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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

Masaya (Nicaragua) Lava lake level drops but remains active through May 2020; weak gas plumes

Shishaldin (United States) Intermittent thermal activity and a possible new cone at the summit crater during February-May 2020

Krakatau (Indonesia) Strombolian explosions, ash plumes, and crater incandescence during April 2020

Taal (Philippines) Eruption on 12 January with explosions through 22 January; steam plumes continuing into March

Unnamed (Tonga) Additional details and pumice raft drift maps from the August 2019 submarine eruption

Klyuchevskoy (Russia) Strombolian activity November 2019 through May 2020; lava flow down the SE flank in April

Nyamuragira (DR Congo) Intermittent thermal anomalies within the summit crater during December 2019-May 2020

Nyiragongo (DR Congo) Activity in the lava lake and small eruptive cone persists during December 2019-May 2020

Kavachi (Solomon Islands) Discolored water plumes seen using satellite imagery in 2018 and 2020

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



Masaya (Nicaragua) — June 2020 Citation iconCite this Report

Masaya

Nicaragua

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

All times are local (unless otherwise noted)


Lava lake level drops but remains active through May 2020; weak gas plumes

Masaya, which is about 20 km NW of the Nicaragua’s capital of Managua, is one of the most active volcanoes in that country and has a caldera that contains a number of craters (BGVN 43:11). The Santiago crater is the one most currently active and it contains a small lava lake that emits weak gas plumes (figure 85). This report summarizes activity during February through May 2020 and is based on Instituto Nicaragüense de Estudios Territoriales (INETER) monthly reports and satellite data. During the reporting period, the volcano was relatively calm, with only weak gas plumes.

Figure (see Caption) Figure 85. Satellite images of Masaya from Sentinel-2 on 18 April 2020, showing and a small gas plume drifting SW (top, natural color bands 4, 3, 2) and the lava lake (bottom, false color bands 12, 11, 4). Courtesy of Sentinel Hub Playground.

According to INETER, thermal images of the lava lake and temperature data in the fumaroles were taken using an Omega infrared gun and a forward-looking infrared (FLIR) SC620 thermal camera. The temperatures above the lava lake have decreased since November 2019, when the temperature was 287°C, dropping to 96°C when measured on 14 May 2020. INETER attributed this decrease to subsidence in the level of the lava lake by 5 m which obstructed part of the lake and concentrated the gas emissions in the weak plume. Convection continued in the lava lake, which in May had decreased to a diameter of 3 m. Many landslides had occurred in the E, NE, and S walls of the crater rim due to rock fracturing caused by the high heat and acidity of the emissions.

During the reporting period, the MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system recorded numerous thermal anomalies from the lava lake based on MODIS data (figure 86). Infrared satellite images from Sentinel-2 regularly showed a strong signature from the lava lake through 18 May, after which the volcano was covered by clouds.

Figure (see Caption) Figure 86. Thermal anomalies at Masaya during February through May 2020. The larger anomalies with black lines are more distant and not related to the volcano. Courtesy of MIROVA.

Measurements of sulfur dioxide (SO2) made by INETER in the section of the Ticuantepe - La Concepción highway (just W of the volcano) with a mobile DOAS system varied between a low of just over 1,000 metric tons/day in mid-November 2019 to a high of almost 2,500 tons/day in late May. Temperatures of fumaroles in the Cerro El Comalito area, just ENE of Santiago crater, ranged from 58 to 76°C during February-May 2020, with most values in the 69-72°C range.

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

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); 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).


Shishaldin (United States) — June 2020 Citation iconCite this Report

Shishaldin

United States

54.756°N, 163.97°W; summit elev. 2857 m

All times are local (unless otherwise noted)


Intermittent thermal activity and a possible new cone at the summit crater during February-May 2020

Shishaldin is located near the center of Unimak Island in Alaska, with the current eruption phase beginning in July 2019 and characterized by ash plumes, lava flows, lava fountaining, pyroclastic flows, and lahars. More recently, in late 2019 and into January 2020, activity consisted of multiple lava flows, pyroclastic flows, lahars, and ashfall events (BGVN 45:02). This report summarizes activity from February through May 2020, including gas-and-steam emissions, brief thermal activity in mid-March, and a possible new cone within the summit crater. The primary source of information comes from the Alaska Volcano Observatory (AVO) reports and various satellite data.

Volcanism during February 2020 was relatively low, consisting of weakly to moderately elevated surface temperatures during 1-4 February and occasional small gas-and-steam plumes (figure 37). By 6 February both seismicity and surface temperatures had decreased. Seismicity and surface temperatures increased slightly again on 8 March and remained elevated through the rest of the reporting period. Intermittent gas-and-steam emissions were also visible from mid-March (figure 38) through May. Minor ash deposits visible on the upper SE flank may have been due to ash resuspension or a small collapse event at the summit, according to AVO.

Figure (see Caption) Figure 37. Photo of a gas-and-steam plume rising from the summit crater at Shishaldin on 22 February 2020. Photo courtesy of Ben David Jacob via AVO.
Figure (see Caption) Figure 38. A Worldview-2 panchromatic satellite image on 11 March 2020 showing a gas-and-steam plume rising from the summit of Shishaldin and minor ash deposits on the SE flank (left). Aerial photo showing minor gas-and-steam emissions rising from the summit crater on 11 March (right). Some erosion of the snow and ice on the upper flanks is a result of the lava flows from the activity in late 2019 and early 2020. Photo courtesy of Matt Loewen (left) and Ed Fischer (right) via AVO.

On 14 March, lava and a possible new cone were visible in the summit crater using satellite imagery, accompanied by small explosion signals. Strong thermal signatures due to the lava were also seen in Sentinel-2 satellite data and continued strongly through the month (figure 39). The lava reported by AVO in the summit crater was also reflected in satellite-based MODIS thermal anomalies recorded by the MIROVA system (figure 40). Seismic and infrasound data identified small explosions signals within the summit crater during 14-19 March.

Figure (see Caption) Figure 39. Sentinel-2 thermal satellite images (bands 12, 11, 8A) show a bright hotspot (yellow-orange) at the summit crater of Shishaldin during mid-March 2020 that decreases in intensity by late March. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 40. MIROVA thermal data showing a brief increase in thermal anomalies during late March 2020 and on two days in late April between periods of little to no activity. Courtesy of MIROVA.

AVO released a Volcano Observatory Notice for Aviation (VONA) stating that seismicity had decreased by 16 April and that satellite data no longer showed lava or additional changes in the crater since the start of April. Sentinel-2 thermal satellite imagery continued to show a weak hotspot in the crater summit through May (figure 41), which was also detected by the MIROVA system on two days. A daily report on 6 May reported a visible ash deposit extending a short distance SE from the summit, which had likely been present since 29 April. AVO noted that the timing of the deposit corresponds to an increase in the summit crater diameter and depth, further supporting a possible small collapse. Small gas-and-steam emissions continued intermittently and were accompanied by weak tremors and occasional low-frequency earthquakes through May (figure 42). Minor amounts of sulfur dioxide were detected in the gas-and-steam emissions during 20 and 29 April, and 2, 16, and 28 May.

Figure (see Caption) Figure 41. Sentinel-2 thermal satellite images (bands 12, 11, 8A) show occasional gas-and-steam emissions rising from Shishaldin on 26 February (top left) and 24 April 2020 (bottom left) and a weak hotspot (yellow-orange) persisting at the summit crater during April and early May 2020. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 42. A Worldview-1 panchromatic satellite image showing gas-and-steam emissions rising from the summit of Shishaldin on 1 May 2020 (local time) (left). Aerial photo of the N flank of Shishaldin with minor gas-and-steam emissions rising from the summit on 8 May (right). Photo courtesy of Matt Loewen (left) and Levi Musselwhite (right) via AVO.

Geologic Background. The beautifully symmetrical Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." A steam plume often rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the W and NE sides at 1,500-1,800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of Strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century.

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


Krakatau (Indonesia) — June 2020 Citation iconCite this Report

Krakatau

Indonesia

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

All times are local (unless otherwise noted)


Strombolian explosions, ash plumes, and crater incandescence during April 2020

Krakatau, located in the Sunda Strait between Indonesia’s Java and Sumatra Islands, experienced a major caldera collapse around 535 CE, forming a 7-km-wide caldera ringed by three islands. On 22 December 2018, a large explosion and flank collapse destroyed most of the 338-m-high island of Anak Krakatau (Child of Krakatau) and generated a deadly tsunami (BGVN 44:03). The near-sea level crater lake inside the remnant of Anak Krakatau was the site of numerous small steam and tephra explosions. A larger explosion in December 2019 produced the beginnings of a new cone above the surface of crater lake (BGVN 45:02). Recently, volcanism has been characterized by occasional Strombolian explosions, dense ash plumes, and crater incandescence. This report covers activity from February through May 2020 using information provided by the Indonesian Center for Volcanology and Geological Hazard Mitigation, also known as Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), the Darwin Volcanic Ash Advisory Center (VAAC), and various satellite data.

Activity during February 2020 consisted of dominantly white gas-and-steam emissions rising 300 m above the crater, according to PVMBG. According to the Darwin VAAC, a ground observer reported an eruption on 7 and 8 February, but no volcanic ash was observed. During 10-11 February, a short-lived eruption was detected by seismograms which produced an ash plume up to 1 km above the crater drifting E. MAGMA Indonesia reported two eruptions on 18 March, both of which rose to 300 m above the crater. White gas-and-steam emissions were observed for the rest of the month and early April.

On 10 April PVMBG reported two eruptions, at 2158 and 2235, both of which produced dark ash plumes rising 2 km above the crater followed by Strombolian explosions ejecting incandescent material that landed on the crater floor (figures 108 and 109). The Darwin VAAC issued a notice at 0145 on 11 April reporting an ash plume to 14.3 km altitude drifting WNW, however this was noted with low confidence due to the possible mixing of clouds. During the same day, an intense thermal hotspot was detected in the HIMAWARI thermal satellite imagery and the NASA Global Sulfur Dioxide page showed a strong SO2 plume at 11.3 km altitude drifting W (figure 110). The CCTV Lava93 webcam showed new lava flows and lava fountaining from the 10-11 April eruptions. This activity was evident in the MIROVA (Middle InfraRed Observation of Volcanic Activity) graph of MODIS thermal anomaly data (figure 111).

Figure (see Caption) Figure 108. Webcam (Lava93) images of Krakatau on 10 April 2020 showing Strombolian explosions, strong incandescence, and ash plumes rising from the crater. Courtesy of PVMBG and MAGMA Indonesia.
Figure (see Caption) Figure 109. Webcam image of incandescent Strombolian explosions at Krakatau on 10 April 2020. Courtesy of PVMBG and MAGMA Indonesia.
Figure (see Caption) Figure 110. Strong sulfur dioxide emissions rising from Krakatau and drifting W were detected using the TROPOMI instrument on the Sentinel-5P satellite on 11 April 2020 (top row). Smaller volumes of SO2 were visible in Sentinel-5P/TROPOMI maps on 13 (bottom left) and 19 April (bottom right). Courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 111. Thermal activity at Anak Krakatau from 29 June-May 2020 shown on a MIROVA Log Radiative Power graph. The power and frequency of the thermal anomalies sharply increased in mid-April. After the larger eruptive event in mid-April the thermal anomalies declined slightly in strength but continued to be detected intermittently through May. Courtesy of MIROVA.

Strombolian activity rising up to 500 m continued into 12 April and was accompanied by SO2 emissions that rose 3 km altitude, drifting NW according to a VAAC notice. PVMBG reported an eruption on 13 April at 2054 that resulted in incandescence as high as 25 m above the crater. Volcanic ash, accompanied by white gas-and-steam emissions, continued intermittently through 18 April, many of which were observed by the CCTV webcam. After 18 April only gas-and-steam plumes were reported, rising up to 100 m above the crater; Sentinel-2 satellite imagery showed faint thermal anomalies in the crater (figure 112). SO2 emissions continued intermittently throughout April, though at lower volumes and altitudes compared to the 11th. MODIS satellite data seen in MIROVA showed intermittent thermal anomalies through May.

Figure (see Caption) Figure 112. Sentinel-2 thermal satellite images showing the cool crater lake on 20 March (top left) followed by minor heating of the crater during April and May 2020. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

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

Information Contacts: 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/); 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).


Taal (Philippines) — June 2020 Citation iconCite this Report

Taal

Philippines

14.002°N, 120.993°E; summit elev. 311 m

All times are local (unless otherwise noted)


Eruption on 12 January with explosions through 22 January; steam plumes continuing into March

Taal volcano is in a caldera system located in southern Luzon island and is one of the most active volcanoes in the Philippines. It has produced around 35 recorded eruptions since 3,580 BCE, ranging from VEI 1 to 6, with the majority of eruptions being a VEI 2. The caldera contains a lake with an island that also contains a lake within the Main Crater (figure 12). Prior to 2020 the most recent eruption was in 1977, on the south flank near Mt. Tambaro. The United Nations Office for the Coordination of Humanitarian Affairs in the Philippines reports that over 450,000 people live within 40 km of the caldera (figure 13). This report covers activity during January through February 2020 including the 12 to 22 January eruption, and is based on reports by Philippine Institute of Volcanology and Seismology (PHIVOLCS), satellite data, geophysical data, and media reports.

Figure (see Caption) Figure 12. Annotated satellite images showing the Taal caldera, Volcano Island in the caldera lake, and features on the island including Main Crater. Imagery courtesy of Planet Inc.
Figure (see Caption) Figure 13. Map showing population totals within 14 and 17 km of Volcano Island at Taal. Courtesy of the United Nations Office for the Coordination of Humanitarian Affairs (OCHA).

The hazard status at Taal was raised to Alert Level 1 (abnormal, on a scale of 0-5) on 28 March 2019. From that date through to 1 December there were 4,857 earthquakes registered, with some felt nearby. Inflation was detected during 21-29 November and an increase in CO2 emission within the Main Crater was observed. Seismicity increased beginning at 1100 on 12 January. At 1300 there were phreatic (steam) explosions from several points inside Main Crater and the Alert Level was raised to 2 (increasing unrest). Booming sounds were heard in Talisay, Batangas, at 1400; by 1402 the plume had reached 1 km above the crater, after which the Alert Level was raised to 3 (magmatic unrest).

Phreatic eruption on 12 January 2020. A seismic swarm began at 1100 on 12 January 2020 followed by a phreatic eruption at 1300. The initial activity consisted of steaming from at least five vents in Main Crater and phreatic explosions that generated 100-m-high plumes. PHIVOLCS raised the Alert Level to 2. The Earth Observatory of Singapore reported that the International Data Center (IDC) for the Comprehensive test Ban Treaty (CTBT) in Vienna noted initial infrasound detections at 1450 that day.

Booming sounds were heard at 1400 in Talisay, Batangas (4 km NNE from the Main Crater), and at 1404 volcanic tremor and earthquakes felt locally were accompanied by an eruption plume that rose 1 km; ash fell to the SSW. The Alert Level was raised to 3 and the evacuation of high-risk barangays was recommended. Activity again intensified around 1730, prompting PHIVOLCS to raise the Alert Level to 4 and recommend a total evacuation of the island and high-risk areas within a 14-km radius. The eruption plume of steam, gas, and tephra significantly intensified, rising to 10-15 km altitude and producing frequent lightning (figures 14 and 15). Wet ash fell as far away as Quezon City (75 km N). According to news articles schools and government offices were ordered to close and the Ninoy Aquino International Airport (56 km N) in Manila suspended flights. About 6,000 people had been evacuated. Residents described heavy ashfall, low visibility, and fallen trees.

Figure (see Caption) Figure 14. Lightning produced during the eruption of Taal during 1500 on 12 January to 0500 on 13 January 2020 local time (0700-2100 UTC on 12 January). Courtesy of Chris Vagasky, Vaisala.
Figure (see Caption) Figure 15. Lightning strokes produced during the first days of the Taal January 2020 eruption. Courtesy of Domcar C Lagto/SIPA/REX/Shutterstock via The Guardian.

In a statement issued at 0320 on 13 January, PHIVOLCS noted that ashfall had been reported across a broad area to the north in Tanauan (18 km NE), Batangas; Escala (11 km NW), Tagaytay; Sta. Rosa (32 km NNW), Laguna; Dasmariñas (32 km N), Bacoor (44 km N), and Silang (22 km N), Cavite; Malolos (93 km N), San Jose Del Monte (87 km N), and Meycauayan (80 km N), Bulacan; Antipolo (68 km NNE), Rizal; Muntinlupa (43 km N), Las Piñas (47 km N), Marikina (70 km NNE), Parañaque (51 km N), Pasig (62 km NNE), Quezon City, Mandaluyong (62 km N), San Juan (64 km N), Manila; Makati City (59 km N) and Taguig City (55 km N). Lapilli (2-64 mm in diameter) fell in Tanauan and Talisay; Tagaytay City (12 km N); Nuvali (25 km NNE) and Sta (figure 16). Rosa, Laguna. Felt earthquakes (Intensities II-V) continued to be recorded in local areas.

Figure (see Caption) Figure 16. Ashfall from the Taal January 2020 eruption in Lemery (top) and in the Batangas province (bottom). Photos posted on 13 January, courtesy of Ezra Acayan/Getty Images, Aaron Favila/AP, and Ted Aljibe/AFP via Getty Images via The Guardian.

Magmatic eruption on 13 January 2020. A magmatic eruption began during 0249-0428 on 13 January, characterized by weak lava fountaining accompanied by thunder and flashes of lightning. Activity briefly waned then resumed with sporadic weak fountaining and explosions that generated 2-km-high, dark gray, steam-laden ash plumes (figure 17). New lateral vents opened on the N flank, producing 500-m-tall lava fountains. Heavy ashfall impacted areas to the SW, including in Cuenca (15 km SSW), Lemery (16 km SW), Talisay, and Taal (15 km SSW), Batangas (figure 18).

Figure (see Caption) Figure 17. Ash plumes seen from various points around Taal in the initial days of the January 2020 eruption, posted on 13 January. Courtesy of Eloisa Lopez/Reuters, Kester Ragaza/Pacific Press/Shutterstock, Ted Aljibe/AFP via Getty Images, via The Guardian.
Figure (see Caption) Figure 18. Map indicating areas impacted by ashfall from the 12 January eruption through to 0800 on the 13th. Small yellow circles (to the N) are ashfall report locations; blue circles (at the island and to the S) are heavy ashfall; large green circles are lapilli (particles measuring 2-64 mm in diameter). Modified from a map courtesy of Lauriane Chardot, Earth Observatory of Singapore; data taken from PHIVOLCS.

News articles noted that more than 300 domestic and 230 international flights were cancelled as the Manila Ninoy Aquino International Airport was closed during 12-13 January. Some roads from Talisay to Lemery and Agoncillo were impassible and electricity and water services were intermittent. Ashfall in several provinces caused power outages. Authorities continued to evacuate high-risk areas, and by 13 January more than 24,500 people had moved to 75 shelters out of a total number of 460,000 people within 14 km.

A PHIVOLCS report for 0800 on the 13th through 0800 on 14 January noted that lava fountaining had continued, with steam-rich ash plumes reaching around 2 km above the volcano and dispersing ash SE and W of Main Crater. Volcanic lighting continued at the base of the plumes. Fissures on the N flank produced 500-m-tall lava fountains. Heavy ashfall continued in the Lemery, Talisay, Taal, and Cuenca, Batangas Municipalities. By 1300 on the 13th lava fountaining generated 800-m-tall, dark gray, steam-laden ash plumes that drifted SW. Sulfur dioxide emissions averaged 5,299 metric tons/day (t/d) on 13 January and dispersed NNE (figure 19).

Figure (see Caption) Figure 19. Compilation of sulfur dioxide plumes from TROPOMI overlaid in Google Earth for 13 January from 0313-1641 UT. Courtesy of NASA Global Sulfur Dioxide Monitoring Page and Google Earth.

Explosions and ash emission through 22 January 2020. At 0800 on 15 January PHIVOLCS stated that activity was generally weaker; dark gray, steam-laden ash plumes rose about 1 km and drifted SW. Satellite images showed that the Main Crater lake was gone and new craters had formed inside Main Crater and on the N side of Volcano Island.

PHIVOLCS reported that activity during 15-16 January was characterized by dark gray, steam-laden plumes that rose as high as 1 km above the vents in Main Crater and drifted S and SW. Sulfur dioxide emissions were 4,186 t/d on 15 January. Eruptive events at 0617 and 0621 on 16 January generated short-lived, dark gray ash plumes that rose 500 and 800 m, respectively, and drifted SW. Weak steam plumes rose 800 m and drifted SW during 1100-1700, and nine weak explosions were recorded by the seismic network.

Steady steam emissions were visible during 17-21 January. Infrequent weak explosions generated ash plumes that rose as high as 1 km and drifted SW. Sulfur dioxide emissions fluctuated and were as high as 4,353 t/d on 20 January and as low as 344 t/d on 21 January. PHIVOLCS reported that white steam-laden plumes rose as high as 800 m above main vent during 22-28 January and drifted SW and NE; ash emissions ceased around 0500 on 22 January. Remobilized ash drifted SW on 22 January due to strong low winds, affecting the towns of Lemery (16 km SW) and Agoncillo, and rose as high as 5.8 km altitude as reported by pilots. Sulfur dioxide emissions were low at 140 t/d.

Steam plumes through mid-April 2020. The Alert Level was lowered to 3 on 26 January and PHIVOLCS recommended no entry onto Volcano Island and Taal Lake, nor into towns on the western side of the island within a 7-km radius. PHIVOLCS reported that whitish steam plumes rose as high as 800 m during 29 January-4 February and drifted SW (figure 20). The observed steam plumes rose as high as 300 m during 5-11 February and drifted SW.

Sulfur dioxide emissions averaged around 250 t/d during 22-26 January; emissions were 87 t/d on 27 January and below detectable limits the next day. During 29 January-4 February sulfur dioxide emissions ranged to a high of 231 t/d (on 3 February). The following week sulfur dioxide emissions ranged from values below detectable limits to a high of 116 t/d (on 8 February).

Figure (see Caption) Figure 20. Taal Volcano Island producing gas-and-steam plumes on 15-16 January 2020. Courtesy of James Reynolds, Earth Uncut.

On 14 February PHIVOLCS lowered the Alert Level to 2, noting a decline in the number of volcanic earthquakes, stabilizing ground deformation of the caldera and Volcano Island, and diffuse steam-and-gas emission that continued to rise no higher than 300 m above the main vent during the past three weeks. During 14-18 February sulfur dioxide emissions ranged from values below detectable limits to a high of 58 tonnes per day (on 16 February). Sulfur dioxide emissions were below detectable limits during 19-20 February. During 26 February-2 March steam plumes rose 50-300 m above the vent and drifted SW and NE. PHIVOLCS reported that during 4-10 March weak steam plumes rose 50-100 m and drifted SW and NE; moderate steam plumes rose 300-500 m and drifted SW during 8-9 March. During 11-17 March weak steam plumes again rose only 50-100 m and drifted SW and NE.

PHIVOLCS lowered the Alert Level to 1 on 19 March and recommended no entry onto Volcano Island, the area defined as the Permanent Danger Zone. During 8-9 April steam plumes rose 100-300 m and drifted SW. As of 1-2 May 2020 only weak steaming and fumarolic activity from fissure vents along the Daang Kastila trail was observed.

Evacuations. According to the Disaster Response Operations Monitoring and Information Center (DROMIC) there were a total of 53,832 people dispersed to 244 evacuation centers by 1800 on 15 January. By 21 January there were 148,987 people in 493 evacuation. The number of residents in evacuation centers dropped over the next week to 125,178 people in 497 locations on 28 January. However, many residents remained displaced as of 3 February, with DROMIC reporting 23,915 people in 152 evacuation centers, but an additional 224,188 people staying at other locations.

By 10 February there were 17,088 people in 110 evacuation centers, and an additional 211,729 staying at other locations. According to the DROMIC there were a total of 5,321 people in 21 evacuation centers, and an additional 195,987 people were staying at other locations as of 19 February.

The number of displaced residents continued to drop, and by 3 March there were 4,314 people in 12 evacuation centers, and an additional 132,931 people at other locations. As of 11 March there were still 4,131 people in 11 evacuation centers, but only 17,563 staying at other locations.

Deformation and ground cracks. New ground cracks were observed on 13 January in Sinisian (18 km SW), Mahabang Dahilig (14 km SW), Dayapan (15 km SW), Palanas (17 km SW), Sangalang (17 km SW), and Poblacion (19 km SW) Lemery; Pansipit (11 km SW), Agoncillo; Poblacion 1, Poblacion 2, Poblacion 3, Poblacion 5 (all around 17 km SW), Talisay, and Poblacion (11 km SW), San Nicolas (figure 21). A fissure opened across the road connecting Agoncillo to Laurel, Batangas. New ground cracking was reported the next day in Sambal Ibaba (17 km SW), and portions of the Pansipit River (SW) had dried up.

Figure (see Caption) Figure 21. Video screenshots showing ground cracks that formed during the Taal unrest and captured on 15 and 16 January 2020. Courtesy of James Reynolds, Earth Uncut.

Dropping water levels of Taal Lake were first observed in some areas on 16 January but reported to be lake-wide the next day. The known ground cracks in the barangays of Lemery, Agoncillo, Talisay, and San Nicolas in Batangas Province widened a few centimeters by 17 January, and a new steaming fissure was identified on the N flank of the island.

GPS data had recorded a sudden widening of the caldera by ~1 m, uplift of the NW sector by ~20 cm, and subsidence of the SW part of Volcano Island by ~1 m just after the main eruption phase. The rate of deformation was smaller during 15-22 January, and generally corroborated by field observations; Taal Lake had receded about 30 cm by 25 January but about 2.5 m of the change (due to uplift) was observed around the SW portion of the lake, near the Pansipit River Valley where ground cracking had been reported.

Weak steaming (plumes 10-20 m high) from ground cracks was visible during 5-11 February along the Daang Kastila trail which connects the N part of Volcano Island to the N part of the main crater. PHIVOLCS reported that during 19-24 February steam plumes rose 50-100 m above the vent and drifted SW. Weak steaming (plumes up to 20 m high) from ground cracks was visible during 8-14 April along the Daang Kastila trail which connects the N part of Volcano Island to the N part of the main crater.

Seismicity. Between 1300 on 12 January and 0800 on 21 January the Philippine Seismic Network (PSN) had recorded a total of 718 volcanic earthquakes; 176 of those had magnitudes ranging from 1.2-4.1 and were felt with Intensities of I-V. During 20-21 January there were five volcanic earthquakes with magnitudes of 1.6-2.5; the Taal Volcano network (which can detect smaller events not detectable by the PSN) recorded 448 volcanic earthquakes, including 17 low-frequency events. PHIVOLCS stated that by 21 January hybrid earthquakes had ceased and both the number and magnitude of low-frequency events had diminished.

Geologic Background. Taal is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. Though not topographically prominent, its prehistorical eruptions have greatly changed the landscape of SW Luzon. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, and several eruptive centers lie submerged beneath the lake. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all historical eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones that have grown about 25% in area during historical time. Powerful pyroclastic flows and surges from historical eruptions have caused many fatalities.

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/); Disaster Response Operations Monitoring and Information Center (DROMIC) (URL: https://dromic.dswd.gov.ph/); United Nations Office for the Coordination of Humanitarian Affairs, Philippines (URL: https://www.unocha.org/philippines); James Reynolds, Earth Uncut TV (Twitter: @EarthUncutTV, URL: https://www.earthuncut.tv/, YouTube: https://www.youtube.com/user/TyphoonHunter); Chris Vagasky, Vaisala Inc., Louisville, Colorado, USA (URL: https://www.vaisala.com/en?type=1, Twitter: @COweatherman, URL: https://twitter.com/COweatherman); Earth Observatory of Singapore, Nanyang Technological University, 50 Nanyang Avenue, Singapore (URL: https://www.earthobservatory.sg/); 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/); Relief Web, Flash Update No. 1 - Philippines: Taal Volcano eruption (As of 13 January 2020, 2 p.m. local time) (URL: https://reliefweb.int/report/philippines/flash-update-no-1-philippines-taal-volcano-eruption-13-january-2020-2-pm-local); Bloomberg, Philippines Braces for Hazardous Volcano Eruption (URL: https://www.bloomberg.com/news/articles/2020-01-12/philippines-raises-alert-level-in-taal-as-volcano-spews-ash); National Public Radio (NPR), Volcanic Eruption In Philippines Causes Thousands To Flee (URL: npr.org/2020/01/13/795815351/volcanic-eruption-in-philippines-causes-thousands-to-flee); Reuters (http://www.reuters.com/); Agence France-Presse (URL: http://www.afp.com/); Pacific Press (URL: http://www.pacificpress.com/); Shutterstock (URL: https://www.shutterstock.com/); Getty Images (URL: http://www.gettyimages.com/); Google Earth (URL: https://www.google.com/earth/).


Unnamed (Tonga) — March 2020 Citation iconCite this Report

Unnamed

Tonga

18.325°S, 174.365°W; summit elev. -40 m

All times are local (unless otherwise noted)


Additional details and pumice raft drift maps from the August 2019 submarine eruption

In the northern Tonga region, approximately 80 km NW of Vava’u, large areas of floating pumice, termed rafts, were observed starting as early as 7 August 2019. The area of these andesitic pumice rafts was initially 195 km2 with the layers measuring 15-30 cm thick and were produced 200 m below sea level (Jutzeler et al. 2020). The previous report (BGVN 44:11) described the morphology of the clasts and the rafts, and their general westward path from 9 August to 9 October 2019, with the first sighting occurring on 9 August NW of Vava’u in Tonga. This report updates details regarding the submarine pumice raft eruption in early August 2019 using new observations and data from Brandl et al. (2019) and Jutzeler et al. (2020).

The NoToVE-2004 (Northern Tonga Vents Expedition) research cruise on the RV Southern Surveyor (SS11/2004) from the Australian CSIRO Marine National Facility traveled to the northern Tonga Arc and discovered several submarine basalt-to-rhyolite volcanic centers (Arculus, 2004). One of these volcanic centers 50 km NW of Vava’u was the unnamed seamount (volcano number 243091) that had erupted in 2001 and again in 2019, unofficially designated “Volcano F” for reference purposes by Arculus (2004) and also used by Brandl et al. (2019). It is a volcanic complex that rises more than 1 km from the seafloor with a central 6 x 8.7 km caldera and a volcanic apron measuring over 50 km in diameter (figures 19 and 20). Arculus (2004) described some of the dredged material as “fresh, black, plagioclase-bearing lava with well-formed, glassy crusts up to 2cm thick” from cones by the eastern wall of the caldera; a number of apparent flows, lava or debris, were observed draping over the northern wall of the caldera.

Figure (see Caption) Figure 19. Visualization of the unnamed submarine Tongan volcano (marked “Volcano F”) using bathymetric data to show the site of the 6-8 August 2020 eruption and the rest of the cone complex. Courtesy of Philipp Brandl via GEOMAR.
Figure (see Caption) Figure 20. Map of the unnamed submarine Tongan volcano using satellite imagery, bathymetric data, with shading from the NW. The yellow circle indicates the location of the August 2019 activity. Young volcanic cones are marked “C” and those with pit craters at the top are marked with “P.” Courtesy of Brandl et al. (2019).

The International Seismological Centre (ISC) Preliminary Bulletin listed a particularly strong (5.7 Mw) earthquake at 2201 local time on 5 August, 15 km SSW of the volcano at a depth of 10 km (Brandl et al. 2019). This event was followed by six slightly lower magnitude earthquakes over the next two days.

Sentinel-2 satellite imagery showed two concentric rings originating from a point source (18.307°S 174.395°W) on 6 August (figure 21), which could be interpreted as small weak submarine plumes or possibly a series of small volcanic cones, according to Brandl et al. (2019). The larger ring is about 1.2 km in diameter and the smaller one measures 250 m. By 8 August volcanic activity had decreased, but the pumice rafts that were produced remained visible through at least early October (BGVN 44:11). Brandl et al. (2019) states that, due to the lack of continued observed activity rising from this location, the eruption was likely a 2-day-long event during 6-8 August.

Figure (see Caption) Figure 21. Sentinel-2 satellite image of possible gas/vapor emissions (streaks) on 6 August 2019 drifting NW, which is the interpreted site for the unnamed Tongan seamount. The larger ring is about 1.2 km in diameter and the smaller one measures 250 m. Image using False Color (urban) rendering (bands 12, 11, 4); courtesy of Sentinel Hub Playground.

The pumice was first observed on 9 August occurred up to 56 km from the point of origin, according to Jutzeler et al. (2020). By calculating the velocity (14 km/day) of the raft using three satellites, Jutzeler et al. (2020) determined the pumice was erupted immediately after the satellite image of the submarine plumes on 6 August (UTC time). Minor activity at the vent may have continued on 8 and 11 August (UTC time) with pale blue-green water discoloration (figure 22) and a small (less than 1 km2) diffuse pumice raft 2-5 km from the vent.

Figure (see Caption) Figure 22. Sentinel-2 satellite image of the last visible activity occurring W of the unnamed submarine Tongan volcano on 8 August 2019, represented by slightly discolored blue-green water. Image using Natural Color rendering (bands 4, 3, 2) and enhanced with color correction; courtesy of Sentinel Hub Playground.

Continuous observations using various satellite data and observations aboard the catamaran ROAM tracked the movement and extent of the pumice raft that was produced during the submarine eruption in early August (figure 23). The first visible pumice raft was observed on 8 August 2019, covering more than 136.7 km2 between the volcanic islands of Fonualei and Late and drifting W for 60 km until 9 August (Brandl et al. 2019; Jutzeler 2020). The next day, the raft increased to 167.2-195 km2 while drifting SW for 74 km until 14 August. Over the next three days (10-12 August) the size of the raft briefly decreased in size to less than 100 km2 before increasing again to 157.4 km2 on 14 August; at least nine individual rafts were mapped and identified on satellite imagery (Brandl et al. 2019). On 15 August sailing vessels observed a large pumice raft about 75 km W of Late Island (see details in BGVN 44:11), which was the same one as seen in satellite imagery on 8 August.

Figure (see Caption) Figure 23. Map of the extent of discolored water and the pumice raft from the unnamed submarine Tongan volcano between 8 and 14 August 2019 using imagery from NASA’s MODIS, ESA’s Sentinel-2 satellite, and observations from aboard the catamaran ROAM (BGVN 44:11). Back-tracing the path of the pumice raft points to a source location at the unnamed submarine Tongan volcano. Courtesy of Brandl et al. (2019).

By 17 August high-resolution satellite images showed an area of large and small rafts measuring 222 km2 and were found within a field of smaller rafts for a total extent of 1,350 km2, which drifted 73 km NNW through 22 August before moving counterclockwise for three days (figure f; Jutzeler et al., 2020). Small pumice ribbons encountered the Oneata Lagoon on 30 August, the first island that the raft came into contact (Jutzeler et al. 2020). By 2 September, the main raft intersected with Lakeba Island (460 km from the source) (figure 24), breaking into smaller ribbons that started to drift W on 8 September. On 19 September the small rafts (less than 100 m x less than 2 km) entered the strait between Viti Levu and Vanua Levu, the two main islands of Fiji, while most of the others were stranded 60 km W in the Yasawa Islands for more than two months (Jutzeler et al., 2020).

Figure (see Caption) Figure 24. Time-series map of the raft dispersal from the unnamed submarine Tongan volcano using multiple satellite images. A) Map showing the first days of the raft dispersal starting on 7 August 2019 and drifting SW from the vent (marked with a red triangle). Precursory seismicity that began on 5 August is marked with a white star. By 15-17 August the raft was entrained in an ocean loop or eddy. The dashed lines represent the path of the sailing vessels. B) Map of the raft dispersal using high-resolution Sentinel-2 and -3 imagery. Two dispersal trails (red and blue dashed lines) show the daily dispersal of two parts of the raft that were separated on 17 August 2019. Courtesy of Jutzeler et al. (2020).

References: Arculus, R J, SS2004/11 shipboard scientists, 2004. SS11/2004 Voyage Summary: NoToVE-2004 (Northern Tonga Vents Expedition): submarine hydrothermal plume activity and petrology of the northern Tofua Arc, Tonga. https://www.cmar.csiro.au/data/reporting/get file.cfm?eovpub id=901.

Brandl P A, Schmid F, Augustin N, Grevemeyer I, Arculus R J, Devey C W, Petersen S, Stewart M , Kopp K, Hannington M D, 2019. The 6-8 Aug 2019 eruption of ‘Volcano F’ in the Tofua Arc, Tonga. Journal of Volcanology and Geothermal Research: https://doi.org/10.1016/j.jvolgeores.2019.106695

Jutzeler M, Marsh R, van Sebille E, Mittal T, Carey R, Fauria K, Manga M, McPhie J, 2020. Ongoing Dispersal of the 7 August 2019 Pumice Raft From the Tonga Arc in the Southwestern Pacific Ocean. AGU Geophysical Research Letters: https://doi.orh/10.1029/2019GL086768.

Geologic Background. A submarine volcano along the Tofua volcanic arc was first observed in September 2001. The newly discovered volcano lies NW of the island of Vava'u about 35 km S of Fonualei and 60 km NE of Late volcano. The site of the eruption is along a NNE-SSW-trending submarine plateau with an approximate bathymetric depth of 300 m. T-phase waves were recorded on 27-28 September 2001, and on the 27th local fishermen observed an ash-rich eruption column that rose above the sea surface. No eruptive activity was reported after the 28th, but water discoloration was documented during the following month. In early November rafts and strandings of dacitic pumice were reported along the coast of Kadavu and Viti Levu in the Fiji Islands. The depth of the summit of the submarine cone following the eruption determined to be 40 m during a 2007 survey; the crater of the 2001 eruption was breached to the E.

Information Contacts: Jan Steffen, Communication and Media, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany; Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Klyuchevskoy (Russia) — June 2020 Citation iconCite this Report

Klyuchevskoy

Russia

56.056°N, 160.642°E; summit elev. 4754 m

All times are local (unless otherwise noted)


Strombolian activity November 2019 through May 2020; lava flow down the SE flank in April

Klyuchevskoy is part of the Klyuchevskaya volcanic group in northern Kamchatka and is one of the most frequently active volcanoes of the region. Eruptions produce lava flows, ashfall, and lahars originating from summit and flank activity. This report summarizes activity during October 2019 through May 2020, and is based on reports by the Kamchatkan Volcanic Eruption Response Team (KVERT) and satellite data.

There were no activity reports from 1 to 22 October, but gas emissions were visible in satellite images. At 1020 on 24 October (2220 on 23 October UTC) KVERT noted that there was a small ash component in the ash plume from erosion of the conduit, with the plume reaching 130 km ENE. The Aviation Colour Code was raised from Green to Yellow, then to Orange the following day. An ash plume continued on the 25th to 5-7 km altitude and extending 15 km SE and 70 km SW and reached 30 km ESE on the 26th. Similar activity continued through to the end of the month.

Moderate gas emissions continued during 1-19 November, but the summit was obscured by clouds. Strong nighttime incandescence was visible at the crater during the 10-11 November and thermal anomalies were detected on 8 and 10-13 November. Explosions produced ash plumes up to 6 km altitude on the 20-21st and Strombolian activity was reported during 20-22 November. Degassing continued from 23 November through 12 December, and a thermal anomaly was visible on the days when the summit was not covered by clouds. An ash plume was reported moving to the NW on the 13th, and degassing with a thermal anomaly and intermittent Strombolian activity then resumed, continuing through to the end of December with an ash plume reported on the 30th.

Gas-and-steam plumes continued into January 2020 with incandescence noted when the summit was clear (figure 33). Strombolian activity was reported again starting on the 3rd. A weak ash plume produced on the 6th extended 55 km E, and on the 21st an ash plume reached 5-5.5 km altitude and extended 190 km NE (figure 34). Another ash plume the next day rose to the same altitude and extended 388 km NE. During 23-29 Strombolian activity continued, and Vulcanian activity produced ash plumes up to 5.5 altitude, extending to 282 km E on the 30th, and 145 km E on the 31st.

Figure (see Caption) Figure 33. Incandescence and degassing were visible at Klyuchevskoy through January 2020, seen here on the 11th. Courtesy of KVERT.
Figure (see Caption) Figure 34. A low ash plume at Klyuchevskoy on 21 January 2020 extended 190 km NE. Courtesy of KVERT.

Strombolian activity continued throughout February with occasional explosions producing ash plumes up to 5.5 km altitude, as well as gas-and-steam plumes and a persistent thermal anomaly with incandescence visible at night. Starting in late February thermal anomalies were detected much more frequently, and with higher energy output compared to the previous year (figure 35). A lava fountain was reported on 1 March with the material falling back into the summit crater. Strombolian activity continued through early March. Lava fountaining was reported again on the 8th with ejecta landing in the crater and down the flanks (figure 36). A strong persistent gas-and-steam plume containing some ash continued along with Strombolian activity through 25 March (figure 37), with Vulcanian activity noted on the 20th and 25th. Strombolian and Vulcanian activity was reported through the end of March.

Figure (see Caption) Figure 35. This MIROVA thermal energy plot for Klyuchevskoy for the year ending 29 April 2020 (log radiative power) shows intermittent thermal anomalies leading up to more sustained energy detected from February through March, then steadily increasing energy through April 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 36. Strombolian explosions at Klyuchevskoy eject incandescent ash and gas, and blocks and bombs onto the upper flanks on 8 and 10 March 2020. Courtesy of IVS FEB RAS, KVERT.
Figure (see Caption) Figure 37. Weak ash emission from the Klyuchevskoy summit crater are dispersed by wind on 19 and 29 March 2020, with ash depositing on the flanks. Courtesy of IVS FEB RAS, KVERT.

Activity was dominantly Strombolian during 1-5 April and included intermittent Vulcanian explosions from the 6th onwards, with ash plumes reaching 6 km altitude. On 18 April a lava flow began moving down the SE flank (figures 38). A report on the 26th reported explosions from lava-water interactions with avalanches from the active lava flow, which continued to move down the SE flank and into the Apakhonchich chute (figures 39 and 40). This continued throughout April and May with sustained Strombolian and intermittent Vulcanian activity at the summit (figures 41 and 42).

Figure (see Caption) Figure 38. Strombolian activity produced ash plumes and a lava flow down the SE flank of Klyuchevskoy on 18 April 2020. Courtesy of IVS FEB RAS, KVERT.
Figure (see Caption) Figure 39. A lava flow descends the SW flank of Klyuchevskoy and a gas plume is dispersed by winds on 21 April 2020. Courtesy of Yu. Demyanchuk, IVS FEB RAS, KVERT.
Figure (see Caption) Figure 40. Sentinel-2 thermal satellite images show the progression of the Klyuchevskoy lava flow from the summit crater down the SE flank from 19-29 April 2020. Associated gas plumes are dispersed in various directions. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 41. Strombolian activity at Klyuchevskoy ejects incandescent ejecta, gas, and ash above the summit on 27 April 2020. Courtesy of D. Bud'kov, IVS FEB RAS, KVERT.
Figure (see Caption) Figure 42. Sentinel-2 thermal satellite images of Klyuchevskoy show the progression of the SE flank lava flow through May 2020, with associated gas plumes being dispersed in multiple directions. Courtesy of Sentinel Hub Playground.

Geologic Background. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank 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/); 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).


Nyamuragira (DR Congo) — June 2020 Citation iconCite this Report

Nyamuragira

DR Congo

1.408°S, 29.2°E; summit elev. 3058 m

All times are local (unless otherwise noted)


Intermittent thermal anomalies within the summit crater during December 2019-May 2020

Nyamuragira (also known as Nyamulagira) is located in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo and consists of a lava lake that reappeared in the summit crater in mid-April 2018. Volcanism has been characterized by lava emissions, thermal anomalies, seismicity, and gas-and-steam emissions. This report summarizes activity during December 2019 through May 2020 using information from monthly reports by the Observatoire Volcanologique de Goma (OVG) and satellite data.

According to OVG, intermittent eruptive activity was detected in the lava lake of the central crater during December 2019 and January-April 2020, which also resulted in few seismic events. MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows thermal anomalies within the summit crater that varied in both frequency and power between August 2019 and mid-March 2020, but very few were recorded afterward through late May (figure 88). Thermal hotspots identified by MODVOLC from 15 December 2019 through March 2020 were mainly located in the active central crater, with only three hotspots just outside the SW crater rim (figure 89). Sentinel-2 thermal satellite imagery also showed activity within the summit crater during January-May 2020, but by mid-March the thermal anomaly had visibly decreased in power (figure 90).

Figure (see Caption) Figure 88. The MIROVA graph of thermal activity (log radiative power) at Nyamuragira during 27 July through May 2020 shows variably strong, intermittent thermal anomalies with a variation in power and frequency from August 2019 to mid-March 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 89. Map showing the number of MODVOLC hotspot pixels at Nyamuragira from 1 December 2019 t0 31 May 2020. 37 pixels were registered within the summit crater while 3 were detected just outside the SW crater rim. Courtesy of HIGP-MODVOLC Thermal Alerts System.
Figure (see Caption) Figure 90. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) confirmed ongoing thermal activity (bright yellow-orange) at Nyamuragira from February into April 2020. The strength of the thermal anomaly in the summit crater decreased by late March 2020, but was still visible. Courtesy of Sentinel Hub Playground.

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

Information Contacts: Information contacts: Observatoire Volcanologique de Goma (OVG), Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo; 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/exp.


Nyiragongo (DR Congo) — June 2020 Citation iconCite this Report

Nyiragongo

DR Congo

1.52°S, 29.25°E; summit elev. 3470 m

All times are local (unless otherwise noted)


Activity in the lava lake and small eruptive cone persists during December 2019-May 2020

Nyiragongo is located in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo, part of the western branch of the East African Rift System and contains a 1.2 km-wide summit crater with a lava lake that has been active since at least 1971. Volcanism has been characterized by strong and frequent thermal anomalies, incandescence, gas-and-steam emissions, and seismicity. This report summarizes activity during December 2019 through May 2020 using information from monthly reports by the Observatoire Volcanologique de Goma (OVG) and satellite data.

In the December 2019 monthly report, OVG stated that the level of the lava lake had increased. This level of the lava lake was maintained for the duration of the reporting period, according to later OVG monthly reports. Seismicity increased starting in November 2019 and was detected in the NE part of the crater, but it decreased by mid-April 2020. SO2 emissions increased in January 2020 to roughly 7,000 tons/day but decreased again near the end of the month. OVG reported that SO2 emissions rose again in February to roughly 8,500 tons/day before declining to about 6,000 tons/day. Unlike in the previous report (BGVN 44:12), incandescence was visible during the day in the active lava lake and activity at the small eruptive cone within the 1.2-km-wide summit crater has since increased, consisting of incandescence and some lava fountaining (figure 72). A field survey was conducted on 3-4 March where an OVG team observed active lava fountains and ejecta that produced Pele’s hair from the small eruptive cone (figure 73). During this survey, OVG reported that the level of the lava lake had reached the second terrace, which was formed on 17 January 2002 and represents remnants of the lava lake at different eruption stages. There, the open surface lava lake was observed; gas-and-steam emissions accompanied both the active lava lake and the small eruptive cone (figures 72 and 73).

Figure (see Caption) Figure 72. Webcam image of Nyiragongo in February 2020 showing an open lava lake surface and incandescence from the active crater cone within the 1.2 km-wide summit crater visible during the day, accompanied by white gas-and-steam emissions. Courtesy of OVG (Rapport OVG February 2020).
Figure (see Caption) Figure 73. Webcam image of Nyiragongo on 4 March 2020 showing an open lava lake surface and incandescence from the active crater cone within the 1.2 km-wide summit crater visible during the day, accompanied by white gas-and-steam emissions. Courtesy of OVG (Rapport OVG Mars 2020).

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data continued to show frequent strong thermal anomalies within 5 km of the summit crater through May 2020 (figure 74). Similarly, the MODVOLC algorithm reported multiple thermal hotspots almost daily within the summit crater between December 2019 and May 2020. These thermal signatures were also observed in Sentinel-2 thermal satellite imagery within the summit crater (figure 75).

Figure (see Caption) Figure 74. Thermal anomalies at Nyiragongo from 27 July through May 2020 as recorded by the MIROVA system (Log Radiative Power) were frequent and strong. Courtesy of MIROVA.
Figure (see Caption) Figure 75. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) showed ongoing thermal activity (bright yellow-orange) in the summit crater at Nyiragongo during January through April 2020. Courtesy of Sentinel Hub Playground.

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

Information Contacts: Observatoire Volcanologique de Goma (OVG), Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo; 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).


Kavachi (Solomon Islands) — May 2020 Citation iconCite this Report

Kavachi

Solomon Islands

8.991°S, 157.979°E; summit elev. -20 m

All times are local (unless otherwise noted)


Discolored water plumes seen using satellite imagery in 2018 and 2020

Kavachi is a submarine volcano located in the Solomon Islands south of Gatokae and Vangunu islands. Volcanism is frequently active, but rarely observed. The most recent eruptions took place during 2014, which consisted of an ash eruption, and during 2016, which included phreatomagmatic explosions (BGVN 42:03). This reporting period covers December 2016-April 2020 primarily using satellite data.

Activity at Kavachi is often only observed through satellite images, and frequently consists of discolored submarine plumes for which the cause is uncertain. On 1 January 2018 a slight yellow discoloration in the water is seen extending to the E from a specific point (figure 20). Similar faint plumes were observed on 16 January, 25 February, 2 March, 26 April, 6 May, and 25 June 2018. No similar water discoloration was noted during 2019, though clouds may have obscured views.

Figure (see Caption) Figure 20. Satellite images from Sentinel-2 revealed intermittent faint water discoloration (yellow) at Kavachi during the first half of 2018, as seen here on 1 January (top left), 25 February (top right), 26 April (bottom left), and 25 June (bottom right). Images with “Natural color” rendering (bands 4, 3, 2); courtesy of Sentinel Hub Playground.

Activity resumed in 2020, showing more discolored water in satellite imagery. The first instance occurred on 16 March, where a distinct plume extended from a specific point to the SE. On 25 April a satellite image showed a larger discolored plume in the water that spread over about 30 km2, encompassing the area around Kavachi (figure 21). Another image on 30 April showed a thin ribbon of discolored water extending about 50 km W of the vent.

Figure (see Caption) Figure 21. Sentinel-2 satellite images of a discolored plume (yellow) at Kavachi beginning on 16 March (top left) with a significant large plume on 25 April (right), which remained until 30 April (bottom left). Images with “Natural color” rendering (bands 4, 3, 2); courtesy of Sentinel Hub Playground.

Geologic Background. Named for a sea-god of the Gatokae and Vangunu peoples, Kavachi is one of the most active submarine volcanoes in the SW Pacific, located in the Solomon Islands south of Vangunu Island. Sometimes referred to as Rejo te Kvachi ("Kavachi's Oven"), this shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 1 km long many times since its first recorded eruption during 1939. Residents of the nearby islands of Vanguna and Nggatokae (Gatokae) reported "fire on the water" prior to 1939, a possible reference to earlier eruptions. The roughly conical edifice rises from water depths of 1.1-1.2 km on the north and greater depths to the SE. Frequent shallow submarine and occasional subaerial eruptions produce phreatomagmatic explosions that eject steam, ash, and incandescent bombs. On a number of occasions lava flows were observed on the ephemeral islands.

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


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. 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).

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Bulletin of the Global Volcanism Network - Volume 37, Number 03 (March 2012)

Managing Editor: Richard Wunderman

Akutan (United States)

Steaming, seismically active

False Reports (Unknown)

Pakistan: Peculiar activity emitted less than 5 m3 of frothy basalt

Fournaise, Piton de la (France)

Increased seismicity and eruption during late 2010

Hierro (Spain)

Update on submarine eruption

Kelut (Indonesia)

Amid quiet, a look back at aspects of the 2007 eruption

Long Valley (United States)

2009 summary, deep seismic swarm at Mammoth Mountain

Maderas (Nicaragua)

Destructive 2005 seismicity; youngest deposits dated 70.4 ± 6.1 ka B.P

Puyehue-Cordon Caulle (Chile)

June 2011 eruption emits circum-global ash clouds

Reventador (Ecuador)

Dome growth; lava and pyroclastic flows; lahar takes bridge



Akutan (United States) — March 2012 Citation iconCite this Report

Akutan

United States

54.134°N, 165.986°W; summit elev. 1303 m

All times are local (unless otherwise noted)


Steaming, seismically active

We report Akutan non-eruptive seismic activity after our mid-1996 report (BGVN 21:06) through December 2010. AVO (Alaska Volcano Observatory) reporting emphasized seismicity in 2000, 2007, 2008, 2009, and 2010, including seismicity during 2007 triggered by an M 8.2 earthquake in the Kurile islands.

Background. Akutan Island is home to indigenous people located in several coastal villages, and the base of a large fish processing facility. The island resides in the Aleutian arc, a string of islands projecting ~2,000 km into the Bering Sea from the Alaskan Peninsula (figure 2).

Figure (see Caption) Figure 2. Akutan, an island ~32 km by ~20 km, lies on the E Aleutian arc in the Bering Sea near the coast of Alaska. Courtesy of Neal and McGimsey (1996), revised by GVP.

Akutan Island (figure 3) has a vegetated coast line dotted with spectacular bridges and caves created by the erosion of numerous lava tubes. Waythomas and others (1998) presented a map showing that much of the coastline is susceptible to rockfall avalanches and points out that these may trigger local tsunamis. The authors also analyzed the likely path of lava flows.

Figure (see Caption) Figure 3. Akutan Island and its volcanic features, including fumaroles, hot springs, and a new steaming area. A cindercone resides in the NE quadrant of the generally circular caldera. The fumarole field, shown in red, is down slope on the E flank of the summit. The Trident seafood plant, shown as a yellow star, lays along the E coast. Courtesy of AVO, revised by GVP.

A 2 km diameter caldera atop the 1,303 m high volcano is breached to the NW, and elsewhere encircled by crater walls 60 to 365 m high. The caldera contains a ~200 m high cinder cone, and a small lake. Fumeroles lay along the summit flank toward the E (Miller and others, 1998). The cinder cone has been the site of all historical eruptive activity (Richter and others, 1998; Waythomas and others, 1998).

The village of Akatan ( figure 4), ~ 13 km E of the volcano, hosts the Trident seafood plant, the largest such plant in North America, employing up to 900 seasonal workers (McGimsey, 2011). Akutan villagers and seafood plant employees fled the island during the 1996 seismic events (Li and others, 2000). The cited references provide many details omitted here.

Figure (see Caption) Figure 4. Akutan coastal image with seafood plant in foreground adjacent to Akutan village. Image courtesy of AVO, created by Helena Buurman.

According to Diefenbach and others (2009), Akutan has been the most active of the volcanoes monitored by AVO, having over 20 eruptions since 1790; more than any other Alaskan volcano.

A 2009 report by AVO noted that 11 eruptions occurred at Akutan during 1980-1992, many lasting several months (table 5). The most recent eruption started in December 2009 but the eruption's end was not clearly constrained (table 5). A seismic swarm took place in 1996, an episode without a corresponding eruption.

Table 5. Akutan eruptions tabulated from January 1980 to 2009. Courtesy of Diefenbach and others (2009).

Start Date End Date VEI
08 Jul 1980 08 Jul 1980 2
07 Oct 1982 May 1983 2
03 Feb 1986 14 Jun 1986 2
31 Jan 1987 24 Jun 1987 2
26 Mar 1988 20 Jul 1988 2
27 Feb 1989 31 Mar 1989 2
22 Jan 1990 22 Jan 1990 2
06 Sep 1990 01 Oct 1990 2
15 Sep 1991 28 Nov 1991 2
08 Mar 1992 31 May 1992 2
18 Dec 1992 -- 1

From 1980 to 2009, Alaskan eruptions made up to 77% of the total reported in the United States (Diefenbach and others, 2009). Note that, even though during 1980-2009 Akutan erupted more times than other US volcanoes, this distinction is only one of many that can be used for comparisons. For example, in the course of that interval and the 11 recorded eruptions at Akutan, it clearly emitted less material and the eruptive intervals spanned much less time than eruptions at either Kilauea or Mt. St. Helens.

1996 seismicity. In March 1996, two strong earthquake swarms struck the island, causing minor damage and prompting some residents and dozens of plant employees to leave the island. The seismicity, reported in BGVN 21:06, was probably the result of a magmatic intrusion (Lu and others, 2000). They stated the following:

"In March 1996 an intense swarm of volcano-tectonic earthquakes (~3,000 felt by local residents, M max = 5.1, cumulative moment of 2.7 × 1018 N m) beneath Akutan Island in the Aleutian volcanic arc, Alaska, produced extensive ground cracks but no eruption of Akutan volcano. Synthetic aperture radar interferograms that span the time of the swarm reveal complex island-wide deformation: the western part of the island including Akutan volcano moved upward, while the eastern part moved downward. The axis of the deformation approximately aligns with new ground cracks on the western part of the island and with Holocene normal faults that were reactivated during the swarm on the eastern part of the island. The axis is also roughly parallel to the direction of greatest compressional stress in the region. No ground movements greater than 2.83 cm were observed outside the volcano's summit caldera for periods of 4 years before or 2 years after the swarm. We modeled the deformation primarily as the emplacement of a shallow, E-W trending, north dipping dike plus inflation of a deep, Mogi-type [spherical] magma body beneath the volcano. The pattern of subsidence on the eastern part of the island is poorly constrained. It might have been produced by extensional tectonic strain that both reactivated preexisting faults on the eastern part of the island and facilitated magma movement beneath the western part. Alternatively, magma intrusion beneath the volcano might have been the cause of extension and subsidence in the eastern part of the island."

The 11 March 1996 swarm involved more than 80 earthquakes of M 3.0 or greater with the largest measuring M 5.2. The 13 March swarm involved more than 120 events of M 3.0 or greater with the largest measuring M 5.3 (Waythomas and others, 1998).

As a result, new ground cracks developed ( figure 5) and Waythomas and others (1998) described them as follows: "Numerous fresh, linear ground cracks were discovered in three areas on Akutan Island during field studies in the summer of 1996. Ground breaks and cracks likely formed during the strong seismic swarms in March. The ground cracks extend discontinuously from the NE side of the island near Lava Point to the island's SE side [figure 5].

"The most extensive ground cracks are between Lava Point and the volcano summit [ figure 6]. In this area, the cracks are confined to a zone 300 to 500 m wide and 3 km long. Vertical displacement of the ground surface along individual cracks is 30 to 80 cm. The ground cracks probably formed as magma moved toward the surface between the two most recently active vents on the volcano. Ground cracks on the SE side of the island occur on known faults, indicating that they probably formed in response to motion along these preexisting structures. No ground cracks were found at the head of Akutan Harbor even though this was an area where numerous earthquakes occurred from March through July, 1996."

Figure (see Caption) Figure 5. Location of ground cracks and seismometers on Akutan, as published in 1998. Three sets of ground cracks, shown as black lines, presumably formed during the March 1996 earthquake swarm. The most extensive breaks occurred on the NW flank of the volcano near Lava Point with the other two shorter sets to the SE in line with the first. On the map, the green triangles locate seven monitoring stations, one at the summit, and others spread throughout the island as well as one at the village. Courtesy of AVO, Waythomas and others (1998), annotated by GVP.
Figure (see Caption) Figure 6. Ground breaks like this were found at Akutan in a zone about 300-500 m wide and ~ 3,000 m long on the NW flank of the volcano. Surface deposits offset by the cracks consist of course tephra and colluvium. The backpack in the lower left delineates scale (distant figures removed for clarity). Courtesy of AVO, Waythomas and others (1998).

A permanent seismic network was installed during the summer of 1996 which currently consists of seven short-period stations and five broadband stations (figure 5).

Akutan seismicity, 2000 to 2010. According to AVO annual reports covering the interval 1997-2011, noteworthy seismicity occurred during the years 2000, 2007, 2008, 2009, and 2010.

On 19 January 2000, five earthquakes occurred in less than 30 minutes with epicenters 10-11 km E of the summit at hypocentral depths of ~5-6 km. This was the same region as the March 1996 volcanic swarm.

Akutan was one of several Alaska volcanoes with behavioral anomalies triggered by the M 8.2 earthquake generated in the Kurile Islands on 12 January 2007 at 0423 UTC (McGimsey, 2011). Seismologists located four of the seven largest triggered M 0.0-0.5 earthquakes at Akutan and found their depths in the range from +0.86 to -2.17 km (figure 7). The locations fell along the trend of intense seismicity and ground breakage that occurred in March 1996 at Akutan (Neal and others, 1997; Waythomas and others, 1998; Lu and others, 2005). The AVO Akutan seismic network recorded the triggered seismicity.

Figure (see Caption) Figure 7. Epicenters at Akutan triggered by the 13 January 2007, M 8.2 Kurile Islands earthquake (the event occurred at 0423 UTC, 12 January 2007). The four largest events (red dots) lie along the same trend (blue line) as that of intense seismicity with accompanied ground breakage that occurred during dike intrusion in March 1996 (Waythomas and others, 1998). Open triangles mark locations of seismic stations. Plot of earthquake locations by John Power. Courtesy of AVO, McGimsey and others (2011).

In early October 2007, AVO remote sensors detected signs of renewed inflation of the W flank during the previous month using GPS time series. This inflation was in the same area that inflated during the 1996 seismic crisis. A few days later, on 8 October 2007, the manager of the Trident seafood processing plant called to alert AVO of strong steaming near Hot Springs Bay (figure 8) at a spot significantly up slope from established hot springs in the valley. This plume location was considered "new" by local observers. The established lower-valley thermal springs rarely emit a concentrated, vertically rising steam plume and most earlier reports of steaming arose from the prominent fumarole field located at the 460 m elevation of the E flank at the headwaters of Hot Springs Bay valley. This is also the area of maximum deflation following the 1996 seismic swarms. No unusual seismic activity was noted for the period of W-flank inflation or the location of this steaming episode (McGimsey and others, 2011).

Figure (see Caption) Figure 8. Midway up Akutan's Hot Springs Bay valley on the E flank of Akutan from a point well upslope of the previously active hot springs area, a steam column rises from a new site. AVO photo taken 8 October 2007 by David Abbasian.

In 2008, over 100 seismic events were recorded. During the next two years, Akutan seismic events decreased to about half that number. During 2010 low frequency earthquakes doubled compared to 2009 (Table 6).

Table 6. Akutan seismic activity for 2008-2010 compiled from AVO/USGS annual reports. Total earthquakes (in the second column) summed those in the Volcano-tectonic and Low frequency columns. '--' indicates data not reported. Courtesy of AVO.

Year Total earthquakes Volcano-tectonic Low-frequency
2008 105 -- --
2009 45 41 4
2010 42 34 8

According to AVO, Akutan seismic events during the years 2009 and 2010 were temporally spread roughly throughout the months except for a tight cluster of M 2 earthquakes reported at depths of between ~5 km to ~10 km during the first weeks of January 2010. The majority of earthquakes in 2010 were located within ~5 km of the crater along a N-trending line spanning 10 km. In 2009 the spread was longer, over 20 km.

References. Diefenbach, A.K., Guffanti, M., and Ewert, J.W., 2009, Chronology and references of volcanic eruptions and selected unrest in the United States, 1980-2008: U.S. Geological Survey Open-File Report 2009-1118, 85 p. [http://pubs.usgs.gov/of/2009/1118/].

Dixon, J.P., Stihler, S.D., Power, J.A., and Searcy, C.K., 2010, Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2009: U.S. Geological Survey Data Series 531.

Dixon, J.P., Stihler, S.D., Power, J.A., and Searcy, C.K., 2011, Catalog of earthquake hypocenters at Alaskan Volcanoes: January 1 through December 31, 2010: U.S. Geological Survey Data Series 645.

Kent, T., 2011, Hydrothermal Alteration of Open Fractures in Prospective Geothermal Drill Cores, Akutan Island, Alaska, Fall Meeting of the American Geophysical Union, 2011, Abstract ##V13D-2637.

Lu, Z., Wicks Jr., C., Power, J.A., and Dzurisin, D., 2000, Ground deformation associated with the March 1996 earthquake swarm at Akutan volcano, Alaska, revealed by satellite radar interferometry, J. Geophys. Res., 105(B9), 21,483-21,495 (DOI:10.1029/2000JB900200).

Miller, T.P., McGimsey, R.G., Richter, D.H., Riehle, J.R., Nye, C.J., Yount, M.E., and Dumoulin, J.A., 1998, Catalog of the historically active volcanoes of Alaska: U.S. Geological Survey Open-File Report 98-582, 104 p. (Also available at http://www.avo.alaska.edu/downloads/catalog.php.)

McGimsey, R.G., Neal, C.A., Dixon, J.P., Malik, Nataliya, and Chibisova, M., 2011, 2007 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2010-5242, 110 p.

Neal, C.A. and McGimsey, R.G., 1997, 1996 Volcanic Activity In Alaska And Kamchatka: Summary Of Events And Response Of The Alaska Volcano Observatory: U.S. Geological Survey Open-File Report 97-433.

Richter, D.H., Waythomas, C.F., McGimsey, R.G., and Stelling, P.L., 1998, Geologic map of Akutan Island, Alaska: U.S. Geological Survey Open-File Report 98-135, 22 p., 1 plate.

Waythomas, C.F., Power, J.A., Richter, D.H., and McGimsey, R.G., 1998, Preliminary volcano-hazard assessment for Akutan Volcano east-central Aleutian Islands, Alaska: U.S. Geological Survey Open-File Report 98-0360, 36 p., 1 plate.

Geologic Background. One of the most active volcanoes of the Aleutian arc, Akutan contains 2-km-wide caldera with an active intracaldera cone. An older, largely buried caldera was formed during the late Pleistocene or early Holocene. Two volcanic centers are located on the NW flank. Lava Peak is of Pleistocene age, and a cinder cone lower on the flank produced a lava flow in 1852 that extended the shoreline of the island and forms Lava Point. The 60-365 m deep younger caldera was formed during a major explosive eruption about 1600 years ago and contains at least three lakes. The currently active large cinder cone in the NE part of the caldera has been the source of frequent explosive eruptions with occasional lava effusion that blankets the caldera floor. A lava flow in 1978 traveled through a narrow breach in the north caldera rim almost to the coast. Fumaroles occur at the base of the caldera cinder cone, and hot springs are located NE of the caldera at the head of Hot Springs Bay valley and along the shores of Hot Springs Bay.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA, b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys.


False Reports (Unknown) — March 2012 Citation iconCite this Report

False Reports

Unknown

Unknown, Unknown; summit elev. m

All times are local (unless otherwise noted)


Pakistan: Peculiar activity emitted less than 5 m3 of frothy basalt

According to a report by Rana and Akhtar (2010) of the Geological Survey of Pakistan (GSP), an M 3.9 earthquake with a focal depth of 60 km occurred on 27 January 2010. It was accompanied by "spewing of molten material, burning of rock fragments, emission of steam, sparks and fumes in Sari (Charri) near Wam (Waam) in Ziarat Valley . . .. The molten material expelled from a small scoria cone and four smaller fissures in Tor Zawar mountain." The village of Wam was devastated on 29 October 2008 when a severe earthquake (M 6.2, focal depth 10 km) hit the city of Ziarat (~28 km ESE from Wam). [Note - Throughout this report we have tried to use the spelling of geographic and geologic features as found in the GSP report, with alternative spellings found in other referenced reports placed in parentheses.]

The frothy basalt emitted at Tor Zawar occurred at a spot located hundreds of kilometers from the nearest known Holocene volcanism. The news and various discussions of the site incorrectly attributed the eruption to activity at a mud volcano, a process common in the region. This may be the smallest volume eruption ever documented at a new locality.

Figure 1 shows a geological sketch map of the area of Balochistan Province, Pakistan, where the eruption occurred. The news of volcanic activity was surprising because volcanism has seemingly been absent here for at least the last 10,000 years. The closest identified Holocene volcanoes occur ~400 km N in Afghanistan (Vakak Group and Dacht-Navar Group) and ~800 km W in Iran (Taftan, Bazman, and unnamed volcanoes; figure 2).

Figure (see Caption) Figure 1. Geological sketch map showing the location of the eruption site at Tor Zawar, Pakistan, on 27 January 2010. The site is in the Sari (alternatively Jhari, Charri, or Cherri) area of the Ziarat District of Balochistan Province ~10.6 km N of the village of Wam (Waam). The event took place ~55 km NW of Quetta, Pakistan (~70 km E of the border with Afghanistan) and ~8.1 km E of the town of Gogai. The geological formations on the map are keyed to the stratigraphic section on the right-hand side of the figure. From Kerr, Khan, and McDonald (2010), modified from Khan, Kassi, and Khan (2000).
Figure (see Caption) Figure 2. Map of the Pakistan-Afghanistan-Iran region showing the relative locations of known Holocene volcanoes with respect to the Tor Zawar event. Of those Holocene volcanoes shown, only Taftan volcano in Iran has possible historically recorded eruptions, which occurred in 1902 and 1993. Locations from Siebert and others (2010); map produced by S. Purcell (GVP).

News reports from several sources (e.g., The Nation, 3 February 2010; Balochistan Times, 23 February 2010 and 7 March 2010; Ary News, 2 February 2010) noted that residents in nearby areas observed flames at the mountain top for several nights and, on 1 February 2010, the volcano began erupting lava. Explosions followed by smoke emissions were observed. District Coordinator Officer Siddiq Mandokhel confirmed that lava spewed from the volcano. The newspaper Pak Tribune reported on 3 February 2010 that Mandokhel said "he had personally surveyed the site of occurrence, and said that emittance of chemical gases had begun last night, after which it spewed out a molten lava, the size of a meter".

At least two small groups of earth scientists visited the site within 3 to 5 days after the reported 'eruption' event. The field observations by scientists from the GSP were reported in a GSP Information Release (Rana and Akhtar, 2010). Khadim Durrani (2010) issued on his web site an illustrated interview conducted with Din Mohammed Kakar. The two reports mentioned above contain occasional discrepancies within and between the reports, and both include unlabeled figures. During the periods of field observations, no fresh extrusion of volcanic material or sparks was observed. However, heat was still being emitted.

Table 1 contains a brief summary of possible causes and/or production-mechanisms for the molten material that have been suggested by various sources. Additional details are found in sections below.

Table 1. Various explanations for a molten material source and proposed mechanism of erupted surface deposit at Tor Zawar. See original papers for more details.

Proposed source or mechanism Comments
Melting of existing Bibai volcanics caused by resistive heating due to local power line, lightning, or some combination of surface sources. Mentioned but dismissed by Rana and Akhtar (2010); 'unsupported' according to Kerr and others (2010; Kakar, in Durrani (2010).
Frictionally derived melting along thrust fault. Rana and Akhtar (2010).
Methane gas leakage and flaring with local heating/melting of existing Bibai volcanics. Bilham (personal communication).
Rupture on Gogai Wam fault during 2008 earthquake created chambers from which molten materials rose and eventually erupted through channels in the weak zone. Rana and Akhtar (2010).
Melting from heating of lithosphere either by conduction from below or by advection from an intruding magma. "It is more likely that a small amount of asthenospheric-derived melt has invaded the lower lithosphere," concluded Kerr and others (2010).
60-80 km deep magma ascended to the surface along Bibai and Gogai thrust faults. "Eruption represents a geological event of deep origin," according to Kerr and others (2010).

Field observations by GSP. Two GSP geoscientists, Asif Nazeer Rana and Sardar Saeed Akhtar, visited the site of the molten material (figure 3) on 2 February 2010 and summarized their observations in a GSP report (Rana and Akhtar, 2010). The following information came from that report. Note that most of the figures reproduced below from the GSP report lacked captions.

Figure (see Caption) Figure 3. Photo of the study site (a) and deposit of solidified molten material (b). The circled area in 'a' shows the location of the molten material deposit. The surrounding dark colored rocks are part of the Cretaceous Bibai Volcanics. The village of Wam (Waam) is visible in the upper part of the picture. Note in figure 'b' the shadow of nearby overhead power lines. Photo 'a' by Din Mohammed Kakar in Durrani (2010); photo 'b' courtesy of Rana and Akhtar (2010).

The investigators were told on 2 February 2010 by locals that emission of black, molten material started along with tremors on the night of 27 January 2010. The locals observed that steam was continuously emitted from six fissures, and rock fragments were too hot to handle with bare hands. The erupted molten material (looking like lava, scoria and volcanic glass) was found to be cold and solidified on the surface (figures 4 and 5), but was still hot in the subsurface. Heat was still rising from the site during the 3 days of observation.

Figure (see Caption) Figure 4. (a) Photo of the ejecta cone seen at the surface in the field. Scale provided by red-handled marker pen. Courtesy of Rana and Akhtar (2010). (b) Photo of the ejecta cone removed from the field; some breaking and/or displacement of parts of the cone is apparent. Coin shown was of unknown diameter. Photo courtesy of Kakar, in Durrani (2010).
Figure (see Caption) Figure 5. Two photos showing the eruption site and the in situ chilled molten material; geological hammers for scale. Courtesy of Rana and Akhtar (2010).

The molten material flow solidified in concentric layers on reaching the surface (figure 4). The flow structure was ~15 m2 in area and 15 to 60 cm thick. By 2 February, most of the material had been removed as souvenirs by the locals. Rana and Akhtar (2010) reported that the dimension of the lava structure was "1.9 m x 8.2 m in length and 15 cm to 0.6 m thick." The material remaining on the surface after pilferage "was 2.9 m long and 1.5 m wide," covering a area of ~4.3 m2. The ejecta cone was formed from the molten material; the vent pipe of the cone was 0.9 m deep below the surface, but upon excavation it was observed that the cone widened and became inclined below the surface (figure 6).

Figure (see Caption) Figure 6. Photo of the volcanic pipe from which the ejecta cone in figure 4 was extracted; geological hammer shown for scale. Courtesy of Rana and Akhtar (2010).

The ejected molten material and ejecta cone were excavated. A ditch was dug along the fissures to find the opening of the vent. The solidified sheet of this molten material was removed from the surface after documentation, measurement, and photography. Samples of various volcanic materials, including volcanic glass, scoria, pumice, and lava, were collected for lab analyses and petrographic studies. The newly erupted material at the surface was removed, and the complete structure of the ejecta cone was preserved and packed for display in the GSP Museum of Earth Sciences (figure 7). Deeper areas were excavated, a pipe-shaped feature was discovered at a depth of 1 m, leading down to a cone-shaped vent.

Figure (see Caption) Figure 7. Lava excavated from vent on display at the GSP Museum of Earth Sciences. On the right is Imran Khan, Director General of GSP; on the left front in green sweater is Imtiaz Kazi, Federal Secretary, Ministry of Petroleum and Natural Resources. From GSP 2010-2011 Annual Report.

The cone-shaped vent was fused shut by the solidification of the material in the orifice. Under the ejecta cone, a pipe of 1 m length and 5 cm diameter led vertically down to a funnel-shaped structure (i.e., wider at the top). The ejecta cone was found to be hollow on breaking the pipe and edifice; the structure looked like an oven, with a shiny, black, fine coating on the walls all around. The cone was underlain by two chambers oriented in the NW-SE direction; dimensions of these chambers were not disclosed.

The temperature of the chamber walls was still burning hot, and when dry bushes were put on the mouth of these chambers, they caught fire. The team did not carry a device for measuring soil temperature and steam from the chambers. The smaller, deeper chamber, ~4.75 m from the main chamber, led SE towards an electric power line pole. The temperature of the smaller chamber was seemingly higher than that of the main chamber. The walls of the chambers were still too hot to touch even 10 days after the lava eruption.

Two rock samples, one described as glassy and one as spongy, collected from the Tor Zawar formerly molten material were analyzed chemically at the GSP Geoscience Advance Research Laboratories for major and trace elements chemistry. Analysis revealed sample compositions of silica (SiO2) of 48.02 and 48.27 wt % and total Na2O+K2O of 5.18 and 5.23 wt. %. The two samples were classified as alkaline basalt (based on classification of Cox, Bell, and Pankhurst, 1979).

The depth of the 27 January 2010 M 3.9 earthquake was reported by the Pakistan Meteorological Department to be 60 km. The investigators found this depth to be quite unusual, as a majority of the tremors in this region have had their origin at shallow depths, generally 10-12 km. It was inferred from the previous seismotectonic investigations of 29 October 2009 earthquake (Rana, Sardar, and Qadir, 2008) that earthquake intensities and the alignment and location of most of their epicenters in this area indicated that a blind fault might be running between Gogai and Wam, passing in close proximity to this erution. There is a strong possibility that the present eruption might have occurred close to the fault plane. This blind fault, the Gogai-Wam fault, is suspected to run for nearly 40 km NW-SE, but no trace of any surface rupture was recorded either in the previous study or in the present study.

Visit and assessment by Din Mohammad Kakar. Khadim Durrani interviewed Din Muhammad Kakar, a sedimentary geologist from the University of Balochistan, about his visit and impressions of the site (Durrani, 2010). Kakar noted that a new, small volcano began spewing lava on 29 January 2010 in Pakistan (rather than the 27 January start date reported in the GSP report above). He visited the site on "day 5 after the start of the volcanic activity" (from this, one might infer that his observations were made on 3 February). Kakar observed little molten material other than two "volcanic vents," 2-3 m apart, and the 2-m-deep pit that was dug out by the GSP (figures 8 and 9). He discovered that the GSP and the Frontier Corps (figure 10) had earlier removed parts of the newly erupted cone and the remaining debris. Kakar noted that the heat of the presumed volcanic activity could still be felt in the openings.

Figure (see Caption) Figure 8. Photo of the two volcanic vents (pits/holes/chambers) and scattered pumice fragments. Note the presence of electrical cables and the foot of a power pole, with grounding wire and stake. Photo by Din Mohammed Kakar; courtesy of Durrani (2010).
Figure (see Caption) Figure 9. A close-up view of one of the vents with grounding wire and ground in figure 8. Photo by Din Mohammed Kakar; courtesy of Durrani (2010).
Figure (see Caption) Figure 10. Photo of Pakistan Frontier Corps soldier taking away a large piece of the solidified molten material. Photo published 3 February by European Press Agency; courtesy of Durrani (2010).

According to an Email note from Kakar to Bulletin editors, the chemistry indicates the same alkali basaltic lava as is found in the Bibai volcanics. Kakar noted that the eruption took place within the Late Cretaceous Bibai formation volcanics (see figure 1) (Kahn, 1998). Other exposed rocks in the area include the Parh group (Cretaceous), Dungan formation (Paleocene), and the Ghazij formation (Eocene). In the Kach-Ziarat area, the Bibai formation is sandwiched between Dungan limestone (above) and the Parh formation (below).

Eye witnesses said that there were flames coming out from the vent, possibly the result of ignited natural gas. In discussion with Bulletin editors, Roger Bilham of the University of Colorado offered the possible explanation that the eruption may have represented the remelting of pre-existing rocks of Bibai Volcanics due to ignition and combustion of natural gas.

Kakar said that the regional tectonics and the volcano's origin were not clear. However, the volcano was not a mud volcano, common in Pakistan. There is the possibility of a partial melting at shallow depth due to recent earthquake activities. He recalled the area had been hit by thousands of aftershocks since October 2008. He noted that his research had found a rupture in the basement rock below the 15-km sedimentary cover, and suggested that reactivation of the Bibai thrust might have been responsible for the recent volcanic activity. According to Kakar, the area is sparsely populated and the eruption caused no damage except for cables and poles associated with a tube well used for agricultural purposes.

Petrographic analyses.Two rock samples were sent by the GSP to Cardiff University and analyzed by Kerr and others (2010). The samples showed two petrographically distinct basalt types (figure 11). One type (sample P2) consisted of completely fresh, light brown glass with a few (

Figure (see Caption) Figure 11. Photographs of the 2010 Tor Zawar samples analyzed by Kerr and others (2010). (a) devitrified sample (P1); and (b) glassy sample (P2). Courtesy of Kerr and others (2010).

According to Kerr and others (2010), these two rock types "also have slightly different geochemical signatures that can be partially explained by crustal assimilation. Re-melting of local basaltic rocks by short circuiting of a ruptured high-tension electrical cable is considered unlikely. Mantle melt modeling suggests that the lavas have been largely derived from a source in the garnet-spinel transition zone, i.e. well within the lithosphere [i.e., melt from a depth of 60-80 km]. It is proposed that localized asthenospheric melting resulted in relatively depleted melts which were substantially contaminated by [a] fusible lithospheric mantle en route to the surface. Further small-scale eruptions cannot be ruled out."

Recent geophysical research. In the last week of March 2010, the GSP conducted a geophysical survey in the region of the Tor Zawar vent site (Saeed, Rehman, and Abbas, 2011). According to the report, "The syntheses of the magnetic, resistivity soundings and profiling and ground penetration radar (GPR) survey indicate the presence of highly magnetic dual lobe sources, resistive and prominent reflectors from the radar soundings in and around the vent site. The resistivity pseudo sections delineate the lateral and vertical molten flows which have apparently solidified at shallow depth."

The report concluded that "the radar imaging explicitly shows folding of the overlying fine grained clastics", and that they also saw "fracturing in the compact, hard and brittle rock units of compact gravels/limestone and volcanics due to the pressure exerted by the intrusion."

The presence of older volcanic rocks in the area made it difficult to separate older volcanic rocks and structures from the present eruption activity. The geophysical survey was unable to resolve the source or sources of the molten material that erupted as basalt.

References. Cox, K.G., Bell, J.D., and Pankhurst, R.J., 1979, The interpretation of igneous rocks, George Allen and Unwin, Boston, 450 pp.

Durrani, K., 2010, Ziarat's volcanic coughing - an interview with Din Mohammed Kakar, published by admin, March 2, 2010 in Environment, Geology of Pakistan and Natural Disasters, URL: www.khadimsquetta.com/?p=640. (Note that many of the photos in this website item are not described or labeled.)

Geological Survey of Pakistan (GSP), 2011, GSP Year Book 2010-2011, on GSP web site: http://www.gsp.gov.pk.

Kakar, D.M., Szeliga, W., and Bilham, R., 2010, Seismic Potential of the Pishin/Mach Shear Zone in Northern Baluchistan, Pakistan, Seismological Research Letters, v. 81, no. 2, pp. 324.

Khan, A.T., 1998, Sedimentology and petrology of the volcaniclastic rocks of the Bibai Formation, Ziarat District, Balochistan, Pakiston, Thesis, University of Balochistan, Quetta, 179p.

Khan, A.T., Kassi, M.T. and Khan, A.S., 2000, The Upper Cretaceous Bibai submarine Fan (Bibai Formation), Kach Ziatrat Valley, western Suleiman Thrust-Fold Belt, Pakistan, Acta Mineralogica Pakistanica, v. 11, pp. 1-24.

Kerr, A.C., Khan, M., and McDonald, I., 2010, Eruption of basaltic magma at Tor Zawar, Balochistan, Pakistan on 27 January 2010: geochemical and petrological constraints on petrogenesis, Mineralogical Magazine, v. 74, no. 6, pp. 1027-1036.

MonaLisa, and Jan, M.Q., 2010 (10 January), Geoseismological study of the Ziarat (Balochistan) earthquake (doublet?) Of 28 October 2008, Current Science, v. 98, no. 1, p. 50-57.

Rana, A.N., Sardar, S.A., and Qadir, G.T., 2008, Seismotectonic investigations of October 29, 2008 earthquake of Gogai Ziarat, Balochistan, Information Release No. 874, Geological Survey of Pakistan, Islamabad.

Rana, A.N., and Akhtar, S.S., 2010, Preliminary Report on Eruption of Molten Material in Tor Zawar Mountain, Sari, Ziarat, Balochistan on January 27, 2010, Information Release No. 891, Geological Survey of Pakistan, Islamabad, 24 pp. (Summarized in GSP News. V. 17, no. 1-12, p. 12.) (Note that many of the photos in this website item are not described or labeled.)

Saeed, M., Rehman, M., and Abbas, S.A., 2011, Integrated geophysical modeling of volcanic eruption at Tor Zawar, Ziarat, Balochistan, Information Release No. 920, Geological Survey of Pakistan, Islamabad, 79 pp.

Siebert, L., Simkin, T., and Kimberly, P., 2010, Volcanoes of the World, Third Edition, Smithsonion Institution, Washington, D.C., and University of California Press, Berkeley, CA, 551 pp.

Geologic Background. False or otherwise incorrect reports of volcanic activity.

Information Contacts: Imran Khan, Director General, Geological Survey of Pakistan, Sariab Road, Quetta, Pakistan (URL: http://www.gsp.gov.pk); Din Mohammed Kakar, Geology Department, University of Balochistan, Quetta, Pakistan (URL: http://www.uob.edu.pk/); Andrew C. Kerr, Cardiff University, School of Earth and Ocean Sciences, Cardill, Wales, UK (URL: http://www.Cardiff.ac.uk/earth/contactsandpeople/profiles/kerr-andrew.html); Khadim Durrani; Roger Bilham, University of Colorado.


Piton de la Fournaise (France) — March 2012 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)


Increased seismicity and eruption during late 2010

Our last Bulletin report (BGVN 35:03) covered eruptive activity through the last eruptive episode, which ended 12 January 2010.

Beginning 14 August and through 10 September 2010, the Observatoire Volcanologique du Piton de la Fournaise (OVPDLF) recorded a slow but steady increase in the number and magnitude of earthquakes from Piton de la Fournaise. Inflation of the summit area began in late August. The following report is based on data received from OVPDLF. It discusses eruptions and related behavior as late as 10 December 2010.

On 13 September 2010, localized deformation W of the Dolomieu crater and a small number of landslides in the crater was observed. On 20 September instruments recorded a significant increase in the number of earthquakes located at the W and S of the Dolomieu crater, although their average magnitude was low.

On 24 September, OVPDLF reported the possibility of an impending eruption. During the night, a seismic crisis began with a series of several tens of earthquakes localized under the Dolomieu crater, which was associated with inflation (approximately 3 cm), especially close to the summit. The most significant deformations were measured on the rim and the N and S sides of the volcano, indicating a shallow magma body was distributed directly below the Dolomieu crater. After decreasing on 27 September, seismicity rose again by 29 September. Earthquakes were located at the base of the volcano, and inflation was noted particularly in the E. A significant number of landslides were detected in the crater. The Alert level remained at 1 ("probable or imminent eruption").

Beginning 7 October 2010, there was a steady increase in the number and magnitude of volcano-tectonic (VT) earthquakes. During 10-11 October the summit area inflated 3-7 cm, and an increase in the number of landslides in the crater was detected. The Alert level remained at 1.

Increased seismicity was again recorded on 14 October 2010, with a new seismic crisis of more than several hundred earthquakes. During this phase, significant ground deformation occurred near the summit, which generated numerous rockfalls inside the Dolomieu crater. At 1411, the seismicity moved toward the SE part of the volcano (Château Fort), and at 1910 an eruption began within the Enclos Fouqué, about 1.5 km SE of the Dolomieu crater rim. Lava fountaining occurred from four vents along a fissure. The Alert level was raised to 2 ("eruption in progress in the Fouqué caldera").

Eruptive activity continued on 15-16 October 2010, developing along a fissure. This eruption included low lava fountains and fed a lava flow moving to the ESE. Lava issued from an area close to the old Château Fort crater at the base of the SE flank of Dolomieu crater and remained within the Enclos Fouqué. Four small cones were active along the eruptive fissure; lava fountaining occured from three of them. A lava flow moved slowly about 1.6 km to the E and SE and approached the break in slope at the Grandes pentes. OVPDLF measured lava temperatures of ~1,100°C.

On 17 October 2010 explosions and degassing accompanied lava emissions. These explosions and degassing decreased on 18 October. The volcanic tremor also decreased to one-seventh compared to the beginning of the eruption. The number of VT events remained low (7/day); the strongest event occurred at 2323, a M 1.4 earthquake localized at about 1,600 m depth under the Bory summit crater. The base and the summit of the volcano remained in inflation. Preliminary estimation of the lava volume erupted was 600,000 m3.

During 19-21 October consistent eruptive activity continued, with weak emissions and small lava fountains at the main eruptive vents located along the eruptive fissure. Explosive activity and degassing decreased, and tremor remained stable. Lava flows extended ESE to ~2 km. Gas emissions decreased, but concentrated to the S and W of the fissure.

On 22 October 2010 eruptions continued, located close to the Château Fort area, in the southern portion of the Enclos Fouqué. During 22-26 October lava fountains and gas emissions originated from one vent, and lava traveled ESE. Gas emissions decreased significantly. At this point, only one cone was active and only a few lava fountains were observed. Volcanic tremor was stable. No earthquakes had been reported since the previous day. GPS ground deformation showed a weak deflation under the volcano.

A sudden increase in activity and tremor began on 27 October 2010 and continued on 28 October. On 29 October, observation made during a flight disclosed that a part of summit cone 3 (the only active cone) had collapsed. Some lava ejecta and gas emissions occurred from this cone, which also contained a small active lava pond. Lava from this cone fed a small, slow moving lava flow. This new lava field remained upstream of the cone named Gros Benard. On 31 October, OVPDLF reported that the eruption had ended.

On 9 December 2010, following a seismic crisis and inflation, a new eruption began from an eruptive fissure oriented N-S, just above the Mi-Côte peak, at ~2,500 m elevation, characterized by lava fountaining and two lava flows. Many small landslides occurred in the Dolomieu crater. Later that day lava flows from two fissures on the N flank of Piton de la Fournaise, ~1 km NW of the Dolomieu crater rim, traveled about 1.5 km N and NW. On 10 December 2010, seismicity and deformation measurements indicated that eruption of lava had stopped.

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: Laurent Michon and Patrick Bachélery, Laboratoire GéoSciences Réunion, Institut de Physique du Globe de Paris, Université de La Réunion, CNRS, UMR 7154-Géologie des Systèmes Volcaniques, La Réunion, France; Guillaume Levieux, and Thomas Staudacher, and Valérie Ferrazzini, Observatoire Volcanologique du Piton de la Fournaise (OVPDLF), Institut de Physique du Globe de Paris, 14 route nationale 3, 27ème km, 97418 La Plaine des Cafres, La Réunion, France (URL: http://www.ipgp.fr/fr/ovpf/actualites-ovpf/).


Hierro (Spain) — March 2012 Citation iconCite this Report

Hierro

Spain

27.73°N, 18.03°W; summit elev. 1500 m

All times are local (unless otherwise noted)


Update on submarine eruption

[NOTE: The location shown on the summary page is that for the main summit of Hierro volcano on El Hierro Island. The location of the submarine vent of Hierro that erupted beginning in October 2011 was found to be at latitude 27°37.18' N and longitude 17° 59.58' W.]

In BGVN 36:10 we discussed a submarine eruption of a vent of Hierro volcano that began in early October 2011 S of La Restinga, a town at the southermost tip of El Hierro Island (figure 7). The eruption was preceded by increased seismicity, although this seismicity declined significantly by mid-November 2011 (figures 8 and 9). Based on seismic activity monitored by the Instituto Geográfico Nacional (IGN-National Geographic Institute), authorities for the Canary Islands decided in late March 2012 to shut down the web cameras at La Restinga. Volcanic tremor was still present, although at minimal levels, and some seismicity continued beneath the island. The patch of brown water over the submarine vent (location shown in figure 8) continued to be observed throughout both March and April (figure 10).

Figure (see Caption) Figure 7. Location maps showing the Canary Islands, with volcanoes, and their intra-plate location with respect to plate boundaries. Information on the locations and latest eruptions of the volcanoes is found in table 1. El Hierro Island (and its volcano of the same name) appears on the SW margin of the archipelago. (a) Geographic and geodynamic setting of the NW African continental margin with the Canary Islands; numbers on the Canary Islands show the ages of the oldest surface volcanism, in millions of years before present (Ma). The Canary Islands developed in a geodynamic setting characterized by Jurassic oceanic lithosphere formed during the first stage of opening of the Atlantic at 180-150 Ma and lying close to a passive continental margin on the African plate. The archipelago lies adjacent to a region of intense deformation comprising the Atlas mountains, a part of the Alpine orogenic belt. The intraplate Canary Islands archipelago is within the African plate, bounded by the Azores-Gibralter fault on the north and the mid-Atlantic ridge on the west. (b) Close-up view of the Canary Islands, showing the names of the islands, and the ages of the oldest surface volcanism for each island. Courtesy of Viñuela (2012) and Carracedo and others (2002).

Table 1. Background information on the six main Canary Islands and their volcanoes. Latest eruption dates are from Siebert and others (2010) and Smithsonian's Global Volcanism Program website. The volcano age indicates date of oldest volcanic rocks of each island (Carracedo and others, 2002).

Volcano/island name Location Summit elevation (m) Year(s) of latest eruption(s) Volcano age (Ma)
Fuerteventura 28.358°N 14.02°W 529 1803-05 20.6
Gran Canaria 28.00°N 15.58°W 1,950 1125 14.5
Hierro/El Hierro 27.23°N 18.03°W 1,500 2011-12, 1793 1.12
Lanzarote 29.03°N 13.63°W 670 1824, 1730 15.5
La Palma 28.57°N 17.83°W 2,426 1971, 1949, 1712 1.77
Tenerife 28.271°N 16.641°W 3,715 1909, 1798 11.6
Figure (see Caption) Figure 8. Topographic map of El Hierro Island showing the locations of IGN seismic monitoring stations. A small red triangle offshore of the southernmost tip of the island locates the submarine vent of Hierro that began erupting in October 2011. The pronounced curved form on the N side of the island resulted from lateral collapse; see figure 11b. Courtesy of IGN.
Figure (see Caption) Figure 9. Cumulative energy (in joules) based on daily seismic monitoring at El Hierro island from 18 July 2011 through 19 March 2012. The sharp upturn in the curve occurred ~27 September 2011, leveled out ~9 October 2011, resumed to a sharp upturn on ~29 October 2011 to level out again ~21 November 2011. Since that time, the seismic energy has not increased measureably. Courtesy of IGN.
Figure (see Caption) Figure 10. A natural-color satellite image collected on 10 February 2012 showed the site of the Hierro submarine vent eruption, offshore from the fishing village of La Restinga. Bright aquamarine-colored water indicated high concentrations of volcanic material in the water above the vent, which lies at a water depth of between 200 and 300 m. A patch of turbulent light brown water on the sea surface indicated the area most strongly affected. This image was acquired by the Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite. NASA Earth Observatory image prepared by Jesse Allen and Robert Simmon, using EO-1 ALI data.

Bathymetry and water chemistry. For 4 months following the eruption (a period from 22 October 2011 through 26 February 2012), the Instituto Oceanográfico Español (IOE-Spanish Oceanographic Institute) conducted 12 oceanographic cruise legs (called La Campaña Bimbache-Bimbache Campaign; Bimbache refers to native inhabitants of El Hierro), documenting the submarine morphology and water chemistry changes resulting from the eruption. Reports of these cruises on board the research vessel Ramon Margalef are found on the IEO web site; some highlights follow.

During the 7th leg, 8-12 January 2012, IEO scientists found that the volcano's summit was ~130 m below the water surface, 30 m more since its last survey on 2 December 2011. The diameter of the volcano's base was about 800 m, and its height ~200 m above the ocean floor. The total volume of material emitted since the eruption onset in October 2011 to the date of this cruise leg, calculated by bathymetry compared to 1998, was 145 x 106 m3. This volume included a new eruptive cone and associated lava flows. This new material nearly completely covered the W escarpment of the submarine canyon where the eruption was located. It was also found that a split in the top of the cone recorded in the bathymetric survey of 30 November 2011 no longer existed.

During the 9th leg, 6-8 February 2012, Hierro volcano was found to have grown somewhat more in height. The most significant differences between this and the 7th leg (January 2012) occurred at the top of the cone, including a slight increase in the elevation of its summit, which now reached to ~120 m below the water surface, and the emergence of a secondary cone, ~23 m high, attached to the side of the main cone, with a summit depth of 200 m. The emergence of the secondary cone and the greater mass of material on the volcano flank had caused a flattening of the structure. The slope ranged between 25° and 30° on the N flank, with slopes of up to 35° on the E and W flanks.

The 10th leg, 9-13 February 2012, was dedicated to water sampling. Observers found very high levels of hydrogen sulfide (H2.S), with a below normal pH, and very high partial pressure of CO2.

The IEO report of the 11th leg, 23-24 February 2012, notes that the coordinates of the main summit of the new volcano were: latitude 27°37.18' N and longitude 17° 59.58' W.

During a cruise from 5 to 9 April 2012 by researchers from IEO and the University of Las Palmas de Gran Canaria (ULPGC), 19 hydrographic stations were occupied. Data was collected on the physical-chemical properties of the water around the volcano (including temperature, salinity, depth, fluorescence, turbidity, dissolved oxygen, pH, alkalinity, total inorganic carbon, and CO2 partial pressure). The researchers intend to quantify the environmental impact caused by the volcano 7 months after the beginning of the eruption. The physical-chemical properties of the water column in an area of 500 m radius around the submarine volcanic cone where found to be still significantly affected. At this stage, the degassing of the volcano was fundamentally of CO2, with complete absence of sulfur compounds.

Remote submarine vessel observations. The University of Las Palmas de Gran Canaria (ULPGC) web site on 16 March 2012 reported initial filming of the submarine vent using the robot submarine vessel Atlantic Explorer. They reported particles of tephra in the mouth of the still-active vent. At a depth of 120 m, hot jets emerged from a vent, forming converging water convection cells reaching upwards to depths of ~40-60 m. From the same depths, some pyroclastic ejecta were seen in the form of large volcanic bombs. The SW flank of the main volcanic vent cone sloped steeply and was the resting place of many large pyroclastics, some of which are similar to the hollow volcanic bombs (lava balloons) that reached the ocean surface during November and December 2011. Marine life had returned to near the vent, and at a depth of ~170 m and under a rain of ash they observed a school of fish (possibly amberjack).

Geologic setting. Carracedo and others (2012a) provided further details on the geologic setting of El Hierro island and the 2011 vent eruption. They state that "As early as 1793, administrative records of El Hierro indicate that a swarm of earthquakes was felt by locals; fearing a greater volcanic catastrophe, the first evacuation plan of an entire island in the history of the Canaries was prepared. The 1793 eruption was probably submarine . . . over the next roughly 215 years the island was seismically quiet. Yet seismic and volcanic activity are expected on this youngest Canary Island due to its being directly above the presumed location of the Canary Island hot spot, a mantle plume that feeds upwelling magma just under the surface, similar to the Hawaiian Islands." Currently, roughly 10,000 people live on the island of El Hierro.

The report continued (references have been removed): "El Hierro, 1.12 million years old, is the youngest of the Canary Islands and rests on a nearly 3,500-m-deep ocean bed (figure 11a). According to stratigraphic data, two eruptions are known to have occurred on El Hierro, one ~4,000 years ago at Tanganasoga volcano complex and one 2,500 ± 70 years ago at Montaña Chamuscada cinder cone (figure 11b). The principal configuration of El Hierro is controlled by a three-armed rift zone system. The last stage of growth of El Hierro started some 158,000 years ago, characterized by volcanism that concentrated mainly at the crests of the three-armed rift system."

Figure (see Caption) Figure 11. El Hierro maps and diagrams to illustrate the setting and context of the 2011 eruption. (a) Location of the submarine vent (red star); image from Masson and others (2002); inset shows the island's location within the Canary Islands archipelago. (b) Simplified geological map of El Hierro, showcasing two recent eruptions. (c) Epicenter distribution migrating southward, 19 July to 8 October 2011 (data from IGN). (d) Hypocenter depths increased during 3 August to 9 October 2011, and then they became shallower (

Carracedo and others (2012a) described the pattern of earthquakes detected by IGN's permanent seismic network. The pattern consisted of an event every few minutes and an average short-period body wave magnitude of about M 1-2. Though the most of these quakes were largely insignificant in terms of seismic hazards, they initially focused N of the island (figure 11c), concentrated within the lower oceanic crust at depths of 8 and 14 km, in agreement with petrological evidence of previous eruptions. The seismic and petrological data are thus in line with a scenario of a magma batch becoming trapped as an intrusion horizon near the base or within the oceanic crust. Shifting seismic foci suggested that magma progressively accumulated and expanded laterally in a southward direction along the southern rift zone, which caused a vertical surface deformation of ~40 mm based on GPS measurements.

The report continues: "Soon after the initial earthquake swarm was observed by the permanent seismometers associated with IGN, efforts were made to mobilize a more complete monitoring seismic and GPS array spaced roughly 2,000 m apart throughout the island. This expanded network, completely installed by September 2011, allowed scientists to follow the progress of the recent activity at El Hierro."

"The new instruments revealed that earthquakes and magma transport remained active but as of the beginning of October 2011 showed no sign of having breached the oceanic crust. Instead, magma continued to move south until, on 9 October, the magma apparently progressed rapidly toward the surface, as indicated by the first-time occurrence of shallow earthquakes (at depths of

"The eruption continued through 15 October, with the appearance of submarine volcanic 'bombs' with cores of white and porous pumice-like material encased in a fine coating of basaltic glass [figure 12; see figure 4 in BGVN 36:10 showing a cross-section view of a bomb]. These bombs are probably xenoliths from pre-island sedimentary rocks that were picked up and heated by the ascending magma, causing them to partially melt and vesiculate." According to Carracedo and others (2012b), "the interiors of these floating rocks are glassy and vesicular (similar to pumice), with frequent mingling between the pumice-like interior and the enveloping basaltic magma. These floating rocks have become known locally as 'restingolites' after the nearby village of La Restinga." Some 'restingolite' samples contain quartz crystals, jasper fragments, gypsum aggregates and carbonate relicts, materials more compatible with sedimentary rocks than with a purely igneous origin for the cores of the floating stones. Figure 13 shows one explanation for the formation these bombs.

Figure (see Caption) Figure 12. Lava fragments ('restingolites') floating on the sea surface about 2 km offshore from La Restinga village on 27 November 2011. At some times a few hundreds of these fragments were present. They arrived at the sea surface at high temperature and, while cooling, they vaporized sea water, suffered intense degassing, and, in some cases broke into small pieces. Courtesy of Alicia Rielo, IGN.
Figure (see Caption) Figure 13. Sketch summarizing the inferred structure of El Hierro Island and the 2011 intrusive and extrusive events. Ascending magma that, according to the distribution of seismic events prior to eruption, moved sub-horizontally from N to S in the oceanic crust and contacted pre-volcanic sedimentary rocks. The floating blocks were attributed to magma-sediment interaction beneath the volcano. These blocks, called 'restingolites', were carried toward the ocean floor during eruption, being melted and vesiculated while immersed in magma. Once erupted onto the ocean floor, they separated from the erupting lava and floated on the sea surface due to their high vesicularity and low density (from Troll and others, 2011). Courtesy of Carracedo and others (2012b).

2012 El Hierro Conference. A conference on the 2011-2012 submarine eruption will take place in the Canary Islands on 10-15 October 2012. The scientific program will cover a broad variety of topics related to volcanic risk management at oceanic island volcanoes and the balance between short-term hazards posed by volcanoes and benefits of volcanism over geologic time.

References. Carracedo, J-C., Perez-Torrado, F-J., Rodriguez-Gonzalez, A., Fernandez-Turiel, J-L., Klügel, A., Troll, V.R., and Wiesmaier, S., 2012a, The ongoing volcanic eruption of El Hierro, Canary Islands, Eos, Transactions, American Geophysical Union, v. 93, no. 9, pp. 89-90.

Carracedo, J.C., Torrado, F.P., González, A.R., Soler, V., Turiel, J.L.F., Troll, V.R., and Wiesmaier, S., 2012b, The 2011 submarine volcanic eruption in El Hierro (Canary Islands), Geology Today, v. 28, issue 2, pp. 53-58.

Carracedo, J.C., 2008, Canarian Volcanoes: La Palma, La Gomera and El Hierro, 213 pp., Editorial Rueda, Madrid.

Carracedo, J.C., Pérez, F.J., Ancochea, E., Meco J., Hernán, F., Cubas C.R., Casillas, R., Rodriguez, E., and Ahijado, A., 2002, Cenozoic volcanism II: The Canary Islands, in: The Geology of Spain, Gibbons, W., and Moreno, T., eds, The Geological Society of London, pp. 439-472.

Carracedo, J.C., Badiola, E.R., Guillou, H.J., de La Nuez, J., and Torrado, F.J.P., 2001, Geology and volcanology of La Palma and El Hierro, western Canaries, Estudios Geológicos, v. 57, no. 5-6, pp. 171-295.

Guillou, H., Carracedo, J.C., Torrado, F.P., and Badiola, E.R., 1996, K-Ar ages and magnetic stratigraphy of a hotspot-induced, fast grown oceanic island: El Hierro, Canary Islands, Journal of Volcanology and Geothermal Research, v. 73, no. 1-2, pp. 141-155.

Masson, D.G., Watts, A.B., Gee, M.J.R., Urgeles, R., Mitchell, N.C., Le Bas, T.P., and Canals, M., 2002, Slope failures on the flanks of the western Canary Islands, Earth-Science Reviews, v. 57, no. 1-2, pp. 1-35.

Siebert, L., Simkin, T., and Kimberly, P., 2010, Volcanoes of the World, Third Edition, Smithsonian Institution, Washington, D.C., and University of California Press, Berkeley, 551 pp.

Troll, V.R., Klügel, A., Longpré, M.-A., Burchardt, S., Deegan, F.M., Carracedo, J.C., Wiesmaier, S., Kueppers, U., Dahren, B., Blythe, L.S., Hansteen, T., Freda, C.D., Budd, A., Jolis, E.M., Jonsson, E., Meade, F., Berg, S., Mancini, L., and Polacci, M., 2011, Floating sandstones off El Hierro (Canary Islands, Spain): the peculiar case of the October 2011 eruption. Solid Earth Discussion, v. 3, pp. 975-999.

Viñuela, J.M., 2012, (online) The Canary Islands Hot Spot, www.mantleplumes.org/Canary.html, updated 21 December 2007, accessed 27 March 2012.

Geologic Background. The triangular island of Hierro is the SW-most and least studied of the Canary Islands. The massive shield volcano is truncated by a large NW-facing escarpment formed as a result of gravitational collapse of El Golfo volcano about 130,000 years ago. The steep-sided scarp towers above a low lava platform bordering 12-km-wide El Golfo Bay, and three other large submarine landslide deposits occur to the SW and SE. Three prominent rifts oriented NW, NE, and S form prominent topographic ridges. The subaerial portion of the volcano consists of flat-lying Quaternary basaltic and trachybasaltic lava flows and tuffs capped by numerous young cinder cones and lava flows. Holocene cones and flows are found both on the outer flanks and in the El Golfo depression. Hierro contains the greatest concentration of young vents in the Canary Islands. Uncertainty surrounds the report of an eruption in 1793. A submarine eruption took place about 2 km SSW off the southern point of the island during 2011-12.

Information Contacts: Alicia Felpeto Rielo, Instituto Geográfico Nacional (IGN), General Ibáñez de Ibero, 3. 28003, Madrid, España (URL: http://www.ign.es/); Volcano Discovery (URL: http://www.volcanodiscovery.com); Earthquake Report (URL: http://www.earthquake-report.com); University of Las Palmas de Gran Canaria (ULPGC) (URL: http://www.ulpgc.es); Canaries News (URL: http://www.canariesnews.com); Instituto Oceanográfico Español (IEO) (URL: htp://www.ieo.es).


Kelut (Indonesia) — March 2012 Citation iconCite this Report

Kelut

Indonesia

7.93°S, 112.308°E; summit elev. 1731 m

All times are local (unless otherwise noted)


Amid quiet, a look back at aspects of the 2007 eruption

A memorable eruption at Kelut began in August 2007 injecting what became a substantial lava dome in the midst of a crater lake. The process was devoid of large violent steam explosions of the kind often associated with molten lava extruding into a lake. The passively emplaced lava dome evaporated and displaced most or all of the crater lake. Dome extrusion had clearly stopped by April 2008 (BGVN 33:07) or perhaps by May 2008 (De Bélizal and others, 2012). Since then and as late as April 2012, the Center of Volcanology and Geological Hazard Mitigation (CVGHM), has noted ongoing quiet, at times broken by the emergence of diffuse white plumes. Those plume were seen in June 2009 rising 50-150 m above the crater and the new dome was still emitting steam in February 2012. As of 30 March 2012, the Alert Level remained Green, although CVGHM recommended that people not approach the lava dome due to instability of the area and the presence of potentially high temperatures and poisonous gases.

Three short subsections follow. The first discusses uplift at Kelut during 2007-2008 as part of a larger survey of volcanic deformation on Java (Philibosian and Simons, 2011). The next subsection discusses a paper that provides an overview on the unexpectedly tranquil eruption, which, though of substantial size, was one of Kelut's few substantial yet passive eruptions in the historic record (De Bélizal and others, 2012). The authors surveyed residents to assess how they felt about how authorities had managed the crisis. The third subsection below discusses the dome's declining thermal output in early 2008, and presents a photo taken in February 2011 showing the steaming dome's spiny upper surface.

2007-2008 deformation. Philibosian and Simons (2011) discussed satellite-borne (Japanese ALOS) L-band synthetic aperture radar used to conduct a comprehensive survey of volcanic deformation on Java during 2007-2008. For Kelut, the authors found a possible 15 cm line-of-sight change in late 2008, an uplift. The area of uplift was limited to the very top of Kelut and was only a few hundred meters wide. However, the authors state that, given there were only two radar acquisitions after this late 2008 uplift, it was "difficult to judge whether this was permanent, real deformation rather than a short-term atmospheric effect." According to the authors, "the volcano did not exhibit a significant deformation before or during the dome extrusion in our time series" (figure 13).

Figure (see Caption) Figure 13. Time series of Kelut's deformation during October 2006-January 2009 (summing all the time steps and for satellite track 428). The plot shows the 15-cm line-of-sight change consistent with an uplift peaking during late 2008. The period of observed lava dome extrusion (shown in red) corresponded with a minor uplift (under 5 cm along the line of sight). Taken from Philibosian and Simons (2011).

2007 eruption and crisis management revisited. De Bélizal and others (2012) discuss a survey conducted shortly after the end of an evacuation process triggered by Kelut's eruption that started in 2007.

The authors summarized Kelut's unrest that started prior to the extrusions first seen in August by noting that earlier, on 1 November 2007, CVGHM recorded a new peak of seismicity with signals having reached shallow depths beneath the crater floor. The crater lake temperature recorded by a thermal camera increased significantly by 6 November. A steam plume developed, reaching 550 m above the crater lake. A new lava dome extruded through the ~350 m diameter crater lake (BGVN 33:03). Progressively, nearly all the lake water vaporized as the lava dome grew to a diameter of 400 m and a height of 260 m representing a volume of ~35 x 106 m3.

According to De Bélizal and others (2012), "recorded volcanic seismicity decreased shortly after the onset of dome growth. Tiltmeter records also showed the absence of any significant deformation on the flanks of the volcano. These data suggested that the magmatic pressure decreased within the volcano therefore greatly reducing the likelihood of a violent explosion. Thus, on 8 November 2007, Indonesian authorities decided to end the emergency phase. The volcano Alert Level was lowered to Level 3 'Siaga' until 30 November, when it was then lowered to Level 2 'Waspada' until August 2008."

The passively extrusive and unexpectedly non-explosive eruption was the first here in recent historical times. This called for careful monitoring of both the eruptive behavior of the volcano and the stability of a lake-bound dome plugging the vent. Tourism and agriculture ceased on its flanks for many months in anticipation of potential sudden signs of renewed activity.

The article stated that the crisis management team ordered an evacuation, which followed the rise to Alert Level 4 on 16 October 2007 (BGVN 33:03), but it noted that many residents disregarded the order because they did not consider that an eruption was imminent. The authors conducted interviews with members of the crisis management team, and undertook a questionnaire-based survey in the settlement nearest to the crater to determine how residents reacted to the crisis and how they thought authorities managed the crisis. The survey was carried out while Kelut was still under surveillance for fear of an explosive phase. According to the authors, the crisis management team "was well organized and strategic"; however, the results "showed that crisis management was not fully integrated with the way of life of the local communities at risk, and that information, communication and trust were lacking."

Decreasing thermal alerts in 2008 and an early 2011 photo. During November and December 2007, there were numerous days with MODVOLC thermal alerts. This number decreased in January 2008 to only six days that month. After January 2008, thermal alerts had been absent as late as 27 April 2012. The probable cause was the cooling of the dome to the point where the levels of thermal radiation emitted dropped below the threshold values needed to create MODVOLC alerts.

A photo of Kelut taken by Daniel Quinn in early 2011 shows the steaming, rough-surfaced lava dome in the crater (figure 14). The photo only showed a small portion of the entire crater floor, but on the N side of the dome, the crater floor contained a dark brown, muddy-colored patch of water the photographer considered a large puddle. Some 2010 photos on the Picassa website showed a small body of water on the crater floor at that time.

Figure (see Caption) Figure 14. A late January or early February 2011 photo taken of Kelut's new dome from a high spot on the NNW rim. Apparent are both the dome's spiny upper surface, and many areas of the dome still emitting small amounts of steam. The photo appeared on the Picassa website and is used with the permission of the photographer, Daniel Quinn.

According to Daniel Quinn, the photo in figure 14 was taken on the rim at a spot accessed via a small pavilion he passed walking from the car parking area. He took the photo having walked clockwise about as far around the rim as he could travel before reaching vertical cliffs. Pungent odors were absent during his visit.

References. De Bélizal, É., Lavigne, F., Gaillard, J., Grancher, D., Pratomo, I., and Komorowski, J. , 2012. The 2007 eruption of Kelut volcano (East Java, Indonesia): Phenomenology, crisis management and social response, Geomorphology, v. 136, issue 1, p. 165-175.

Philibosian, B., and Simons, M., 2011. A survey of volcanic deformation on Java using ALOS PALSAR interferometric time series, Geochemistry Geophysics Geosystems, v. 12, no. 11, 8 November 2011, Q11004, 20 pp. (DOI:10.1029/2011GC003775).

Geologic Background. The relatively inconspicuous Kelut stratovolcano contains a summit crater lake that has been the source of some of Indonesia's most deadly eruptions. A cluster of summit lava domes cut by numerous craters has given the summit a very irregular profile. Satellitic cones and lava domes are also located low on the E, W, and SSW flanks. Eruptive activity has in general migrated in a clockwise direction around the summit vent complex. More than 30 eruptions have been recorded from Gunung Kelut since 1000 CE. The ejection of water from the crater lake during the typically short but violent eruptions has created pyroclastic flows and lahars that have caused widespread fatalities and destruction. After more than 5000 people were killed during an eruption in 1919, an ambitious engineering project sought to drain the crater lake. This initial effort lowered the lake by more than 50 m, but the 1951 eruption deepened the crater by 70 m, leaving 50 million cubic meters of water after repair of the damaged drainage tunnels. After more than 200 deaths in the 1966 eruption, a new deeper tunnel was constructed, and the lake's volume before the 1990 eruption was only about 1 million cubic meters.

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


Long Valley (United States) — March 2012 Citation iconCite this Report

Long Valley

United States

37.7°N, 118.87°W; summit elev. 3390 m

All times are local (unless otherwise noted)


2009 summary, deep seismic swarm at Mammoth Mountain

This report on Long Valley caldera, California, summarizes USGS reports for 2009. The volcano remained non-eruptive. Long Valley Observatory (LVO) is now part of the California Volcano Observatory (CalVO). A tectonic earthquake sequence during 2011 in nearby Hawthorne, Nevada, is also discussed.

Long Valley caldera entered relative quiescence in the spring of 1999 (BGVN 26:07) following unrest that began in 1980 (SEAN 07:05); this relative quiescence continued through 2009.

Seismicity during 2009 was characterized by a low level of seismicity within the caldera, and a typical higher level of seismicity in the surrounding Sierra Nevada range (figure 41). Three recorded earthquakes were larger than M 3.0, yet none of them occurred within the region of Long Valley caldera as delimited by LVO. The largest earthquakes within Long Valley caldera were an M 2.7 on 9 January in the S moat, and a pair of M 2.3 earthquakes on 10 December that were located beneath the resurgent dome.

Figure (see Caption) Figure 41. Seismicity in the region of Long Valley caldera and the surrounding Seirra Nevada range. The upper red dashed outline indicates volcanic areas associated with Long Valley caldera (including Mammoth Mountain and Inyo Craters), and the red dashed and dotted outline indicates the adjacent Sierra Nevada range. Earthquake epicenters are shown with symbols proportional to earthquake magnitudes, according to the scale at top-right. Modified from USGS-LVO.

Deep seismic swarm at Mammoth Mountain.At Mammoth Mountain, increased seismicity began in late May, and a deep seismic swarm occurred on 29 September. The 29 September seismic swarm included over 50 M ≥0.5 high-frequency earthquakes that occurred at depths of 20-25 km, depths inferred to be in the mafic lower crust (figure 42). The high frequencies of these earthquakes indicated brittle-rock failure similar to shallow earthquakes that typically occur at <10 km depth, and were distinctly different than the long-period earthquakes that occur within the silicic upper crust, at depths of 10-25 km. The increased seismicity at Mammoth Mountain during 2009 produced more earthquakes there than occurred within Long Valley caldera (figures 41, 42, and 43).

Figure (see Caption) Figure 42. Map (left) and cross-section (right) views focusing on Mammoth Mountain seismicity during 2009. Note the two main clusters of earthquakes at ~0-7 km and ~20-25 km depth. Earthquakes are shown by symbols proportional to earthquake magnitude, shown by the scale at left. The line A-A' on the map indicates the plane of projection of the cross-section. The inferred mafic lower crust and silicic upper crust regions are indicated to the right of the cross-section. The cross-section also indicates interpreted brittle and plastic zones and the typical source area for deep, long-period (LP) earthquakes. Modified from USGS-LVO.
Figure (see Caption) Figure 43. Plot of the cumulative number of earthquakes within Long Valley caldera (dashed line) and beneath Mammoth Mountain (solid line, highlighted in orange) during 2009. The 29 September deep earthquake swarm took place within a longer episode of enhanced seismicity at Mammoth Mountain that lasted from mid-2009 through at least the end of the year. Mammoth Mountain's cumulative 2009 seismicity surpassed that at the rest of the Long Valley caldera area. Courtesy of USGS-LVO.

Slow inflation of the caldera's resurgent dome. Deformation trends during 2007-2009 highlighted slow inflation of the resurgent dome. At the end of 2009, the height of the resurgent dome remained ~75 cm higher than prior to the onset of unrest in 1980. Measurements since 2007 indicated horizontal displacement rates of ~5 mm/year, mostly in a pattern radiating away from the resurgent dome (figure 44).

Figure (see Caption) Figure 44. Horizontal displacement rates determined by GPS at different measurement sites in and around Long Valley caldera during the start of 2007 to early 2010, which highlight a trend of expansion away from the resurgent dome. Displacement rate vectors are relative to two reference sites located off the map in the Sierra Nevada range. Ellipses around arrows represent standard 2σ errors on the measurements. Light gray arrows represent insignificant displacement rates. The black dashed outline indicates the extent of Long Valley caldera, the gray dashed outline labeled "inflation source" indicates the resurgent dome, and the gray dashed outline at the SW edge of Long Valley caldera indicates Mammoth Mountain. From S to N, the brown dashed outlines indicate the Inyo Domes, Mono Craters, and Mono Lake islands. Modified from USGS-LVO.

During 2009, soil CO2 emission measurements revealed variations typical of most previous years. The increase in seismicity at Mammoth Mountain on 29 September did not produce a corresponding increase in CO2 emissions.

2011 Hawthorne, Nevada, earthquake sequence. In March 2011, an earthquake sequence (mentioned in LVO weekly activity updates) began in Hawthorne, Nevada (~100 km NNE of the center of Long Valley caldera) that, according to Smith and others (2011), initially sparked brief concerns of unrest at Mud Springs volcano (figure 45). Mud Springs volcano is a probable Pleistocene volcano of the Aurora-Bodie volcanic field, Nevada (Wood and Kienle, 1992). The Hawthorne earthquakes did not show volcanic signatures in near-source seismograms (Smith and others, 2011), and the sequence was quickly identified as tectonic in origin.

Figure (see Caption) Figure 45. Mapped epicenters and magnitudes (legend, bottom right) of the 2011 Hawthorne, Nevada, earthquake sequence through 19 May 2011. Hawthorne is ~10 km to the NE of the top right margin of the image. Green triangles mark the locations of three temporary seismometers (TVH1-3) installed during 17-19 April 2011. Mud Springs volcano and its associated lava flows are labeled at the bottom of the image. Modified from the Nevada Seismological Laboratory, University of Nevada, Reno.

According to Smith and others (2011), "An additional concern, as the sequence . . . proceeded, was a clear progression eastward toward the Wassuk Range front fault. The east dipping range bounding fault is capable of M 7+ events, and poses a significant hazard to the community of Hawthorne and local military facilities. The Hawthorne Army Depot is an ordinance storage facility and the nation's storage site for surplus mercury."

Earthquakes of the March 2011 sequence were as strong as M 4.6 (figure 46); the largest earthquakes may have been felt in Bridgeport, CA (~60 km SW of Hawthorne, and ~70 km NNW from the center of Long Valley caldera), according to LVO. The earthquakes occurred along at least two shallow faults, originating at 2-6 km depth (Smith and others, 2011). The earthquake sequence "slowly decreased in intensity through mid-2011" (Smith and others, 2011).

Figure (see Caption) Figure 46. Mapped areas of felt responses to the M 4.6 earthquake that occurred on 16 April 2011 (see scale at bottom). The hypocenter is indicated by the red star (center). This was the strongest earthquake of the 2011 Hawthorne, Nevada earthquake sequence. The red triangle near the bottom of the map shows the location of Long Valley caldera. Modified from the Nevada Seismological Laboratory, University of Nevada, Reno.

References. Smith, K.D., Johnson, C., Davies, J.A., Agbaje, T., Antonijevic, S.K., and Kent, G., 2011. The 2011 Hawthorne, Nevada, Earthquake Sequence; Shallow Normal Faulting. American Geophysical Union, Fall Meeting 2011, Abstract ##S53B-2284.

Wood, C.A. and Kienle, J., 1992. Volcanoes of North America: United States and Canada, Cambridge University Press, 354 p., pgs. 256-262.

Geologic Background. The large 17 x 32 km Long Valley caldera east of the central Sierra Nevada Range formed as a result of the voluminous Bishop Tuff eruption about 760,000 years ago. Resurgent doming in the central part of the caldera occurred shortly afterwards, followed by rhyolitic eruptions from the caldera moat and the eruption of rhyodacite from outer ring fracture vents, ending about 50,000 years ago. During early resurgent doming the caldera was filled with a large lake that left strandlines on the caldera walls and the resurgent dome island; the lake eventually drained through the Owens River Gorge. The caldera remains thermally active, with many hot springs and fumaroles, and has had significant deformation, seismicity, and other unrest in recent years. The late-Pleistocene to Holocene Inyo Craters cut the NW topographic rim of the caldera, and along with Mammoth Mountain on the SW topographic rim, are west of the structural caldera and are chemically and tectonically distinct from the Long Valley magmatic system.

Information Contacts: Dave Hill, California Volcano Observatory (CalVO), formerly theLong Valley Observatory (LVO), U.S. Geological Survey, Menlo Park, CA (URL: http://volcanoes.usgs.gov/observatories/calvo/); Nevada Seismological Laboratory, Laxalt Mineral Engineering Building, Room 322, University of Nevada-Reno, Reno, NV 89557 (URL: http://www.seismo.unr.edu/).


Maderas (Nicaragua) — March 2012 Citation iconCite this Report

Maderas

Nicaragua

11.446°N, 85.515°W; summit elev. 1394 m

All times are local (unless otherwise noted)


Destructive 2005 seismicity; youngest deposits dated 70.4 ± 6.1 ka B.P

In this report we present seismicity at Maderas from 1998 through 2011, highlight the 2005 earthquake swarm, describe the "Tomography Under Costa Rica and Nicaragua" (TUCAN) Broadband Seismometer Experiment and the subsequent analysis of an Mw 6.3 event also from 2005, and summarize results from fieldwork conducted in 2009 with new age dates from Kapelancyzk and others (2012).

The 2009 field investigation also characterized two distinct phases of volcanism at Maderas, as recent as the Upper Pleistocene (70.4 ± 6.1 ka before present). Despite this interval without documented eruptions, it is plausible that the volcano could erupt again, but risk of a future eruption from Maderas is considered low (Kapelancyzk, 2011). More likely are hazards associated with non-eruptive processes such as seismically triggered mass wasting and gas emissions. A deadly lahar in 1996 (BGVN 21:09) emphasized that non-eruptive processes still offer considerable hazards and justify efforts to watch for and catalog non-eruptive events.

Maderas and Concepción volcanoes sit at opposite ends of the dumbbell-shaped Ometepe Island (figure 1). The population on the island is estimated at 30,000 however seasonal tourism increases that number during the year. These volcanoes are monitored by the Instituto Nicaragüense de Estudios Territoriales (INETER) with seismic stations and regular field investigations by staff volcanologists.

Figure (see Caption) Figure 1. This map of Central America focuses on Maderas volcano; the inset zooms in on Lake Nicaragua and Ometepe Island. Dashed lines represent the large-scale geologic features, the Nicaraguan depression (ND) to the S and the Median Trough (MT) to the N; triangles represent volcanic centers (Kapelanczyk and others, 2012).

Seismicity. One seismic station is located on Ometepe Island within a network of ~32 stations in Nicaragua. From 1998 to 2011, INETER reported that seismicity was irregular although in most years, they located fewer than four earthquakes (table 1). Earthquakes were frequently ML < 3.5 (ML= Local earthquake magnitude) with focal depths ranging between the surface and 179 km.

Table 1. Earthquakes located near Maderas volcano from 1998 through 2011. For each year, the table also lists the range of the earthquakes' local magnitudes (ML), the range of their focal depths, and their average focal depths. INETER did not comment on earthquakes that were anomalously deep (e.g. 179 km below sea level). Courtesy of INETER.

Year EQ Count ML Range of focal depths (km) Avg. focal depths (km)
1998 1 3.6 0 0
2000 1 3.3 1 1
2003 3 2.2-3.7 1-176 62
2004 3 2.3-3.7 4-7 6
2005 406 1.0-4.8 0-24 7
2006 11 1.9-3.3 4-11 7
2007 2 1.9-2.8 1-3 2
2008 1 2.1 179 179
2009 1 3.5 172 172
2011 1 2.3 11 11

During 2005, INETER's network registered a total of 2,785 earthquakes throughout Nicaragua; 2,629 of these events were located by seismologists, 78 caused shaking that was strong enough to be reported by local populations, and 406 were located near Maderas volcano. Many of these events were located beneath Lake Nicaragua and S of Maderas volcano (figure 2). According to an interview presented in a La Prensa news article, 71% of the events were attributed to strain release along the subduction zone while 27% were associated with the volcanic chain. INETER reported that a significant number of earthquakes also occurred offshore in the Pacific Ocean with magnitudes greater than 5.0.

Figure (see Caption) Figure 2. (Left) A map of epicenters for the entire year of 2005 plotted for Nicaragua and the surrounding region. (Right) A map of epicenters for the month of September 2005 plotted for the Lake Nicaragua region. On both maps, note the concentration of epicenters around Maderas at the SE portion of Ometepe Island. Courtesy of INETER.

Large regional earthquake. In their monthly bulletins, INETER reported that the earthquake swarm from August through September 2005 included an ML 5.7 earthquake that occurred on 3 August. The USGS National Earthquake Information Center reported this event as Ms 6.2 (Ms = surface-wave magnitude). This earthquake was located ~15 km S of Maderas volcano (figure 3) and INETER reported that many homes on Ometepe Island were destroyed. Shaking was felt by local residents on the Pacific coast of Nicaragua as well as the interior of the country and in Costa Rica. INETER noted that this was the first time in memory that an event of this magnitude occurred near Maderas. Aftershocks continued for several weeks after the event (La Prensa).

Figure (see Caption) Figure 3. Map views of initial (left) and double-difference (right) relocated hypocenters. The green and red stars correspond to the Mw 5.3 and 6.3 fore and main shock, respectively (Mw = moment magnitude). The initial hypocenters were cataloged by INETER except for the main shock, which was located separately using TUCAN P and S phase data (horizontal plane 95% confidence ellipse shown). The red inverted triangle represents the INETER catalog location of the main shock. Note that contour intervals are inconsistent with those elsewhere in the literature. Map is modified from French and others (2010).

This major seismic event was also captured by the "Tomography Under Costa Rica and Nicaragua" (TUCAN) Broadband Seismometer Experiment. This array of instruments was in the field from July 2004 to March 2006 (French and others, 2010). Project collaborators conducted a relocation and directivity analysis based on data from 16 of the 48 TUCAN stations. They determined the rupture was on a vertical, N60°E striking main shock plane; a secondary fault, with a strike of N350°E-N355°E, was also activated during the 5 hours following the main event.

The seismic analysis provided important insight into the regional tectonic setting while also characterizing activity that was independent from the coincident volcanism at Concepción Volcano. Just six days prior to the 3 August 2005 Mw 6.3 event, INETER reported high local seismicity and an ash explosion from Concepción (BGVN 30:07). Explosive activity had begun on 28 July but they lacked any other local diagnostic signatures at Maderas or Concepción related to the Mw 6.3 event. French and others (2010) conclude that "the eruption was not triggered at short time scales by stress transfer from slip on this fault. No earthquakes in [the] analysis relocated beneath Concepción either before or after the eruption."

These were also significant findings as they correlate well with the larger interpretation of the region's tectonic setting, supporting the "bookshelf model" (LaFemina and others, 2002). This model addresses the complexities of Nicaragua's deforming tectonic blocks that include clockwise rotation and slip on NE-striking left-lateral faults.

Volcanic history. In 2009, field investigations by Michigan Technological University student Lara Kapelanczyk yielded new age dates and geologic mapping for Maderas. Previous investigators had characterized Maderas as a small-volume (~30 km3) stratovolcano (Carr and others, 2007), lacking historic volcanic activity (Borgia and others, 2000), and having unique structural characteristics variously attributed to gravitational spreading (van Wyk de Vries and Borgia, 1996) and localized faulting (Mathieu and others, 2011).

Geologic mapping and rock sampling during field campaigns in 2009 contributed to new insight about the eruptive history of Maderas as well as the geologic hazards of the area. Geomorphologic characteristics also distinguish Maderas as an older volcanic site compared to its frequently active neighbor, Concepción (figure 4). Satellite remote sensing also distinguishes deep ravines that cut through the edifice of Maderas, features that suggest long-term, uninterrupted erosion. As recent as March 2010 (BGVN 36:10), Concepción has erupted ash and tephra.

Figure (see Caption) Figure 4. A view across Lake Nicaragua in March 2010 toward the twin volcanoes on Ometepe Island, Concepción (left) and Maderas (right). Intermittent ash explosions characterized Concepción's activity in 2010. In this view, a diffuse ash plume covered Concepción's summit and was dissipating at a low altitude, spreading toward the shoreline. Courtesy of Lara Kapelanczyk, Michigan Technological University.

Geochemical data and 40Ar/39Ar dating determined that Maderas is an andesitic volcano with lava flows dating from 179.2 ± 16.4 ka to 70.4 ± 6.1 ka. These ages are significant in that, for the first time, quantitative data shows that Maderas has not been active for tens of thousands of years.

Kapelanczyk (2011) concluded that, during its lifespan, edifice construction at Maderas was marked by fault displacements that cross the major sectors of the volcano (figure 5). These major events led to the formation of a central graben and distinguish two phases of activity at Maderas: cone growth with pre-graben lava flows and post-graben lava flows. Pre-graben activity included the formation of a lateral vent and two littoral maars to the NE while post-graben activity included a lateral vent to the NW. Maar structures were also described in this research as well as structural information about the summit crater which includes a small lake, Laguna de Maderas (figure 6).

Figure (see Caption) Figure 5. Geologic map of Maderas volcano (Kapelancyzk and others, 2012). Note the normal faults (heavy black lines) bounding the NNW-trending graben crossing the structure, an extension of the San Ramon fault zone (Funk and others, 2009). Pre- and post-graben lithologies and structures were recognized by Kapelancyzk (2011). Laguna de Maderas appears as the gray area within the summit crater.
Figure (see Caption) Figure 6. View inside of the Maderas summit crater looking SE toward Laguna de Maderas, the summit crater lake. Courtesy of Lara Kapelanczyk, Michigan Technological University.

Based on the new information about Maderas's volcanic history, the risk associated with eruptions is considered low (Kapelanczyk, 2011). However, geophysical monitoring is important due to processes such as occasional, significant earthquakes and the potential for debris flows on the steep flanks.

In 1996 a deadly lahar occurred on the E flank (BGVN 21:09). This event was triggered during a heavy rainstorm and released a significant volume of material, enough to destroy the town of El Corozal and other settlements nearby. Deep, steep-sided ravines have cut through the slopes, especially on the lower NE and SW flanks (figure 7).

Figure (see Caption) Figure 7. This satellite image of Ometepe Island was processed by GVP using near-, mid-infrared, and infrared bands (4,5,7). Water-poor soils appear cyan; brown-to-red areas indicate moist soils; water is black. A small pond is located within the circular crater of Maderas (Laguna de Maderas) and deep erosional features radiate from the summit, distinguishing the relatively older edifice from the neighboring volcano, Concepción. Recent lava flows on Concepción appear black/blue and have distinctive terminal lobes. Landsat acquired this ETM+ image on 27 January 2000 (NASA Landsat Program, 2003).

References. Borgia, A., Delaney, P.T. and Denlinger, R.P., 2000. Spreading volcanoes. Annual Review of Earth and Planetary Sciences, 28, 539-570.

Carr, M.J., Saginor, I., Alvarado, G.E., Bolge, L.L., Lindsay, F.N., Milidakis, K., Turrin, B.D., Feigenson, M.D. and Swisher, C.C., 2007. Element fluxes from the volcanic front of Nicaragua and Costa Rica. Geochemistry, Geophysics, Geosystems (G3), 8, 6.

French, S.W., Warren, L.M., Fischer, K.M., Abers, G.A., Strauch, W., Protti, J.M., and Gonzalez, V., 2010. Constraints on upper plate deformation in the Nicaraguan subduction zone from earthquake relocation and directivity analysis, Geochemistry, Geophysics, Geosystems (G3), 11, 3.

Funk, J., Mann, P., McIntosh, K., and Stephens, J., 2009. Cenozoic tectonics of the Nicaraguan depression, Nicaragua, and Median Trough, El Salvador, based on seismic-reflection profiling and remote-sensing data, GSA Bulletin 121, 11-12, 1491-1521.

Kapelanczyk, L.N., 2011. An eruptive history of Maderas Volcano using new 40Ar/39Ar ages and geochemical analyses [Master's thesis]: Houghton, MI, Michigan Technological University, 118 p.

Kapelanczyk, L.N., Rose, W.I., and Jicha, B.R., 2012. An eruptive history of Maderas volcano using new 40Ar/39Ar ages and geochemical analyses. Bulletin of Volcanology, In Review.

LaFemina, P.C., Dixon, T.H., and Strauch, W., 2002. Bookshelf faulting in Nicaragua, Geology, 30, 751-754.

Mathieu, L., van Wyk de Vries, B., Pilato, M. and Troll, V.R., 2011. The interaction between volcanoes and strike-slip, transtensional and transpressional fault zones: Analogue models and natural examples. Journal of Structural Geology, 33, 898-906.

NASA Landsat Program, 2003, Landsat ETM+ scene 7dx20000127, SLC-Off, USGS, Sioux Falls, Jan. 27, 2000.

van Wyk de Vries, B. and Borgia, A., 1996. The role of basement in volcano deformation. Geological Society Special Publication, 110, 95-110.

Geologic Background. Volcán Maderas is a roughly conical stratovolcano that forms the SE end of the dumbbell-shaped Ometepe island in Lake Nicaragua. The basaltic-to-trachydacitic edifice is cut by numerous faults and grabens, the largest of which is a NW-SE-oriented graben that cuts the summit and has at least 140 m of vertical displacement. The small Laguna de Maderas lake occupies the bottom of the 800-m-wide summit crater, which is located at the western side of the central graben. The SW side of the edifice has been affected by large-scale slumping. Several pyroclastic cones, some of which may have originated from littoral explosions produced by lava flow entry into Lake Nicaragua, are situated on the lower NE flank down to the level of Lake Nicaragua. The latest period of major growth was considered to have taken place more than 3000 years ago, but later detailed mapping has shown that the most recent dated eruptive activity took place about 70,000 years ago and that it has likely been inactive for tens of thousands of years (Kapelanczyk et al., 2012). A lahar in September 1996 killed six people in an E-flank village, but associated volcanic activity was not confirmed.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); Global Land Cover Facility (URL: http:// http://www.glcf.umiacs.umd.edu/); National Earthquake Information Center (NEIC), US Geological Survey, Geologic Hazards Team Office, Colorado School of Mines, 1711 Illinois St., Golden, CO 80401, USA (URL: https://earthquake.usgs.gov/); La Prensa (URL: http://archivo.laprensa.com.ni).


Puyehue-Cordon Caulle (Chile) — March 2012 Citation iconCite this Report

Puyehue-Cordon Caulle

Chile

40.59°S, 72.117°W; summit elev. 2236 m

All times are local (unless otherwise noted)


June 2011 eruption emits circum-global ash clouds

Until 4 June 2011, the volcanic complex named Puyehue-Cordón Caulle had been quiet since its last major eruption in 1960. This report summarizes an increase in seismicity in early 2011 and the ensuing eruption that began on 4 June 2011. Our previous and only reports on the complex were in March and April 1972, which offered and then dismissed a report of a 1972 eruption (CSLP Cards 1362 and 1371). Information here goes through 2011 but omits some remote sensing observations. The eruption continued through at least April 2012, but in March and again in April 2012 the eruption's diminished vigor resulted in successively lowered alert statuses. During the height of the eruption the vent emitted ash plumes and generated significant ashfall, and flights were cancelled as far away as Australia and New Zealand. Pyroclastic flows occurred, with runout distances up to 10 km.

The Puyehue-Cordón Caulle complex includes Puyehue volcano at the SE end and the Cordillera Nevada caldera at the NW end. The current eruption discussed here vented at a location roughly between these two features, along the same fissure complex that had been active in the 1960 eruption. Available information failed to disclose any other eruptive sites during the reporting interval. Although the eruption continues as this report goes to press in March 2012, the report discusses activity only during 2011. A subsequent report will discuss further details, including satellite data on eruptive plumes, and updates since the end of the 2011 reporting period. This report also contains a table that condenses reporting from the Buenos Aires Volcanic Ash Advisory Center (VAAC).

Precursory seismicity. The Southern Andes Volcanological Observatory-National Geology and Mining Service (SERNAGEOMIN) reported that on 26 April 2011 an overflight of the volcano was conducted in response to recent increased seismicity and observations of fumarolic activity by nearby residents. Scientists confirmed fumarolic activity, but did not observe any other unusual activity.

On 27 April a seismic swarm (with about 140 events under ML 3.0) was detected at depths of 4-6 km below the complex. Most were hybrid earthquakes, the largest being M 3.9. Lower levels of seismicity continued through 29 April. That day the Alert Level was raised to Yellow (on a scale from Green to Yellow to Red).

According to SERNAGEOMIN, between 2000 on 2 June and 1959 on 3 June 2011, about 1,450 earthquakes occurred at Puyehue-Cordón Caulle (~60 earthquakes/hour, on average). More than 130 earthquakes occurred with magnitudes greater than 2.0. The earthquakes were mostly hybrid and long-period, and located in the SE sector of the Cordón Caulle rift zone at depths of 2-5 km. A flight over the volcano revelaed no significant changes. Area residents reported feeling earthquakes during the evening of 3 June through the morning of 4 June.

For a six-hour period on 4 June, seismicity increased to an average of 230 earthquakes/hour, with hypocenter depths of 1-4 km. About 12 events were of magnitudes greater than 4.0, and 50 events were of magnitudes greater than 3.0. As a result of the increased seismicity, the Alert Level was raised from Yellow to Red on 4 June.

Eruption. On 4 June 2011, an explosion from Cordón Caulle produced a set of plumes, including an ash plume described as 5 km wide and with its top at ~12 km altitude. Portions of the plume bifurcated; at ~5 km altitude a part of the plume drifted S, and at ~10 km altitude parts drifted W and E. A news account (Agency France-Presse) around this time, quoting a government official, said the eruption would lead to the evacuation of 4,270 residents.

According to the Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI), SERNAGEOMIN had noted the presence of pyroclastic flow deposits, but not lava. Residents reported a strong sulfur odor and significant ash and pumice fall. According to the BBC, the number of evacuees rose to 3,500-4,000 during the next several days.

According to SERNAGEOMIN, the eruption from the Cordón Caulle rift zone, although somewhat diminished, continued on 5 June. At least five pyroclastic flows were generated from partial collapses of the eruptive column and traveled N in the Nilahue River drainage. These pyroclastic flows extended up to 10 km from the vent.

Figures 1-3 show scenes of the volcano from various perspectives, including a natural color January 2012 image from space.

Figure (see Caption) Figure 1. Puyehue-Cordón Caulle's eruption seen in a long-exposure photo taken during 4-6 June 2011. The photo depicts molten material discharging over a wide area near the eruption column's base. Above the glowing, molten material there grew a substantial, rapidly rising ash plume. Much of the scene is lit by numerous bolts of lightning. Courtesy of Daniel Basualto, European Pressphoto Agency.
Figure (see Caption) Figure 2. A long-exposure photograph of the eruption at the Puyehue-Cordón Caulle complex taken on 5 June 2011. The complex scene shows a wide eruption column aglow with prominent lightning strikes branching across its surface. The long exposure is evidenced by the long star trails (with stars forming streaks due to the Earth's rotation) and the superimposition of many distinct bolts of lightning. Courtesy of Franscisco Negroni, Agencia Uno/European Pressphoto Agency.
Figure (see Caption) Figure 3. Satellite photo acquired on 26 January 2012 of the Puyehue-Cordón Caulle area. The natural color image was taken by the Advanced Land Imager aboard the Earth Observing (EO-1) satellite. The emissions, which blow in a narrow band toward the SE, can clearly be observed emanating from the Cordón Caulle fissure complex and not from the Puyehue volcano itself. According to a NASA Earth Observatory report, after 8 months of ceaseless activity, the landscape around the Puyehue-Cordón Caulle complex was covered in ash. The light-colored ash appears most clearly on the rocky, alpine slopes surrounding the active vent and the Puyehue caldera. Within the caldera, the ash appears slightly darker, possibly because it may be resting on wet snow that is melting and ponding during the South American summer. NASA also noted that evergreen forests on the E side of the volcano complex have been damaged by months of nearly continuous ashfall, and are now an unhealthy brown, while forests to the W had only received intermittent coatings of ash and appeared relatively healthy. Courtesy of NASA (Robert Simmon, Mike Carlowicz, and Jesse Allen).

Eruptive plumes were dense, oftentimes continuous, and extended E over Argentina and then the Atlantic Ocean (table 1). Ashfall reached up to about 15 cm thick in Argentina and adjacent parts of Chile (figures 4-6). Numerous flights were cancelled as far away as Australia and New Zealand, and many airports were forced to close temporarily (see section below).

Table 1. The Puyehue-Cordón Caulle ash plume altitudes and drift distances and directions documented by aviation authorities between 4 June 2011 and 3 January 2012. A plume on any particular date may be a continuation of a plume on the previous day(s). All maximum plume heights are stated in altitudes (a.s.l.). '-' indicates data not reported. Cloud cover often prevented video camera and satellite observations. Data from the Buenos Aires Volcanic Ash Advisory Center (VAAC) and SERNAGEOMIN.

Date (2011) Max. plume altitude (km) Plume drift Remarks
04 Jun 10.7-13.7 870 km ESE 5-km-wide ash-and-gas plume.
05 Jun 10.7-12.2 1,778 km ESE Plume drifted over Atlantic Ocean toward Australia.
06 Jun -- 178 km ENE --
07 Jun 5.5-9.8 E Continuous emission, plume 65-95 km wide; large ash cloud drifted E over Atlantic Ocean.
08 Jun 10 1,200 km NE, SE Plume moved over Atlantic Ocean.
09 Jun -- 200 km ENE Cloud cover obscured view.
10 Jun 6 SE Cloud cover obscured view.
11 Jun 6-10 350 km E, 600 km ENE Explosion caused plume to rise to 10 km a.s.l.
12 Jun 10 300 km E, 1,000 km ENE Series of explosions, tremor lasted 2 hr, 20 min; 4 hybrid earthquakes.
13 Jun 11 250 km SE Incandescence, tremor.
14 Jun 5.5-7.6 -- Explosions generated pyroclastic flows.
15 Jun-21 Jun 4-8 1,400 km ESE Small explosions on 15 June, ashfall heavy, pulses of tremor.
22 Jun-28 Jun 4-6 1,450 km NNW, 200-900 km various Active lava flow.
29 Jun-05 Jul 4-6 200-900 km NW, N, E Active lava flow.
06 Jul-12 Jul 3-4 75 km NE Explosions on 7-8 Jul caused windows to vibrate in Riñinahue.
13 Jul-19 Jul 4-7 80-240 km E, 150 km NW Incandescence on 18 July. Active lava flow.
20 Jul-26 Jul 3-5 100-250 km E, SE, 80 km E Incandescence on 20 Jul. Active lava flow.
27 Jul-02 Aug 4-7 100-200 km SE, 80-400 km various Incandescence on 26 and 29-30 Jul. Active lava flow.
03 Aug-09 Aug 4-5 100-700 km SE, 1,000 km NE --
10 Aug-16 Aug 4 100-150 km E, SE Mostly white plumes.
17 Aug-23 Aug 4-6 200-270 km NW, 500 km NW, SE Two explosions, harmonic tremor for 25 minutes; incandescence on 18-19 Aug.
24 Aug-30 Aug 3 -- Four explosions; ashfall in Temuco.
31 Aug-06 Sep 3 30-80 km SE, E --
07 Sep-13 Sep 3-6 10-60 km NE, E, SE --
14 Sep-20 Sep 5-6 60 km E, 40-70 km N, NW --
21 Sep-27 Sep 5-7 30-300 km various --
28 Sep-04 Oct 6 30-300 km various --
05 Oct-11 Oct 6 30-60 km various --
12 Oct-18 Oct 5-7 30-200 km various --
19 Oct-25 Oct 4-10 50-250 km various Explosion and incandescence on 22 Oct; lava flows reported on previous days.
26 Oct-01 Nov 7-10 30-350 km various Small incandescent explosions on 28-31 Oct.
02 Nov-08 Nov 4-7 30-120 km various --
09 Nov-15 Nov 6-9 90-250 km NE, 200 km NW, 400 km SE Small explosions and incandescence; ashfall on Chile/Argentine border.
16 Nov-22 Nov 5-6 250 km SE, 100 km SW Incandescence on 20 Nov.
23 Nov-29 Nov 5-6 -- Ash plume reached Atlantic Ocean.
30 Nov-06 Dec 4-5 90-100 km various Incandescence.
07 Dec-13 Dec 5-6 90 km SE, 250 km ENE Ashfall to E.
14 Dec-20 Dec 5 30-270 km SE, S, NE --
21 Dec-27 Dec 3-7 20-250 km various Small incandescent explosions.
28 Dec-03 Jan 2012 3-7 20-260 km various Small incandescent explosions; ash fell up to 580 km SE, in Argentina.
Figure (see Caption) Figure 4. Photograph published on 6 June 2011 of workers using earth-moving equipment to remove the ash that fell 100 km SE of the Puyehue-Cordón Caulle in San Carlos de Bariloche, Argentina. As discussed in a subsection below, the ash led to the cancellation of numerous public activities, and flights were suspended. Courtesy of Alfredo Leiva, Associated Press.
Figure (see Caption) Figure 5. Photograph of an Air Austral jet stranded at the airport at San Carlos de Beriloche, Argentina, on 7 June 2011 after being covered with ash that blew over the Andes from the Puyehue-Cordón Caulle complex. Courtesy of Alfredo Leiva, Associated Press.
Figure (see Caption) Figure 6. A member of the media walks along a road covered with ash from the Puyehue-Cordón Caulle complex that crossed Cardenal Samoré pass, a major linkage along the border between Argentina and Chile. Courtesy of Ivan Alvarado, Reuters.

According to news accounts (BBC, MailOnline, Merco Press), the Nilahue river, which runs off the N slopes of the volcano, became clogged with ash and overflowed its banks. The press reports said that the river water was steaming, having been locally heated up to 45°C by hot volcanic material, and more than four million salmon and other fish died.

During 4-5 June, ashfall several centimeters thick was reported in San Carlos de Bariloche, Argentina (about 100 km SE of the volcano) and in surrounding areas (figures 4-6). ONEMI reported that the Cardenal Samoré mountain pass border crossing between Argentina and Chile had temporarily closed on 4 June due to poor visibility caused by the heavy ashfall. According to a press report (EMOL), the road crossing the border was covered with ash that locally reached 10-15 cm thick. According to MailOnline and Boston.com, ash covered Lake Nahuel Huapi, Argentina's largest lake, which lies in the eastern foothills of the Andes. Videos documenting the eruption are abundant on the YouTube website (a search there using "Puyehue volcano" brings up over 400 hits. See several examples in the Reference list below).

By 9 June 2011, pumice and vitreous tephra had accumulated in many area lakes and rivers, darkening the color or their waters (figure 7).

Figure (see Caption) Figure 7. Photo of ash-clogged Nilahue River (Chile) with steam hanging above the river. Courtesy of Reuters.

A government observation flight on 11 June revealed that the vent was located at the head of the Nilahue River's basin, a spot immediately N of the 1960 eruption fissure. Observers found that abundant amounts of ash had accumulated around the vent, as well as to the E and SW.

Scientists aboard an observation flight on 13 June reported that the eruption formed a cone located in the center of a crater ~300 to ~400 m in diameter. Gas-and-steam plumes rose from two or three locations along the same fissure as the eruptive vent. Scientists watching a strong ash emission saw the lower part of the ash column collapse. Dark gray ash plumes that rose to an altitude of ~11 km. Instrumental records around that time registered pulses of tremor. At other points on 13 June, plume heights oscillated.

On 20 June, a news article (Agency France-Presse) reported that authorities had ended the evacuation, enabling residents to return home.

SERNAGEOMIN personnel along with regional authorities flew over the Puyehue-Cordón Caulle complex on 20 June. They observed a viscous lava flow, confirming speculation of magma ascent based on seismic data from the previous few days. A 50-m-wide lava flow had traveled 200 m NW and 100 m NE from the point of emission, filling a depression. A white plume with a gray base rose 3-4 km above the crater. Devastated vegetation from pyroclastic flows was observed near the Nilahue and Abutment rivers. Pulses of tremor were detected by the seismic network.

Plumes continued through at least the end of 2011. Although there were no new aerial observations, the seismic signals indicated that the lava flow remained active. Ashfall was periodically reported in areas downwind, including on 22 June in Riñinahue (5-10 mm of ash), Llifen, Futrono, and Curarrehue, and on 25 June in Riñinahue, Pucón, and Melipeuco (in the region of Araucanía).

Decline in seismicity. By the end of June, seismic activity had decreased further. During July through at least 31 December 2011, the eruption continued at a low level. Numerous plumes (mostly white, but sometimes containing ash) were noted during this period, often rising as high as 2.5 km above the crater (4.7 km altitude) and occasionally higher. Cloudy weather often prevented satellite and camera observations. Some of the ash plumes dropped ash in nearby communities, and some ash plumes extended for hundreds of kilometers, continuing to disrupt air traffic. Occasional incandescence and lava flows were noted.

During 18-19 August 2011, a period of harmonic tremor lasted about 25 minutes and may have indicated lava emission. Incandescence was observed at night. An observation flight on 19 August showed that solidified lava had filled up a depression around the cliffs of the Cordón Caulle area; no active lava flows were noted.

On 30 October 2011 seismicity indicated a possible minor lava effusion. Ashfall was reported in Río Bueno (80 km WNW).

During the night of 11-12 November 2011, crater incandescence and small explosions were observed. Satellite imagery showed ash plumes drifting 90 km NE on 11 November and 400 km SE on 12 November. Ash fell in areas on the border of Chile and Argentina, and at Paso Samore on 12 November. As of 31 December 2011, the Alert Level remained at Red.

Disruption of airline traffic. Based upon a review of news accounts on the Internet, the massive ash plumes resulting from the eruption caused major delays and cancellations of air traffic worldwide. Between 4-14 June, numerous flights were cancelled or disrupted in Paraguay, Chile, southern Argentina, Uruguay, and Brazil. News accounts (Reuters, CBS News, Global Media Post) reported that the two major airports serving Buenos Aires, Argentina, and the international airport in Montevideo, Uruguay, closed for several days as did many airports in southern Argentina, including those in Patagonia. One of the worst hit airports serves the ski resort city of San Carlos de Bariloche, Argentina. On 9 June alone, workers removed about 15,000 tons of volcanic ash (600 truckloads) from the airport's main runway.

According to news accounts (Sydney Morning Herald, Agency France-Presse, Stuff, Australian Associated Press), by the middle of June, the ash plume that had been drifting mostly E since the beginning of the eruption had reached Australia and New Zealand. This caused flight disruptions and airport closures in Australia.

By the third week in June, according to the Associated Press, plumes from the eruption had circumnavigated the globe, arrived in the W part of Chile (in Coyhaique, 550 km S of the volcano), and again caused the cancellation of domestic flights. During the last week of June, numerous flights in and around Argentina and Chile were again cancelled, as well as some flights in Uruguay. According to Stuff, Associated Press, and South Africa To, ash from the second circumnavigation of the ash plume again disrupted flights at Capetown and Port Elizabeth, South Africa, as well as in Australia.

During the first two weeks of July, numerous flights in and around Argentina and Uruguay were cancelled and some airports remained closed. According to Merco, the first private plane landed around 17 July at the airport in Bariloche, Argentina, since the airport had closed on 4 June. On 17 September, the first commercial flights resumed at Bariloche.

Ash clouds remained a problem for months after the eruption. According to news articles, several domestic and international flights in Argentina, Brazil, Chile and Uruguay were cancelled on 16 October due to re-suspended ash kicked up by high winds in the region. Flights resumed the next day. According to the Agency France-Presse, airborne ash again disrupted or cancelled flights in Uruguay and Argentina on 22 and 26 November.

References (sample of videos available on Youtube):

1. !!Rock, ash fill overflowing river in Chile (Cordon Caulle)!!; MSNBC.com, uploaded by ThisisMotherNature on 10 June 2011. URL: http://www.youtube.com/watch?v=Mw3132MPfvE [Lahar scenes; MSNBC newscast in English]

2. Chile Volcano Erupts (Breathtaking Raw Video) 4th June 2011; (original author uncertain), uploaded by horrificStorms on 14 June 2011. URL: http://www.youtube.com/watch?feature=fvwp&NR=1&v=ZIq0tlYVb9U [Umbrella cloud forms above rising ash plume, seen from the ground; a yet-unidentified newscast]

3. Dormant Puyehue volcano in Chile erupts after lying dormant for decades; SkyNews, 2011, uploaded by TruthTube451 on 5 June 2011. URL: http://www.youtube.com/watch?NR=1&feature=endscreen&v=xhANgMJdvsk Source: SkyNews (URL: http://news.sky.com) [Newscast showing rising plumes, ashfall, and scenes of mitigation efforts]

4. Buzo intentando nadar en el lago Nahuel Huapi, el cuál se encuentra cubierto por una gruesa capa de cenizas volcánicas emitidas por volcán Puyehue. Uploaded by SonyOficial on 14 June 2011. URL: http://www.youtube.com/watch?v=4_cXUVZJxP8&feature=fvsr [An amusing attempt to enter Nahuel Huapi Lake to scuba dive beneath a thick mat of floating tephra. This video exceeded 1 million views on 16 November 2011.]

Geologic Background. The Puyehue-Cordón Caulle volcanic complex (PCCVC) is a large NW-SE-trending late-Pleistocene to Holocene basaltic-to-rhyolitic transverse volcanic chain SE of Lago Ranco. The 1799-m-high Pleistocene Cordillera Nevada caldera lies at the NW end, separated from Puyehue stratovolcano at the SE end by the Cordón Caulle fissure complex. The Pleistocene Mencheca volcano with Holocene flank cones lies NE of Puyehue. The basaltic-to-rhyolitic Puyehue volcano is the most geochemically diverse of the PCCVC. The flat-topped, 2236-m-high volcano was constructed above a 5-km-wide caldera and is capped by a 2.4-km-wide Holocene summit caldera. Lava flows and domes of mostly rhyolitic composition are found on the E flank. Historical eruptions originally attributed to Puyehue, including major eruptions in 1921-22 and 1960, are now known to be from the Cordón Caulle rift zone. The Cordón Caulle geothermal area, occupying a 6 x 13 km wide volcano-tectonic depression, is the largest active geothermal area of the southern Andes volcanic zone.

Information Contacts: Southern Andes Volcanological Observatory-National Geology and Mining Service (SERNAGEOMIN), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); 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/productos.php); Robert Simmon, Mike Carlowicz, and Jesse Allen, NASA Earth Observatory (URL: http://earthobservatory.nasa.gov); Agency France-Presse (URL: http://www.afp.com/afpcom/en/); Associated Press (URL: http://www.ap.org/); Australian Associated Press (AAP) (URL: http://aap.com.au/); BBC News (URL: http://www.bbc.co.uk/); Big Pond News (URL: http://bigpondnews.com); Boston.com (URL: http://www.boston.com); CBS News (URL: https://www.cbsnews.com/); EMOL (URL: http://www.emol.com/); europaPress (URL: http://www.europapress.es); European Pressphoto Agency (URL: http://wn.com/european_pressphoto_agency); Flight Global (URL: http://www.flightglobal.com); Global Media Post (URL: http://www.globalmediapost.com; La Mañana Neuquén (URL: http://www.lmneuquen.com.ar/); Mail Online (URL: http://www.dailymail.com.uk); MercoPress (URL: http://en.mercopress.com); Reuters (URL: http://www.reuters.com); Sky News (URL: news.sky.com); Stuff (URL: http://www.stuff.co.nz); South Africa To (URL: http://www.southafrica.to); Sydney Morning Herald (URL: http://news.smh.com.au/); The Telegraph (URL: http://bigpondnews.com).


Reventador (Ecuador) — March 2012 Citation iconCite this Report

Reventador

Ecuador

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

All times are local (unless otherwise noted)


Dome growth; lava and pyroclastic flows; lahar takes bridge

Reventador discharged a series of small eruptions and lava flows during 2007-2009 (BGVN 33:04; 33:08; 34:03; and 34:09). Our last report (BGVN 34:09) discussed events through 26 October 2009. Since then seismicity generally remained moderate to low through at least April 2012, and ash emissions accompanying lava-dome growth intermittently occurred. Much of this report stems from work by the Instituto Geofísico-Escuela Politécnica Nacional (IG). The andesitic volcano contains a 4-km summit caldera that opens to form a large U-shaped scarp that funnels material SE (see map in BGVN 28:06). A VEI 4 eruption on 3 November 2002 (BGVN 27:11) occurred unexpectedly after a 26-year repose.

During this reporting interval, October 2009-April 2012, small plumes with occasional ash emissions accompanied dome growth (table 5). In August 2011, the top of the growing lava dome first reached the same height as the highest part of the rim. MODVOLC thermal alerts, which are satellite based using the MODIS instrument, were absent during 2011, possibly due to masking effects of cloud cover. The two tallest plumes noted in table 5 rose to approximately 7 km altitude. In addition, as discussed below in text, pyroclastic flows were also seen during the reporting interval. Lahars were common, including one that destroyed a bridge over a river on the SE flank on 25 May 2010.

Table 5. Summary of behavior and plumes at Reventador between mid-October 2009 and 18 April 2012. Some aspects of the October 2009 activity were previously reported (BGVN 34:09). Cloud cover frequently prevented observations of the volcano, and minor plumes may not have been recorded or were omitted. Heights above crater were converted to altitude by adding the summit elevation of 3.6 km. '-' indicates data not reported. Data provided by the Instituto Geofísico-Escuela Politécnica Nacional (IG), the Guayaquil Meteorolgical Watch Office (MWO) in Ecuador, and the Washington Volcanic Ash Advisory Center (VAAC).

Date Plume altitude (km) Plume drift direction Remarks
14 Oct 2009 -- -- Increased seismicity and harmonic tremor. Residents during the middle of October heard roaring and booming noises and saw glowing.
16-17 Oct 2009 -- -- An IG field party saw a lava flow on the cone's S flank on the 16th and 17th. An overflight on the 16th also revealed a lava flow on the N flank.
19 Oct 2009 -- -- An areal infrared (FLIR) camera took images of S flank lava flows that covered a large area. A plume with little or no ash rose to 7.5 km altitude and drifted NW, W, and S. An explosion ejected glowing material from the crater and blocks rolled down the flanks.
21-22 Oct 2009 -- -- Aerial infrared observations again imaged the N flank lava flow, and detected multiple lobes in the S-flank flows. A part of the lava dome's base had been removed but the dome itself had gained some small spines, especially towards the S. Material near the crater had temperatures up to 400°C.
05 Nov 2009 7 NE Pilot report. Ash not seen in satellite imagery, although weather clouds were present.
07 Nov 2009 4 -- --
14 Nov 2009 -- 10-20 km W, WNW --
20 Nov 2009 6.1 -- --
18 Feb 2010 -- -- Ash not identified in satellite imagery.
08 Apr 2010 4.6-6.7 W Pilot report. Cloud cover prevented satellite observation.
20-23 Apr 2010 4.9-5.5 S 200-m-long pyroclastic flow seen during IG flight on 20th (see text). Plume height and direction from aviation reports on 23rd.
26 Apr 2010 4 -- --
29 Apr 2010 -- -- Low ash content.
07 May 2010 5.2 -- Pilot report. Cloud cover prevented satellite observation.
08 May 2010 -- -- IG reported lahars including some that later destroyed a bridge over Marker river (see text).
30 Aug 2010 -- -- Pilot report. Ash not seen in satellite imagery.
09 Sep 2010 5.5 -- Pilot report.
28 Sep 2010 5.6 NW Ash fell on Reventador amid seismic episodes (see text).
30 Sep 2010 -- NW Satellite detected diffuse plume but no ash. IG reported ash over Reventador.
06 Oct 2010 -- NE Steam plume also emitted that day.
02 Nov 2010 4.6 -- Cloud cover prevented satellite observation.
04 Jan 2011 5.2 -- Ash not detected by satellite, and no reports of ashfall. IG later inferred extensive dome growth during 2011 (see text).
14 Jul 2011 -- -- An IG flight revealed the dome's top had reached as high as the highest point on the rim. Plumes were continuous though fumarolic (probably not ash bearing). Seismicity had started in May 2011 but became more pronounced around the start of July.
03-09 Aug 2011 -- -- Cloud cover hid the lava dome but IG seismic instruments recored both long-period and explosion earthquakes.
06-07 Jan 2012 -- -- IG field inspection revealed constant steam-and-gas emissions a lava dome that rose ten's of meters above crater rim.
11 Feb 2012 5.2 NW Pilot report. IG noted that on the 12th, seismicity increased a lava flow was detected on the NE flank.
16 Feb 2012 -- 19 km SE Ash detected by satellite.
18 Feb 2012 3.6 -- --
26 Mar 2012 -- 25 km NNW --
18 Apr 2012 5.6 NW --

On 20 April 2010, IG scientists flying over Reventador saw an explosion that generated a pyroclastic flow. It traveled ~200 m down the S flank. Recent deposits from earlier pyroclastic flows were also seen on the same flank. Steam-and-gas emissions also continued. On 8 May 2010, IG noted a small lahar inside the caldera.

On 25 May a destructive lahar took place that was detected for 90 minutes by the seismic network. It traveled down the SE flank and destroyed a bridge over the Marker River, ~8 km SE of the summit area. The loss of the bridge disrupted travel along Route E45 between Baeza (~34 km SSW) to Lago Agrio (also called Nueva Loja, ~121 NE).

On 28 September 2010, IG recorded three seismic episodes from Reventador. Cloud cover prevented observations during the first episode. The second seismic episode was accompanied by a steam plume containing a small amount of ash that rose 400-500 m above the crater. The third episode occurred in conjunction with a steam-and-ash plume that rose 2 km above the crater. Ash fell on the flanks.

In May 2011, seismicity began to increase and became more pronounced by early July.

During an overflight on 14 July 2011, IG scientists noted that the lava dome at the top of the 2008 cone had continued to grow (figures 37 and 38). The dome had reached the same height, or higher, as the highest part of the crater rim formed during 2002 (figures 37 and 38). Intense fumarolic activity produced continuous plumes.

Figure (see Caption) Figure 37. Annotated photo of Reventador taken looking NW on 14 July 2011. The green lines trace the topographic margin of the summit caldera initially formed in the sudden 2002 eruption. The conical structure outlined in orange is a scoria or tephra cone (which includes some lavas) and spills out of the breach toward the viewer. The red line outlines the dome, initially seen in 2004, that grew substantially in 2011. Courtesy of J. Bustillos/Instituto Geofísico-Escuela Politécnica Nacional.
Figure (see Caption) Figure 38. Thermal image of Reventador crater for comparison with the visual image (figure 37), also taken 14 July 2011. The measured temperature of the growing dome was ~150°C. Courtesy of S. Vallejo/Instituto Geofísico-Escuela Politécnica Nacional.

During 3-9 August cloud cover prevented observations of the lava dome, but the seismic network detected long-period and explosion-type earthquakes.

During a field trip on 6-7 January 2012, IG staff observed constant emissions of gas and steam that originated from the growing lava dome. At this point in time the dome had broadened and stood a few ten's of meters above the crater rim.

During 10-13 February 2012, IG detected new activity, including a thermal anomaly, an ash plume, and crater incandescence. This elevated activity continued during 15-21 February. Incandescence near the summit was again observed during 25-26 March but seismicity decreased around this time.

In accordance with these other observations, occasional MODVOLC thermal alerts were posted. Between 1 November 2009-1 April 2012, there were 12 days with MODVOLC thermal alerts. No thermal alerts were detected in 2011. As of 26 April 2012, six days in 2012 had thermal alerts (10, 13, 22, 26 February, 18 March, and 26 April).

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

Information Contacts: Instituto Geofísico-Escuela Politécnica Nacional (IG), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Guayaquil Meteorological Watch Office (MWO); 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/); 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/).

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