Har-Togoo, one 50 m from the degassing holes and one in a remote area on basement rocks, for monitoring during 19-20 March 2003. Every hour 1-3 microseismic events with magnitude <2 were recorded. All seismic events were virtually identical and resembled A-type volcano-tectonic earthquakes (figure 6). Arrival difference between S and P waves were around 0.06-0.3 seconds for the Har-Togoo station and 0.1-1.5 seconds for the remote station. Assuming that the Har-Togoo station was located in the epicentral zone, the events were located at ~1-3 km depth. Seismic episodes similar to volcanic tremors were also recorded (figure 3).

Figure (see Caption) Figure 3. Examples of an A-type volcano-tectonic earthquake and volcanic tremor episodes recorded at the Har-Togoo station on 19 March 2003. Courtesy of Alexei Ivanov.

Conclusions. The abnormal thermal and seismic activities could be the result of either hydrothermal or volcanic processes. This activity could have started in the fall of 2002 when they were directly observed for the first time, or possibly up to five years earlier when marmots started migrating from the area. Further studies are planned to investigate the cause of the fumarolic and seismic activities.

At the end of a second visit in early July, gas venting had stopped, but seismicity was continuing. In August there will be a workshop on Russian-Mongolian cooperation between Institutions of the Russian and Mongolian Academies of Sciences (held in Ulan-Bator, Mongolia), where the work being done on this volcano will be presented.

References. Devyatkin, E.V. and Smelov, S.B., 1979, Position of basalts in sequence of Cenozoic sediments of Mongolia: Izvestiya USSR Academy of Sciences, geological series, no. 1, p. 16-29. (In Russian).

Logatchev, N.A., Devyatkin, E.V., Malaeva, E.M., and others, 1982, Cenozoic deposits of Taryat basin and Chulutu river valley (Central Hangai): Izvestiya USSR Academy of Sciences, geological series, no. 8, p. 76-86. (In Russian).

Geologic Background. The Miocene Har-Togoo shield volcano, also known as Togoo Tologoy, is situated on top of a vast volcanic plateau. The 5,000-year-old Khorog (Horog) cone in the Taryatu-Chulutu volcanic field is located 135 km SW and the Quaternary Urun-Dush cone in the Khanuy Gol (Hanuy Gol) volcanic field is 95 km ENE. Analysis of seismic activity recorded by a network of seismic stations across Mongolia shows that earthquakes of magnitude 2-3.5 are scattered around the Har-Togoo volcano at a distance of 10-15 km.

Information Contacts: Alexei V. Ivanov, Institute of the Earth Crust SB, Russian Academy of Sciences, Irkutsk, Russia; Bekhtur andM. Ulziibat, Research Center of Astronomy and Geophysics, Mongolian Academy of Sciences, Ulan-Bator, Mongolia; M. Ganzorig, Institute of Informatics MAS, Ulan-Bator, Mongolia.


Elgon (Uganda) — December 2005

Elgon

Uganda

1.136°N, 34.559°E; summit elev. 3885 m

All times are local (unless otherwise noted)


False report of activity; confusion caused by burning dung in a lava tube

An eruption at Mount Elgon was mistakenly inferred when fumes escaped from this otherwise quiet volcano. The fumes were eventually traced to dung burning in a lava-tube cave. The cave is home to, or visited by, wildlife ranging from bats to elephants. Mt. Elgon (Ol Doinyo Ilgoon) is a stratovolcano on the SW margin of a 13 x 16 km caldera that straddles the Uganda-Kenya border 140 km NE of the N shore of Lake Victoria. No eruptions are known in the historical record or in the Holocene.

On 7 September 2004 the web site of the Kenyan newspaper The Daily Nation reported that villagers sighted and smelled noxious fumes from a cave on the flank of Mt. Elgon during August 2005. The villagers' concerns were taken quite seriously by both nations, to the extent that evacuation of nearby villages was considered.

The Daily Nation article added that shortly after the villagers' reports, Moses Masibo, Kenya's Western Province geology officer visited the cave, confirmed the villagers observations, and added that the temperature in the cave was 170°C. He recommended that nearby villagers move to safer locations. Masibo and Silas Simiyu of KenGens geothermal department collected ashes from the cave for testing.

Gerald Ernst reported on 19 September 2004 that he spoke with two local geologists involved with the Elgon crisis from the Geology Department of the University of Nairobi (Jiromo campus): Professor Nyambok and Zacharia Kuria (the former is a senior scientist who was unable to go in the field; the latter is a junior scientist who visited the site). According to Ernst their interpretation is that somebody set fire to bat guano in one of the caves. The fire was intense and probably explains the vigorous fuming, high temperatures, and suffocated animals. The event was also accompanied by emissions of gases with an ammonia odor. Ernst noted that this was not surprising considering the high nitrogen content of guano—ammonia is highly toxic and can also explain the animal deaths. The intense fumes initially caused substantial panic in the area.

It was Ernst's understanding that the authorities ordered evacuations while awaiting a report from local scientists, but that people returned before the report reached the authorities. The fire presumably prompted the response of local authorities who then urged the University geologists to analyze the situation. By the time geologists arrived, the fuming had ceased, or nearly so. The residue left by the fire and other observations led them to conclude that nothing remotely related to a volcanic eruption had occurred.

However, the incident emphasized the problem due to lack of a seismic station to monitor tectonic activity related to a local triple junction associated with the rift valley or volcanic seismicity. In response, one seismic station was moved from S Kenya to the area of Mt. Elgon so that local seismicity can be monitored in the future.

Information Contacts: Gerald Ernst, Univ. of Ghent, Krijgslaan 281/S8, B-9000, Belgium; Chris Newhall, USGS, Univ. of Washington, Dept. of Earth & Space Sciences, Box 351310, Seattle, WA 98195-1310, USA; The Daily Nation (URL: http://www.nationmedia.com/dailynation/); Uganda Tourist Board (URL: http://www.visituganda.com/).