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Bulletin of the Global Volcanism Network

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

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

Recently Published Bulletin Reports

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).

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Bulletin of the Global Volcanism Network - Volume 38, Number 01 (January 2013)

Managing Editor: Richard Wunderman

Akita-Komagatake (Japan)

Short lived plume rising to 50 m observed on 14 December 2011

Dona Juana (Colombia)

Seismic swarm in 2010 and monitoring efforts

Heard (Australia)

Satellite imagery reveals lava flows in December 2012

Huila, Nevado del (Colombia)

Dome growth and displaced glacier in 2009; decreasing activity during 2010-2012

Izu-Oshima (Japan)

Non-eruptive May 2010 surface deformation from inferred deep instrusion

Kikai (Japan)

Steam plumes rose to 800 m duing latter half of 2012

Kuchinoerabujima (Japan)

Increased seismicity, 11 December 2011-5 January 2012

San Cristobal (Nicaragua)

Ash eruption during 25-28 December 2012



Akita-Komagatake (Japan) — January 2013 Citation iconCite this Report

Akita-Komagatake

Japan

39.761°N, 140.799°E; summit elev. 1637 m

All times are local (unless otherwise noted)


Short lived plume rising to 50 m observed on 14 December 2011

The Japanese Meterological Agency (JMA) reported that a short-lived plume rose to 50 m above Akita-Komaga-take on 14 December 2011 and was recorded by a camera located to the N of Me-dake's summit.

Aerial observations were conducted in cooperation with the Japan Ground Self Defense Force on 13 December. Areas of snow melt corresponded to geothermal areas that had been previously identified. No new geothermal areas were found.

An M 2.6 earthquake on 27 December at 1234 local time occurred ~2 km W of Me-dake, with a maximum JMA Seismic Intensity of 1 in Senboku-city, Akita Prefecture. The JMA Seismic Intensity scale, used in Japan and Taiwan is classified into 10 categories; 0 to 4, 5 weak, 5 strong, 6 weak, 6 strong, and 7. The seismicity around the area had temporarily increased, but then returned to baseline levels. No volcanic activity related to this seismicity was observed.

JMA reported no activity at Akita-Komaga-take in 2012.

Geologic Background. Two calderas partially filled by basaltic cones cut the summit of Akita-Komagatake volcano. The larger southern caldera is 1.5 x 3 km wide and has a shallow sloping floor that is drained through a narrow gap cutting the SW caldera rim. On its northern side the southern caldera borders a smaller more circular 1.2-km-wide caldera, whose rim is breached widely to the NE. The two calderas were formed following explosive eruptions at the end of the Pleistocene, between about 13,500 and 11,600 years ago. Two cones, Medake and Kodake, occupy the NE corner of the southern caldera, whose long axis trends NE-SW. The 1637-m-high Komagatake (also known as Onamedake) cone within the northern caldera is highest point, and has produced lava flows to the north and east; it has a 100-m-wide summit crater. Small-scale historical eruptions have occurred from cones and fissure vents inside the southern caldera. The temperatures of geothermal areas increased beginning in 2005, and some fumarolic plumes were observed in 2011-12.

Information Contacts: Japan Meteorological Agency (JMA), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/en).


Dona Juana (Colombia) — January 2013 Citation iconCite this Report

Dona Juana

Colombia

1.5°N, 76.936°W; summit elev. 4137 m

All times are local (unless otherwise noted)


Seismic swarm in 2010 and monitoring efforts

Doña Juana, a volcano in repose, is located ~50 km NE of Pasto, the provincial capital where the local Instituto Colombiano de Geología y Minería (INGEOMINAS) volcanic and seismic observatory is based (figure 1). In this report we discuss monitoring efforts that began as early as 2004, highlight elevated seismicity detected in mid-2010, and describe the relatively new national park which encompasses Doña Juana and two other volcanic centers (Petacas and Ánimas). Petacas is ~19 km NE of Doña Juana and Ánimas, 12.5 km NE. Ánimas lacks a clear Holocene age; however, Ánimas is an important landmark in this report because the recent seismicity is often found proximal to this volcano. Listed as a Quaternary volcanic center, Ánimas can be found in the "Preliminary List of Pleistocene Volcanoes" section of the Volcanoes of the World 3rd edition (Siebert and others, 2010).

Figure (see Caption) Figure 1. This map of instrumentation from 2012 shows the monitoring network for Doña Juana with telemetered locations for the observatory in Pasto (red circle). Triangles are short period seismic stations (red triangles correspond to INGEOMINAS stations and the pink triangle is part of the National Seismic Network of Colombia (RSNC)), the orange hexagon is a broadband seismic station, green circles are electronic tiltmeters, and green squares are repeater stations for telemetry. The volcanic centers of Doña Juana and Galeras are labeled with yellow text. Courtesy of INGEOMINAS.

Aerial observations and field investigations. Aerial observations had been collected since 2004 in collaboration with the Colombian Air Force (FAC). Overflights during clear conditions provided views of the lava domes and exposures of bare rock where high elevation and frequent rockfalls limit vegetation (figure 2). Remote sensing images of the region also captured the variations in vegetation and distribution of scree slopes (figure 3).

Figure (see Caption) Figure 2. This SE looking photo of Doña Juana was taken during aerial surveys on 12 March 2007. The town of La Cruz appears in the foreground, ~13 km W of the volcanic edifice (on the skyline). Courtesy of INGEOMINAS.
Figure (see Caption) Figure 3. This false-color ASTER image of Doña Juana from 9 September 2010 provided a clear view of the sharp boundaries between heavy vegetated outer flanks (red) and the scrub-covered dome complex (green). Within the central dome area a pale region is attributed to scree from rockfalls. The lowlands, where agriculture dominates the topography, can be distinguished by the pale pink to white regions. Courtesy of NASA.

During 13-21 September 2006, INGEOMINAS led field investigations around Doña Juana. Four scientists focused on the area's stratigraphy and composition of volcanic deposits for development of a future hazard map as well as enhancing the knowledge of the volcano's eruptive history.

Monitoring stations. Three seismic stations were online in 2008: Lava, Florida, and Páramo (figure 4). The Páramo tiltmeter was also online in 2008. In 2009 two additional stations were online; La Cruz seismic station was installed in April and La Florida electronic tiltmeter was installed in June. In 2011, geochemical monitoring began at hot springs within 7 km of the edifice.

Figure (see Caption) Figure 4. The telemetered monitoring network for Doña Juana in 2012 included seismic and electronic tiltmeter instruments. Regular monitoring efforts also included measurements at hot springs (see text). Names of the two volcanic centers Doña Juana and Ánimas and the local communities are highlighted in green. The largest nearby community is the town of La Cruz, ~13 km NNW of the volcanic edifice. Volcán Ánimas is the nearest volcanic center to Doña Juana (~12.5 km NE); however, there has been no documented Holocene volcanism from this site. Courtesy of INGEOMINAS.

As of December 2012, the monitoring network consisted of four seismic stations, with radio repeaters linked to the Pasto network, and two electronic tiltmeters.

Hot spring investigations. INGEOMINAS routinely monitored six thermal springs located ~7 km N and SW from the summit (figure 4). There were three visits during 2011 (August, October, and December) and a visit in April 2012. Temperature and pH monitoring as well as geochemical analysis were the main goals for these investigations.

In their online April 2012 technical bulletin, INGEOMINAS noted that bicarbonate (HCO3) concentrations varied at all monitoring sites, and highest values were consistent between the Tajumbina (1,276-1,436 mg/L) and Ánimas II (1,159-1,229 mg/L) sites. Of all sites, Ánimas I showed an increase since August 2011 in both temperature (41.2°C to 55.3°C) and pH (6.5 to 6.83).

In April 2012, INGEOMINAS discovered a new hot spring location, Ánimas III. This site was within 1 km of Ánimas I, and at the time of sampling, had a neutral pH (7.02) and a lower temperature (56.6°C) compared to the neighboring Ánimas I and Ánimas II sites.

Seismicity. INGEOMINAS reported trends in local seismicity during 2009-2012 in technical bulletins available online. Limited seismicity was detected in 2009 and an abrupt change appeared in early 2010 (figure 5). Combined seismicity (volcano-tectonic, tremor, long period, hybrid, and a category noted as "VOL") tallied for 2010 produced an average of 241 events per month. INGEOMINAS assigned earthquakes to the "VOL" category if they did not meet the criteria of other earthquake types but could be distinguished by fracturing signals proximal to the volcanic edifice. Volcano-tectonic (VT) earthquakes occurred more frequently than other types, occurring on average 107 times per month.

Figure (see Caption) Figure 5. Monthly earthquakes detected with the Doña Juana seismic network during 2009-2012. The number of earthquakes represents a sum of volcano-tectonic, tremor, long period, hybrid, and 'VOL' (see text) events per month. Bar color alternates from red to blue to distinguish years. Courtesy of INGEOMINAS.

Seismicity peaked in August 2010 owing to three VT swarms. That month the various earthquakes totaled more than 675 events. These were low-magnitude earthquakes (M 0-2.7) with relatively shallow depths (7-10 km below the summit).

The calculated locations of earthquakes were available for events during 2010-2012 (table 1). During this time period, epicenters were frequently dispersed between Doña Juana and Ánimas except for the mid-2010 activity and during January-February 2011. This record of information highlights the significance of August 2010 when VT earthquakes were clustered ~7 km NE of Doña Juana, slightly closer to the older volcanic edifice Ánimas (figure 6).

Table 1. During June 2010-December 2012, earthquake detection was sufficient for calculating magnitudes and locations. During several months (January-May 2010, June and October 2011, and September and November 2012) no locations were determined. "Notes" refer to epicenter characteristics such as clustering locations; "dispersed" events are those that occurred at various depths and distances from the volcanic centers. Courtesy of INGEOMINAS.

Month Total Located Magnitude Depth (km below summit) Notes
Jun 2010 68 0.1-2.6 5-10 ~5 km SW of Ánimas
Jul 2010 14 0.2-1.5 6-10 ~5 km SW of Ánimas
Aug 2010 130 0-2.7 7-10 ~5 km SW of Ánimas
Sep 2010 34 0.2-2.1 1-11 ~5 km SW of Ánimas
Oct 2010 10 0.6-2.7 ~7 dispersed
Nov 2010 5 1.1-2.3 3-6 dispersed
Dec 2010 7 0.2-1.8 4-10 dispersed
Jan 2011 59 0.1-3.1 3-14; 6-8 ~8 km SW of Ánimas; many earthquakes clustered at 6-8 km depth
Feb 2011 1 1.2 7 2 km SW of Ánimas
Mar 2011 7 0.5-2.1 15-50 between Doña Juana and Ánimas
Apr 2011 2 -- 5.7-6.5 between Doña Juana and Ánimas
May 2011 2 0.4, 1.7 8, 11 dispersed
Jun 2011 -- -- -- --
Jul 2011 9 0.3-1.1 6-12 some clustering near Ánimas
Aug 2011 7 -- 4-15 between Doña Juana and Ánimas
Sep 2011 1 0.7 4 between Doña Juana and Ánimas
Oct 2011 -- -- -- --
Nov 2011 9 0.3-1.5 3-8 between Doña Juana and Ánimas
Dec 2011 2 0.9, 1.7 4-6 between Doña Juana and Ánimas
Jan 2012 16 0.3-1.5 1-19 between Doña Juana and Ánimas
Feb 2012 5 0.9-1.7 2-8 between Doña Juana and Ánimas
Mar 2012 2 0.8, 1.3 7 between Doña Juana and Ánimas
Apr 2012 5 0.4-1.3 0-18 dispersed
May 2012 7 0.5-1.4 3-9.5 dispersed
Jun 2012 20 0-2.3 1-14 dispersed
Jul 2012 13 0.7-1.9 1-14 dispersed
Aug 2012 6 0.2-1.9 0-14.5 SW of Doña Juana
Sep 2012 -- -- -- --
Oct 2012 4 0.7-1.3 0-20 SW of Doña Juana
Nov 2012 -- -- -- --
Dec 2012 2 1.1, 0.7 2, 20 ~10 km S of Doña Juana
Figure (see Caption) Figure 6. Volcano-tectonic seismicity during August 2010 was characterized by a swarm located between Doña Juana and Ánimas volcano; ~8 km NE of Doña Juana. Courtesy of INGEOMINAS.

Colombia's 52nd Natural National Park. In 2007, the Doña Juana-Cascabel Volcanic Complex Natural National Park was created both by the Ministry of Environmental, Housing and Territorial Development and the Colombian Natural National Parks (figure 7). This included Doña Juana, Ánimas, and Petacas volcano (located ~19 km NE of Doña Juana) within the 65,858 hectares of preserved land. Within this densely forested region, a series of streams and waterfalls was locally known as El Cascabel. The park was developed to protect diverse flora and fauna, including numerous endangered species such as the Andean condor, the Moor tapir, the spectacled bear, and puma; approximately 11% of the park includes alpine terrain.

Figure (see Caption) Figure 7. This map of biomes includes the Doña Juana-Cascabel Volcanic Complex Natural National Park and surrounding region. Doña Juana is located in the SW portion of the park. Shaded areas indicate low-elevation Amazon through high-elevation Andean environments. The park boundary is indicated by a heavy black line; populated areas are shaded light pink, road systems are represented by gray lines, and major towns are labeled. This map appears in the 2008-2013 Management Plan of PNN CVDJ-C (2008).

References. Department of the Environment, Housing and Territorial Development Special Administration Unit of the system of Natural National Parks (UAESPNN), 2008, Doña Juana-Cascabel Volcanic Complex Natural National Park (PNN CVDJ-C) Management Plan 2008-2013, Popayán, Colombia, July 2008.

Siebert L., Simkin T., and Kimberly P., 2010, Volcanoes of the World, 3rd edition, University of California Press, Berkeley, 558 p.

Geologic Background. The forested Doña Juana stratovolcano contains two calderas, breached to the NE and SW. The summit of the andesitic-dacitic volcano is comprised of a series of post-caldera lava domes. The older caldera, open to the NE, formed during the mid-Holocene, accompanied by voluminous pyroclastic flows. The younger caldera contains the active central cone. The only historical activity took place during a long-term eruption from 1897-1906, when growth of a summit lava dome was accompanied by major pyroclastic flows.

Information Contacts: Instituto Colombiano de Geologia y Mineria (INGEOMINAS), Observatorio Vulcanológico y Sismológico de Pasto, Pasto, Colombia (URL: https://www2.sgc.gov.co/volcanes/index.html); WWF Colombia (URL: http://www.wwf.org.co/?109882/Nuevo-Parque-Nacional-Natural-en-el-piedemonte-Andino-Amazonico-colombiano); Doña Juana-Cascabel Volcanic Complex National Natural Park (URL: http://www.parquesnacionales.gov.co/).


Heard (Australia) — January 2013 Citation iconCite this Report

Heard

Australia

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

All times are local (unless otherwise noted)


Satellite imagery reveals lava flows in December 2012

We received an informal report from Matt Patrick (Hawaiian Volcano Observatory) on a new eruptive episode at Big Ben volcano, Heard Island (figure 16). He noted that MODVOLC thermal alerts reappeared at Heard in September 2012 after a four year hiatus (the last eruptive episode ended on 2 March 2008; BGVN 33:01), suggesting the start of a new eruptive episode at the volcano. Since Heard Island is unsettled and extremely isolated, monitoring of the volcano is possibly primarily through satellite imagery (Patrick, 2013).

Figure (see Caption) Figure 16. A contour map (interval = 200 m) showing the partly ice-covered Heard Island. At the time of map preparation, the brown areas were ice free. Produced and issued in January 2000 by the Australian Antarctic Data Centre, Department of the Environment and Heritage, Commonwealth of Australia.

EO-1 Advanced Land Imager images collected through late 2012 and early 2013 confirm that eruptive activity resumed around September 2012, in the form of a low-level effusive style eruption similar to its other recent eruptions (figures 17 and 18). Patrick noted that the vent crater had enlarged significantly over the four years following the end of the last eruptive phase, March 2006-March 2008.

Figure (see Caption) Figure 17. A series of images documenting the summit crater and subsequent lava advances at Mawson Peak, Heard Island from 3 July 2012 to 5 January 2013. The Earth Observing-1 (EO-1) satellite's Advanced Land Imager (ALI) Band 1 (panchromatic) images (10-m-pixel size) acquired several clear images on 3 July, 9 September, 13 October, 15 and 28 December 2012, and 5 January 2013. North is to the top of the photos. In the first three images the 200-m diameter crater at the summit of Mawson Peak is easily visible, and there is no evidence of activity outside of the crater. Courtesy of Matt Patrick.
Figure (see Caption) Figure 18. EO-1 ALI Band 10-3-2 RGB composites (30-m-pixel size) of the same series of images as in figure 17 (3 July 2012 to 5 January 2013). North is to the top of the photos. The red is the shortwave infrared band (Band 10, 2 microns); red pixels indicate high temperatures suggesting hot lava surfaces. As in figure 17, the 3 July 2012 image shows that the summit crater was cold, with no evidence of lava inside. However, the 9 September 2012 image clearly shows that elevated temperatures (and presumably lava) had appeared in the crater, consistent with the appearance of MODVOLC thermal alerts later that month. Therefore, this eruptive episode appears to have started around September. Courtesy of Matt Patrick.

The 15 December 2012 image in figure 17 shows that a short lava flow from the summit was emplaced on the SW flank. The flow was ~420 m long and had two lobes. By 28 December, a flow consisting of two lobes (presumably the same flow as in the 15 December image) had reached 770 m SW of the summit crater. In the 5 January 2013 image this flow was 780 m long and had changed little over the previous week.

Figure 18 shows that the 9 September and 13 October 2012 images suggested active lava contained with the summit crater. The 15 and 28 December 2012 images showed elevated temperatures on the lava flow SW of the summit, suggesting it was active over this interval, which was consistent with the observed elongation of the flow in the visible images. Fewer high-temperature pixels in the 5 January 2013 image and the meager advancement observed in the visible images, suggested that the flow had stalled by this point.

Overall, the activity as of mid-March 2013 had consisted of lava within the crater and a lava flow of at least 770 m long emplaced SW of the crater. This low-level effusive activity is consistent with the previous three eruptive episodes observed in satellite images at Heard Island (Patrick and Smellie, in review). These three episodes, May 2000-November 2001 (BGVN 25:11, 26:02, 26:03, and 28:01), June 2003-July 2004 (BGVN 29:12), and March 2006-March 2008 (BGVN 31:05, 31:11, 32:03, 32:06, 33:01, and 35:09), each lasted 1-2 years. On this basis, Patrick suggested that this new eruptive episode may persist for a similar duration. MODVOLC thermal alerts were measured nearly continuously from 21 September 2012 through 24 February 2013.

References. Patrick, M., 2013, A new eruptive episode at Big Ben Volcano, Heard Island, informal communication to BGVN, 23 February 2013.

Patrick, M.R., and Smellie, J.L., in review, A spaceborne inventory of volcanic activity in Antarctica and southern oceans, 2000-2010, Antarctic Science, in review in 2013.

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: Matt Patrick, Hawaiian Volcano Observatory (HVO), U.S. Geological Survey, PO Box 51, Hawai'i National Park, HI 96718, USA (URL: https://volcanoes.usgs.gov/observatories/hvo/); Australian Antarctic Data Centre, Department of the Environment and Heritage, Commonwealth of Australia (URL: https://data.aad.gov.au/database/mapcat/heard/heard_island.gif); MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP) 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/).


Nevado del Huila (Colombia) — January 2013 Citation iconCite this Report

Nevado del Huila

Colombia

2.93°N, 76.03°W; summit elev. 5364 m

All times are local (unless otherwise noted)


Dome growth and displaced glacier in 2009; decreasing activity during 2010-2012

Lava dome emplacement occurred at Nevado del Huila's Pico Central (central peak) in late 2008, and was accompanied by seismic unrest and significant sulfur dioxide (SO2) emissions (BGVN 37:10). Extrusion continued between November 2008 and November 2009. Ash plumes were frequently observed by webcameras during late 2008 to December 2009, and satellite imagery reviewed by the Washington Volcanic Ash Advisory Center (VAAC) detected intermittent ash emissions between October 2009 and April 2011. From January 2009 to December 2012, the Instituto Colombiano de Geología y Minería (INGEOMINAS) reported persistent emissions from the lava dome and dramatic changes to the perched glacier as the lava dome expanded across the E and W flanks. Activity generally decreased in November 2010 through 2012.

In this report, we focus on the time period of December 2008-December 2012 and also discuss monitoring efforts overseen by INGEOMINAS with collaborators such as the Colombian Air Force (FAC), the Washington VAAC, and the Sulfur Dioxide Group's Ozone Monitoring Instrument (OMI). The following subsections review webcamera and aerial observations, thermal-camera imaging, satellite images of volcanic plumes, seismicity, SO2 measurements (DOAS, Flyspec, and OMI), acoustic flow monitoring, and new tilt data. The local monitoring network was expanded during this reporting period, adding two infrasound monitoring stations in 2009 and 2012, two webcameras in 2010 and 2012, and instrumentation at the Caloto site that included a broadband seismometer and an electronic tilt station in 2012.

Web-camera observations. From December 2008 to December 2009, the Tafxnú web-camera (located ~15 km S of the volcanic edifice) frequently recorded gas-and-ash plumes rising higher than 2,000 m above the active dome (figure 26). In 2009, plumes (frequently ash-and-gas, but in some cases gas without ash) rose to maximum heights above the dome as follows: 1,000-2,000 m in June; 1,000-2,500 m in November; and 2,000-5,000 m in December.

Figure (see Caption) Figure 26. On 6 and 9 November 2009, summit activity from Nevado del Huila was observed by INGEOMINAS' N-looking Tafxnú web-camera. Accelerated dome growth was noted by INGEOMINAS that month (discussed in text below), and they annotated this image to circle the location of incandescence and summit activity. Note that these images have been altered from the originals; GVP staff increased the brightness and contrast in order to better distinguish the peaks of the Huila complex. (Top images) Incandescence on 6 November was absent at 0331 (left image) but appeared at 0333 within the green circled region (right image). INGEOMINAS suggested this incandescence resulted from dome collapse events exposing hot rock. The darker peak centered in the foreground is Pico Sur, while the active Pico Central is located higher and to the right of that peak in these images. (Bottom images) Plumes of ash and gas drifting NW from Pico Central were observed on 9 November at 0652 (left image) and 0653 (right image). The green circled region in the left-hand image corresponds to the same location circled in the image from 0333 on 6 November. Two water droplets on the camera lens created the local circular distortions. Courtesy of INGEOMINAS.

An additional camera was brought online in July 2010, located in the town of Maravillas (~10 km SE). A third camera, located at the Caloto site (~4 km SSW of the active dome) came online in July 2012 (figures 27 and 28).

Figure (see Caption) Figure 27. This composite image shows, at left, a map view of the three Nevado del Huila webcamera locations and the extent of their viewsheds. Photos at right show camera installation sites. The newest monitoring station (Caloto) was installed on 19 May 2012 on the SW flank. Courtesy of INGEOMINAS.
Figure (see Caption) Figure 28. A map of monitoring stations for Nevado del Huila from June 2012 included locations of webcameras and seismic, geochemical, and geophysical instruments. The summit of Pico Central is located approximately beneath the text BUCB. Note that yellow and black lines represent major and minor roads, respectively, and blue lines represent rivers. Courtesy of INGEOMINAS.

Observations of dome growth and summit activity during 2009-2010. With support from the Colombian Air Force (FAC) during 2009-2012, INGEOMINAS monitored dome growth and geomorphological changes at Huila by conducting aerial observations with helicopters.

During February 2009 and June-December 2009, INGEOMINAS reported numerous episodes of tremor that were likely associated with ash emissions, but cloud cover and nightfall sometimes precluded direct observations. Notable ash plumes were observed on 11 February, 23 July, 3 August, 16-23 October, and 3, 9, 12, 13 and 15 November; ashfall was noted by observers on all days except 11 February. A crack that had formed along the N face of Pico Central in 2007 continued to steam during this time period.

During three overflights conducted in January 2009, INGEOMINAS determined that the Pico Central lava dome had grown since November 2008. With repeat aerial photography, scientists calculated a total dome volume of 52 x 106 m3 with dimensions of 1,000 m N-S and 250 m E-W. The fresh dome rock continuously degassed (figure 29). Tafxnú webcamera images also showed that gas emissions frequently rising above Pico Central were often blue-colored. Due to continued unrest at Nevado del Huila (note that this name is shortened to 'Huila' during the remainder of this report), especially seismicity and active dome growth at Pico Central, INGEOMINAS maintained Orange Alert (Alert Level II; the second highest Alert Level on a 4-color scale from Green/IV-Yellow/III-Orange/II-Red/I) during January-February 2009.

Figure (see Caption) Figure 29. On 28 January 2009, the FAC facilitated observations of Nevado del Huila's growing lava-dome. In this view, the SW flank (centered) emitted a small gas column. This image highlights the zone of active lava dome growth (outlined in yellow) and the perimeter of the crater (outlined in orange). Courtesy of FAC and INGEOMINAS.

On 11 February 2009, a small pulse of tremor was accompanied by an ash plume discharged at Pico Central which was captured by the Taxfnú webcamera during 0745-0751. During that time period, INGEOMINAS noted a small pulse of tremor. On 23 February, an INGEOMINAS passenger on a commercial aircraft saw diffuse gas escaping from both the crater that hosts the dome and from the N-flank crack. During March, the webcamera frequently showed degassing from the crater and the lava dome. Clear conditions enabled observers on commercial flights to observe a white plume rising from Pico Central in the morning of 10 March. INGEOMINAS noted that both seismicity and remote observations of dome growth indicated decreased activity since February. Accordingly, on 31 March 2009, INGEOMINAS reduced the Alert Level to Yellow (II).

Aerial observations in April highlighted the presence of ash covering the S glacier, confirming the ongoing eruption. Elevated temperatures were concentrated at the extreme high and low points of the dome and degassing continued from the higher-elevation portion of the crater (figure 30).

Figure (see Caption) Figure 30. Photos taken on 19 April 2009 showed Nevado del Huila's active dome and the adjacent ash-covered and locally disturbed glacier. (top) In this visible-light view, the active lava dome has extended down the SW flank of Pico Central (yellow line). Cloud cover obscures the upper peaks of Pico Central (left) and Pico Sur (right). The glacier around Pico Central is difficult to distinguish due to ash cover and cracking attributed to dome emplacement. (bottom) This image is a close-up of the lava dome's SW flank with a forward-looking infrared (FLIR) camera which disclosed higher thermal flux from the dome's upper and lower regions. Gas emissions had been more concentrated from the higher region of the dome, however, the bright glow in this image may also be due to the reflective cloud-cover seen in the visible-spectrum image (top). Courtesy of FAC and INGEOMINAS.

During May and June 2009, the dome's surface continued to produce thermal anomalies, and dome growth was inferred based on the observable fragmentation of dome rock and a wider distribution of fresh material. INGEOMINAS noted that the color of the extruded material in the higher region of the dome had changed to a red-brown color (earlier dome rock was distinctively gray).

On 23 July ashfall was reported at the local military base in Santo Domingo and José Jair Cuspian (Caloto). They reported ashfall in the NW sector of the volcanic edifice. INGEOMINAS reported that this ash event coincided with a pulse of tremor registered that day at 0442.

On 3 August there was a pulse of tremor at 0036 and INGEOMINAS received reports of ashfall in the municipalities of Toribío and Santander de Quilichao (~30 km and ~50 km W of the edifice, respectively). Aerial observations on 16 August established that the crater had grown wider.

During September 2009 there were no major changes observed via webcam. On 16 and 23 October, reports of widespread ashfall came from various municipalities of N Cauca, Valle del Cauca, and in the foothills around the volcano (departments of Cauca, Valle, Tolima, and Huila) (figure 31). There were also reports of sulfur odors from the most proximal communities.

Figure (see Caption) Figure 31. An ash plume from Nevado del Huila's newly-formed crater and fumarolic sites was observed from aircraft on 23 October 2009. (top) A dark curtain of ash ("Cortina de cenizas") drifted SE from Pico Central that day; the plume height was ~1,000 m above the crater. The Washington VAAC reported ash in satellite images at 1015 that day, and noted that the ash plume rose to 6 km altitude, was ~46 km long, and drifting SE at 5 m/s. (bottom) A closer view of the W flank highlights gas-and-ash plumes rising from the upper crater (orange outline) while isolated sites released white plumes, including the site on the N flank of Pico Central (at left) where steam from a fissure had been observed consistently since November 2007. The accumulation of newly erupted material was typically observed from the upper region of the dome (circled in blue); the extent of the dome is outlined with yellow. Ashfall had covered the snow and glaciers of Huila; however, cracks in the glacier remained visible as jagged black and white lines, particularly on Pico Sur (right-hand edge of photo). Courtesy of FAC and INGEOMINAS.

At 0541 on 16 October 2009, the webcamera captured images of an ash plume rising in pulses from Pico Central and drifting E. Accordingly, the Alert Level was raised from Yellow (III) to Orange (II), where it stayed until 5 January 2010. An overflight on 23 October provided views of both intense fumarolic activity from the dome and a column of ash that reached up to 1,000 m above the crater. The summit and glaciers were covered by ashfall, lava extrusion was continuing from the upper region of the crater, and there were thermal anomalies where gas emissions were concentrated. An 11-minute-long episode of tremor that began at 0200 on 28 October was thought to signify dome rock extrusion.

Based on observations during overflights on 30 October and 2 November, INGEOMINAS calculated that the dome volume had increased by ~9 x 106 m3 since the previous estimate in January 2009. Aerial observers saw ash emitted in pulses.

Rapid dome growth occurred in November as witnessed during five aerial investigations (2, 4, 6, 10, and 25 November). On 3 November, an explosion was heard and ashfall was reported by the communities of Inzá, Mosoco, Jambaló y Belalcázar, and other communities SW of the volcano. New layers of ash had accumulated around the summits of Huila, often appearing brown-red as opposed to the gray material deposited in previous months (figure 32). A weekly INGEOMINAS report announced that by 10 November 2009, the dome volume had increased by ~16 x 106 m3 since the previous estimate, more than doubling the amount of growth that had occurred during January-October 2009.

Figure (see Caption) Figure 32. Aerial photos from November 2009 documented rapid changes on Nevado del Huila's Pico Central. (top) On 4 November INGEOMINAS observed additional ejecta surrounding the lava dome and elevated ash emissions. In this photo of the S face of Pico Central, steam and ash rise from the crater, and brown-red ash and blocks cover the glacier that surrounds the active dome. Dome rock extends from the center of Pico Central to lower elevations on the W flank. (bottom) This view of Nevado del Huila's SE flank on 25 November 2009 reveals the increased size of the lava dome which towers above Pico Sur, the rugged-looking peak centered in this view. Ash covered snow and glacial ice surrounds the immediate region of the dome while plumes of gas drift westerly. The dark gray, rounded peak to the lower left is Cerro Negro, the location of a seismic station that remained offline during this reporting period. Courtesy of FAC and INGEOMINAS.

Gas emissions were observed by the webcamera at Tafxnú and during four overflights in December 2009; however, fumarolic activity dropped during the first week of December. Aerial observations determined that 2008 dome rock was being covered by 2009 lava that contained fewer large blocks; the 2008 dome material was distinctively more gray and blocky. During an overflight on 29 December, clear weather allowed INGEOMINAS scientists to observe minor dome collapse events, new cracks in the glacier along the lower E dome contact, and additional dome rock extending down the E flank.

In January 2010, dome growth continued and notably expanded the dome E by ~50 m, further displacing portions of the Pico Central glacier. Gray ash continued to be deposited in the area, covering the glacier surfaces. White plumes were observed this month during overflights and from the webcamera. On 5 January, INGEOMINAS reduced the Alert Level from Orange (II) to Yellow (III); this status was maintained until 15 June 2010.

On 22 February 2010, scientists on board an FAC helicopter noted displaced glacial ice, some steaming along the dome edge, and the surface textures of the 2008 and 2009 lava domes persisted (blocky vs. smaller clast sizes, respectively; figure 33). Based on aerial observations, INGEOMINAS calculated a total dome volume of at least 70 x 106 m3.

Figure (see Caption) Figure 33. During an overflight on 22 February 2010, Nevado del Huila's active dome, displaced ice, and gas emissions were visible. Fresh volcanic material clearly began to extend W and E, divided by the long axis of the Huila complex. (Top) An aerial view of Pico Central's S-facing peak where the active dome was shedding material to the W and E. (Middle) Degassing dome rock is visible along the W flank. The blocky gray rock centered in this region was attributed to 2008 lava extrusion. (Bottom) New dome rock is in contact with the fragmented glacial ice on the E flank, and dome steaming is visible along the margin. Courtesy of FAC and INGEOMINAS.

INGEOMINAS reported that on 12 April additional ash had accumulated on the glacier and lava extrusion was continuing. Columns of gas continued to be emitted from the surface of the new dome, at the contact of 2008 and 2009 lava, and from the crack that had formed in 2007 on the N flank of Pico Central.

No overflights were conducted in June, however the Alert Level was raised to Orange (II) due to increased seismicity, primarily hybrid earthquakes and SO2 emissions (see seismic and SO2 discussion below). INGEOMINAS suggested that the marked increase in hybrid earthquakes may have been linked with the ascent of new magmatic material within the volcanic edifice.

In July, degassing continued and intermittent, small ash emissions were observed toward the end of the month by the ground-based cameras Tafxnú and Maravillas. By 16 July, INGEOMINAS reduced the Alert Level to Yellow (III), due to the reduction in seismicity and SO2 flux, where it remained through August. The Washington VAAC reported possible ash plumes drifting from Huila during 28-30 of July but an absence of such plumes during August.

A 19 August flight revealed that snow had accumulated on the dome. INGEOMINAS noted that some episodes of tremor were likely related to the process of lava dome extrusion and these conditions did not show wide variations in August. Minor ash emissions were reported toward the end of the month. The Maravillas camera detected incandescence on 26 and 29 August, possibly from hot rockfalls from the lava dome.

A pulse of tremor on 30 August at 0635 coincided with ash emissions also observed by the Tafxnú camera. In the afternoon that day, people in the town of Toribío (~30 km W) noted an ash plume. There was also a report that the Símbola River changed color due to the presence of ash. The VAAC noted a hotspot at the summit in satellite images on 31 August.

During September, webcameras imaged plumes of gas as well as gray and reddish-colored emissions attributed to volcanic ash. These plumes were not visible in satellite imagery; however, the Washington VAAC released two notices on 9 September in response to reports from INGEOMINAS that ground-based observations included continuous emissions of gases and some ash.

During the first week of September, the Maravillas webcamera and local populations observed incandescence from the active dome; INGEOMINAS attributed the activity to hot rockfalls on the dome. On 9 September, INGEOMINAS raised the Alert Level to Orange (II); seismicity (particularly energetic tremor) and frequent incandescence were considerations for this announcement. On 9 September, both webcameras captured images of ash and incandescence. On 10 September, drumbeat earthquakes (earthquake signatures related to dome extrusion) had appeared in the seismic records. The last time that drumbeat earthquakes had been detected from Huila was in November 2008 (BGVN 37:10). By 21 September, INGEOMINAS announced that 1,799 drumbeat earthquakes had been detected over the past 13 days.

An overflight on 15 September determined that conditions at the dome were continuing to change; extrusion continued from the highest part of the dome (near the contact with the crater wall). They also observed a debris flow containing rocks and ice that had originated from the edge of the dome and had traveled ~1.5 km down the E flank (figure 34). By the end of the month, gas emissions continued and incandescence was observed by the webcameras.

Figure (see Caption) Figure 34. On 15 September 2010 INGEOMINAS observed debris flows along the E flank of Nevado del Huila. (top) Snow had visibly collected on the active dome that continued to degass and displace the glacier. Near the dome, the glacier was notably fragmented and discolored due to overlying debris and ash. (bottom) This view is a closeup of the area below the fragmented glacier on Huila's E flank. The extent of the debris flow is visible as a 1.5 km long trace of gray material that had incorporated blocks of ice and rocks. Courtesy of FAC and INGEOMINAS.

Aerial observations on 29 September, 1 October, and 4 November confirmed ongoing dome growth. On 1 October, the VAAC reported ash drifting from the summit. On 12 October, INGEOMINAS reduced the Alert Level to Yellow (III); they stated that conditions appeared to have stabilized, in particular local seismicity and gas-and-ash emissions. The webcameras continued to capture images of white gas emissions during the second week of October. White plumes and some incandescence were visible in October. Thermal images from 4 November found that the W-central dome's temperature was 250°C. On 11 November the Washington VAAC reported ash drifting from the summit.

Observations during January-December 2011. The webcameras continued to record images of white plumes rising from the Pico Central dome throughout 2011. Aerial observations during the year noted frequent gas emissions and infrequent ash plumes. During an overflight on 25 January, a FLIR camera detected temperatures up to 90°C from various locations on the dome (figure 35). During an overflight on 29 March, observers noted degassing and odors of sulfur.

Figure (see Caption) Figure 35. In these photo pairs taken during an overflight on 25 January 2011, INGEOMINAS measured surface temperatures of Nevado del Huila's lava dome. (top) These photos are centered on the E flank of Huila. The thermal image is zoomed in on the brown-colored lava dome that continued to steam and degass, forming a small plume rising above Pico Central. For the dome, the minimum ("BAJA") and maximum ("ALTA") temperatures were less than 30 and 68.3°C, respectively. (bottom) These photos are viewing the S-facing Pico Central with the lava dome (centered). Gas emissions were rising from the highest region of the dome and the minimum and maximum temperatures were less than 30 and 80.6°C, respectively. Courtesy of FAC and INGEOMINAS.

On 19 April, the Washington VAAC reported that an ash plume was detected in enhanced multispectral imagery at 0315. The plume was drifting NNW from Huila. The announcement included a note that the ash plume did not appear to be the result of an explosive event. Later that day, after sunrise, INGEOMINAS confirmed that low seismicity was detected, a white plume was visible, but ash emissions were absent.

Aerial observations on 26 April included intense degassing from the NW side of the lava dome; the emissions were gray. A thermal camera detected temperatures of the dome in the range of 78-83°C. The glacier also appeared to have further deformed since the last aerial observations in March.

In May, degassing was observed with the webcameras on days where weather conditions permitted clear views. On 6 and 20 June, scientists confirmed that degassing continued during an overflight; they also observed the accumulation of snow on the lava dome as well as on the surrounding glacier. On 20 June, notable rockfalls were visible from the lava dome that contributed to scree along the dome's lower edges.

Degassing continued to appear in clear webcamera views and during overflights in June-July and September-December. Aerial observers on 22 October saw snow avalanches on the Pico Norte glacier and intense steaming from the upper regions of the dome.

Observations during January-December 2012. Throughout 2012, INGEOMINAS recorded observations of the dome based primarily on webcamera images. No major changes were noted in the weekly and monthly online reports; pervasive steaming and white plumes were frequently observed throughout the year by the two webcameras (Tafxnú and Maravillas). INGEOMINAS maintained Yellow Alert (III) during 2012.

One overflight was conducted by INGEOMINAS in 2012. On 14 January 2012, scientists observed the usual degassing and noted that snow had collected on the dome and glacier. That day's clear viewing conditions allowed detailed observations of the lava dome texture and INGEOMINAS attributed the spiny texture of the dome to late-stage extrusion (figure 36).

Figure (see Caption) Figure 36. On 14 January 2012, clear conditions provided aerial views of Nevado del Huila's lava dome texture. (top) This view of the dome's SE face is centered on the part of the lava dome that had started to accumulate snow cover. Steaming was visible from some regions of the dome but a strong plume was not visible during this overflight. (bottom) INGEOMINAS noted that the higher region of the dome had distinguishable spines that may have formed recently. Courtesy of FAC and INGEOMINAS.

Declining seismicity during January-August 2009. During 2009, four seismometers (two broadband and two short-period stations) were maintained by INGEOMINAS. Ash emissions in October 2009 temporarily disabled the short-period Verdún 2 station, located ~5 km N of the active dome. The Cerro Negro short-period station, closest to the active dome, was not operating during this reporting period (2009-2012). In general, three to four seismic stations were operating during 2009-2012.

In 2009, a total of nine earthquakes were large enough for people nearby to feel shaking; these events had magnitudes between 2.8 and 4.8 with focal depths between 6.2 and 12 km. The epicenters were 3-25 km away from the closest seismic station, CENE, which was located ~3 km S of Pico Central. INGEOMINAS highlighted these earthquakes in their monthly technical bulletins.

From January to September 2009, INGEOMINAS reported a decreasing trend in seismicity. In particular, volcano-tectonic (VT) and long period (LP) earthquakes were becoming less frequent on a monthly basis (figure 37). INGEOMINAS described VT earthquakes as resulting from rock-fracturing events, and LP earthquakes from fluid transport processes within the volcanic edifice. Large daily counts of LP earthquakes generally became less frequent over time. Low levels of tremor, hybrid events, and superficial activity (rockfalls and explosions) were detected throughout this time interval.

Figure (see Caption) Figure 37. Nevado del Huila's seismicity, in particular VT, LP, and tremor earthquakes, decreased overall during January-August 2009. In this plot, the number of events were tallied per day and plotted over time. The legend in the upper right-hand corner lists terminology in Spanish that relates to these conventions: VT (red), LP (yellow), hybrid (orange), explosions (red with black outlines), tremor (blue), and surface activity such as rockfalls (green). Explosions were detected during this time period, but are difficult to read from this plot. Explosions were detected mainly in June and July; see previous subsection "Observations of dome growth and summit activity during 2009-2010" for descriptions of explosive activity. Courtesy of INGEOMINAS.

Clustered epicenters in 2009. Beginning in January 2009, INGEOMINAS described a clustering of seismicity notable in distinct regions of the volcanic edifice. These consisted of three regions, the SW sector, the SE sector, and beneath the central edifice (Pico Central). This pattern was particularly clear in June, October, and December. The June 2009 map of seismicity appears in figure 38. The deepest earthquakes (8-12 km) tended to occur S of the edifice while shallow events were distributed throughout the area. Several deep and distal earthquakes occurred each month with depths between 10-20 km and epicenters up to 25 km from the edifice; these events have been attributed to regional faults.

Figure (see Caption) Figure 38. A map with cross-sections plotting epicenters and hypocenters of volcano-tectonic and hybrid earthquakes during June 2009 at Nevado del Huila. Three zones of clustered activity took place beneath the volcanic edifice (dashes lines). Note the yellow bar for scale (10 km) and the yellow text labeling five seismic stations (marked with blue squares). Four stations were operating; Cerro Negro (CENE) was offline during this reporting period. The active summit area of Pico Central is ~3 km N of the CENE station. Courtesy of INGEOMINAS.

Peaks in seismicity and ash emissions between October 2009 and May 2010. INGEOMINAS reported an abrupt increase in seismicity in October 2009. The occurrence of VT, LP, hybrid, and tremor events had more than doubled since September. On 12 October, a swarm of VT events was detected (figure 39). During the onset of elevated seismicity, INGEOMINAS reported ash emissions during 17-21 October and the Washington VAAC released reports of ash observations from satellite imagery on 16 October.

Figure (see Caption) Figure 39. Seismicity from January 2009 through May 2010 detected from Nevado del Huila included notable peaks in LP earthquakes. In their May 2010 report, INGEOMINAS noted that tremor had been recorded continuously throughout January-May. The legend in the upper left-hand corner lists VT (red), LP (yellow), hybrid (orange), explosions (red with black outlines), tremor (blue), and surface activity such as rockfalls (green). Explosions were detected during this time period, but are difficult to read from this plot. Courtesy of INGEOMINAS.

The appearance of volcanic ash in satellite images was periodically reported by the Washington VAAC from October through mid-November 2009. Aided by the web-camera Tafxnú, INGEOMINAS reported observations of ash plumes frequently occurring through November.

The Washington VAAC reported that, after 15 November 2009, volcanic ash was no longer visible in satellite images. In their monthly technical report, INGEOMINAS noted seismic signals suggesting ash emissions in December 2009, and visual observations of white plumes from the summit that were inferred to be gas-rich. As seen on figure 39, LP events peaked dramatically during 9-10 December when signals characterized as drumbeats were detected (see BGVN 37:10 for additional descriptions of drumbeat earthquakes). INGEOMINAS suggested the onset of drumbeat earthquakes was associated with the extrusion of new material to the surface and growth of the lava dome.

INGEOMINAS reported an average of 995 LP earthquakes per month during January-March 2010. VT events tallied on a monthly basis averaged 239 during that same time interval, suggesting an absence of discernible major changes in the volcanic system since the drumbeat earthquake swarm in December 2009. Tremor was detected more frequently over time and from February to May an average increase of 37 events per month was recorded.

As seen at the right on figure 39, during April-May 2010, very high LP seismicity returned. LP earthquakes peaked in May, with a total of 5,141 events. During April-May, the Washington VAAC released advisories in response to possible ash plumes from Huila, however, they did not detect ash due to frequent cloud cover, and because numerous reports indicated eruptions at night, when satellite instruments offer fewer means of detecting ash.

An ML 3.8 earthquake shook the towns of Toéz and Tálaga (15 km SSW and 22 km S respectively) at 0708 on 23 May. These towns are located SW of Pico Central. The earthquake was located 8.13 km SW of Pico Central and was 7.2 km deep (relative to the elevation of the active crater).

Seismicity and ash observations during June-December 2010. In June, direct observations of ash plumes were rare due to weather conditions; however, the Washington VAAC reported ash visible in satellite imagery on 2 June 2010. While LP seismicity remained low in early June 2010, hybrid seismicity emerged from background levels (figure 40). During January-May, typically 3-34 hybrid earthquakes were detected per month. By 14 June, more than 200 hybrid events were occurring per day; however, by 24 June, hybrid earthquakes had decreased to less than 50 events per day. Hybrid earthquakes, events INGEOMINAS attributes to the combined mechanisms of fluid transport and rock fractures, rarely dominate Huila's seismic records.

Figure (see Caption) Figure 40. Seismicity from Nevado del Huila during 2010 included peaks of LP, VT, and tremor episodes. The legend in the upper left-hand corner lists VT (red), LP (yellow), hybrid (orange), explosions (red with black outlines), tremor (blue), and surface activity such as rockfalls (green). Explosions were detected during this time period, but are difficult to read from this plot. Courtesy of INGEOMINAS.

As seen on figure 40, during August-November 2010, elevated tremor persisted (630-2,576 episodes per month). LP seismicity peaked in May and then twice between September and December. For the tallest peak (September 2010), counts reached more than 1,000 events per day.

On 3 December at 2054 a felt M 3.4 earthquake within the Páez River drainage centered 6.2 km S of Pico Central had a relatively shallow focal depth of 5.2 km (as measured beneath the crater). Another felt earthquake was reported by residents in the Belalcázar-Cauca area on 29 December. This ML 2.9 event occurred at 2106 with a focal depth of 8 km, located 8.5 km SW of Pico Central. This earthquake lacked any noticeable effect on the stability of the volcanic system.

Seismicity in 2011. In 2011, INGEOMINAS noted that both LP earthquakes and tremor were decreasing over time (figure 41). Tremor persisted at low levels. In June VT and LP earthquakes notably increased to 434 and 623 events, respectively, but returned to background levels during the following month.

Figure (see Caption) Figure 41. This plot of Nevado del Huila's seismicity during January-December 2011 shows a general decline in seismicity. This plot excludes VT earthquakes, highlighting instead the daily count of LP, hybrid, and tremor events. Courtesy of INGEOMINAS.

In November 2011, several moderate earthquakes (M≤4) struck near Huila. In particular, three events had magnitudes 2.8, 3.2, and 4.0. For example, on 26 November, inhabitants of Mesa de Toéz felt an M 4.0 event whose epicenter was 8.5 km SW of Pico Central with a depth of 7.4 km (as measured below the crater). VT epicenters in November were widely distributed throughout the edifice and local region (figure 42). Depths of these earthquakes were within the range of past VT earthquakes (0-12 km). Persistent seismicity SW of Huila also continued in November.

Figure (see Caption) Figure 42. A map and cross-sections showing Nevado del Huila's VT epicenters during November 2011. The active dome is ~3 km N of CENE. INGEOMINAS noted four areas where seismicity was clustered (yellow shaded ovals). Note that the largest highlighted region has been an area of persistent seismicity throughout the year (for example, see figure 38). Seismic stations are marked with blue squares and labels (DIAB, VER2, CENE, BUCO, and MARA). Courtesy of INGEOMINAS.

Seismicity in 2012. The low-level seismicity observed in the last months of 2011 continued through 2012. In a comparison with 2011, the average number of events per year was remarkably reduced in 2012 (VT, LP, and tremor); hybrid earthquakes, however, were the exceptions. The average for hybrid earthquakes per month was slightly higher in 2012 (table 4). Hybrid earthquakes were quite variable in number during 2011, ranging from 0 to 60 per month.

Table 4. Monthly counts for volcanic-tectonic, long period, tremor, and hybrid events detected at Nevado del Huila during 2011-2012. More event types and data appear in INGEOMINAS online reports. Courtesy of INGEOMINAS.

Month Volcanic-tectonic Long-period Tremor Hybrid
Jan 2011 284 388 220 2
Feb 2011 217 1,064 154 15
Mar 2011 217 876 168 13
Apr 2011 168 634 152 0
May 2011 136 729 220 0
Jun 2011 434 623 128 60
Jul 2011 165 416 77 25
Aug 2011 143 491 51 32
Sep 2011 137 304 27 8
Oct 2011 110 371 50 13
Nov 2011 176 219 32 2
Dec 2011 164 195 32 34
2011 Avg: 196 526 109 17
 
Jan 2012 155 245 27 28
Feb 2012 111 159 12 18
Mar 2012 145 200 27 21
Apr 2012 154 244 19 21
May 2012 87 200 34 13
Jun 2012 121 183 11 18
Jul 2012 109 208 14 16
Aug 2012 118 178 15 30
Sep 2012 93 172 5 14
Oct 2012 168 257 18 23
Nov 2012 171 205 9 14
Dec 2012 158 227 26 32
2012 Avg: 133 207 18 21

The wide distribution of epicenters noted in November and December 2011 persisted during January-February 2012, but fewer earthquakes were detected during these months. From March through December, significant clustering was absent, although, in October some events appeared concentrated along Huila's N-S axis.

The largest earthquake in 2012 occurred in March; a 3.8 earthquake shook the town of Toribio (in Cauca) at 0248 on 15 March. The epicenter was 1.8 km E of Pico Central with a focal depth of approximately 3.2 km. Seismicity that month was slightly higher than February (table 4). Throughout the year, VT earthquakes were typically less than M 2.6.

Infrasound monitoring 2009-2012. Augmenting seismic monitoring efforts, an infrasound station installed at the Diablo monitoring site (located ~5 km NNW of the active dome) became operational in July 2009. An additional acoustic monitoring system was installed at the Caloto station (located ~3.7 km from the active dome) in May 2012. Data collected with infrasonic microphones complements seismic instrumentation and can be analyzed with similar techniques. The method has also detected distant explosions from volcanoes such as Sakura-jima, Japan (BGVN 20:08), Fuego, Guatemala (BGVN 36:06), and Stromboli, Italy (BGVN 26:07).

Sulfur dioxide emissions during 2009-2012. INGEOMINAS conducted routine sulfur dioxide (SO2) gas monitoring with differential optical absorption spectroscopy (DOAS) equipment from January 2009 through December 2012. With this mobile scanner, INGEOMINAS conducted traverses along the Pan-American Highway between the cities of Calí and Popayán (figure 43).

Figure (see Caption) Figure 43. On 14 and 24 August 2010, INGEOMINAS technicians traversed routes along the Pan-American Highway with mobile DOAS equipment to measure Nevado del Huila's SO2 gas fluxes. These images include color-coded line segments that correspond to high and low concentrations (red and blue, respectively). The approximate locations of the plume have been shaded to correspond with the locations of high SO2 flux. The plots shows the wavelength on the x-axis and concentration-pathlength (ppm-m) on the y-axis. (Top) This image includes the mapped route between the towns of Santander de Quilichao and Villarrica where the gas plume was scanned on 14 August. The wind speed was 10.8 m/s, wind direction was 294°, and SO2 flux was 28.2 kg/s (1,441 t/d). (Bottom) This image includes the results from 24 August when field technicians traversed routes between Pescador and Villarrica. SO2 flux was 23.3 kg/s (2,020 t/d); wind speed and direction were not reported. Courtesy of INGEOMINAS.

Scanning DOAS systems at fixed locations were operating during 2009-2012. During October 2009, elevated SO2 emissions were detected by the Calí and Santander de Quilichao stations (figure 44). In September 2009, a station was operating in Manantial (~53 km W of Huila).

Figure (see Caption) Figure 44. During 7 January 2009-27 November 2012, INGEOMINAS measured the SO2 flux from Nevado del Huila in a series of numbered campaigns (x-axis). A total of 137 values were reported from three detection methods, scan DOAS stations (corresponding to numbers 33 and 35 dating from October 2009, and 55-57 dating from June 2010), FLYSPEC (numbers 118-122 dating from May 2012, and 128 and 129 dating from August 2012), and mobile DOAS (all other values). Red and blue highlighting distinguishes the datasets from each year. SO2 detection was conducted several times each month and the maximum value from each measurement was reported. Courtesy of INGEOMINAS.

Wind velocity has a strong bearing on the computed SO2 flux. In their December 2011 technical bulletin, INGEOMINAS discussed the variability in windspeed and direction, including the Weather Research and Forecasting (WRF) modeling system used for calculations during 2011 (figure 45). The WRF was public domain software available online and was developed in order to provide atmospheric simulations based on numerical modeling.

Figure (see Caption) Figure 45. INGEOMINAS released the source of their windspeed data used for SO2 flux calculations in their December 2011 technical report. (top) This plot shows the datapoints used throughout 2011 for windspeed values determined by the WRF Model. (bottom) These images show a map of the expected aerial extent of the gas plume, a series of photos showing plume conditions during the SO2 surveys, and a table of the measurements from three surveys in December. Courtesy of INGEOMINAS.

In May and August 2012, INGEOMINAS reported the results from FLYSPEC (a portable UV spectrometer) surveys and discussed the variations observed in SO2 flux. They emphasized that SO2 fluxes were low, a finding consistent with previous measurements during this post-crisis period (dome growth had ceased by November 2009). They also mentioned that seismicity had been low in May 2012, particularly in those events related to fluid motion (LP earthquakes, for example).

Flux calculations required wind speed data from the WRF models and daily forecasts from the Institute of Hydrology, Meteorology, and Environmental Studies (IDEAM), Colombia. Wind speeds in the range of 6-12 m/s during 8-29 May 2012 were applied to SO2 flux calculations.

Elevated SO2 emissions from Huila were detected almost daily by the OMI spectrometer during 2009-2012. The AURA satellite maps SO2 in the atmospheric column using ultraviolet solar backscatter. A flux can be estimated for the OMI spectrometer data by looking at the total mass of SO2 measured and the time it took to accumulate. On this basis, INGEOMINAS compared peaks in SO2 flux detected during traverses with DOAS (mobile and scanning) with OMI data for October 2009 (figure 46).

Figure (see Caption) Figure 46. In October 2009, elevated SO2 flux was detected from Nevado del Huila by three remote sensing techniques. (Top) The plotted values show combined datasets from mobile DOAS, OMI, and scan DOAS. (Bottom) The OMI spectrometer on the AURA satellite detected 9.95 kt of SO2 on 20 October 2009 (left) during its pass at 2414-2417 local time (coverage area of 368,974 km2, recording a maximum value of 43.3 Dobson Units (DU)). On 26 October 2009 (right) it detected 7.79 kt of SO2 during its pass at 2337-2340 local time (coverage area of 314,303 km2, recording a maximum value of 31.12 DU). Courtesy of INGEOMINAS and Simon Carn, Michigan Technological University and Joint Center for Earth Systems Technology, University of Maryland Baltimore County.

Lahar investigations. INGEOMINAS maintained seven early warning systems to warn of downstream flooding in vulnerable municipalities such as Belalcázar. At sites within the drainages of the Páez and Símbola rivers, flow monitoring with geophones has continued since October 2006, employing equipment installed by the INGEOMINAS Popayan Observatory in collaboration with the Nasa Kiwe Corporation (CNK). CNK is a relief group that has been active in this area of Colombia since the 1994 earthquake and resultant landslides that devastated the Cauca and Huila regions, including communities along the Páez river (BGVN 19:05). Those events also damaged the Tierradentro archaeological sites, a UNESCO World Heritage Site since 1995.

Following Huila's 2007 lahars (BGVN 33:01), Worni and others (2012) conducted fieldwork and reconstructed events in order to model future lahars for mitigation purposes. The researchers argued that large-volume lahars (tens to hundreds of millions of cubic meters) require targeted studies. The authors noted that "in 1994, 2007, and 2008, Huila volcano produced lahars with volumes of up to 320 million m3." To constrain the dimensions of simulated flows, they used inundation depths, travel duration, and observations of flow deposits from the April 2007 events and applied the two programs LAHARZ and FLO-2D for lahar modeling.

LAHARZ was developed by USGS scientists in order to provide a deterministic inundation forecasting tool; this program was designed to run in a Geographic Information System (GIS) environment (Schilling, 1998; Iverson and others, 1998). "For user-selected drainages and user-specified lahar volumes, LAHARZ can delineate a set of nested lahar-inundation zones that depict gradations in hazard in a manner that is rapid, objective, and reproducible" (Schilling, 1998). Worni and others (2012) presented results from the semi-empirical LAHARZ models along with physically-based results from FLO-2D (FLO-2D Software I, 2009) in order to forecast future inundation areas with specified flow volumes (figure 47). The authors concluded that, despite local deviations, the two models produced reasonable inundation depths (differing by only 10%) and encouraged future investigations that could address sources of uncertainty such as the effects of sediment entrainment that would cause dynamic changes in lahar volumes.

Figure (see Caption) Figure 47. Results are shown from two modeling programs to understand lahar hazards from Nevado del Huila, FLO-2D (top three images) and LAHARZ (bottom three images), for the specified flow volumes. Note the modeled effects on the Belalcázar region (located ~20 km S of Huila). Three scenarios are presented based on lahar flow volumes of 3 x 108, 6 x 108, and 10 x 108 m3. Image from Worni and others (2012).

Deformation monitoring during 2009-2012. An electronic tilt station was operating in July 2009, located at the Diablo monitoring site ~6.26 km NW of Pico Central (4.1 km above sea level). Telemetered data from a new electronic tilt station became available in May 2012; the station was located in the town of Caloto, located ~4 km SSW of Pico Central (4.2 km above sea level). Data from Diablo and Caloto was presented in the monthly technical bulletins posted online by INGEOMINAS.

After seven months of calibrations, INGEOMINAS developed an initial baseline for the new tilt data. The N and E components of Caloto recorded minor fluctuations during this time period. The trend of the E component was generally stable while the N component detected a gradual excursion during 17 June-25 September 2012.

References. FLO-2D Software I, 2009, FLO-2D User's Manual. Available at: www.flo-2d.com.

Iverson, R.M., Schilling, S.R, and Vallance, J.W., 1998, Objective delineation of areas at risk from inundation by lahars, Geological Society of America Bulletin, v. 110, no. 8, pg. 972-984.

Schilling, S.P, 1998, LAHARZ: GIS programs for automated mapping of lahar-inundation hazard zones, U.S. Geological Survey Open-File Report 98-638, 80 p.

Worni, R., Huggle, C., Stoffel, M., and Pulgarín, B., 2012, Challenges of modeling current very large lahars at Nevado del Huila Volcano, Colombia, Bulletin of Volcanology, 74: 309-324.

Geologic Background. Nevado del Huila, the highest peak in the Colombian Andes, is an elongated N-S-trending volcanic chain mantled by a glacier icecap. The andesitic-dacitic volcano was constructed within a 10-km-wide caldera. Volcanism at Nevado del Huila has produced six volcanic cones whose ages in general migrated from south to north. The high point of the complex is Pico Central. Two glacier-free lava domes lie at the southern end of the volcanic complex. The first historical activity was an explosive eruption in the mid-16th century. Long-term, persistent steam columns had risen from Pico Central prior to the next eruption in 2007, when explosive activity was accompanied by damaging mudflows.

Information Contacts: Instituto Colombiano de Geologia y Mineria (INGEOMINAS), Observatorio Vulcanológico y Sismológico de Popayán, Popayán, Colombia; Washington Volcanic Ash Advisory Center (VAAC), NOAA Science Center Room 401, 5200 Auth road, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/); Ozone Monitoring Instrument (OMI), Sulfur Dioxide Group, Joint Center for Earth Systems Technology, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA (URL: https://so2.gsfc.nasa.gov/); Nasa Kiwe Corporation (CNK) (URL: http://www.nasakiwe.gov.co/index.php); Weather Research Forecasting (WRF) (URL: http://www.wrf-model.org/index.php).


Izu-Oshima (Japan) — January 2013 Citation iconCite this Report

Izu-Oshima

Japan

34.724°N, 139.394°E; summit elev. 758 m

All times are local (unless otherwise noted)


Non-eruptive May 2010 surface deformation from inferred deep instrusion

Oshima is an active volcano located on the northern tip of the Izu-Bonin volcanic arc. Our last report of activity at Oshima (BGVN 21:08) enumerated a flurry of shallow low-frequency earthquakes beneath the top and W flank of the volcano that started on 5 August 1996.

Since those relatively benign events, the Japan Meteorological Agency (JMA) had not observed any subsequent events worthy of note until May 2010 when land surface inflation was detected. The inflation was registered by a strainmeter, a Global Positioning System (GPS) network (run by the Geospatial Information Authority of Japan, GSI), and a tiltmeter network (run by the National Research Institute for Earth Science and Disaster Prevention, NIED).

In July 2010 seismicity in the shallow parts of and around Oshima began to increase. (High seismicity synchronous with inflation of the edifice was seen earlier, including in 2004 and 2007). These events were considered to be due to magma intrusion into the deeper part of the volcano. There were no remarkable changes in surface phenomenon. In September, the inflation that was detected in May began declining. Seismicity in the shallow parts of and around Oshima continued at a low level with some small earthquakes which temporally increased in the western offshore areas of Oshima on 22 December 2010.

The earthquakes increased in frequency again on 9 February 2011. GPS and strainmeter measurements indicated contraction since January, but the trend reversed to show inflation in October 2011. Seismicity remained at a low level. Very low level gas emissions were sometimes observed by a camera positioned on the NW summit. Based on a field survey on 28 October, no remarkable change in surface phenomena was observed.

No remarkable activity has been noted since October 2011. Throughout the noted activity, JMA held the Alert Level at 1.

Geologic Background. Izu-Oshima volcano in Sagami Bay, east of the Izu Peninsula, is the northernmost of the Izu Islands. The broad, low stratovolcano forms an 11 x 13 km island and was constructed over the remnants of three dissected stratovolcanoes. It is capped by a 4-km-wide caldera with a central cone, Miharayama, that has been the site of numerous historical eruptions. More than 40 cones are located within the caldera and along two parallel rift zones trending NNW-SSE. Although it is a dominantly basaltic volcano, strong explosive activity has occurred at intervals of 100-150 years throughout the past few thousand years. Historical activity dates back to the 7th century CE. A major eruption in 1986 produced spectacular lava fountains up to 1600 m height and a 16-km-high eruption column; more than 12,000 people were evacuated from the island.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/).


Kikai (Japan) — January 2013 Citation iconCite this Report

Kikai

Japan

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

All times are local (unless otherwise noted)


Steam plumes rose to 800 m duing latter half of 2012

Kikai is a 17 x 20 km mostly submarine caldera as close as ~40 km from the S margin of the island of Kyushu (see figure 1 in BGVN 37:07; also see Shinohara and others, 2002, for 16 journal articles devoted to this volcano. Maeno, 2008, offers an online overview). A few areas on the caldera rim lie above water (figure 2). Mild-to-moderate emissions have often occurred at the dome called Iwo-dake (alternately spelled Iodake, figure 2). Table 4 summarizes the seismicity and steam plume observations for July-December 2012, an interval of calm, absence of tremor, and low hazard status.

Figure (see Caption) Figure 2. A shaded-relief, contour map of Kikai caldera that labels three islands on the N caldera rim, Satsuma Iwo-jima, Showa Iwo-jima, and Take-shima. Satsuma Iwo-jima contains the highest point of the complex (704 m elevation). On that island, the cones Iwo-dake (a rhyolitic volcano) and Inamura-dake (a basaltic volcano) both reflect post-caldera volcanism focused along or just inside the caldera's wall (the shaded, scalloped line trending NE across the island). The island Showa Iwo-jima emerged during the caldera's last major eruptions, during 1934-1935, starting with floating pumices and including late-stage lava emissions that helped armor the island and allowed it to erode only modestly during the subsequent decades of breaking waves. The caldera floor chiefly resides 300-500 m below sea level but it also contains some post-eruptive cones. From Fukashi Maeno (2008).

Table 4. Monthly summary of seismicity and plume observations at Kikai during July-December 2012. All reported plumes were described as white. Data courtesy of JMA.

Month Earthquakes per month Maximum steam plume height (m above Iwo-dake crater rim)
Jul 2012 238 800
Aug 2012 187 300
Sep 2012 193 500
Oct 2012 219 700
Nov 2012 168 400
Dec 2012 -- --

We last reported on Kikai activity through mid-2012 (BGVN 37:07) covering generally small steam plumes and monthly seismicity of up to ~200 earthquakes per month through June 2012. This report is a compilation of subsequent monthly reports of volcanic activity through December 2012 from Japan Meteorological Agency (JMA) monthly reports. The Alert Level remained constant at Level 2 (on a scale of 1-5: 2 = "Do not approach the crater"), before being downgraded to Level 1 in December 2012.

Between July and September 2012, plume emissions at the Iwo-dake summit crater continued (table 4). Weak incandescence was recorded at night with a high-sensitivity camera on 22 July, 28 August, 6 November and 22-24 November. Seismic activity remained at low levels. No unusual ground deformation was observed in GPS data through December 2012.

An aerial observation conducted by the Japan Maritime Self-Defense Force (JMSDF) on 11 September 2012 revealed white plumes rising from Iwo-dake's summit crater and flanks.

The results of a field survey conducted from 17-20 November 2012 showed no remarkable change in white fumes from Iwo-dake. Infrared images also found that the temperature distribution had remained essentially unchanged. Aerial monitoring conducted by the Japan Coast Guard (JCG) on 25 November 2012 revealed the presence of brown and green discolored water around the eastern coast (similar findings as a previous survey) as well as patterns of steaming similar to those observed during the field survey. SO2 emissions during 17-20 November 2012 were measured to be ~400 tons/day; a previous survey conducted in July 2012 yielded an estimated flux of ~500 tons/day.

References. Shinohara, H., Iguchi, M., Hedenquist, J.W., and Koyaguchi, T., 2002, Preface to special volume, Earth, Planets and Space 54 (3), pp. 173-174.

Maeno, F, 2008, Geology and eruptive history of Kikai Caldera, Earthquake Research Institute, University of Tokyo (URL: http://www.eri.u-tokyo.ac.jp/fmaeno/kikai/kikaicaldera.html); accessed 23 February 2013.

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/); MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).


Kuchinoerabujima (Japan) — January 2013 Citation iconCite this Report

Kuchinoerabujima

Japan

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

All times are local (unless otherwise noted)


Increased seismicity, 11 December 2011-5 January 2012

Since a small eruption in 1980, Kuchinoerabu-jima experienced numerous periods of elevated seismicity, with volcanic earthquakes and tremor detected at least through December 2009 (BGVN 35:11). The volcano is located in the Ryukyu Island arc, off Japan's SW coast (figure 4).

Figure (see Caption) Figure 4. A map of the major volcanoes of Japan. Kuchinoerabu-jima is at the lower left. Courtesy of USGS/CVO.

Recent monthly reports of volcanic activity from the Japan Meteorological Agency (JMA) translated into English resumed in October 2010. The only recent English-translated JMA report on Kuchinoerabu-jima available online through December 2012 was in January 2012. We know of no other recent report on this volcano's seismic activity; therefore, this report summarizes seismicity between December 2011 and January 2012.

According to JMA, seismicity increased to a relatively high level immediately after 11 December 2011, but then decreased on 5 January 2012. On 20 January 2012, the Alert Level was lowered from 2 to 1; JMA noted that the possibility of an eruption was minimal.

During the December 2011-January 2012 period, no significant change in plume activity was observed, and plume heights remained below 100 m above the crater. According to a field survey on 11 January, infrared images (compared to images obtained in December 2011) showed no significant change in temperature distribution either at the summit or on the W slope of Shin-dake (also refered to as Shin-take), the youngest and most active cone.

Field surveys found that sulfur dioxide levels were 50 and 100 metric tons/day on 12 and 13 January 2012, respectively, which were lower than those recorded in December 2011 (200 metric tons/day on 9 December 2011).

According to JMA, continuous GPS measurements have established a baseline across Shin-dake, collecting data since September 2010. Shin-dake's rate of change in surface deformation at the stations has been slowing since September 2011.

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), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/).


San Cristobal (Nicaragua) — January 2013 Citation iconCite this Report

San Cristobal

Nicaragua

12.702°N, 87.004°W; summit elev. 1745 m

All times are local (unless otherwise noted)


Ash eruption during 25-28 December 2012

Our last report highlighted monitoring efforts at San Cristóbal and the explosive eruption that began on 8 September 2012 (BGVN 37:08). By 16 September 2012, seismicity and emissions had decreased; however, the Instituto Nicaragüense de Estudios Territoriales (INETER) announced in late December 2012 that volcanic activity had re-started. In this report, we cover the time period of 25-31 December when seismicity, explosions, and gas-and-ash emissions were reported.

At 2000 on 25 December 2012, observers noted a series of gas-and-ash explosions from the summit. The wind carried the fine- to sand-sized ash SW. Several hours prior to this activity, INETER had reported that seismicity was elevated but sulfur dioxide emissions (SO2) were relatively low compared to measurements from previous days.

During the early hours of the morning on 26 December, winds dispersed fine ash NW, W, and SW. Sand-size ash was fell on the W and SW flanks (figure 28). Civil Defense authorities from the municipality of Chinandega reported an ash plume up to 500 m above the summit and described the event as a "moderate eruption" similar to the 8 September 2012 event.

Figure (see Caption) Figure 28. A view S toward San Cristóbal with an ash plume drifting westerly on 26 December 2012. The lower hills to the right are part of El Chonco, an older volcanic edifice. Photograph by Hector Retamal, AFP, Getty Images.

On 26 December, government officials reported to Reuters that local inhabitants were evacuating. Rosario Murillo, a government spokeswoman, called on residents within a 3 km radius of the volcano to leave the area; some families had already self-evacuated.

By 1000 that day, INETER reported that seismicity had increased, and that they had received reports from Civil Defense stating that an eruption of fine ash rose to ~2,500 m above the crater. By the early afternoon, four major seismic events were detected and interpreted as explosions at the summit. Ashfall from these events primarily affected an area within a 5-6 km radius of the summit: El Viejo, Las Rojas, Banderas, Abraham Rugama, and those communities north of Chinandega's urban limit Grecia (particularly two communities called ##1 and ##4; see figure 19 in BGVN 36:12 for major town locations).

In their second communication on 26 December, INETER suggested that local inhabitants protect their water sources from ashfall, particularly those communities W, SW, and S of the volcano. They also announced that grazing lands would be closed in those regions due to the quantity of ash that had fallen. Research at Raupehu, New Zealand, and elsewhere has found that grazing animals can suffer damage to their teeth and poisoning due to elevated sulfur and fluorine if they consume ash-covered plants (Cronin and others, 2003). Precautions were also recommended for young children who could be adversely affected by inhaling fine ash. INETER noted that aviation traffic had been alerted to the presence of ash in the region.

The Washington Volcanic Ash Advisory Center (VAAC) detected ash from San Cristóbal during 26-28 December. Emissions were ongoing during that time period; plumes rose 2.4-4.3 km a.s.l. and drifted approximately W over the Pacific Ocean as far as 670 km WNW from the summit (figure 29).

Figure (see Caption) Figure 29. The aerial extent of observed volcanic ash from San Cristóbal was concentrated in three discrete regions mainly offshore of Central America at 0430 on 28 December 2012. The red polygons were developed by the VAAC as geospatial files (KML) for display in Google Earth. Courtesy of Washington VAAC and Google Earth.

INETER reported to local news agencies that 7 of the 13 municipalities of Chinandega were affected by ashfall by 27 December. Visibility was greatly reduced within the urban city of Chinandega. Emissions continued from the summit and reached 200 m above the crater rim in the morning. At the time of their second online notice, a plume of fine ash was visible rising up to 500 m above the crater, and small-to-moderate sized explosions of gas and ash continued.

On 28 December, the minister of Agriculture and Forestry told the local news agency, La Jornada, that while 2 millimeters of ash had fallen in some areas around the volcanic edifice, the farming areas should not be adversely affected since most of the crops had already been harvested. The public utility company, ENACAL, conducted investigations into water quality for the region.

News agencies reported that up to 20 km of highway was affected by ashfall along the Pan-American Highway between Honduras and Nicaragua. Vehicles opted to use headlights due to reduced visibility. La Jornada reported that a total of 268 people had left the area of San Cristóbal by 28 December and 68 were evacuated by the national humanitarian agency (Nicaraguan Humanitarian Rescue Unit, UHR).

INETER reported that small to moderate sized explosions had occurred in the morning of 28 December and a significant increase in SO2 flux was detected. This announcement included warnings regarding eye, skin, and respiratory irritation due to volcanic gases. There were also recommendations regarding ash removal from roofs and structures. Ash was distributed NW, W, and SW from the volcano and satellite images detected ash extending across the Pacific Ocean following the regional airstream offshore of El Salvador.

After an explosion of ash and gas at 1100 on 28 December, emissions throughout the day were ash-poor. Seismicity also decreased that day and, by 29 December, explosions had ceased and diffuse gas emissions continued. In their online bulletin, INETER reported that, as of 31 December, no ash explosions had been detected over the past two days. Gas emissions continued from the summit but SO2 levels had returned to normal.

Volcanic hazards map for San Cristóbal. A map of volcanic hazards was available on the INETER website for the region of San Cristóbal (figure 30). Volcanic ballistics, lahars, landslides, lava flows, and tephrafall were assessed and likely impacted areas were delineated. The tephrafall region corresponded to the prevailing winds and correlated well with ash-effected regions during the December 2012 events.

Figure (see Caption) Figure 30. Volcanic hazards from San Cristóbal include ejecta, lahars, landslides, and lava flows. This map was released in April 2006 and developed to show the aerial extent of potential events. Densely populated regions are yellow, road systems are black, and rivers are blue; additional color regions correspond to hazards listed in the key (in Spanish). The brown circle has a radius of 5 km and encompasses the main volcanic edifice indicating the maximum expected extent of ballistics (volcanic bombs for example); the two tan regions indicate the extent of possible tephra fall (where lighter shading indicates a medium-level risk zone and darker is higher-level risk); red regions follow major drainages where lahars and landslides could occur; the region shaded pink encompasses the areas most likely effected by future lava flows. Courtesy of INETER.

Reference. Cronin, S.J., Neall, V.E., Lecointre, J.A., Hedley, M.J., and Loganathan, P., 2003, Environmental hazards of fluoride in volcanic ash: a case study from Ruapehu volcano, New Zealand, Journal of Volcanology and Geothermal Research, 121, 271-291.

Geologic Background. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1745-m-high youngest cone, named San Cristóbal (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km W of San Cristóbal; it and the eroded Moyotepe volcano, 4 km NE of San Cristóbal, are of Pleistocene age. Volcán Casita, containing an elongated summit crater, lies immediately east of San Cristóbal and was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/); La Jornada (URL: http://www.lajornadanet.com/diario/archivo/2012/diciembre/28/1.php); La Prensa de Nicaragua (URL: http://www.laprensa.com.ni/2012/12/27/ambito/128746/imprimir); Reuters.

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