Logo link to homepage

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

Kuchinoerabujima (Japan) Eruption and ash plumes begin on 11 January 2020 and continue through April 2020

Soputan (Indonesia) Minor ash emissions during 23 March and 2 April 2020

Heard (Australia) Eruptive activity including a lava flow during October 2019-April 2020

Kikai (Japan) Ash explosion on 29 April 2020

Fuego (Guatemala) Ongoing ash explosions, block avalanches, and intermittent lava flows

Ebeko (Russia) Frequent moderate explosions, ash plumes, and ashfall continue, December 2019-May 2020

Piton de la Fournaise (France) Fissure eruptions in February and April 2020 included lava fountains and flows

Sabancaya (Peru) Daily explosions with ash emissions, large SO2 flux, ongoing thermal anomalies, December 2019-May 2020

Sheveluch (Russia) Lava dome growth and thermal anomalies continue through April 2020, but few ash explosions

Dukono (Indonesia) Numerous ash explosions continue through March 2020

Etna (Italy) Strombolian explosions and ash emissions continue, October 2019-March 2020

Merapi (Indonesia) Explosions produced ash plumes, ashfall, and pyroclastic flows during October 2019-March 2020



Kuchinoerabujima (Japan) — May 2020 Citation iconCite this Report

Kuchinoerabujima

Japan

30.443°N, 130.217°E; summit elev. 657 m

All times are local (unless otherwise noted)


Eruption and ash plumes begin on 11 January 2020 and continue through April 2020

Kuchinoerabujima encompasses a group of young stratovolcanoes located in the northern Ryukyu Islands. All historical eruptions have originated from the Shindake cone, with the exception of a lava flow that originated from the S flank of the Furudake cone. The most recent previous eruptive period took place during October 2018-February 2019 and primarily consisted of weak explosions, ash plumes, and ashfall. The current eruption began on 11 January 2020 after nearly a year of dominantly gas-and-steam emissions. Volcanism for this reporting period from March 2019 to April 2020 included explosions, ash plumes, SO2 emissions, and ashfall. The primary source of information for this report comes from monthly and annual reports from the Japan Meteorological Agency (JMA) and advisories from the Tokyo Volcanic Ash Advisory Center (VAAC). Activity has been limited to Kuchinoerabujima's Shindake Crater.

Volcanism at Kuchinoerabujima was relatively low during March through December 2019, according to JMA. During this time, SO2 emissions ranged from 100 to 1,000 tons/day. Gas-and-steam emissions were frequently observed throughout the entire reporting period, rising to a maximum height of 1.1 km above the crater on 13 December 2019. Satellite imagery from Sentinel-2 showed gas-and-steam and occasional ash emissions rising from the Shindake crater throughout the reporting period (figure 7). Though JMA reported thermal anomalies occurring on 29 January and continuing through late April 2020, Sentinel-2 imagery shows the first thermal signature appearing on 26 April.

Figure (see Caption) Figure 7. Sentinel-2 thermal satellite images showed gas-and-steam and ash emissions rising from Kuchinoerabujima. Some ash deposits can be seen on 6 February 2020 (top right). A thermal anomaly appeared on 26 April 2020 (bottom right). Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images courtesy of Sentinel Hub Playground.

An eruption on 11 January 2020 at 1505 ejected material 300 m from the crater and produced ash plumes that rose 2 km above the crater rim, extending E, according to JMA. The eruption continued through 12 January until 0730. The resulting ash plumes rose 400 m above the crater, drifting SW while the SO2 emissions measured 1,300 tons/day. Ashfall was reported on Yakushima Island (15 km E). Minor eruptive activity was reported during 17-20 January which produced gray-white plumes that rose 300-500 m above the crater. On 23 January, seismicity increased, and an eruption produced an ash plume that rose 1.2 km altitude, according to a Tokyo VAAC report, resulting in ashfall 2 km NE of the crater. A small explosion was detected on 24 January, followed by an increase in the number of earthquakes during 25-26 January (65-71 earthquakes per day were registered). Another small eruptive event detected on 27 January at 0148 was accompanied by a volcanic tremor and a change in tilt data. During the month of January, some inflation was detected at the base on the volcano and a total of 347 earthquakes were recorded. The SO2 emissions ranged from 200-1,600 tons/day.

An eruption on 1 February 2020 produced an eruption column that rose less than 1 km altitude and extended SE and SW (figure 8), according to the Tokyo VAAC report. On 3 February, an eruption from the Shindake crater at 0521 produced an ash plume that rose 7 km above the crater and ejected material as far as 600 m away. As a result, a pyroclastic flow formed, traveling 900-1,500 m SW. The previous pyroclastic flow that was recorded occurred on 29 January 2019. Ashfall was confirmed in the N part of Yakushima Island with a large amount in Miyanoura (32 km ESE) and southern Tanegashima. The SO2 emissions measured 1,700 tons/day during this event.

Figure (see Caption) Figure 8. Webcam images from the Honmura west surveillance camera of an ash plume rising from Kuchinoerabujima on 1 February 2020. Courtesy of JMA (Weekly bulletin report 509, February 2020).

Intermittent small eruptive events occurred during 5-9 February; field observations showed a large amount of ashfall on the SE flank which included lapilli that measured up to 2 cm in diameter. Additionally, thermal images showed 5-km-long pyroclastic flow deposits on the SW flank. An eruption on 9 February produced an ash plume that rose 1.2 km altitude, drifting SE. On 13 February a small eruption was detected in the Shindake crater at 1211, producing gray-white plumes that rose 300 m above the crater, drifting NE. Small eruptive events also occurred during 20-21 February, resulting in gas-and-steam emissions that rose 200 m above the crater. During the month of February, some horizontal extension was observed since January 2020 using GNSS data. The total number of earthquakes during this month drastically increased to 1225 compared to January. The SO2 emissions ranged from 300-1,700 tons/day.

By 2 March 2020, seismicity decreased, and activity declined. Gas-and-steam emissions continued infrequently for the duration of the reporting period. The SO2 emissions during March ranged from 700-2,100 tons/day, the latter of which occurred on 15 March. Seismicity increased again on 27 March. During 5-8 April 2020, small eruptive events were detected, generating ash plumes that rose 900 m above the crater (figure 9). The SO2 emissions on 6 April reached 3,200 tons/day, the maximum measurement for this reporting period. These small eruptive events continued from 13-20 and 23-25 April within the Shindake crater, producing gray-white plumes that rose 300-800 m above the crater.

Figure (see Caption) Figure 9. Webcam images from the Honmura Nishi (top) and Honmura west (bottom) surveillance cameras of ash plumes rising from Kuchinoerabujima on 6 March and 5 April 2020. Courtesy of JMA (Weekly bulletin report 509, March and April 2020).

Geologic Background. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. The youngest cone, centrally-located Shindake, formed after the NW side of Furudake was breached by an explosion. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Soputan (Indonesia) — May 2020 Citation iconCite this Report

Soputan

Indonesia

1.112°N, 124.737°E; summit elev. 1785 m

All times are local (unless otherwise noted)


Minor ash emissions during 23 March and 2 April 2020

Soputan is a stratovolcano located in the northern arm of Sulawesi Island, Indonesia. Previous eruptive periods were characterized by ash explosions, lava flows, and Strombolian eruptions. The most recent eruption occurred during October-December 2018, which consisted mostly of ash plumes and some summit incandescence (BGVN 44:01). This report updates information for January 2019-April 2020 characterized by two ash plumes and gas-and-steam emissions. The primary source of information come from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and the Darwin Volcanic Ash Advisory Center (VAAC).

Activity during January 2019-April 2020 was relatively low; three faint thermal anomalies were observed at the summit at Soputan in satellite imagery for a total of three days on 2 and 4 January, and 1 October 2019 (figure 17). The MIROVA (Middle InfraRed Observation of Volcanic Activity) based on analysis of MODIS data detected 12 distal hotspots and six low-power hotspots within 5 km of the summit during August to early October 2019. A single distal thermal hotspot was detected in early March 2020. In March, activity primarily consisted of white to gray gas-and-steam plumes that rose 20-100 m above the crater, according to PVMBG. The Darwin VAAC issued a notice on 23 March 2020 that reported an ash plume rose to 4.3 km altitude; minor ash emissions had been visible in a webcam image the previous day (figure 18). A second notice was issued on 2 April, where an ash plume was observed rising 2.1 km altitude and drifting W.

Figure (see Caption) Figure 17. Sentinel-2 thermal satellite imagery detected a total of three thermal hotspots (bright yellow-orange) at the summit of Soputan on 2 and 4 January and 1 October 2019. Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 18. Minor ash emissions were seen rising from Soputan on 22 March 2020. Courtesy of MAGMA Indonesia.

Geologic Background. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.

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/); 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).


Heard (Australia) — May 2020 Citation iconCite this Report

Heard

Australia

53.106°S, 73.513°E; summit elev. 2745 m

All times are local (unless otherwise noted)


Eruptive activity including a lava flow during October 2019-April 2020

Heard Island is located on the Kerguelen Plateau in the southern Indian Ocean and contains Big Ben, a snow-covered stratovolcano with intermittent volcanism reported since 1910. Due to its remote location, visual observations are rare; therefore, thermal anomalies and hotspots detected by satellite-based instruments are the primary source of information. This report updates activity from October 2019 to April 2020.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed three prominent periods of strong thermal anomaly activity during this reporting period: late October 2019, December 2019, and the end of April 2020 (figure 41). These thermal anomalies were relatively strong and occurred within 5 km of the summit. Similarly, the MODVOLC algorithm reported a total of six thermal hotspots during 28 October, 1 November 2019, and 26 April 2020.

Figure (see Caption) Figure 41. Thermal anomalies at Heard from 29 April 2019 through April 2020 as recorded by the MIROVA system (Log Radiative Power) were strong and frequent in late October, during December 2019, and at the end of April 2020. Courtesy of MIROVA.

Six thermal satellite images ranging from late October 2019 to late March showed evidence of active lava at the summit (figure 42). These images show hot material, possibly a lava flow, extending SW from the summit; a hotspot also remained at the summit. Cloud cover was pervasive during the majority of this reporting period, especially in April 2020, though gas-and-steam emissions were visible on 25 April through the clouds.

Figure (see Caption) Figure 42. Thermal satellite images of Heard Island’s Big Ben showing strong thermal signatures representing a lava flow in the SW direction from 28 October to 17 December 2019. These thermal anomalies are located NE from Mawson Peak. A faint thermal anomaly is also captured on 26 March 2020. Satellite images with atmospheric penetration (bands 12, 11, and 8A), courtesy of Sentinel Hub Playground.

Geologic Background. Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben because of its extensive ice cover. The historically active Mawson Peak forms the island's high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported at this isolated volcano, but observations are infrequent and additional activity may have occurred.

Information Contacts: 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Kikai (Japan) — May 2020 Citation iconCite this Report

Kikai

Japan

30.793°N, 130.305°E; summit elev. 704 m

All times are local (unless otherwise noted)


Ash explosion on 29 April 2020

The Kikai caldera is located at the N end of Japan’s Ryukyu Islands and has been recently characterized by intermittent ash emissions and limited ashfall in nearby communities. On Satsuma Iwo Jima island, the larger subaerial fragment of the Kikai caldera, there was a single explosion with gas-and-steam and ash emissions on 2 November 2019, accompanied by nighttime incandescence (BGVN 45:02). This report covers volcanism from January 2020 through April 2020 with a single-day eruption occurring on 29 April based on reports from the Japan Meteorological Agency (JMA).

Since the last one-day eruption on 2 November 2019, volcanism at Kikai has been relatively low and primarily consisted of 107-170 earthquakes per month and intermittent white gas-and-steam emissions rising up to 1.3 km above the crater summit. Intermittent weak hotspots were observed at night in the summit in Sentinel-2 thermal satellite imagery and webcams, according to JMA (figures 14 and 15).

Figure (see Caption) Figure 14. Weak thermal hotspots (bright yellow-orange) were observed on 7 January (top) and 6 April 2020 (bottom) at Satsuma Iwo Jima (Kikai). Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 15. Incandescence at night on 10 January 2020 was observed at Satsuma Iwo Jima (Kikai) in the Iodake crater with the Iwanogami webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, January 2nd year of Reiwa [2020]).

Weak incandescence continued in April 2020. JMA reported SO2 measurements during April were 400-2000 tons/day. A brief eruption in the Iodake crater on 29 April 2020 at 0609 generated a gray-white ash plume that rose 1 km above the crater (figure 16). No ashfall or ejecta was observed after the eruption on 29 April.

Figure (see Caption) Figure 16. The Iwanogami webcam captured a brief gray-white ash and steam plume rising above the Iodake crater rim on Satsuma Iwo Jima (Kikai) on 29 April 2020 at 0609 local time. The plume rose 1 km above the crater summit. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, April 2nd year of Reiwa [2020]).

Geologic Background. Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. It was the source of one of the world's largest Holocene eruptions about 6,300 years ago when rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km E of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Fuego (Guatemala) — April 2020 Citation iconCite this Report

Fuego

Guatemala

14.473°N, 90.88°W; summit elev. 3763 m

All times are local (unless otherwise noted)


Ongoing ash explosions, block avalanches, and intermittent lava flows

Fuego is a stratovolcano in Guatemala that has been erupting since 2002 with historical eruptions that date back to 1531. Volcanism is characterized by major ashfalls, pyroclastic flows, lava flows, and lahars. The previous report (BGVN 44:10) detailed activity that included multiple ash explosions, ash plumes, ashfall, active lava flows, and block avalanches. This report covers this continuing activity from October 2019 through March 2020 and consists of ash plumes, ashfall, incandescent ejecta, block avalanches, and lava flows. The primary source of information comes from the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), the Washington Volcanic Ash Advisory Center (VAAC), and various satellite data.

Summary of activity October 2019-March 2020. Daily activity persisted throughout October 2019-March 2020 (table 20) with multiple ash explosions recorded every hour, ash plumes that rose to a maximum of 4.8 km altitude each month drifting in multiple directions, incandescent ejecta reaching a 500 m above the crater resulting in block avalanches traveling down multiple drainages, and ashfall affecting communities in multiple directions. The highest rate of explosions occurred on 7 November with up to 25 per hour. Dominantly white fumaroles occurred frequently throughout this reporting period, rising to a maximum altitude of 4.5 km and drifting in multiple directions. Intermittent lava flows that reached a maximum length of 1.2 km were observed each month in the Seca (Santa Teresa) and Ceniza drainages (figure 128), but rarely in the Trinidad drainage. Thermal activity increased slightly in frequency and strength in late October and remained relatively consistent through mid-March as seen in the MIROVA analysis of MODIS satellite data (figure 129).

Table 20. Activity summary by month for Fuego with information compiled from INSIVUMEH daily reports.

Month Ash plume heights (km) Ash plume distance (km) and direction Drainages affected by avalanche blocks Villages reporting ashfall
Oct 2019 4.3-4.8 km 10-25 km, W-SW-S-NW Seca, Taniluyá, Ceniza, Trinidad, El Jute, Honda, and Las Lajas Panimaché I and II, Morelia, Santa Sofía, Porvenir, Finca Palo Verde, La Rochela, San Andrés Osuna, Sangre de Cristo, and San Pedro Yepocapa
Nov 2019 4.0-4.8 km 10-20 km, W-SW-S-NW Seca, Taniluyá, Trinidad, Las Lajas, Honda, and Ceniza Panimaché I and II, Morelia, Santa Sofía, Porvenir, Sangre de Cristo, Finca Palo Verde, and San Pedro Yepocapa
Dec 2019 4.2-4.8 km 10-25 km, W-SW-S-SE-N-NE Seca, Taniluya, Ceniza, Trinidad, and Las Lajas Morelia, Santa Sofía, Finca Palo Verde, El Porvenir, Sangre de Cristo, San Pedro Yepocapa, Panimaché I and II, La Rochela, and San Andrés Osuna
Jan 2020 4.3-4.8 km 10-25 km, W-SW-S-N-NE-E Seca, Ceniza, Taniluyá, Trinidad, Honda, and Las Lajas Morelia, Santa Sofía, Sangre de Cristo, San Pedro Yepocapa, Panimaché I and II, El Porvenir, Finca Palo Verde, Rodeo, La Rochela, Alotenango, El Zapote, Trinidad, La Reina, Ceilán
Feb 2020 4.3-4.8 km 8-25 km, W-SW-S-SE-E-NE-N-NW Seca, Ceniza, Taniluya, Trinidad, Las Lajas, Honda, La Rochela, El Zapote, and San Andrés Osuna Panimache I and II, Morelia, Santa Sofia, Sangre de Cristo, San Pedro Yepocapa, Rodeo, La Reina, Alotenango, Yucales, Siquinalá, Santa Lucia, El Porvenir, Finca Los Tarros, La Soledad, Buena Vista, La Cruz, Pajales, San Miguel Dueñas, Ciudad Vieja, San Miguel Escobar, San Pedro las Huertas, Antigua, La Rochela, and San Andrés Osuna
Mar 2020 4.3-4.8 km 10-23 km, W-SW-S-SE-N-NW Seca, Ceniza, Trinidad, Taniluyá, Las Lajas, Honda, La Rochela, El Zapote, San Andrés Osuna, Morelia, Panimache, and Santa Sofia San Andrés Osuna, La Rochela, El Rodeo, Chuchu, Panimache I and II, Santa Sofia, Morelia, Finca Palo Verde, El Porvenir, Sangre de Cristo, La Cruz, San Pedro Yepocapa, La Conchita, La Soledad, Alotenango, Aldea la Cruz, Acatenango, Ceilan, Taniluyá, Ceniza, Las Lajas, Trinidad, Seca, and Honda
Figure (see Caption) Figure 128. Sentinel-2 thermal satellite images of Fuego between 21 November 2019 and 20 March 2020 showing lava flows (bright yellow-orange) traveling generally S and W from the crater summit. An ash plume can also be seen on 21 November 2019, accompanying the lava flow. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 129. Thermal activity at Fuego increased in frequency and strength (log radiative power) in late October 2019 and remained relatively consistent through February 2020. In early March, there is a small decrease in thermal power, followed by a short pulse of activity and another decline. Courtesy of MIROVA.

Activity during October-December 2019. Activity in October 2019 consisted of 6-20 ash explosions per hour; ash plumes rose to 4.8 km altitude, drifting up to 25 km in multiple directions, resulting in ashfall in Panimaché I and II (8 km SW), Morelia (9 km SW), San Pedro Yepocapa (8 km NW), Sangre de Cristo (8 km WSW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Finca Palo Verde, La Rochela and San Andrés Osuna. The Washington VAAC issued multiple aviation advisories for a total of nine days in October. Continuous white gas-and-steam plumes reached 4.1-4.4 km altitude drifting generally W. Weak SO2 emissions were infrequently observed in satellite imagery during October and January 2020 (figure 130) Incandescent ejecta was frequently observed rising 200-400 m above the summit, which generated block avalanches that traveled down the Seca (W), Taniluyá (SW), Ceniza (SSW), Trinidad (S), El Jute, Honda, and Las Lajas (SE) drainages. During 3-7 October lahars descended the Ceniza, El Mineral, and Seca drainages, carrying tree branches, tree trunks, and blocks 1-3 m in diameter. During 6-8 and 13 October, active lava flows traveled up to 200 m down the Seca drainage.

Figure (see Caption) Figure 130. Weak SO2 emissions were observed rising from Fuego using the TROPOMI instrument on the Sentinel-5P satellite. Top left: 17 October 2019. Top right: 17 November 2019. Bottom left: 20 January 2020. Bottom right: 22 January 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

During November 2019, the rate of explosions increased to 5-25 per hour, the latter of which occurred on 7 November. The explosions resulted in ash plumes that rose 4-4.8 km altitude, drifting 10-20 km in the W direction. Ashfall was observed in Panimaché I and II, Morelia, Santa Sofía, Porvenir, Sangre de Cristo, Finca Palo Verde, and San Pedro Yepocapa. Multiple Washington VAAC notices were issued for 11 days in November. Continuous white gas-and-steam plumes rose up to 4.5 km altitude drifting generally W. Incandescent ejecta rose 100-500 m above the crater, generating block avalanches in Seca, Taniluyá, Trinidad, Las Lajas, Honda, and Ceniza drainages. Lava flows were observed for a majority of the month into early December measuring 100-900 m long in the Seca and Ceniza drainages.

The number of explosions in December 2019 decreased compared to November, recording 8-19 per hour with incandescent ejecta rising 100-400 m above the crater. The explosions generated block avalanches that traveled in the Seca, Taniluya, Ceniza, Trinidad, and Las Lajas drainages throughout the month. Ash plumes continued to rise above the summit crater to 4.8 km drifting up to 25 km in multiple directions. The Washington VAAC issued multiple daily notices almost daily in December. A continuous lava flow observed during 6-15, 21-22, 24, and 26 November through 9 December measured 100-800 m long in the Seca and Ceniza drainages.

Activity during January-March 2020. Incandescent Strombolian explosions continued daily during January 2020, ejecting material up to 100-500 m above the crater. Ash plumes continued to rise to a maximum altitude of 4.8 km, resulting in ashfall in all directions affecting Morelia, Santa Sofía, Sangre de Cristo, San Pedro Yepocapa, Panimaché I and II, El Porvenir, Finca Palo Verde, Rodeo, La Rochela, Alotenango, El Zapote, Trinidad, La Reina, and Ceilán. The Washington VAAC issued multiple notices for a total of 12 days during January. Block avalanches resulting from the Strombolian explosions traveled down the Seca, Ceniza, Taniluyá, Trinidad, Honda, and Las Lajas drainages. An active lava flow in the Ceniza drainage measured 150-600 m long during 6-10 January.

During February 2020, INSIVUMEH reported a range of 4-16 explosions per hour, accompanied by incandescent material that rose 100-500 m above the crater (figure 131). Block avalanches traveled in the Santa Teresa, Seca, Ceniza, Taniluya, Trinidad, Las Lajas, Honda, La Rochela, El Zapote, and San Andrés Osuna drainages. Ash emissions from the explosions continued to rise 4.8 km altitude, drifting in multiple directions as far as 25 km and resulting in ashfall in the communities of Panimache I and II, Morelia, Santa Sofia, Sangre de Cristo, San Pedro Yepocapa, Rodeo, La Reina, Alotenango, Yucales, Siquinalá, Santa Lucia, El Porvenir, Finca Los Tarros, La Soledad, Buena Vista, La Cruz, Pajales, San Miguel Dueñas, Ciudad Vieja, San Miguel Escobar, San Pedro las Huertas, Antigua, La Rochela, and San Andrés Osuna. Washington VAAC notices were issued almost daily during the month. Lava flows were active in the Ceniza drainage during 13-20, 23-24, and 26-27 February measuring as long as 1.2 km.

Figure (see Caption) Figure 131. Incandescent ejecta rose several hundred meters above the crater of Fuego on 6 February 2020, resulting in block avalanches down multiple drainages. Courtesy of Crelosa.

Daily explosions and incandescent ejecta continued through March 2020, with 8-17 explosions per hour that rose up to 500 m above the crater. Block avalanches from the explosions were observed in the Seca, Ceniza, Trinidad, Taniluyá, Las Lajas, Honda, Santa Teresa, La Rochela, El Zapote, San Andrés Osuna, Morelia, Panimache, and Santa Sofia drainages. Accompanying ash plumes rose 4.8 km altitude, drifting in multiple directions mostly to the W as far as 23 km and resulting in ashfall in San Andrés Osuna, La Rochela, El Rodeo, Chuchu, Panimache I and II, Santa Sofia, Morelia, Finca Palo Verde, El Porvenir, Sangre de Cristo, La Cruz, San Pedro Yepocapa, La Conchita, La Soledad, Alotenango, Aldea la Cruz, Acatenango, Ceilan, Taniluyá, Ceniza, Las Lajas, Trinidad, Seca, and Honda. Multiple Washington VAAC notices were issued for a total of 15 days during March. Active lava flows were observed from 16-21 March in the Trinidad and Ceniza drainages measuring 400-1,200 m long and were accompanied by weak to moderate explosions. By 23 March, active lava flows were no longer observed.

Geologic Background. Volcán Fuego, one of Central America's most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); 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/); 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); Crelosa, 3ra. avenida. 8-66, Zona 14. Colonia El Campo, Guatemala Ciudad de Guatemala (URL: http://crelosa.com/, post at https://www.youtube.com/watch?v=1P4kWqxU2m0&feature=youtu.be).


Ebeko (Russia) — June 2020 Citation iconCite this Report

Ebeko

Russia

50.686°N, 156.014°E; summit elev. 1103 m

All times are local (unless otherwise noted)


Frequent moderate explosions, ash plumes, and ashfall continue, December 2019-May 2020

The current moderate explosive eruption of Ebeko has been ongoing since October 2016, with frequent ash explosions that have reached altitudes of 1.3-6 km (BGVN 42:08, 43:03, 43:06, 43:12, 44:12). Ashfall is common in Severo-Kurilsk, a town of about 2,500 residents 7 km ESE, where the Kamchatka Volcanic Eruptions Response Team (KVERT) monitor the volcano. During the reporting period, December 2019-May 2020, the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

During December 2019-May 2020, frequent explosions generated ash plumes that reached altitudes of 1.5-4.6 km (table 9); reports of ashfall in Severo-Kurilsk were common. Ash explosions in late April caused ashfall in Severo-Kurilsk during 25-30 April (figure 24), and the plume drifted 180 km SE on the 29th. There was also a higher level of activity during the second half of May (figure 25), when plumes drifted up to 80 km downwind.

Table 9. Summary of activity at Ebeko, December 2019-May 2020. S-K is Severo-Kurilsk (7 km ESE of the volcano). TA is thermal anomaly in satellite images. In the plume distance column, only plumes that drifted more than 10 km are indicated. Dates based on UTC times. Data courtesy of KVERT.

Date Plume Altitude (km) Plume Distance Plume Directions Other Observations
30 Nov-05 Dec 2019 3 -- NE, E Intermittent explosions.
06-13 Dec 2019 4 -- E Explosions all week. Ashfall in S-K on 10-12 Dec.
15-17 Dec 2019 3 -- E Explosions. Ashfall in S-K on 16-17 Dec.
22-24 Dec 2019 3 -- NE Explosions.
01-02 Jan 2020 3 30 km N N Explosions. TA over dome on 1 Jan.
03, 05, 09 Jan 2020 2.9 -- NE, SE Explosions. Ashfall in S-K on 8 Jan.
11, 13-14 Jan 2020 3 -- E Explosions. Ashfall in S-K.
19-20 Jan 2020 3 -- E Ashfall in S-K on 19 Jan.
24-31 Jan 2020 4 -- E Explosions.
01-07 Feb 2020 3 -- E, S Explosions all week.
12-13 Feb 2020 1.5 -- E Explosions. Ashfall in S-K.
18-19 Feb 2020 2.3 -- SE Explosions.
21, 25, 27 Feb 2020 2.9 -- S, SE, NE Explosions. Ashfall in S-K on 22 Feb.
01-02, 05 Mar 2020 2 -- S, E Explosions.
08 Mar 2020 2.5 -- NE Explosions.
13, 17 Mar 2020 2.5 -- NE, SE Bursts of gas, steam, and small amount of ash.
24-25 Mar 2020 2.5 -- NE, W Explosions.
29 Mar-02 Apr 2020 2.2 -- NE, E Explosions. Ashfall in S-K on 1 Apr. TA on 30-31 Mar.
04-05, 09 Apr 2020 1.5 -- NE Explosions. TA on 5 Apr.
13 Apr 2020 2.5 -- SE Explosions.
18, 20 Apr 2020 -- -- -- TA on 18, 20 Apr.
24 Apr-01 May 2020 3.5 180 km SE on 29 Apr E, SE Explosions all week. Ashfall in S-K on 25-30 Apr.
01-08 May 2020 2.6 -- E Explosions all week. Ashfall in S-K on 3-5 May. TA on 3 May.
08-15 May 2020 4 -- E Explosions. Ashfall in S-K on 8-12 May. TA during 12-14 May.
14-15, 19-21 May 2020 3.6 80 km SW, S, SE during 14, 20-21 May -- Explosions. TA on same days.
22-29 May 2020 4.6 60 km SE E, SE Explosions all week. Ashfall in S-K on 22, 24 May.
29-31 May 2020 4.5 -- E, S Explosions. TA on 30 May.
Figure (see Caption) Figure 24. Photo of ash explosion at Ebeko at 2110 UTC on 28 April 2020, as viewed from Severo-Kurilsk. Courtesy of KVERT (L. Kotenko).
Figure (see Caption) Figure 25. Satellite image of Ebeko from Sentinel-2 on 27 May 2020, showing a plume drifting SE. Image using natural color rendering (bands 4, 3, 2) courtesy of Sentinel Hub Playground.

Geologic Background. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Information Contacts: 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/); 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Piton de la Fournaise (France) — May 2020 Citation iconCite this Report

Piton de la Fournaise

France

21.244°S, 55.708°E; summit elev. 2632 m

All times are local (unless otherwise noted)


Fissure eruptions in February and April 2020 included lava fountains and flows

Piton de la Fournaise is a massive basaltic shield volcano on the French island of Réunion in the western Indian Ocean. Recent volcanism is characterized by multiple fissure eruptions, lava fountains, and lava flows (BGVN 44:11). The activity during this reporting period of November 2019-April 2020 is consistent with the previous eruption, including lava fountaining and lava flows. Information for this report comes from the Observatoire Volcanologique du Piton de la Fournaise (OVPF) and various satellite data.

Activity during November 2019-January 2020 was relatively low; no eruptive events were detected, according to OVPF. Edifice deformation resumed during the last week in December and continued through January. Seismicity significantly increased in early January, registering 258 shallow earthquakes from 1-16 January. During 17-31 January, the seismicity declined, averaging one earthquake per day.

Two eruptive events took place during February-April 2020. OVPF reported that the first occurred from 10 to 16 February on the E and SE flanks of the Dolomieu Crater. The second took place during 2-6 April. Both eruptive events began with a sharp increase in seismicity accompanied by edifice inflation, followed by a fissure eruption that resulted in lava fountains and lava flows (figure 193). MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed the two eruptive events occurring during February-April 2020 (figure 194). Similarly, the MODVOLC algorithm reported 72 thermal signatures proximal to the summit crater from 12 February to 6 April. Both of these eruptive events were accompanied by SO2 emissions that were detected by the Sentinel-5P/TROPOMI instrument (figures 195 and 196).

Figure (see Caption) Figure 193. Location maps of the lava flows on the E flank at Piton de la Fournaise on 10-16 February 2020 (left) and 2-6 April 2020 (right) as derived from SAR satellite data. Courtesy of OVPF-IPGP, OPGC, LMV (Monthly bulletins of the Piton de la Fournaise Volcanological Observatory, February and April 2020).
Figure (see Caption) Figure 194. Two significant eruptive events at Piton de la Fournaise took place during February-April 2020 as recorded by the MIROVA system (Log Radiative Power). Courtesy of MIROVA.
Figure (see Caption) Figure 195. Images of the SO2 emissions during the February 2020 eruptive event at Piton de la Fournaise detected by the Sentinel-5P/TROPOMI satellite. Top left: 10 February 2020. Top right: 11 February 2020. Bottom left: 13 February 2020. Bottom right: 14 February 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 196. Images of the SO2 emissions during the April 2020 eruptive event at Piton de la Fournaise detected by the Sentinel-5P/TROPOMI satellite. Left: 4 April 2020. Middle: 5 April 2020. Right: 6 April 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

On 10 February 2020 a seismic swarm was detected at 1027, followed by rapid deformation. At 1050, volcanic tremors were recorded, signaling the start of the eruption. Several fissures opened on the E flank of the Dolomieu Crater between the crater rim and at 2,000 m elevation, as observed by an overflight during 1300 and 1330. These fissures were at least 1 km long and produced lava fountains that rose up to 10 m high. Lava flows were also observed traveling E and S to 1,700 m elevation by 1315 (figures 197 and 198). The farthest flow traveled E to an elevation of 1,400 m. Satellite data from HOTVOLC platform (OPGC - University of Auvergne) was used to estimate the peak lava flow rate on 11 February at 10 m3/s. By 13 February only one lava flow that was traveling E below the Marco Crater remained active. OVPF also reported the formation of a cone, measuring 30 m tall, surrounded by three additional vents that produced lava fountains up to 15 m high. On 15 February the volcanic tremors began to decrease at 1400; by 16 February at 1412 the tremors stopped, indicating the end of the eruptive event.

Figure (see Caption) Figure 197. Photo of a lava flow and degassing at Piton de la Fournaise on 10 February 2020. Courtesy of OVPF-IPGP.
Figure (see Caption) Figure 198. Photos of the lava flows at Piton de la Fournaise taken during the February 2020 eruption by Richard Bouchet courtesy of AFP News Service.

Volcanism during the month of March 2020 consisted of low seismicity, including 21 shallow volcanic tremors and near the end of the month, edifice inflation was detected. A second eruptive event began on 2 April 2020, starting with an increase in seismicity during 0815-0851. Much of this seismicity was located on the SE part of the Dolomieu Crater. A fissure opened on the E flank, consistent with the fissures that were active during the February 2020 event. Seismicity continued to increase in intensity through 6 April located dominantly in the SE part of the Dolomieu Crater. An overflight on 5 April at 1030 showed lava fountains rising more than 50 m high accompanied by gas-and-steam plumes rising to 3-3.5 km altitude (figures 199 and 200). A lava flow advanced to an elevation of 360 m, roughly 2 km from the RN2 national road (figure 199). A significant amount of Pele’s hair and clusters of fine volcanic products were produced during the more intense phase of the eruption (5-6 April) and deposited at distances more than 10 km from the eruptive site (figure 201). It was also during this period that the SO2 emissions peaked (figure 196). The eruption stopped at 1330 after a sharp decrease in volcanic tremors.

Figure (see Caption) Figure 199. Photos of a lava flow (left) and lava fountains (right) at Piton de la Fournaise during the April 2020 eruption. Left: photo taken on 2 April 2020 at 1500. Right: photo taken on 5 April 2020 at 1030. Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, April 2020).
Figure (see Caption) Figure 200. Photo of the lava fountains erupting from Piton de la Fournaise on 4 April 2020. Photo taken by Richard Bouchet courtesy of Geo Magazine via Jeannie Curtis.
Figure (see Caption) Figure 201. Photos of Pele’s hair deposited due to the April 2020 eruption at Piton de la Fournaise. Samples collected near the Gîte du volcan on 7 April 2020 (left) and a cluster of Pele’s hair found near the Foc-Foc car park on 9 April 2020 (right). Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, April 2020).

Geologic Background. The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion in the western Indian Ocean is one of the world's most active volcanoes. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano.

Information Contacts: Observatoire Volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris, 14 route nationale 3, 27 ème km, 97418 La Plaine des Cafres, La Réunion, France (URL: http://www.ipgp.fr/fr); 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/); 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); GEO Magazine (AFP story at URL: https://www.geo.fr/environnement/la-reunion-fin-deruption-au-piton-de-la-fournaise-200397); AFP (URL: https://twitter.com/AFP/status/1227140765106622464, Twitter: @AFP, https://twitter.com/AFP); Jeannie Curtis (Twitter: @VolcanoJeannie, https://twitter.com/VolcanoJeannie).


Sabancaya (Peru) — June 2020 Citation iconCite this Report

Sabancaya

Peru

15.787°S, 71.857°W; summit elev. 5960 m

All times are local (unless otherwise noted)


Daily explosions with ash emissions, large SO2 flux, ongoing thermal anomalies, December 2019-May 2020

Although tephrochronology has dated activity at Sabancaya back several thousand years, renewed activity that began in 1986 was the first recorded in over 200 years. Intermittent activity since then has produced significant ashfall deposits, seismic unrest, and fumarolic emissions. A new period of explosive activity that began in November 2016 has been characterized by pulses of ash emissions with some plumes exceeding 10 km altitude, thermal anomalies, and significant SO2 plumes. Ash emissions and high levels of SO2 continued each week during December 2019-May 2020. The Observatorio Vulcanologico INGEMMET (OVI) reports weekly on numbers of daily explosions, ash plume heights and directions of drift, seismicity, and other activity. The Buenos Aires Volcanic Ash Advisory Center (VAAC) issued three or four daily reports of ongoing ash emissions at Sabancaya throughout the period.

The dome inside the summit crater continued to grow throughout this period, along with nearly constant ash, gas, and steam emissions; the average number of daily explosions ranged from 4 to 29. Ash and gas plume heights rose 1,800-3,800 m above the summit crater, and multiple communities around the volcano reported ashfall every month (table 6). Sulfur dioxide emissions were notably high and recorded daily with the TROPOMI satellite instrument (figure 75). Thermal activity declined during December 2019 from levels earlier in the year but remained steady and increased in both frequency and intensity during April and May 2020 (figure 76). Infrared satellite images indicated that the primary heat source throughout the period was from the dome inside the summit crater (figure 77).

Table 6. Persistent activity at Sabancaya during December 2019-May 2020 included multiple daily explosions with ash plumes that rose several kilometers above the summit and drifted in many directions; this resulted in ashfall in communities within 30 km of the volcano. Satellite instruments recorded SO2 emissions daily. Data courtesy of OVI-INGEMMET.

Month Avg. Daily Explosions by week Max plume Heights (m above crater) Plume drift (km) and direction Communities reporting ashfall Min Days with SO2 over 2 DU
Dec 2019 16, 13, 5, 5 2,600-3,800 20-30 NW Pinchollo, Madrigal, Lari, Maca, Achoma, Coporaque, Yanque, Chivay, Huambo, Cabanaconde 27
Jan 2020 10, 8, 11, 14, 4 1,800-3,400 30 km W, NW, SE, S Chivay, Yanque, Achoma 29
Feb 2020 8, 11, 20, 19 2,000-2,200 30 km SE, E, NE, W Huambo 29
Mar 2020 14, 22, 29, 18 2,000-3,000 30 km NE, W, NW, SW Madrigal, Lari, Pinchollo 30
Apr 2020 12, 12, 16, 13, 8 2,000-3,000 30 km SE, NW, E, S Pinchollo, Madrigal, Lari, Maca, Ichupampa, Yanque, Chivay, Coporaque, Achoma 27
May 2020 15, 14, 6, 16 1,800-2,400 30 km SW, SE, E, NE, W Chivay, Achoma, Maca, Lari, Madrigal, Pinchollo 27
Figure (see Caption) Figure 75. Sulfur dioxide anomalies were captured daily from Sabancaya during December 2019-May 2020 by the TROPOMI instrument on the Sentinel-5P satellite. Some of the largest SO2 plumes are shown here with dates listed in the information at the top of each image. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 76. Thermal activity at Sabancaya declined during December 2019 from levels earlier in the year but remained steady and increased slightly in frequency and intensity during April and May 2020, according to the MIROVA graph of Log Radiative Power from 23 June 2019 through May 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 77. Sentinel-2 satellite imagery of Sabancaya confirmed the frequent ash emissions and ongoing thermal activity from the dome inside the summit crater during December 2019-May 2020. Top row (left to right): On 6 December 2019 a large plume of steam and ash drifted N from the summit. On 16 December 2019 a thermal anomaly encircled the dome inside the summit caldera while gas and possible ash drifted NW. On 14 April 2020 a very similar pattern persisted inside the crater. Bottom row (left to right): On 19 April an ash plume was clearly visible above dense cloud cover. On 24 May the infrared glow around the dome remained strong; a diffuse plume drifted W. A large plume of ash and steam drifted SE from the summit on 29 May. Infrared images use Atmospheric penetration rendering (bands 12, 11, 8a), other images use Natural Color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

The average number of daily explosions during December 2019 decreased from a high of 16 the first week of the month to a low of five during the last week. Six pyroclastic flows occurred on 10 December (figure 78). Tremors were associated with gas-and-ash emissions for most of the month. Ashfall was reported in Pinchollo, Madrigal, Lari, Maca, Achoma, Coporaque, Yanque, and Chivay during the first week of the month, and in Huambo and Cabanaconde during the second week (figure 79). Inflation of the volcano was measured throughout the month. SO2 flux was measured by OVI as ranging from 2,500 to 4,300 tons per day.

Figure (see Caption) Figure 78. Multiple daily explosions at Sabancaya produced ash plumes that rose several kilometers above the summit. Left image is from 5 December and right image is from 11 December 2019. Note pyroclastic flows to the right of the crater on 11 December. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-49-2019/INGEMMET Semana del 2 al 8 de diciembre de 2019 and RSSAB-50-2019/INGEMMET Semana del 9 al 15 de diciembre de 2019).
Figure (see Caption) Figure 79. Communities to the N and W of Sabancaya recorded ashfall from the volcano the first week of December and also every month during December 2019-May 2020. The red zone is the area where access is prohibited (about a 12-km radius from the crater). Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-22-2020/INGEMMET Semana del 25 al 31 de mayo del 2020).

During January and February 2020 the number of daily explosions averaged 4-20. Ash plumes rose as high as 3.4 km above the summit (figure 80) and drifted up to 30 km in multiple directions. Ashfall was reported in Chivay, Yanque, and Achoma on 8 January, and in Huambo on 25 February. Sulfur dioxide flux ranged from a low of 1,200 t/d on 29 February to a high of 8,200 t/d on 28 January. Inflation of the edifice was measured during January; deformation changed to deflation in early February but then returned to inflation by the end of the month.

Figure (see Caption) Figure 80. Ash plumes rose from Sabancaya every day during January and February 2020. Left: 11 January. Right: 28 February. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-02-2020/INGEMMET Semana del 06 al 12 de enero del 2020 and RSSAB-09-2020/INGEMMET Semana del 24 de febrero al 01 de marzo del 2020).

Explosions continued during March and April 2020, averaging 8-29 per day. Explosions appeared to come from multiple vents on 11 March (figure 81). Ash plumes rose 3 km above the summit during the first week of March and again the first week of April; they were lower during the other weeks. Ashfall was reported in Madrigal, Lari, and Pinchollo on 27 March and 5 April. On 17 April ashfall was reported in Maca, Ichupampa, Yanque, Chivay, Coporaque, and Achoma. Sulfur dioxide flux ranged from 1,900 t/d on 5 March to 10,700 t/d on 30 March. Inflation at depth continued throughout March and April with 10 +/- 4 mm recorded between 21 and 26 April. Similar activity continued during May 2020; explosions averaged 6-16 per day (figure 82). Ashfall was reported on 6 May in Chivay, Achoma, Maca, Lari, Madrigal, and Pinchollo; heavy ashfall was reported in Achoma on 12 May. Additional ashfall was reported in Achoma, Maca, Madrigal, and Lari on 23 May.

Figure (see Caption) Figure 81. Explosions at Sabancaya on 11 March 2020 appeared to originate simultaneously from two different vents (left). The plume on 12 April was measured at about 2,500 m above the summit. Courtesy of OVI-INGEMMET (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-11-2020/INGEMMET Semana del 9 al 15 de marzo del 2020 and RSSAB-15-2020/INGEMMET Semana del 6 al 12 de abril del 2020).
Figure (see Caption) Figure 82. Explosions dense with ash continued during May 2020 at Sabancaya. On 11 and 29 May 2020 ash plumes rose from the summit and drifted as far as 30 km before dissipating. Courtesy of OVI-INGEMMET (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya , RSSAB-20-2020/INGEMMET Semana del 11 al 17 de mayo del 2020 and RSSAB-22-2020/INGEMMET Semana del 25 al 31 de mayo del 2020).

Geologic Background. Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.

Information Contacts: Observatorio Volcanologico del INGEMMET (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa, Peru (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); 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/); 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).


Sheveluch (Russia) — May 2020 Citation iconCite this Report

Sheveluch

Russia

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

All times are local (unless otherwise noted)


Lava dome growth and thermal anomalies continue through April 2020, but few ash explosions

The eruption at Sheveluch has continued for more than 20 years, with strong explosions that have produced ash plumes, lava dome growth, hot avalanches, numerous thermal anomalies, and strong fumarolic activity (BGVN 44:05). During this time, there have been periods of greater or lesser activity. The most recent period of increased activity began in December 2018 and continued through October 2019 (BGVN 44:11). This report covers activity between November 2019 to April 2020, a period during which activity waned. The volcano is monitored by the Kamchatka Volcanic Eruptions Response Team (KVERT) and Tokyo Volcanic Ash Advisory Center (VAAC).

During the reporting period, KVERT noted that lava dome growth continued, accompanied by incandescence of the dome blocks and hot avalanches. Strong fumarolic activity was also present (figure 53). However, the overall eruption intensity waned. Ash plumes sometimes rose to 10 km altitude and drifted downwind over 600 km (table 14). The Aviation Color Code (ACC) remained at Orange (the second highest level on a four-color scale), except for 3 November when it was raised briefly to Red (the highest level).

Figure (see Caption) Figure 53. Fumarolic activity of Sheveluch’s lava dome on 24 January 2020. Photo by Y. Demyanchuk; courtesy of KVERT.

Table 14. Explosions and ash plumes at Sheveluch during November 2019-April 2020. Dates and times are UTC, not local. Data courtesy of KVERT and the Tokyo VAAC.

Dates Plume Altitude (km) Drift Distance and Direction Remarks
01-08 Nov 2019 -- 640 km NW 3 November: ACC raised to Red from 0546-0718 UTC before returning to Orange.
08-15 Nov 2019 9-10 1,300 km ESE
17-27 Dec 2019 6.0-6.5 25 km E Explosions at about 23:50 UTC on 21 Dec.
20-27 Mar 2020 -- 45 km N 25 March: Gas-and-steam plume containing some ash.
03-10 Apr 2020 10 km 526 km SE 8 April: Strong explosion at 1910 UTC.
17-24 Apr 2020 -- 140 km NE Re-suspended ash plume.

KVERT reported thermal anomalies over the volcano every day, except for 25-26 January, when clouds obscured observations. During the reporting period, thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm recorded hotspots on 10 days in November, 13 days in December, nine days in January, eight days in both February and March, and five days in April. The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, detected numerous hotspots every month, almost all of which were of moderate radiative power (figure 54).

Figure (see Caption) Figure 54. Thermal anomalies at Sheveluch continued at elevated levels during November 2019-April 2020, as seen on this MIROVA Log Radiative Power graph for July 2019-April 2020. Courtesy of MIROVA.

High sulfur dioxide levels were occasionally recorded just above or in the close vicinity of Sheveluch by the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Copernicus Sentinel-5 Precursor satellite, but very little drift was observed.

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: 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/); 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/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); 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/).


Dukono (Indonesia) — May 2020 Citation iconCite this Report

Dukono

Indonesia

1.693°N, 127.894°E; summit elev. 1229 m

All times are local (unless otherwise noted)


Numerous ash explosions continue through March 2020

The ongoing eruption at Dukono is characterized by frequent explosions that send ash plumes to about 1.5-3 km altitude (0.3-1.8 km above the summit), although a few have risen higher. This type of typical activity (figure 13) continued through at least March 2020. The ash plume data below (table 21) were primarily provided by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and the Darwin Volcanic Ash Advisory Centre (VAAC). During the reporting period of October 2019-March 2020, the Alert Level remained at 2 (on a scale of 1-4) and the public was warned to remain outside of the 2-km exclusion zone.

Table 21. Monthly summary of reported ash plumes from Dukono for October 2019-March 2020. The direction of drift for the ash plume through each month was highly variable; notable plume drift each month was only indicated in the table if at least two weekly reports were consistent. Data courtesy of the Darwin VAAC and PVMBG.

Month Plume Altitude (km) Notable Plume Drift
Oct 2019 1.8-3 Multiple
Nov 2019 1.8-2.3 E, SE, NE
Dec 2019 1.8-2.1 E, SE
Jan 2020 1.8-2.1 E, SE, SW, S
Feb 2020 2.1-2.4 S, SW
Mar 2020 1.5-2.3 Multiple
Figure (see Caption) Figure 13.Satellite image of Dukono from Sentinel-2 on 12 November 2019, showing an ash plume drifting E. Image uses natural color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

During the reporting period, high levels of sulfur dioxide were only recorded above or near the volcano during 30-31 October and 4 November 2019. High levels were recorded by the Ozone Mapping and Profiler Suite (OMPS) instrument aboard the Suomi National Polar-orbiting Partnership (NPP) satellite on 30 October 2019, in a plume drifting E. The next day high levels were also recorded by the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Copernicus Sentinel-5 Precursor satellite on 31 October (figure 14) and 4 November 2019, in plumes drifting SE and NE, respectively.

Figure (see Caption) Figure 14. Sulfur dioxide emission on 31 October 2019 drifting E, probably from Dukono, as recorded by the TROPOMI instrument aboard the Sentinel-5P satellite. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Geologic Background. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

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/); 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Etna (Italy) — April 2020 Citation iconCite this Report

Etna

Italy

37.748°N, 14.999°E; summit elev. 3320 m

All times are local (unless otherwise noted)


Strombolian explosions and ash emissions continue, October 2019-March 2020

Mount Etna is a stratovolcano located on the island of Sicily, Italy, with historical eruptions that date back 3,500 years. The most recent eruptive period began in September 2013 and has continued through March 2020. Activity is characterized by Strombolian explosions, lava flows, and ash plumes that commonly occur from the summit area, including the Northeast Crater (NEC), the Voragine-Bocca Nuova (or Central) complex (VOR-BN), the Southeast Crater (SEC, formed in 1978), and the New Southeast Crater (NSEC, formed in 2011). The newest crater, referred to as the "cono della sella" (saddle cone), emerged during early 2017 in the area between SEC and NSEC. This reporting period covers information from October 2019 through March 2020 and includes frequent explosions and ash plumes. The primary source of information comes from the Osservatorio Etneo (OE), part of the Catania Branch of Italy's Istituo Nazionale di Geofisica e Vulcanologica (INGV).

Summary of activity during October 2019-March 2020. Strombolian activity and gas-and-steam and ash emissions were frequently observed at Etna throughout the entire reporting period, according to INGV and Toulouse VAAC notices. Activity was largely located within the main cone (Voragine-Bocca Nuova complex), the Northeast Crater (NEC), and the New Southeast Crater (NSEC). On 1, 17, and 19 October, ash plumes rose to a maximum altitude of 5 km. Due to constant Strombolian explosions, ground observations showed that a scoria cone located on the floor of the VOR Crater had begun to grow in late November and again in late January 2020. A lava flow was first detected on 6 December at the base of the scoria cone in the VOR Crater, which traveled toward the adjacent BN Crater. Additional lava flows were observed intermittently throughout the reporting period in the same crater. On 13 March, another small scoria cone had formed in the main VOR-BN complex due to Strombolian explosions.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows multiple episodes of thermal activity varying in power from 22 June 2019 to March 2020 (figure 286). The power and frequency of these thermal anomalies significantly decreased between August to mid-September. The pulse of activity in mid-September reflected a lava flow from the VOR Crater (BGVN 44:10). By late October through November, thermal anomalies were relatively weaker and less frequent. The next pulse in thermal activity reflected in the MIROVA graph occurred in early December, followed by another shortly after in early January, both of which were due to new lava flows from the VOR Crater. After 9 January the thermal anomalies remained frequent and strong; active lava flows continued through March accompanied by Strombolian explosions, gas-and-steam, SO2, and ash emissions. The most recent distinct pulse in thermal activity was seen in mid-March; on 13 March, another lava flow formed, accompanied by an increase in seismicity. This lava flow, like the previous ones, also originated in the VOR Crater and traveled W toward the BN Crater.

Figure (see Caption) Figure 286. Multiple episodes of varying activity at Etna from 22 June 2019 through March 2020 were reflected in the MIROVA thermal energy data (Log Radiative Power). Courtesy of MIROVA.

Activity during October-December 2019. During October 2019, VONA (Volcano Observatory Notice for Aviation) notices issued by INGV reported ash plumes rose to a maximum altitude of 5 km on 1, 17, and 19 October. Strombolian explosions occurred frequently. Explosions were detected primarily in the VOR-BN Craters, ejecting coarse pyroclastic material that fell back into the crater area and occasionally rising above the crater rim. Ash emissions rose from the VOR-BN and NEC while intense gas-and-steam emissions were observed in the NSEC (figure 287). Between 10-12 and 14-20 October fine ashfall was observed in Pedara, Mascalucia, Nicolosi, San Giovanni La Punta, and Catania. In addition to these ash emissions, the explosive Strombolian activity contributed to significant SO2 plumes that drifted in different directions (figure 288).

Figure (see Caption) Figure 287. Webcam images of ash emissions from the NE Crater at Etna from the a) CUAD (Catania) webcam on 10 October 2019; b) Milo webcam on 11 October 2019; c) Milo webcam on 12 October 2019; d) M.te Cagliato webcam on 13 October 2019. Courtesy of INGV (Report 42/2019, ETNA, Bollettino Settimanale, 07/10/2019 - 13/10/2019, data emissione 15/10/2019).
Figure (see Caption) Figure 288. Strombolian activity at Etna contributed to significant SO2 plumes that drifted in multiple directions during the intermittent explosions in October 2019. Top left: 1 October 2019. Top right: 2 October 2019. Middle left: 15 October 2019. Middle right: 18 October 2019. Bottom left: 13 November 2019. Bottom right: 1 December 2019. Captured by the TROPOMI instrument on the Sentinel 5P satellite, courtesy of NASA Global Sulfur Dioxide Monitoring Page.

The INGV weekly bulletin covering activity between 25 October and 1 November 2019 reported that Strombolian explosions occurred at intervals of 5-10 minutes from within the VOR-BN and NEC, ejecting incandescent material above the crater rim, accompanied by modest ash emissions. In addition, gas-and-steam emissions were observed from all the summit craters. Field observations showed the cone in the crater floor of VOR that began to grow in mid-September 2019 had continued to grow throughout the month. During the week of 4-10 November, Strombolian activity within the Bocca Nuova Crater was accompanied by gas-and-steam emissions. The explosions in the VOR Crater occasionally ejected incandescent ejecta above the crater rim (figures 289 and 290). For the remainder of the month Strombolian explosions continued in the VOR-BN and NEC, producing sporadic ash emissions. Isolated and discontinuous explosions in the New Southeast Crater (NSEC) also produced fine ash, though gas-and-steam emissions still dominated the activity at this crater. Additionally, the explosions from these summit craters were frequently accompanied by strong SO2 emissions that drifted in different directions as discrete plumes.

Figure (see Caption) Figure 289. Photo of Strombolian activity and crater incandescence in the Voragine Crater at Etna on 15 November 2019. Photo by B. Behncke, taken by Tremestieri Etneo. Courtesy of INGV (Report 47/2019, ETNA, Bollettino Settimanale, 11/11/2019 - 17/11/2019, data emissione 19/11/2019).
Figure (see Caption) Figure 290. Webcam images of summit crater activity during 26-29 November and 1 December 2019 at Etna. a) image recorded by the high-resolution camera on Montagnola (EMOV); b) and c) webcam images taken from Tremestieri Etneo on the southern slope of Etna showing summit incandescence; d) image recorded by the thermal camera on Montagnola (EMOT) showing summit incandescence at the NSEC. Courtesy of INGV (Report 49/2019, ETNA, Bollettino Settimanale, 25/11/2019 - 01/12/2019, data emissione 03/12/2019).

Frequent Strombolian explosions continued through December 2019 within the VOR-BN, NEC, and NSEC Craters with sporadic ash emissions observed in the VOR-BN and NEC. On 6 December, Strombolian explosions increased in the NSEC; webcam images showed incandescent pyroclastic material ejected above the crater rim. On the morning of 6 December a lava flow was observed from the base of the scoria cone in the VOR Crater that traveled toward the adjacent Bocca Nuova Crater. INGV reported that a new vent opened on the side of the saddle cone (NSEC) on 11 December and produced explosions until 14 December.

Activity during January-March 2020. On 9 January 2020 an aerial flight organized by RAI Linea Bianca and the state police showed the VOR Crater continuing to produce lava that was flowing over the crater rim into the BN Crater with some explosive activity in the scoria cone. Explosive Strombolian activity produced strong and distinct SO2 plumes (figure 291) and ash emissions through March, according to the weekly INGV reports, VONA notices, and satellite imagery. Several ash emissions during 21-22 January rose from the vent that opened on 11 December. According to INGV’s weekly bulletin for 21-26 January, the scoria cone in the VOR crater produced Strombolian explosions that increased in frequency and contributed to rapid cone growth, particularly the N part of the cone. Lava traveled down the S flank of the cone and into the adjacent Bocca Nuova Crater, filling the E crater (BN-2) (figure 292). The NEC had discontinuous Strombolian activity and periodic, diffuse ash emissions.

Figure (see Caption) Figure 291. Distinct SO2 plumes drifting in multiple directions from Etna were visible in satellite imagery as Strombolian activity continued through March 2020. Top left: 21 January 2020. Top right: 2 February 2020. Bottom left: 10 March 2020. Bottom right: 19 March 2020. Captured by the TROPOMI instrument on the Sentinel 5P satellite, courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 292. a) A map of the lava field at Etna showing cooled flows (yellow) and active flows (red). The base of the scoria cone is outlined in black while the crater rim is outlined in red. b) Thermal image of the Bocca Nuova and Voragine Craters. The bright orange is the warmest temperature measure in the flow. Courtesy of INGV, photos by Laboratorio di Cartografia FlyeEye Team (Report 10/2020, ETNA, Bollettino Settimanale, 24/02/2020 - 01/03/2020, data emissione 03/03/2020).

Strombolian explosions continued into February 2020, accompanied by ash emissions and lava flows from the previous months (figure 293). During 17-23 February, INGV reported that some subsidence was observed in the central portion of the Bocca Nuova Crater. During 24 February to 1 March, the Strombolian explosions ejected lava from the VOR Crater up to 150-200 m above the vent as bombs fell on the W edge of the VOR crater rim (figure 294). Lava flows continued to move into the W part of the Bocca Nuova Crater.

Figure (see Caption) Figure 293. Webcam images of A) Strombolian activity and B) effusive activity fed by the scoria cone grown inside the VOR Crater at Etna taken on 1 February 2020. C) Thermal image of the lava field produced by the VOR Crater taken by L. Lodato on 3 February (bottom left). Image of BN-1 taken by F. Ciancitto on 3 February in the summit area (bottom right). Courtesy of INGV; Report 06/2020, ETNA, Bollettino Settimanale, 27/01/2020 - 02/02/2020, data emissione 04/02/2020 (top) and Report 07/2020, ETNA, Bollettino Settimanale, 03/02/2020 - 09/02/2020, data emissione 11/02/2020 (bottom).
Figure (see Caption) Figure 294. Photos of the VOR intra-crater scoria cone at Etna: a) Strombolian activity resumed on 25 February 2020 from the SW edge of BN taken by B. Behncke; b) weak Strombolian activity from the vent at the base N of the cone on 29 February 2020 from the W edge of VOR taken by V. Greco; c) old vent present at the base N of the cone, taken on 17 February 2020 from the E edge of VOR taken by B. Behncke; d) view of the flank of the cone, taken on 24 February 2020 from the W edge of VOR taken by F. Ciancitto. Courtesy of INGV (Report 10/2020, ETNA, Bollettino Settimanale, 24/02/2020 - 01/03/2020, data emissione 03/03/2020).

During 9-15 March 2020 Strombolian activity was detected in the VOR Crater while discontinuous ash emissions rose from the NEC and NSEC. Bombs were found in the N saddle between the VOR and NSEC craters. On 9 March, a small scoria cone that had formed in the Bocca Nuova Crater and was ejecting bombs and lava tens of meters above the S crater rim. The lava flow from the VOR Crater was no longer advancing. A third scoria cone had formed on 13 March NE in the main VOR-BN complex due to the Strombolian explosions on 29 February. Another lava flow formed on 13 March, accompanied by an increase in seismicity. The weekly report for 16-22 March reported Strombolian activity detected in the VOR Crater and gas-and-steam and rare ash emissions observed in the NEC and NSEC (figure 295). Explosions in the Bocca Nuova Crater ejected spatter and bombs 100 m high.

Figure (see Caption) Figure 295. Map of the summit crater area of Etna showing the active vents and lava flows during 16-22 March 2020. Black hatch marks indicate the crater rims: BN = Bocca Nuova, with NW BN-1 and SE BN-2; VOR = Voragine; NEC = North East Crater; SEC = South East Crater; NSEC = New South East Crater. Red circles indicate areas with ash emissions and/or Strombolian activity, yellow circles indicate steam and/or gas emissions only. The base is modified from a 2014 DEM created by Laboratorio di Aerogeofisica-Sezione Roma 2. Courtesy of INGV (Report 13/2020, ETNA, Bollettino Settimanale, 16/03/2020 - 22/03/2020, data emissione 24/03/2020).

Geologic Background. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Information Contacts: Sezione di Catania - Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/it/); 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/); 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Boris Behncke, Sonia Calvari, and Marco Neri, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: https://twitter.com/etnaboris, Image at https://twitter.com/etnaboris/status/1183640328760414209/photo/1).


Merapi (Indonesia) — April 2020 Citation iconCite this Report

Merapi

Indonesia

7.54°S, 110.446°E; summit elev. 2910 m

All times are local (unless otherwise noted)


Explosions produced ash plumes, ashfall, and pyroclastic flows during October 2019-March 2020

Merapi is a highly active stratovolcano located in Indonesia, just north of the city of Yogyakarta. The current eruption episode began in May 2018 and was characterized by phreatic explosions, ash plumes, block avalanches, and a newly active lava dome at the summit. This reporting period updates information from October 2019-March 2020 that includes explosions, pyroclastic flows, ash plumes, and ashfall. The primary reporting source of activity comes from Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG, the Center for Research and Development of Geological Disaster Technology, a branch of PVMBG) and Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM).

Some ongoing lava dome growth continued in October 2019 in the NE-SW direction measuring 100 m in length, 30 m in width, and 20 m in depth. Gas-and-steam emissions were frequent, reaching a maximum height of 700 m above the crater on 31 October. An explosion at 1631 on 14 October removed the NE-SW trending section of the lava dome and produced an ash plume that rose 3 km above the crater and extended SW for about 2 km (figures 90 and 91). The plume resulted in ashfall as far as 25 km to the SW. According to a Darwin VAAC notice, a thermal hotspot was detected in HIMAWARI-8 satellite imagery. A pyroclastic flow associated with the eruption traveled down the SW flank in the Gendol drainage. During 14-20 October lava flows from the crater generated block-and-ash flows that traveled 1 km SW, according to BPPTKG.

Figure (see Caption) Figure 90. An ash plume rising 3 km above Merapi on 14 October 2019.
Figure (see Caption) Figure 91. Webcam image of an ash plume rising above Merapi at 1733 on 14 October 2019. Courtesy of BPPTKG via Jaime S. Sincioco.

At 0621 on 9 November 2019, an eruption produced an ash plume that rose 1.5 km above the crater and drifted W. Ashfall was observed in the W region as far as 15 km from the summit in Wonolelo and Sawangan in Magelang Regency, as well as Tlogolele and Selo in Boyolali Regency. An associated pyroclastic flow traveled 2 km down the Gendol drainage on the SE flank. On 12 November aerial drone photographs were used to measure the volume of the lava dome, which was 407,000 m3. On 17 November, an eruption produced an ash plume that rose 1 km above the crater, resulting in ashfall as far as 15 km W from the summit in the Dukun District, Magelang Regency (figure 92). A pyroclastic flow accompanying the eruption traveled 1 km down the SE flank in the Gendol drainage. By 30 November low-frequency earthquakes and CO2 gas emissions had increased.

Figure (see Caption) Figure 92. An ash plume rising 1 km above Merapi on 17 November 2019. Courtesy of BPPTKG.

Volcanism was relatively low from 18 November 2019 through 12 February 2020, characterized primarily by gas-and-steam emissions and intermittent volcanic earthquakes. On 4 January a pyroclastic flow was recorded by the seismic network at 2036, but it wasn’t observed due to weather conditions. On 13 February an explosion was detected at 0516, which ejected incandescent material within a 1-km radius from the summit (figure 93). Ash plumes rose 2 km above the crater and drifted NW, resulting in ashfall within 10 km, primarily S of the summit; lightning was also seen in the plume. Ash was observed in Hargobinangun, Glagaharjo, and Kepuharjo. On 19 February aerial drone photographs were used to measure the change in the lava dome after the eruption; the volume of the lava had decreased, measuring 291,000 m3.

Figure (see Caption) Figure 93. Webcam image of an ash plume rising from Merapi at 0516 on 13 February 2020. Courtesy of MAGMA Indonesia and PVMBG.

An explosion on 3 March at 0522 produced an ash plume that rose 6 km above the crater (figure 94), resulting in ashfall within 10 km of the summit, primarily to the NE in the Musuk and Cepogo Boyolali sub-districts and Mriyan Village, Boyolali (3 km from the summit). A pyroclastic flow accompanied this eruption, traveling down the SSE flank less than 2 km. Explosions continued to be detected on 25 and 27-28 March, resulting in ash plumes. The eruption on 27 March at 0530 produced an ash plume that rose 5 km above the crater, causing ashfall as far as 20 km to the W in the Mungkid subdistrict, Magelang Regency, and Banyubiru Village, Dukun District, Magelang Regency. An associated pyroclastic flow descended the SSE flank, traveling as far as 2 km. The ash plume from the 28 March eruption rose 2 km above the crater, causing ashfall within 5 km from the summit in the Krinjing subdistrict primarily to the W (figure 94).

Figure (see Caption) Figure 94. Images of ash plumes rising from Merapi during 3 March (left) and 28 March 2020 (right). Images courtesy of BPPTKG (left) and PVMBG (right).

Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities during historical time.

Information Contacts: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), Center for Research and Development of Geological Disaster Technology (URL: http://merapi.bgl.esdm.go.id/, Twitter: @BPPTKG); 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/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/, Twitter: https://twitter.com/BNPB_Indonesia); 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/); Jamie S. Sincioco, Phillipines (Twitter: @jaimessincioco, Image at https://twitter.com/jaimessincioco/status/1227966075519635456/photo/1).

Search Bulletin Archive by Publication Date

Select a month and year from the drop-downs and click "Show Issue" to have that issue displayed in this tab.

   

The default month and year is the latest issue available.

Bulletin of the Global Volcanism Network - Volume 28, Number 08 (August 2003)

Managing Editor: Edward Venzke

Arenal (Costa Rica)

Ongoing lava extrusion and intermittent pyroclastic flows late 2001 through mid-2003

Colima (Mexico)

Explosions in July and August generate pyroclastic flows and create a new summit crater

Etna (Italy)

Ash emissions during April from Bocca Nuova; volcanic seismicity and ash puff on 11 August

Fournaise, Piton de la (France)

Lava eruption from three fissures during 22-27 August

Kanlaon (Philippines)

Frequent ash explosions from 7 March until 23 July 2003

Karthala (Comoros)

Increased shallow seismic activity to 100 events per day by late August

Krakatau (Indonesia)

Continued shallow volcanic seismicity through mid-August

Masaya (Nicaragua)

Fumarolic emissions and low-level seismicity from April 2002 through May 2003

Nyamuragira (DR Congo)

Rumbling and explosion sounds April-June, but no confirmed eruptions

Nyiragongo (DR Congo)

Continued lava lake activity during May-June; ashfall in local villages

Popocatepetl (Mexico)

Continuing intermittent eruptions; ashfall in June and July

Ruang (Indonesia)

Rapid decrease in activity following September 2002 eruption

Soputan (Indonesia)

Lava avalanches and ash explosions during 18-22 July 2003

Soufriere Hills (United Kingdom)

Major dome collapse and explosive activity during 12-13 July

Stromboli (Italy)

Explosive activity in the summit craters and thermal signatures in the lava-flow field

Tandikat-Singgalang (Indonesia)

Increased seismicity during January 2003

Tangkuban Parahu (Indonesia)

Elevated seismicity during August-October 2002

Whakaari/White Island (New Zealand)

Large crater lake floods the active vent; new hazards identified



Arenal (Costa Rica) — August 2003 Citation iconCite this Report

Arenal

Costa Rica

10.463°N, 84.703°W; summit elev. 1670 m

All times are local (unless otherwise noted)


Ongoing lava extrusion and intermittent pyroclastic flows late 2001 through mid-2003

This report concerns Arenal behavior during November 2001 through August 2003, although some reports were absent (specifically, November and December 2001 and January, February, and April 2002). The available reports portrayed an interval with only a few pyroclastic flows and with plumes generally under 500 m. Lava flows continued to travel down Arenal's slopes; in many cases these flows did not follow well-defined channels. Spatter and related deposition from crater C caused a slightly higher summit elevation. During 2002 lavas descended along many routes down the W, NW, N, and NE flanks. Seismicity remained prominent during the interval, with the number of monthly eruption signals in the hundreds (200-800) and monthly tremor duration in the hundreds of hours.

Seismicity registered during March 2000-December 2001 and for the year 2002 appears as figures 96 and 97, where the numbers of eruptions plotted monthly were inferred. The seismic station VACR (table 22) returned to service on 28 March 2000, registering totals for four days at the end of March consisting of 164 eruptions and 45 hours of tremor. Also reported this month, the electronic distance measuring network (sub-radial lines) continued to show a contraction averaging 7-10 ppm per year. Similar conclusions were stated for August 2003, although in that case deflation was only mentioned on Arenal's W flank. In accord with that observation, dry tilt in the radial direction showed a deflation equivalent to 5 µrad per year, a value that has prevailed through mid-2003.

Figure (see Caption) Figure 96. Arenal seismicity registered during March 2000-December 2001 (eruptions inferred). The blank areas before March 2000 and during July 2001 were due to equipment down-times. Known pyroclastic flows are shown, but some may be missing because some monthly reports were not available. Courtesy of OVSICORI-UNA.
Figure (see Caption) Figure 97. Arenal seismicity registered during 2002 (eruption counts seismically inferred). Note change in scale compared to previous figure. The number of eruptions decreased compared to those registered in the year 2000. On the other hand, long-period (LP) earthquakes grew substantially in number during the last months of 2002; tremor repeatedly reached over 400 hours per month during mid-2002. Courtesy of OVSICORI-UNA.

Table 22. Background describing the OVSICORI-UNA seismic station at Arenal (station VACR), as well as the typical kinds of seismic and audible acoustical signals and corresponding eruptive conditions. Courtesy of OVSICORI-UNA.

Seismic Station Features
Name VACR
Location 10.477°N, 84.684°W
Elevation 360 m
Location relative to crater 2.7 km NNE
Instrument Ranger SS-short-period (1 Hz)
Gain 60 decibels (dB)
Amplification 9,605-times normalized at 1 Hz
Typical seismic signals recorded at Arenal include those registered in association with explosions and gas eruptions; these signals often correspond to sounds similar to a locomotive or jet engine. Tremors typically correlate to strong degassing and discharge of lava flows. The following types of tremor signal are known to occur: low frequency (typically less than 2.0 Hz), mid-frequency (typically 2.0-3.0 Hz), high frequency (typically above 3.0 Hz), polychromatic (occurring in any frequency range), monochromatic (low-frequency range), and spasmodic (high-frequency range).

The number of monthly earthquakes generally dropped or held steady during 2002 compared to 2000-2001 (figure 97). Tremor duration, however, did increase through July 2002, approaching 700 hours a month, typically several times larger than seen in the previous two years. Long-period (LP) earthquakes suddenly became prominent in November and December 2002 (roughly 3- to 7-fold more numerous than seen earlier in 2002).

Two prominent PFs occurred during 2000-2001: in August 2000 and March 2001. They did not correlate with short-term increases in precursory seismicity. However, the August 2000 PF took place after clear increases in the number of earthquakes, the duration of tremor (figure 96), and the number of explosions.

One of a series of PFs judged smaller than the one in March occurred on 16 June 2001. They descended the NW flank for an unstated distance in the direction of Balneario de Tabacón (the Tabacón hot springs and resort complex). Associated seismic signals persisted for ~48 minutes. Although seismicity during June 2001 was comparatively low overall, May 2001 seismicity was moderately high, although not outstanding (figure 96).

During March 2002, Arenal's lava traveled down the N and NE flanks. Eruptive vigor remained low in terms of the number of eruptions and quantity of ejected pyroclastics. On the NE, E, and SE flanks there had been acidic rains and tephra falls. These, in combination with the steep slopes, unconsolidated material, and high rainfall, had caused vegetation to recede. This led to greater erosion, and small cold avalanches swept down the drainages Calle de Arenas, Manolo, Guillermina, and Agua Caliente.

On 18 May 2002 a pyroclastic flow resulted from the structural failure of a lava channel's margin in the region adjacent to the active crater (Crater C). The pyroclastic flow descended to ~900 m elevation, traveling roughly NW. Otherwise, the eruptive vigor around this time continued to remain low; a few eruptions produced columns that rose ~500 m above Crater C. Some minor changes took place in the lava flow channels during May 2002.

Although reports for June and July 2002 were absent during the preparation of this report, the August report mentioned sporadic Strombolian eruptions during those months. Lava that began to be emitted in May 2002 traveled NW and stopped during August. After that, a new lava flow began during August, heading NW in its upper reaches. Very close to the crater, it divided into two arms, heading W and NW. The August effusive activity had increased over recent months, yet, overall the eruptive vigor around that time generally remained low with few eruptions bearing ash, and columns failing to rise more than 500 m above crater C's summit.

Low activity again prevailed during September-December 2002, but lava flows continued to emerge. During September lavas were active on Arenal's W flank, and to some extent on its NW, N, and NE flanks. During October, lavas chiefly descended the NW slopes. During November, the NW-flank lava flow that began to be emitted during August 2002 stopped advancing. A new lava flow began to descend the W flank. Flows down the NW-NE flanks were noted in reports for December 2002-August 2003. In addition, during December 2002 and January and August 2003, some lavas appeared active on the SW flank. During January 2003 plumes again rose to under 500 m high, and calm generally prevailed in February through August as well. Two noteworthy events broke the relative calm of 2003; these occurred during February, May, and September.

On 21 February 2003 at about 0825, NE-flank residents witnessed a small pyroclastic flow descending the same flank. Other details were not disclosed in the OVSICORI-UNA reports; nor was the May PF much described. The 5 September 2003 PF will be discussed in a later report.

Geologic Background. Conical Volcán Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1670-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. Arenal lies along a volcanic chain that has migrated to the NW from the late-Pleistocene Los Perdidos lava domes through the Pleistocene-to-Holocene Chato volcano, which contains a 500-m-wide, lake-filled summit crater. The earliest known eruptions of Arenal took place about 7000 years ago, and it was active concurrently with Cerro Chato until the activity of Chato ended about 3500 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. An eruptive period that began with a major explosive eruption in 1968 ended in December 2010; continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows characterized the eruption from vents at the summit and on the upper western flank.

Information Contacts: E. Fernández, E. Duarte, E. Malavassi, R. Sáenz, V. Barboza, R. Van der Laat, T. Marino, E. Hernández, and F. Chavarría, Observatorio Vulcanológico y Sismológico de Costa Rica (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica.


Colima (Mexico) — August 2003 Citation iconCite this Report

Colima

Mexico

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

All times are local (unless otherwise noted)


Explosions in July and August generate pyroclastic flows and create a new summit crater

In February 2003 lava emission at Colima ceased, ending an earlier eruptive stage (BGVN 28:06); after the termination of lava emission a new eruptive stage began. A series of small explosions during March-June was followed by the explosion on 17 July 2003 (BGVN 28:07), the first of three large explosions in July and August. The 17 July explosion sent blocks up to 500 m and an ash column higher than 3,000 m. The explosion was accompanied by five pyroclastic flows with runout distances up to 2 km on the W-SW slopes of the volcano (figure 66).

Figure (see Caption) Figure 66. Photo of the WSW flank of Colima showing the paths of pyroclastic flows that followed the 17 July 2003 explosion. Arrows mark five of the pyroclastic-flow deposits. Courtesy of Colima Volcano Observatory.

The second large explosion was recorded on 2 August at 1541. The Washington VAAC reported a plume to ~7.6 km altitude. The third large explosion occurred on 28 August at 2352 and produced an ash column at least 3 km high with ashfall up to 60 km W-NW of the volcano. The explosion was accompanied by pyroclastic flows out to 2.5 km, covering the majority of the volcano's flanks; the total deposit volume was about 244,000 m3.

As a result of this explosion sequence, a new crater 200 m across and 30 m deep formed at the summit (figure 67). About 2 x 106 m3 of the material of the former lava dome was ejected as volcanic bombs and projectiles out to distances of ~1.0-2.5 km. The seismic energy released during these three large explosions was lower than during the 1999 explosions (BGVN 24:01).

Figure (see Caption) Figure 67. A view of Colima's new crater on 30 August 2003, a result of an explosive sequence that began on 17 July 2003. The airplane wing can be seen in the foreground. Courtesy of Colima Volcano Observatory.

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 high point of the complex) on the north and the historically active Volcán de Colima at the south. A group of late-Pleistocene cinder cones is located on the floor of the Colima graben west and east of the 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, producing thick debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions have destroyed the summit (most recently in 1913) and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.

Information Contacts: Observatorio Vulcanológico de la Universidad de Colima, Colima, Col., 28045, México (URL: https://portal.ucol.mx/cueiv/).


Etna (Italy) — August 2003 Citation iconCite this Report

Etna

Italy

37.748°N, 14.999°E; summit elev. 3320 m

All times are local (unless otherwise noted)


Ash emissions during April from Bocca Nuova; volcanic seismicity and ash puff on 11 August

Activity at Etna since the end of the last flank eruption on 28 January 2003 (BGVN 28:01) was characterized by intense degassing at the Northeast Crater (NEC). In April, ash emission was observed from Bocca Nuova crater (BN), and ash fell for about 1 hour on E-flank villages. On 17 April a helicopter survey, aided by use of a thermal camera, revealed a cinder cone within the S pit of BN with a hot vent at its top. However, no degassing was taking place from this vent, and the pit appeared mostly obstructed by debris from the crater walls. Rare explosions from the vent caused little emission of juvenile material on the crater floor. Another helicopter-borne thermal survey in May showed that the summit craters were mostly obstructed.

Only a hot crack within the S pit of BN was observed during a June field survey. A new vent on the N rim of the Voragine (VOR), detected during a June field survey, was ~0.5 m wide, and the temperature measured through a thermal camera was ~500°C, much higher than the two vents within the crater. Given the presence of hot features within the summit craters and the obstructions observed inside BN, Southeast Crater (SEC), and VOR, it is possible that renewal of explosive activity at these summit craters could be accompanied by sudden, unpredictable gas explosions.

On the afternoon of 11 August an increase in volcanic tremor at the summit seismic stations lasted about 15 minutes and was followed by about 30 minutes of strong explosion earthquakes recorded at all summit stations of the INGV-CT seismic network. This was the first such event recorded at Etna since the end of the flank eruption. The INGV-CT web camera at Milo (~11 km from the summit) showed a puff of red ash from the summit of NEC. Red glows from the same crater were reported that night. A field survey on 14 August did not reveal any explosive activity or sounds of explosions from the crater. There were no explosion earthquakes or increased volcanic tremor between 11 and 16 August.

Periodic measurements of the gas plume from the summit using both COSPEC (SO2 flux) and FTIR (SO2/HCl and HCl/HF ratios) showed decreases in all three values since the end of the flank eruption. This suggests a general decreasing trend in gas output from Etna's summit craters.

Geologic Background. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Information Contacts: Sonia Calvari, Istituto Nazionale di Geofisica e Vulcanologia, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/).


Piton de la Fournaise (France) — August 2003 Citation iconCite this Report

Piton de la Fournaise

France

21.244°S, 55.708°E; summit elev. 2632 m

All times are local (unless otherwise noted)


Lava eruption from three fissures during 22-27 August

Five months of slow inflation at Piton de la Fournaise and the eruptive series that occurred between May and July 2003 (BGVN 28:05 and 28:06) were followed by new activity in August. Ongoing eruptions in June at the Dolomieu crater had ceased by mid-July, but at 1848 on 22 August seismic activity was again detected beneath the crater. Around 2120 that night an eruptive fissure opened in the Bory crater (adjacent to Dolomieu on the W), followed at 2210 by a second fissure at ~2,450-2,470 m elevation on the N flank. Both fissures remained active for a short time.

At 2330 a final fissure opened on the N flank ~250 m below the second fissure, at 2,200 m elevation. Most of the activity was focused at this third fissure, opening a new crater ~50 m E of the 1998 Piton Kapor crater. During this activity on 22 August lava flowed down into la Plaine des Osmondes. The 36 hours following the initial activity were characterized by a substantial increase in tremor intensity and lava emissions, but by 2152 on 27 August the eruption abruptly ceased. A series of long-period events were observed after 27 August through at least 1 September.

Geologic Background. The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion in the western Indian Ocean is one of the world's most active volcanoes. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano.

Information Contacts: Observatoire volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris, 14 RN3, le 27Km, 97418 La Plaine des Cafres, La Réunion, France.


Kanlaon (Philippines) — August 2003 Citation iconCite this Report

Kanlaon

Philippines

10.412°N, 123.132°E; summit elev. 2435 m

All times are local (unless otherwise noted)


Frequent ash explosions from 7 March until 23 July 2003

A report on 19 September 2003 from the Philippine Institute of Volcanology and Seismology (PHIVOLCS) summarized activity at Canlaon from 7 March to 23 July 2003. This included the ash ejections of 10 and 11 July (BGVN 28:07). There were 46 ash explosions recorded since March, characterized by emission of steam clouds with small amounts of ash rising 100-1,500 m above the active crater. Prevailing winds dispersed the ash mainly SW and SE, which settled predominantly over the mid-upper slopes of the volcano.

Seismic activity remained elevated through this period, with epicenters of some high-frequency events located near the active crater, focal depths ranged from near-surface down to 18 km. From June to July, the numbers of recorded low-frequency volcanic earthquakes and low-frequency short-duration harmonic tremor events increased. This coincided with phreatic episodes between 8 June and 23 July 2003.

On 23 July an ash explosion was observed from Kanlaon Volcano Observatory, 8.5 km ESE of the crater. Ash-laden steam clouds were ejected to heights of ~800 m above the active crater. After 23 July only weak steam emission was noted, and seismic activity returned to low levels.

Geologic Background. Kanlaon volcano (also spelled Canlaon), the most active of the central Philippines, forms the highest point on the island of Negros. The massive andesitic stratovolcano is dotted with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km SW from Kanlaon. The summit contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller, but higher, historically active vent, Lugud crater, to the south. Historical eruptions, recorded since 1866, have typically consisted of phreatic explosions of small-to-moderate size that produce minor ashfalls near the volcano.

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, PHIVOLCS Building, C.P. Garcia Avenue, Univ. of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/).


Karthala (Comoros) — August 2003 Citation iconCite this Report

Karthala

Comoros

11.75°S, 43.38°E; summit elev. 2361 m

All times are local (unless otherwise noted)


Increased shallow seismic activity to 100 events per day by late August

Since July 2003, Karthala has exhibited significant, but relatively shallow, seismicity. As of 28 August, P. Bachelery of the University of La Réunion reported that an average of 100 seismic events/day were being recorded, some felt by the local population.

The first seismic station was installed at the Karthala Volcanological Observatory in 1988 by the University of La Réunion and the Institut de Physique du Globe de Paris (IPGP). During the summer and fall of 2000 increased seismicity was reported, and an earthquake swarm was recorded in October 2000 (BGVN 25:10). In April 1991, a notable increase in the number of seismic events began and, after about three months of seismic activity, there was an eruption in July (BGVN 16:06 and 16:08).

Geologic Background. The southernmost and largest of the two shield volcanoes forming Grand Comore Island (also known as Ngazidja Island), Karthala contains a 3 x 4 km summit caldera generated by repeated collapse. Elongated rift zones extend to the NNW and SE from the summit of the Hawaiian-style basaltic shield, which has an asymmetrical profile that is steeper to the S. The lower SE rift zone forms the Massif du Badjini, a peninsula at the SE tip of the island. Historical eruptions have modified the morphology of the compound, irregular summit caldera. More than twenty eruptions have been recorded since the 19th century from the summit caldera and vents on the N and S flanks. Many lava flows have reached the sea on both sides of the island. An 1860 lava flow from the summit caldera traveled ~13 km to the NW, reaching the W coast to the N of the capital city of Moroni.

Information Contacts: Patrick Bachelery, Laboratoire des Sciences de la Terre, Université de La Réunion BP 7151, 15 Avenue, René Cassin, 97715 Saint-Denis (URL: http://volcano.ipgp.jussieu.fr/karthala/stationkar.html).


Krakatau (Indonesia) — August 2003 Citation iconCite this Report

Krakatau

Indonesia

6.102°S, 105.423°E; summit elev. 155 m

All times are local (unless otherwise noted)


Continued shallow volcanic seismicity through mid-August

Due to continued foggy weather, no visual observations could be made at Krakatau during July and through 17 August. Throughout this period the volcano remained at Alert Level 2. Seismicity reported by the Volcanological Survey of Indonesia (VSI) between 30 June and 17 August consisted mostly of shallow volcanic events (table 4), although 36 deep volcanic earthquakes were recorded during the week of 30 June-6 July.

Table 4. Seismicity at Krakatau, 30 June-17 August 2003. Courtesy of VSI.

Date Deep volcanic (A-type) Shallow volcanic (B-type) Tectonic
30 Jun-06 Jul 2003 36 123 9
07 Jul-13 Jul 2003 5 112 13
14 Jul-20 Jul 2003 4 28 8
21 Jul-27 Jul 2003 8 33 6
28 Jul-03 Aug 2003 7 37 2
04 Aug-10 Aug 2003 6 25 4
11 Aug-17 Aug 2003 2 22 8

Geologic Background. The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.

Information Contacts: Dali Ahmad and Nia Haerani, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi. esdm.go.id/).


Masaya (Nicaragua) — August 2003 Citation iconCite this Report

Masaya

Nicaragua

11.985°N, 86.165°W; summit elev. 594 m

All times are local (unless otherwise noted)


Fumarolic emissions and low-level seismicity from April 2002 through May 2003

During April 2002-May 2003, monthly visits were made to Masaya for observations and temperature measurements. This report summarizes the recorded activity.

Between April and October the volcano continued to emit large amounts of gas. Tremors stayed consistently above 40 RSAM units. Seismicity was low, with fewer than 50 total earthquakes during the observation period; temperatures generally remained constant.

Fumarole temperature measurements in the Santiago crater on 22 April 2002 showed only a slight variation from October 2001. On 9 May, however, temperatures showed an increase of 20°C since April; again on 4 June a 20°C increase from May was observed. Measurements by Jaime Cardenas of the National Park at El Comalito and San Fernando on 10 and 30 April also showed little change from previous measurements. Similarly, on 5 and 21 May and in June measurements at El Comalito and San Fernando showed no significant changes. The temperatures at El Comalito and San Fernando fumaroles remained constant through the rest of the year.

In July 2002 tremor stayed above 40 RSAM units, and the volcano continued to emit great amounts of gas. Seismic stations registered 20 earthquakes. On 7 July several rumblings were reported. During a visit to the volcano emissions of dark-colored gases were seen. Landslides were observed to have extended to the inner crater, which had a diameter of 20 m; the diameter was 10 m when the crater opened on 23 April 2001. Gas emanations were abundant; a plume rising more than 1,000 m was observed. Fumarole temperatures varied between 106 and 89.3°C.

In August 2002 gas emissions continued. Martha Navarro and Virginia Tenorio visited on 15 August and observed and clearly heard gases emanating from two locations in the inner crater. Gas columns mixed with vapor reached heights of up to 700 m. The emission of gases was lower than during the previous month, possibly due to decreased rainfall. The tremor continued to stay above 40 RSAM units, and 11 earthquakes were registered.

Navarro visited the volcano twice in September. Gas columns were low and there was little vapor on 13 September; on 30 September she observed greater gas emissions and within the inner crater she could hear with greater force the sound of gas emissions. Weeds within an area of 600 m had been affected by acid rain. A small collapse along the N and E walls was observed within the crater.

On 3 October park guards reported a small collapse from the W wall. Observations on 7 and 28 October showed more water vapor than in September, as well as greater gas emissions and louder sounds associated with them. Through September and October tremor remained above 40 RSAM units; no earthquakes were registered. On 6, 16, and 18 December fumarole temperature measurements were taken with an infrared camera at Santiago crater; measurements on those dates were 216°C, 230°C, and 205°C respectively.

Through December 2002 and January and February 2003 fumarole temperatures at El Comalito and San Fernando remained constant. The low level of gas and vapor exhalation continued; columns reached as high as 100 m at the mouth of the crater. RSAM stayed constant at 30 units, with frequency between 1.5 and 2 Hz. In both January and February two earthquakes were registered. During 25 and 26 February there was a small earthquake swarm in Masaya caldera, with earthquakes located under the lake. Six earthquakes registered in March, with 3 Hz frequency, and five registered in April, with 2.8 Hz. RSAM stayed at 20 units, with frequencies between 1.5 and 2 Hz, in March and April.

Gustavo Chigna (INSIVUMEH-Guatemala) reported that the sulfur-dioxide measurements obtained using COSPEC on 28 March yielded a flux of 840 t/d. Measurements by Glyn Williams-Jones (University of Hawaii) with a 2FlySPEC (gas measurement spectrometer) on 28 March showed a value of 849 t/d. On 8 and 22 May measurements at El Comalito and San Fernando showed little variation. The temperatures at the six fumaroles at El Comalito ranged between 59.5°C at fumarole 6 and 76.4°C at fumarole 3. At San Fernando temperatures ranged from 56.4°C at fumarole 4 to 63.6°C at fumarole 2. The seismic tremor stayed constant with 20 units RSAM, with frequencies of 1.5-2 Hz. Only one earthquake registered, with 3 Hz frequency. Pedro Pérez measured the fumarole temperatures in the Santiago crater at 175°C on 15 May.

Gas monitoring. A scientific and technical team from ITER, INETER, and WESTSYSTEMS (Italy) installed a geochemical station, developed by WESTSYSTEMS, for continuous monitoring of diffuse CO2 and H2S degassing at El Comalito. The observation site was selected after a 1999 diffuse degassing survey at Masaya. The station has been in operation since 15 March 2002.

Geologic Background. Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras caldera and is itself a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The Nindirí and Masaya cones, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6,500 years ago. Historical lava flows cover much of the caldera floor and there is a lake at the far eastern end. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals have caused health hazards and crop damage.

Information Contacts: Virginia Tenorio, Wilfried Strauch, and Martha Navarro, Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); Nemesio M. Pérez, Instituto Tecnológico y de Energías Renovables (ITER), 38611 Granadilla, Tenerife, Canary Islands, Spain; Giorgio Virgili, WESTSYSTEMS, Via Molise, 3 56025 Pontedera, PI (Italy) (URL: http://www.westsystems.com/).


Nyamuragira (DR Congo) — August 2003 Citation iconCite this Report

Nyamuragira

DR Congo

1.408°S, 29.2°E; summit elev. 3058 m

All times are local (unless otherwise noted)


Rumbling and explosion sounds April-June, but no confirmed eruptions

According to reports from the Goma Volcano Observatory, since late October 2002 tectonic and magmatic seismicity at Nyamuragira has continued. Some of this seismicity was thought to be related to the refilling of a magma chamber emptied by a previous eruption. No eyewitness accounts of activity were reported until 26 February 2003, when a seismic crisis occurred. From 30 April into June 2003, local villagers reported rumblings and sounds of explosions coming from the volcano.

Activity during 27 October-14 December 2002. During 27 October-2 November, seismic data were collected at eight operational stations (Katale, Kibumba, Bulengo, Rusayo, Luboga, Goma, Lwiro, and Kunene). During this time volcanic seismicity was masked by aftershocks from a tectonic earthquake on 24 October 2002. Some rare magmatic events had hypocenters 10-25 km deep. During November 2002 epicenters of magmatic seismicity were concentrated in the NE area where the last eruption took place, an observation consistent with refilling of the magma chamber.

During 3-23 November, magmatic seismicity was more prevalent than tectonic seismicity, the latter dominated by aftershocks of the 24 October earthquake. The distribution of the magmatic earthquakes covered a zone 0-22 km deep, with an earthquake-free zone between approximately 3 and 7 km depth. The latter was interpreted as the location of a magma chamber, the same position as the chamber that fed the 27 July 2002 eruption. The tectonic earthquakes had depths of 0-30 km with an aseismic zone between 12 and 17 km. During the week of 24-30 November both tectonic and magmatic earthquakes were more frequent. Magmatic earthquakes increased at Katale to 348 from 239 during the previous week. High-frequency earthquakes in the E disappeared during the period. High-frequency earthquakes appeared in an isolated area in Virunga and densely NW of Lake Kivu in the area of Kalehe, where a landslide in late April 2003 killed ten people.

During 8-14 December the number of long-period earthquakes fell from to 169 at the Katale station from 239 the previous week, though the number of high-frequency earthquakes increased from 92 to 120. This increase was thought to be related to rifting in the area of the Large African Lakes. In general, volcanic tremors remained omnipresent. The epicenters of these long-period earthquakes were mainly concentrated in the NE of the central crater between 0 and 7 km depths. High-frequency earthquakes were concentrated in the aftershock zone of the 24 October 2002 earthquake in the Territory of Kalehe, NW of Idjwi Island.

Activity during February-March 2003. A seismic crisis started the night of 26 February and continued through the next morning. Seismicity increased greatly at the Goma seismic station; it was mainly tremor, but not at the same high levels of July 2002. Seismograms indicated clear increases in the numbers of both long-period and tectonic earthquakes and an increase in tremor amplitude. Visual observations were limited to the E flank, where the eruption of July 2002 started, but clouds obscured the summit crater.

Although seismic activity and warning phone calls occurred at the same time, there was no visible eruptive activity. Some very minor and brief activity (possibly witnessed) might have occurred in the central crater, which was not visible from the Rumangabo site. Seismic activity in late February included fracturing earthquakes, mainly on the N and NE sides of the volcano. Persistent long-period earthquakes were associated with magma movement. Short-period earthquakes associated with fracturing were observed for the first time.

A fresh outbreak of long-period earthquakes was noted in the NE quadrant during the week of 1-8 March, along with the growing presence of short-period events. Many long-period earthquakes occurred during the week of 16-22 March, including frequent fracture-related earthquakes.

Activity during April-June 2003. From 30 March through 27 April long-period earthquakes were concentrated beneath the NE flank, along with some short-period events. Although the number of long-period earthquakes decreased appreciably in late April and early May, similar seismicity continued through 21 June. The long-period events were distributed along a NW-SE trend, corresponding to the fracture zone towards Nyiragongo.

From 30 April until 1 May, it seemed that there was some renewal of activity, but no eruption was detected. Residents of Katale and Tongo, the closest villages to the volcano, reported some rumblings on 30 April between 1730 and 2130, plus clear sounds of individual explosions. The closest seismic station (Katale) recorded at the same time ~18 distinct explosion signals, directly followed at 1927 by a tectonic earthquake centered under the volcano. Later, seven type-C events followed until 2232. Another tectonic earthquake occurred at 2338.

Residents of Kunene (~12 km SW), Katale (~10 km NE), and Tongo claimed to have heard explosions and growling noises on 9 May. Local tectonic earthquakes from late May through late June were 0-27 km deep, with an aseismic zone at 3-7 km. Seismicity during 22-28 June was dominated by long-period earthquakes concentrated in the NE, in which there was an apparent increase compared to the previous week.

Geologic Background. Africa's most active volcano, Nyamuragira, is a massive high-potassium basaltic shield about 25 km N of Lake Kivu. Also known as Nyamulagira, it has generated extensive lava flows that cover 1500 km2 of the western branch of the East African Rift. The broad low-angle shield volcano contrasts dramatically with the adjacent steep-sided Nyiragongo to the SW. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Historical eruptions have occurred within the summit caldera, as well as from the numerous fissures and cinder cones on the flanks. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Historical lava flows extend down the flanks more than 30 km from the summit, reaching as far as Lake Kivu.

Information Contacts: Goma Volcano Observatory, Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo.


Nyiragongo (DR Congo) — August 2003 Citation iconCite this Report

Nyiragongo

DR Congo

1.52°S, 29.25°E; summit elev. 3470 m

All times are local (unless otherwise noted)


Continued lava lake activity during May-June; ashfall in local villages

Reports from the staff of the Goma Volcano Observatory (GVO) during May to 5 July 2003 noted that the hazard status remained at Yellow ("Vigilance"). Seismicity was characterized by tectonic, long-period, and short-period earthquakes. Deformation across the majority of fractures lacked significant extensional displacements, but the fractures in the S of Shaheru had compressional displacements. In spite of significant crater activity, geochemical and deformation measurements did not suggest any danger to the inhabited zones on the S flank.

During 4-24 May there was ashfall at Kibati (below 2,000 m on the SSE flank, ~8 km from the summit), Rusayo (~8 km from the summit on the SW flank), and Goma (~18 km S). Nightly red glows and degassing were observed each day. Crater observations revealed two pits containing lava fountains, with a NE-SW lengthening of the principal pit. An active lava flow was observed on 7 May inside the crater. During 18-24 May volcanic ash, including Pele's hair, continued to fall in villages around the volcano, including Goma. During 8-28 June the lava lake continued to emit a gas-and-ash plume. The lake was ~700 m below the edge of the crater. Collapses in the crater were observed during 13-14 and 18-20 June.

Seismicity. During 4-24 May 2003, seismic activity was dominated by persistent volcanic tremor. During 4-10 May, only two long-period earthquakes and a short-period fracture earthquake were recorded, although during 11-17 May an increased number of long-period earthquakes were distributed on the N flank along the fracture trending from Nyiragongo to Nyamuragira. A small number of short-period earthquakes occurred to the WSW along the Nyiragongo-Sake axis (Sake is ~24 km NW of Goma). During 18-24 May long-period earthquakes continued to appear in the NE-SE direction; some isolated long-period events were observed ENE towards Kibumba.

During 8-21 June persistent tremor continued, and six long-period earthquakes were reported. These tremors suggested intense activity in the crater. Weaker seismicity during the following week, 22-28 June, remained dominated by tremors caused by lava lake activity.

All earthquakes were recorded at the Kibumba, Rusayo, and Bulengo seismic stations and occurred at depths of 0-27 km, with an aseismic zone at 3-7 km.

Deformation and temperature. During 4-10 May 2003, measurements of deformation along the cracks in the S flank indicated neither contraction nor extension when compared with the previous week. During the next two weeks, no deformation occurred along the cracks at numerous other S-flank sites.

Contraction during 8-14 June along the Shaheru fractures (~2 km S of the crater) was 8 mm in Lower Shaheru and 29 mm in Higher Shaheru, suggesting that magma in the fractures S of Nyiragongo had not moved. During 15-21 June, temperature measurements in fractures at Nyiragongo, Shaheru, and Monigi (~1.5 km NE of the Goma airport) varied less than those measured in April-May. Average temperatures were in the range of 14.6-63.1°C.

During 22-28 June deformation measurements of fractures did not reveal any notable variation compared to previous measurements at Monigi, Mugara, and Nyiragongo Cants. Temperatures measured in the Monigi and Lemera fractures did not vary, while those at Mugara showed a slight increase of 3.6°C between 21 May and 28 June.

Crater observations, 22-23 May 2003. Kasereka and Yalire (GVO) remained at the summit of Nyiragongo during 22-23 May. During their SSE-flank ascent, vegetation was covered with slag and ash from Kibati (2,000 m) to the summit (3,470 m). Two types of Pele's hair were observed: those with a length of 20-40 cm were present from Shaheru (2,200 m) to the huts (3,250 m), and those shorter than 15 cm were present from the huts to the summit.

Upon arrival at the summit they observed a gas plume that covered the entire crater. The crater could only be seen for a few seconds at a time. However, the bottom of the crater was entirely occupied by the lava lake, and not by separate lava-filled pits; the crater bottom had an elliptical form elongated in a NE-SW direction. This lava lake was, when calm, characterized by undulatory movements of low amplitude, and, when agitated, projected materials 40-60 m high. A collapse in the crater was not recorded by the seismic network. For three hours that evening there were explosions in the crater, followed by ashfall on the summit.

For one hour on the morning of 23 May there was a total lull, with no growls or explosions, that corresponded to a decline of volcanic tremor recorded at the Bulengo, Kibumba, and Rusayo stations. The atmosphere immediately above the crater then cleared for at least 10 minutes, and photos were taken of the crater floor showing the single lava lake at the bottom of the crater (figure 31). Measurements could not be taken of the depth of the lava lake surface because the atmosphere was clouded by the gas plume. Analyses by the GVO showed that the pH of rainwater from the air was 4.13 and its conductivity was 2.08 ms/cm.

Figure (see Caption) Figure 31. Photograph of the lava lake (seen through the gas plume) occupying the bottom of the Nyiragongo crater, 23 May 2003. Courtesy of the Goma Volcano Observatory.

Geologic Background. One of Africa's most notable volcanoes, Nyiragongo contained a lava lake in its deep summit crater that was active for half a century before draining catastrophically through its outer flanks in 1977. The steep slopes of a stratovolcano contrast to the low profile of its neighboring shield volcano, Nyamuragira. Benches in the steep-walled, 1.2-km-wide summit crater mark levels of former lava lakes, which have been observed since the late-19th century. Two older stratovolcanoes, Baruta and Shaheru, are partially overlapped by Nyiragongo on the north and south. About 100 parasitic cones are located primarily along radial fissures south of Shaheru, east of the summit, and along a NE-SW zone extending as far as Lake Kivu. Many cones are buried by voluminous lava flows that extend long distances down the flanks, which is characterized by the eruption of foiditic rocks. The extremely fluid 1977 lava flows caused many fatalities, as did lava flows that inundated portions of the major city of Goma in January 2002.

Information Contacts: Goma Volcano Observatory, Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo.


Popocatepetl (Mexico) — August 2003 Citation iconCite this Report

Popocatepetl

Mexico

19.023°N, 98.622°W; summit elev. 5393 m

All times are local (unless otherwise noted)


Continuing intermittent eruptions; ashfall in June and July

Volcanic activity at Popocatépetl during March-July 2003, as reported by the Centro Nacional de Prevención de Desastres (CENAPRED), was similar to that from July 2002 to February 2003 (BGVN 27:10 and 28:02). Activity was comprised principally of multiple exhalations (some with significant ash), volcano-tectonic (VT) earthquakes, and explosions. Daily exhalations averaged 10-30 during March, 5-25 during April and May, and _50 during July. VT earthquakes in these months were M 2-3 at depths of 2-5 km located E or SE of the volcano.

On 28 April and 10 May, low-frequency harmonic tremors during the VT events attained moderate, but significant, amplitude levels lasting 13 and 4 hours, respectively. Eruptive activity during June, presumed to be predominantly phreatic, increased and caused ash-bearing exhalations and explosions. Another significant tremor episode was detected on 8 June. Eruptions on 20 and 28 June caused minor ashfall on some towns near the volcano. During July, many exhalations were explosive and carried significant ash. The largest explosive events in July were recorded on 1, 15, 19, and 25. The event of 19 July (figure 48) caused light ashfall as far as the southern metropolitan area of Mexico City. Aerial photography of the crater on 30 April and 19 May indicated no evidence of new lava dome emplacement during the report period.

Figure (see Caption) Figure 48. Photograph of an eruption at Popocatépetl volcano, 19 July 2003. Courtesy of CENAPRED.

Geologic Background. Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.

Information Contacts: Angel Gómez Vázquez, Alicia Martinez Bringas, Roberto Quass Weppen, Enrique Guevara Ortiz, Gilberto Castela Pescina, and Javier Ortiz Castro, Centro Nacional de Prevención de Desastres (CENAPRED), Av. Delfín Madrigal No.665, Coyoacan, México D.F. 04360, Mexico (URL: https://www.gob.mx/cenapred/); Servando De la Cruz-Reyna and Carlos Valdez Gonzalez, Instituto de Geofísica, UNAM, Cd. Universitaria, Circuito Institutos, Coyoácan, México D.F. 04510, Mexico (URL: http://www.geofisica.unam.mx/).


Ruang (Indonesia) — August 2003 Citation iconCite this Report

Ruang

Indonesia

2.3°N, 125.37°E; summit elev. 725 m

All times are local (unless otherwise noted)


Rapid decrease in activity following September 2002 eruption

Volcanic activity had decreased by 30 September 2002 after a strong eruption on the 25th. After the hazard status was lowered from Alert Level 4 to 3 on 30 September, it was dropped to Level 2 during the week of 7-13 October. However, activity continued to be higher than normal that week, with frequent strong emissions and "thick white ash" rising ~100 m above the summit. Emission earthquakes decreased (table 1). High-pressure plumes decreased in frequency from 14 October through 10 November, but "thick white ash" continued to rise from the summit. No ashfall was reported during October or November. Rainfall on 23 October caused a lahar. No volcanic or emission earthquakes were recorded during 4-10 November, and the Alert Level was reduced to level 1.

Table 1. Seismicity at Ruang, 7 October-10 November 2002. Courtesy of VSI.

Date Emission earthquakes Tectonic earthquakes
07 Oct-13 Oct 2002 3 46
14 Oct-20 Oct 2002 6 39
21 Oct-27 Oct 2002 2 85
28 Oct-03 Nov 2002 2 63
04 Nov-10 Nov 2002 -- 58

Geologic Background. Ruang volcano, not to be confused with the better known Raung volcano on Java, is the southernmost volcano in the Sangihe Island arc, north of Sulawesi Island. The 4 x 5 km island volcano rises to 725 m across a narrow strait SW of the larger Tagulandang Island. The summit contains a crater partially filled by a lava dome initially emplaced in 1904. Explosive eruptions recorded since 1808 have often been accompanied by lava dome formation and pyroclastic flows that have damaged inhabited areas.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi. esdm.go.id/).


Soputan (Indonesia) — August 2003 Citation iconCite this Report

Soputan

Indonesia

1.112°N, 124.737°E; summit elev. 1785 m

All times are local (unless otherwise noted)


Lava avalanches and ash explosions during 18-22 July 2003

On 18 July 2003, large glowing lava avalanches resulted in a pyroclastic surge towards the W and NW. An ash column rose up to 2,000 m above the summit, and the Alert Level was raised to 3. Lava avalanches and ash explosions continued over the next few days, but by 21 July volcanic activity had started to decrease. Night observations showed that areas where glowing lava had illuminated the W slope on 18 and 19 July became dull and gradually disappeared over the three days following the eruption. Volcanic tremor due to fluid movement also ceased as of 22 July. Ash explosions continued sporadically, but were not as thick or as high as during previous observations. On 22 July between 20 of these minor ash explosions were recorded; another 50 ash explosions were reported after that time. No volcanic earthquakes were recorded, although small-amplitude tremor (0.25 mm) was recorded continuously. After 25 July the volcano was lowered to Alert Level 2.

During the week of 28 July-3 August, lava avalanches on the W slope continued, and emissions and avalanche earthquakes dominated seismic records. In addition, a white gas plume rose 50 m.

Geologic Background. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi. esdm.go.id/).


Soufriere Hills (United Kingdom) — August 2003 Citation iconCite this Report

Soufriere Hills

United Kingdom

16.72°N, 62.18°W; summit elev. 915 m

All times are local (unless otherwise noted)


Major dome collapse and explosive activity during 12-13 July

Activity at Soufriere Hills has been high over recent months, culminating in the collapse of a major dome and explosive activity during 12-13 July 2003. A summary of reports by the Montserrat Volcano Observatory (MVO) from 27 June to 12 September 2003 is provided below, with sulphur dioxide emissions and activity data (table 48).

Table 48. Summary of activity at Soufriere Hills, 2 May-12 September 2003. Activity occurred as summarized above, with the addition of three explosion signals during 11-18 August. Courtesy of the Montserrat Volcano Observatory.

Date Rockfall Long-period / Rockfall Long-period Hybrid Volcano-tectonic
02 May-09 May 2003 767 88 138 7 2
09 May-16 May 2003 580 65 55 7 --
16 May-23 May 2003 774 75 81 8 2
30 May-06 Jun 2003 445 34 40 5 1
06 Jun-13 Jun 2003 79 8 16 6 2
13 Jun-20 Jun 2003 48 10 -- 55 --
20 Jun-27 Jun 2003 54 4 2 135 1
27 Jun-04 Jul 2003 193 61 7 37 --
04 Jul-11 Jul 2003 156 12 38 9 --
11 Jul-18 Jul 2003 58 3 24 84 1
18 Jul-25 Jul 2003 -- 6 5 21 --
25 Jul-01 Aug 2003 34 -- 5 30 --
01 Aug-08 Aug 2003 25 -- 5 35 --
08 Aug-15 Aug 2003 12 -- 7 38 2
15 Aug-22 Aug 2003 5 1 6 39 --
22 Aug-29 Aug 2003 7 -- 2 26 --
29 Aug-05 Sep 2003 4 -- -- 18 --
05 Sep-12 Sep 2003 2 -- 3 27 --

Activity was generally at a moderate level in early May, increasing over 7-9 May and remaining high through 23 May. Activity mainly focused towards the NE, with rockfalls and numerous pyroclastic flows along the N side of the Tar River and in the Tar River Valley. On 12 and 13 May, flows were seen on the N and NW flanks in the area of Farrell's Plain and the upper reaches of Tyre's Ghaut. During 21-23 May there was increased activity on the N flanks, with a number of pyroclastic flows into the top of Farrell's Plain, Tyre's Ghaut, and Tuitt's Ghaut. Pulses of vigorous ash venting were observed at the summit, and intense glow on the summit and NE flanks was seen on the nights of 20 and 21 May. Sulfur emissions varied during May, with a high of 744 metric tons/day (t/d) (8.6 kg/s) on 14 May and a low of 300 t/d (3.4 kg/s) on 18 May. Extreme highs of 850 t/d (9.9 kg/s) and 820 t/d (9.5 kg/s) occurred on 4 and 9 May, respectively.

During the first week of June, activity was variable, generally declining to a moderately low level. Most activity through 6 June was focused on the E and NE flank, producing rockfalls and numerous pyroclastic flows in the Tar River Valley and occasionally in White's Ghaut and Tuitt's Ghaut. Activity during the week ending 13 June decreased to a low level, and remained low through 27 June, increasing over 26-27 June on the N flanks. Hybrid earthquake activity developed into a diffuse swarm on 22-23 June, some events at depths of 3 km below the lava dome. SO2 emissions were relatively stable in June, varying between 240 t/d (2.8 kg/s) and 540 t/d (6.3 kg/s).

Sulfur emissions varied between 260 t/d (3 kg/s) and 585 t/d (6.8 kg/s) in July, but jumped to 840 t/d (9.7 kg/s) on 2 July. This could be related to increased activity during the first week of July, with pyroclastic flow and rockfall activity focused on the N flanks of the dome. Most flows occurred in Tuitt's Ghaut, with some in Tyre's Ghaut and White's Ghaut. Sporadic flows also occurred on the W side of the dome in the Gages area.

Activity remained high over the week ending 11 July, with a swarm of several thousand small hybrid earthquakes, at a rate of 1-2 per minute, commencing in the early hours of 9 July. While the size of these earthquakes increased slowly, individual events were below the normal recording threshold. The swarm of hybrid earthquakes intensified slightly over the night of 11 July, with events becoming larger and more closely spaced. Glimpses of the N part of the dome complex on 10 and 11 July confirmed that dome growth switched to the N, as was also shown by the northerly focus to the rockfalls and pyroclastic flows. Pyroclastic flows occurred most frequently in White's Ghaut, Tar River Valley, and Tuitt's Ghaut, with several small flows in Tyre's Ghaut earlier in the week.

By the morning of 12 July, events in the earthquake swarm merged into a continuous tremor signal. A period of prolonged and heavy rainfall between 0600 and 0900 caused mudflows in the Belham Valley. Small pyroclastic flows, the first of which were pale and weakly convective, occurred in the Tar River Valley. Flow activity built slowly through the afternoon until it was almost continuous. There were marked increases in the intensity of the activity at 1827 and again at 2007. Some flows traveled more than 2 km over the surface of the sea at the mouth of the Tar River Valley. Pyroclastic flows also reached the sea in White's Ghaut and the Spanish Point area. These flows resulted in the extremely heavy fallout of ash and accretionary lapilli over the island, particularly S of Woodlands.

A number of explosive events took place towards the end of the dome collapse of 12 July, with the largest occurring between 2300 and midnight. Showers of rock fragments fell on the island, with dense rocks up to 60 mm in diameter recorded. The Washington Volcanic Ash Advisory Center (VAAC) provided a column height of around 16 km for this event. The activity persisted at a high level until around 0200 on 13 July. It began subsiding slowly, declining to very low levels by the following morning, when a sudden Vulcanian explosion occurred from the lava dome. Two more explosions occurred in the next two days, producing pumice that reached 15 cm in size at Richmond Hill (~5 km W) and 4 cm in Olveston. Heavy ashfall from the collapse was experienced over all the inhabited parts of Montserrat, with the greatest thickness (over 15 cm) recorded at Vue Pointe Hotel. North of St Peter's the thickness was less than 1 cm.

The bulk of the dome structure was removed in the collapse, and pyroclastic flows impacted the area between Tar River Valley and Spanish Point. The activity destroyed GPS sites at White's Yard and Hermitage, and a camera site at White's Yard. Solar panels were smashed by falling rocks at Spring Estate GPS site and at Garibaldi Hill. After the collapse, sulfur-dioxide emissions jumped to highs between 1,030 t/d (12 kg/s) and 1,720 t/d (20 kg/s), much higher than any other readings over the past several weeks.

Activity was extremely low through 1 August with only a few events triggering the seismic network. The restrictions of the October 2002 exclusion zone were lifted on 1 August. The pattern of earthquakes through the week of 25 July indicated that dome growth within the explosion crater probably restarted, although it was not possible to confirm this visually due to low clouds. Intense activity began at 0608 on 1 August with an episode of powerful ash venting. There were many strong bursts of gas release and jets of ash; the plume rose to over 3.2 km. This activity declined to very low levels about 0730. Another episode of gas venting began at 0834.

Over the next week activity fluctuated, with periods of relative quiet separating episodes of intense degassing and hybrid earthquake activity. At the beginning of the week the volcano was extremely active with intense ash venting from the explosion crater. It was then fairly quiet with occasional rockfalls and hybrid earthquakes. A good view of the new dome was obtained from the air on 5 August, showing a small southerly directed lobe growing extremely slowly, if at all. Earthquake activity increased on the evening of 7 August with eight large hybrid events occurring overnight.

Through 22 August activity was at low levels; the dome remained a small lobe just over 100 m across. Several small slumps from the interior wall of the 12 July collapse scar produced small rockfalls, light ash in the plume, and the formation of some large fumaroles. By 29 August new fumaroles opened SE of the main explosion crater, towards the upper parts of the Tar River Valley. A strong sulphurous smell and blue haze N of the volcano did not reflect increased activity. SO2 emissions in August were again variable, with a low of 450 t/d (5.4 kg/s) on 6 August and highs approaching 2,500 t/d (29 kg/s) the following week.

Through the latter part of the week ending 5 September, the gas plume was out of reach of the spectrometer network due to winds from Hurricane Fabian. Activity remained low through 12 September, but several episodes of ash venting occurred with a few small earthquakes.

Geologic Background. The complex, dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. The volcano is flanked by Pleistocene complexes to the north and south. English's Crater, a 1-km-wide crater breached widely to the east by edifice collapse, was formed about 2000 years ago as a result of the youngest of several collapse events producing submarine debris-avalanche deposits. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits, including those from an eruption that likely preceded the 1632 CE settlement of the island, allowing cultivation on recently devegetated land to near the summit. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but no historical eruptions were recorded until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.

Information Contacts: Richard Herd, Montserrat Volcano Observatory, Fleming, Montserrat, West Indies (URL: http://www.mvo.ms/).


Stromboli (Italy) — August 2003 Citation iconCite this Report

Stromboli

Italy

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

All times are local (unless otherwise noted)


Explosive activity in the summit craters and thermal signatures in the lava-flow field

The latest effusive eruption at Stromboli ended between 21 and 22 July (BGVN 28:07), when active lava flows on the upper Sciara del Fuoco were no longer visible. Since then explosive Strombolian activity became more common at both summit craters. Four active vents were observed within Crater 1 (the NE crater), and there was one funnel-shaped incandescent depression within Crater 3 (the SW crater). Strombolian activity during the first half of August was very intense at Crater 1, causing a spatter cone to form on the crater floor and incandescent bombs to fall on the outer flanks. Explosive activity at Crater 3 was apparently deeper, and was often accompanied by ash emission.

During the first half of August, thermal images of the apparently inactive lava flow field revealed thermal signatures within cracks on the upper flow field, and within skylights along two lava tubes in the upper Sciara del Fuoco, at ~550 m elevation. Temperatures of over 300°C, and incandescence of these hot spots, suggest endogenous growth. Incandescence and thermal signatures at these sites were not observed between 22 and 31 July.

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: Sonia Calvari, Istituto Nazionale di Geofisica e Vulcanologia, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/).


Tandikat-Singgalang (Indonesia) — August 2003 Citation iconCite this Report

Tandikat-Singgalang

Indonesia

0.39°S, 100.331°E; summit elev. 2854 m

All times are local (unless otherwise noted)


Increased seismicity during January 2003

Seismic activity at Tandikat increased significantly over the week of 20-26 January 2003. One felt earthquake (III on the MMI scale) on 20 January was followed by a significant number of deep volcanic earthquakes. The number of both volcanic and tectonic earthquakes resulted in the volcano's hazard status being upgraded to Alert Level 2 on 25 January. Seismic activity decreased over the period 27 January-16 February (table 1), but remained at an elevated level.

Table 1. Seismicity recorded at Tandikat, 13 January-16 February 2003. Data courtesy of VSI.

Date Shallow Volcanic Deep Volcanic Emission Tremor Tectonic
13 Jan-19 Jan 2002 -- 6 -- -- 22
20 Jan-26 Jan 2002 1 149 -- 2 174
27 Jan-02 Feb 2002 -- 46 4 1 54
03 Feb-09 Feb 2002 -- 24 3 -- 18
10 Feb-16 Feb 2002 -- 19 5 -- 15

Geologic Background. Tandikat and its twin volcano to the NNE, Singgalang, lie across the Bukittinggi plain from Marapi volcano. Volcanic activity has migrated to the SSW from the higher Singgalang, and only Tandikat has had historical activity. The summit of Tandikat has a partially eroded 1.2-km-wide crater containing a large central cone capped by a 360-m-wide crater with a small crater lake. The only three reported historical eruptions, in the late 19th and early 20th centuries, produced only mild explosive activity.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi. esdm.go.id/).


Tangkuban Parahu (Indonesia) — August 2003 Citation iconCite this Report

Tangkuban Parahu

Indonesia

6.77°S, 107.6°E; summit elev. 2084 m

All times are local (unless otherwise noted)


Elevated seismicity during August-October 2002

In August and September 2002 Tankubanparahu showed its first elevated seismicity since 1992 (BGVN 27:09). This activity continued in October of 2002. The volcano is at Alert Level 2.

From September through 6 October, volcanic events dominated seismicity, particularly during the week of 16-22 September, when there were 331 shallow volcanic [B-type] events. Crater fumarole temperatures of 92-95°C were recorded at Domas and Ratu craters; the hotspring temperature at Ciater was 47°C. H2S concentrations were above detections limits, ranging from 80 to more than 100 ppm at Ratu; more than 80 ppm H2S was also recorded at Jagal. A "thin white ash plume" was observed to rise 2.5 m, and a whizzing sound could be heard 50 m away. A strong sulfur smell and sulfur sublimation were noted.

Between 7 and 13 October, volcanic events again dominated seismic activity, but numbers were lower than the previous week, with 151 B-type events, down from 199, and four A-type events, down from five. Tectonic activity occurred at the same rate as the previous week, with 21 events. The following week volcanic activity again dropped, with 57 shallow volcanic (B-type) events. However, deep volcanic (A-type) events increased slightly, to 15. Observations during the week included a "white-thin ash plume" to 2 m and medium-strong gas pressure. A strong sulfur smell and yellow sublimation were also noted. The fumarole temperature at Ratu crater was 95°C.

Shallow volcanic earthquakes increased through the week of 21-27 October, with 123 events. Deep volcanic events dropped to 7, and tectonic activity again remained stable, with 19 events. On 25 October Upas crater was measured at 44°C; a "white-thin ash plume" was only noted to rise 0.5-1 m, and the sulfur smell was weak.

Geologic Background. Gunung Tangkuban Parahu is a broad shield-like stratovolcano overlooking Indonesia's former capital city of Bandung. The volcano was constructed within the 6 x 8 km Pleistocene Sunda caldera, which formed about 190,000 years ago. The volcano's low profile is the subject of legends referring to the mountain of the "upturned boat." The Sunda caldera rim forms a prominent ridge on the western side; elsewhere the rim is largely buried by deposits of the current volcano. The dominantly small phreatic eruptions recorded since the 19th century have originated from several nested craters within an elliptical 1 x 1.5 km summit depression.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi. esdm.go.id/).


Whakaari/White Island (New Zealand) — August 2003 Citation iconCite this Report

Whakaari/White Island

New Zealand

37.52°S, 177.18°E; summit elev. 294 m

All times are local (unless otherwise noted)


Large crater lake floods the active vent; new hazards identified

Following increased SO2 emissions in December 2002 and mud ejections during February and early March 2003 (BGVN 28:02), the active vent at White Island continued to emit a small plume of steam and gases through 4 April, but seismic activity was at a very low level. Seismicity remained low through August 2003.

Scientists visited White Island during the week of 5-11 April for routine monitoring. This fieldwork included sampling high-temperature fumaroles, measuring carbon dioxide output, and geodetic surveying. The crater lake had grown in size and flooded the active vent, greatly reducing the emission of a gas plume from the vent and also reducing the seismicity to very low levels. A minor plume of steam and gases persisted through 20 June, but was not visible the week of 21-27 June; no further mention of a plume was made in reports through August.

Scientists from the Institute of Geological & Nuclear Sciences (IGNS) who visited the island during the week of 28 June-4 July noted striking changes in the crater lake, which had turned a light green color, and was very warm (58°C). The water level had risen several meters, to ~30 m below the crater rim, flooding all the active vents and spreading into all the areas of the crater floor. This lake is the largest to form within the 1978/90 Crater Complex. Fumarole temperatures ranged from 101 to 114°C.

By the first week of August the lake seemed to be semi-permanent, reaching a size of ~300 m long and somewhat less in width, with an unknown depth. As a result, a Science Alert Bulletin issued by the IGNS on 7 August 2003 noted that the existence of the lake created new hazards. Over the last 10-15 years many small ponds and lakelets have formed in topographic lows or the floors of small sub-craters within the 1978/90 Crater Complex. Their lives have typically been short as they have been filled in by the next eruption, or drained as new vents have formed. The small volumes of these lakes was such that they had no influence on eruptive activity.

However, the current lake volume is large enough that it could influence eruptive activity. Ejection of the lake in an eruption could cause flooding of the shallow stream valleys across the Main Crater floor, maybe as far as the sea. Should there be no significant eruptive activity within the next 18-24 months and the lake continues to fill, it may reach overflow level. In this situation water may overflow into drainage channels on Peg 12 Flat, S of the 1978/90 Crater Complex, and these channels may further erode if water is continuously flowing in them.

As of 29 August seismic and hydrothermal activity remained at the low levels recorded during the past four weeks. The lake level had risen since early July, and the temperature was 53°C, down slightly from 58°C on 2 July. The volcano monitoring team installed temporary benchmarks inside the main crater, so changes in the lake level could be observed from the safety of the crater rim. Although the development of the crater lake has been a concern, there is no significant change in volcanic activity on the island, so the hazard status for White Island remains at Alert Level 1.

Geologic Background. The uninhabited Whakaari/White Island is the 2 x 2.4 km emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes. The SE side of the crater is open at sea level, with the recent activity centered about 1 km from the shore close to the rear crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km NW. Descriptions of volcanism since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity there also forms a prominent part of Maori legends. The formation of many new vents during the 19th and 20th centuries caused rapid changes in crater floor topography. Collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining project. Explosive activity in December 2019 took place while tourists were present, resulting in many fatalities. The official government name Whakaari/White Island is a combination of the full Maori name of Te Puia o Whakaari ("The Dramatic Volcano") and White Island (referencing the constant steam plume) given by Captain James Cook in 1769.

Information Contacts: Brad Scott, Institute of Geological & Nuclear Sciences (IGNS), Private Bag 2000, Wairakei, New Zealand (URL: http://www.gns.cri.nz/).

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  Obituaries

Misc 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 subject.

Additional Reports  False Reports