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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

Bagana (Papua New Guinea) Intermittent gas-and-steam emissions and thermal anomalies during June-November 2019

Kerinci (Indonesia) Intermittent gas-and-steam and ash plumes during June-early November 2019

Bezymianny (Russia) Lava dome growth, ongoing thermal anomalies, moderate gas-steam emissions, June-November 2019

Mayon (Philippines) Gas-and-steam plumes and summit incandescence during May-October 2019

Merapi (Indonesia) Low-volume dome growth continues during April-September 2019 with rockfalls and small block-and-ash flows

Manam (Papua New Guinea) Significant eruption on 28 June produced an ash plume up to 15.2 km and pyroclastic flows

Tangkuban Parahu (Indonesia) Phreatic eruption on 27 July followed by intermittent explosions through to 17 September 2019

Sheveluch (Russia) Frequent ash explosions and lava dome growth continue through October 2019

Piton de la Fournaise (France) Three brief eruptive events in July, August, and October 2019

Agung (Indonesia) Quiet returns after explosions on 10 and 13 June 2019

Copahue (Chile-Argentina) New ash emissions begin in early August; intermittent and ongoing through October 2019

Turrialba (Costa Rica) Activity diminishes during March-October 2019, but small ash emissions continue



Bagana (Papua New Guinea) — December 2019 Citation iconCite this Report

Bagana

Papua New Guinea

6.137°S, 155.196°E; summit elev. 1855 m

All times are local (unless otherwise noted)


Intermittent gas-and-steam emissions and thermal anomalies during June-November 2019

Bagana volcano is found in a remote portion of central Bougainville Island in Papua New Guinea. The most recent eruptive phase that began in early 2000 has produced ash plumes and thermal anomalies (BGVN 44:06, 50:01). Activity has remained low between January-July 2019 with rare thermal anomalies and occasional steam plumes. This reporting period updates information for June-November 2019 and includes thermal anomalies and intermittent gas-and-steam emissions. Thermal data and satellite imagery are the primary sources of information for this report.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed an increased number of thermal anomalies within 5 km from the summit beginning in late July-early August (figure 38). Two Sentinel-2 thermal satellite images showed faint, roughly linear thermal anomalies, indicative of lava flows trending EW and NS on 7 July 2019 and 6 August, respectively (figure 39). Weak thermal hotspots were briefly detected in late September-early October after a short hiatus in September. No thermal anomalies were recorded in Sentinel-2 past August due to cloud cover; however, gas-and-steam emissions were visible on 7 July and in September (figures 39, 40, and 41).

Figure (see Caption) Figure 38. Thermal anomalies near the crater summit at Bagana during February-November 2019 as recorded by the MIROVA system (Log Radiative Power) increased in frequency and power in early August. A small cluster was detected in early October after a brief pause in activity in early September. Courtesy of MIROVA.
Figure (see Caption) Figure 39. Sentinel-2 thermal satellite imagery showing small thermal anomalies at Bagana between July-August 2019. Left: A very faint thermal anomaly and a gas-and-steam plume is seen on 7 July 2019. Right: Two small thermal anomalies are faintly seen on 6 August 2019. Both Sentinel-2 satellite images with "Atmospheric penetration" (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 40. A gas-and-steam plume rising from the summit of Bagana on 18 September 2019. Courtesy of Brendan McCormick Kilbride (University of Manchester).

The Deep Carbon Observatory (DCO) scientific team partnered with the Rabaul Volcano Observatory and the Bougainville Disaster Office to observe activity at Bagana and collect gas data using drone technology during two weeks of field work in mid-September 2019. For this field work, the major focus was to understand the composition of the volcanic gas emitted at Bagana and measure the concentration of these gases. Since Bagana is remote and difficult to climb, research about its gas emissions has been limited. The recent advancements in drone technology has allowed for new data collection at the summit of Bagana (figure 41). Most of the emissions consisted of water vapor, according to Brendan McCormick Kilbride, one of the volcanologists on this trip. During 14-19 September there was consistently a strong gas-and-steam plume from Bagana (figure 42).

Figure (see Caption) Figure 41. Degassing plumes seen from drone footage 100 m above the summit of Bagana. Top: Zoomed out view of the summit of Bagana degassing. Bottom: Closer perspective of the gases emitted from Bagana. Courtesy of Kieran Wood (University of Bristol) and the Bristol Flight Laboratory.
Figure (see Caption) Figure 42. Photos of gas-and-steam plumes rising from Bagana between 14-19 September 2019. Courtesy of Brendan McCormick Kilbride (University of Manchester).

Geologic Background. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.

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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Brendan McCormick Kilbride, University of Manchester, Manchester M13 9PL, United Kingdom (URL: https://www.research.manchester.ac.uk/portal/brendan.mccormickkilbride.html, Twitter: https://twitter.com/BrendanVolc); Kieran Wood, University of Bristol, Bristol BS8 1QU, United Kingdom (URL: http://www.bristol.ac.uk/engineering/people/kieran-t-wood/index.html, Twitter: https://twitter.com/DrKieranWood, video posted at https://www.youtube.com/watch?v=A7Hx645v0eU); University of Bristol Flight Laboratory, Bristol BS8 1QU, United Kingdom (Twitter: https://twitter.com/UOBFlightLab).


Kerinci (Indonesia) — December 2019 Citation iconCite this Report

Kerinci

Indonesia

1.697°S, 101.264°E; summit elev. 3800 m

All times are local (unless otherwise noted)


Intermittent gas-and-steam and ash plumes during June-early November 2019

Kerinci, located in Sumatra, Indonesia, is a highly active volcano characterized by explosive eruptions with ash plumes and gas-and-steam emissions. The most recent eruptive episode began in April 2018 and included intermittent explosions with ash plumes. Volcanism continued from June-November 2019 with ongoing intermittent gas-and-steam and ash plumes. The primary source of information for this report comes from Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), the Darwin Volcanic Ash Advisory Centre (VAAC), and MAGMA Indonesia.

Brown- to gray-colored ash clouds drifting in different directions were reported by PVMBG, the Darwin VAAC, and MAGMA Indonesia between June and early November 2019. Ground observations, satellite imagery, and weather models were used to monitor the plume, which ranged from 4.3 to 4.9 km altitude, or about 500-1,100 m above the summit. On 7 June 2019 at 0604 a gray ash emission rose 800 m above the summit, drifting E, according to a ground observer. An ash plume on 12 July rose to 4 km altitude and drifted SW, as determined by satellite imagery and weather models. An eruption produced a gray ash cloud on 31 July that rose to 4.6 km altitude and drifted NE and E, according to PVMBG and the Darwin VAAC (figure 17). Another ash cloud rose up to 4.3 km altitude on 3 August. On 2 September a possible ash plume rose to a maximum altitude of 4.9 km and drifted WSW, according to the Darwin VAAC advisory.

Figure (see Caption) Figure 17. A gray ash plume at Kerinci rose roughly 800 m above the summit on 31 July 2019 and drifted NE and E. Courtesy of MAGMA Indonesia.

Brown ash emissions rose to 4.4 km altitude at 1253 on 6 October, drifting WSW. Similar plumes reached 4.6 km altitude twice on 30 October and moved NE, SE, and E at 0614 and WSW at 1721, based on ground observations. On 1-2 November, ground observers saw brown ash emissions rising up to 4.3 km drifting ESE. Between 3 and 5 November the brown ash plumes rose 100-500 m above the summit, according to PVMBG.

Gas emissions continued to be observed through November, as reported by PVMBG and identified in satellite imagery (figure 18). Seismicity that included volcanic earthquakes also continued between June and early November, when the frequency decreased.

Figure (see Caption) Figure 18. Sentinel-2 thermal satellite imagery showing a typical white gas-and-steam plume at Kerinci on 9 August 2019. Sentinel-2 satellite image with "Atmospheric penetration" (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

Geologic Background. Gunung Kerinci in central Sumatra forms Indonesia's highest volcano and is one of the most active in Sumatra. It is capped by an unvegetated young summit cone that was constructed NE of an older crater remnant. There is a deep 600-m-wide summit crater often partially filled by a small crater lake that lies on the NE crater floor, opposite the SW-rim summit. The massive 13 x 25 km wide volcano towers 2400-3300 m above surrounding plains and is elongated in a N-S direction. Frequently active, Kerinci has been the source of numerous moderate explosive eruptions since its first recorded eruption in 1838.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Bezymianny (Russia) — December 2019 Citation iconCite this Report

Bezymianny

Russia

55.972°N, 160.595°E; summit elev. 2882 m

All times are local (unless otherwise noted)


Lava dome growth, ongoing thermal anomalies, moderate gas-steam emissions, June-November 2019

The long-term activity at Bezymianny has been dominated by almost continuous thermal anomalies, moderate gas-steam emissions, dome growth, lava flows, and an occasional ash explosion (BGVN 44:06). The volcano is monitored by the Kamchatka Volcanic Eruptions Response Team (KVERT. Throughout the reporting period of June to November 2019, the Aviation Colour Code remained Yellow (second lowest of four levels).

According to KVERT weekly reports, lava dome growth continued in June through mid-July 2019. Thereafter the reports did not mention dome growth, but indicated that moderate gas-and-steam emissions (figure 32) continued through November. The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, based on analysis of MODIS data, detected hotspots within 5 km of the summit almost every day. KVERT also reported a thermal anomaly over the volcano almost daily, except when it was obscured by clouds. Infrared satellite imagery often showed thermal anomalies generated by lava flows or dome growth (figure 33).

Figure (see Caption) Figure 32. Photo of Bezymianny showing fumarolic activity on 4 July 2019. Photo by O. Girina (IVS FEB RAS, KVERT); courtesy of KVERT.
Figure (see Caption) Figure 33. Typical infrared satellite images of Bezymianny showing thermal anomalies in the summit crater, including a lava flow to the WNW. Top: 21 August 2019 with SWIR filter (bands 12, 8A, 4). Bottom: 17 September 2019 with Atmospheric Penetration filter (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

Geologic Background. Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); 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).


Mayon (Philippines) — November 2019 Citation iconCite this Report

Mayon

Philippines

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

All times are local (unless otherwise noted)


Gas-and-steam plumes and summit incandescence during May-October 2019

Mayon, located in the Philippines, is a highly active stratovolcano with recorded historical eruptions dating back to 1616. The most recent eruptive episode began in early January 2018 that consisted of phreatic explosions, steam-and-ash plumes, lava fountaining, and pyroclastic flows (BGVN 43:04). The previous report noted small but distinct thermal anomalies, gas-and-steam plumes, and slight inflation (BGVN 44:05) that continued to occur from May into mid-October 2019. This report includes information based on daily bulletins from the Philippine Institute of Volcanology and Seismology (PHIVOLCS) and Sentinel-2 satellite imagery.

Between May and October 2019, white gas-and-steam plumes rose to a maximum altitude of 800 m on 17 May. PHIVOLCS reported that faint summit incandescence was frequently observed at night from May-July and Sentinel-2 thermal satellite imagery showed weaker thermal anomalies in September and October (figure 49); the last anomaly was identified on 12 October. Average SO2 emissions as measured by PHIVOLCS generally varied between 469-774 tons/day; the high value of the period was on 25 July, with 1,171 tons/day. Small SO2 plumes were detected by the TROPOMI satellite instrument a few times during May-September 2019 (figure 50).

Figure (see Caption) Figure 49. Sentinel-2 thermal satellite imagery of Mayon between May-October 2019. Small thermal anomalies were recorded in satellite imagery from the summit and some white gas-and-steam plumes are visible. Top left: 30 May 2019. Top right: 9 June 2019. Bottom left: 22 September 2019. Bottom right: 12 October 2019. Sentinel-2 satellite images with "Atmospheric penetration" (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 50. Small SO2 plumes rising from Mayon during May-September 2019 recorded in DU (Dobson Units). Top left: 28 May 2019. Top right: 26 July 2019. Bottom left: 16 August 2019. Bottom right: 23 September 2019. Courtesy of NASA Goddard Space Flight Center.

Continuous GPS data has shown slight inflation since June 2018, corroborated by precise leveling data taken on 9-17 April, 16-25 July, and 23-30 October 2019. Elevated seismicity and occasional rockfall events were detected by the seismic monitoring network from PHIVOLCS from May to July; recorded activity decreased in August. Activity reported by PHIVOLCS in September-October 2019 consisted of frequent gas-and-steam emissions, two volcanic earthquakes, and no summit incandescence.

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

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://SO2.gsfc.nasa.gov/).


Merapi (Indonesia) — October 2019 Citation iconCite this Report

Merapi

Indonesia

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

All times are local (unless otherwise noted)


Low-volume dome growth continues during April-September 2019 with rockfalls and small block-and-ash flows

Merapi is an active volcano north of the city of Yogyakarta (figure 79) that has a recent history of dome growth and collapse, resulting in block-and-ash flows that killed over 400 in 2010, while an estimated 10,000-20,000 lives were saved by evacuations. The edifice contains an active dome at the summit, above the Gendol drainage down the SE flank (figure 80). The current eruption episode began in May 2018 and dome growth was observed from 11 August 2018-onwards. This Bulletin summarizes activity during April through September 2019 and is based on information from Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG, the Center for Research and Development of Geological Disaster Technology, a branch of PVMBG), Sutopo of Badan Nasional Penanggulangan Bencana (BNPB), MAGMA Indonesia, along with observations by Øystein Lund Andersen and Brett Carr of the Lamont-Doherty Earth Observatory.

Figure (see Caption) Figure 79. Merapi volcano is located north of Yogyakarta in Central Java. Photo courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 80. A view of the Gendol drainage where avalanches and block-and-ash flows are channeled from the active Merapi lava dome. The Gendol drainage is approximately 400 m wide at the summit. Courtesy of Brett Carr, Lamont-Doherty Earth Observatory.

At the beginning of April the rate of dome growth was relatively low, with little morphological change since January, but the overall activity of Merapi was considered high. Magma extrusion above the upper Gendol drainage resulted in rockfalls and block-and-ash flows out to 1.5 km from the dome, which were incandescent and visible at night. Five block-and-ash flows were recorded on 24 April, reaching as far as 1.2 km down the Gendol drainage. The volume of the dome was calculated to be 466,000 m3 on 9 April, a slight decrease from the previous week. Weak gas plumes reached a maximum of 500 m above the dome throughout April.

Six block-and-ash flows were generated on 5 May, lasting up to 77 seconds. Throughout May there were no significant changes to the dome morphology but the volume had decreased to 458,000 by 4 May according to drome imagery analysis. Lava extrusion continued above the Gendol drainage, producing rockfalls and small block-and-ash flows out to 1.2 km (figure 81). Gas plumes were observed to reach 400 m above the top of the crater.

Figure (see Caption) Figure 81. An avalanche from the Merapi summit dome on 17 May 2019. The incandescent blocks traveled down to 850 m away from the dome. Courtesy of Sutopo, BNPB.

There were a total of 72 avalanches and block-and-ash flows from 29 January to 1 June, with an average distance of 1 km and a maximum of 2 km down the Gendol drainage. Photographs taken by Øystein Lund Andersen show the morphological change to the lava dome due to the collapse of rock and extruding lava down the Gendol drainage (figures 82 and 83). Block-and-ash flows were recorded on 17 and 20 June to a distance of 1.2 km, and a webcam image showed an incandescent flow on 26 June (figure 84). Throughout June gas plumes reached a maximum of 250 m above the top of the crater

Figure (see Caption) Figure 82. The development of the Merapi summit dome from 2 June 2018 to 17 June 2019. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 83. Photos taken of the Merapi summit lava dome in June 2019. Top: This nighttime time-lapse photograph shows incandescence at the south-facing side of the dome on the 16 June. Middle: A closeup of a small rockfall from the dome on 17 June. Bottom: A gas plume accompanying a small rockfall on 17 June. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 84. Blocks from an incandescent rockfall off the Merapi dome reached out to 1 km down the Gendol drainage on 26 June 2019. Courtesy of MAGMA Indonesia.

Analysis of drone images taken on 4 July gave an updated dome volume of 475,000 m3, a slight increase but with little change in the morphology (figure 85). Block-and-ash flows traveled 1.1 km down the Gendol drainage on 1 July, 1 km on the 13th, and 1.1 km on the 14th, some of which were seen at night as incandescent blocks fell from the dome (figure 86). During the week of 19-25 July there were four recorded block-and-ash flows reaching 1.1 km, and flows traveled out to around 1 km on the 24th, 27th, and 31st. The morphology of the dome continued to be relatively stable due to the extruding lava falling into the Gendol drainage. Gas plumes reached 300 m above the top of the crater during July.

Figure (see Caption) Figure 85. The Merapi dome on 30 July 2019 producing a weak plume. Courtesy of MAGMA Indonesia.
Figure (see Caption) Figure 86. Incandescent rocks from the hot lava dome at the summit of Merapi form rockfalls down the Gendol drainage on 14 July 2019. Courtesy of Øystein Lund Andersen.

During the week of 5-11 August the dome volume was calculated to be 461,000 m3, a slight decrease from the week before with little morphological changes due to the continued lava extrusion collapsing into the Gendol drainage. There were five block-and-ash flows reaching a maximum of 1.2 km during 2-8 August. Two flows were observed on the 13th and 14th reaching 950 m, out to 1.9 km on the 20th and 22nd, and to 550 m on the 24th. There were 16 observed flows that reached 500-1,000 m on 25-27 August, with an additional flow out to 2 km at 1807 on the 27th (figure 87). Gas plumes reached a maximum of 350 m through the month.

Figure (see Caption) Figure 87. An incandescent rockfall from the Merapi dome that reached 2 km down the Gendol drainage on 27 August 2019. Courtesy of BPPTKG.

Brett Carr was conducting field work at Merapi during 12-26 September. During this time the lava extrusion was low (below 1 m3 per second). He observed small rockfalls with blocks a couple of meters in size, traveling about 50-200 m down the drainage every hour or so, producing small plumes as they descended and resulting in incandescence on the dome at night. Small dome collapse events produced block-and-ash flows down the drainage once or twice per day (figure 88) and slightly larger flows just over 1 km long a couple of times per week.

Figure (see Caption) Figure 88. A rockfall on the Merapi dome, towards the Gendol drainage at 0551 on 20 September 2019. Courtesy of Brett Carr, Lamont-Doherty Earth Observatory.

The dome volume was 468,000 m3 by 19 September, a slight increase from the previous calculation but again with little morphological change. Two block-and-ash flows were observed out to 600 m on 9 September and seven occurred on the 9th out to 500-1,100 m. Two occurred on the 14th down to 750-900 m, three occurred on 17, 20, and 21 September to a maximum distance of 1.2 km, and three more out to 1.5 km through the 26th. A VONA (Volcano Observatory Notice for Aviation) was issued on the 22nd due to a small explosion producing an ash plume up to approximately 3.8 km altitude (about 800 m above the summit) and minor ashfall to 15 km SW. This was followed by a block-and-ash flow reaching as far as 1.2 km and lasting for 125 seconds (figure 89). Preceding the explosion there was an increase in temperature at several locations on the dome. Weak gas plumes were observed up to 100 m above the crater throughout the month.

Figure (see Caption) Figure 89. An explosion at Merapi on 22 September 2019 was followed by a block-and-ash flow that reached 1.2 km down the Gendol drainage. Courtesy of BPPTKG.

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

Information Contacts: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), Center for Research and Development of Geological Disaster Technology (URL: http://merapi.bgl.esdm.go.id/, Twitter: @BPPTKG); Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/, Twitter: https://twitter.com/BNPB_Indonesia); Øystein Lund Andersen? (Twitter: @OysteinLAnderse, URL: http://www.oysteinlundandersen.com); Sutopo Purwo Nugroho, BNPB (Twitter: @Sutopo_PN, URL: https://twitter.com/Sutopo_PN); Brett Carr, Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY, USA (URL: https://www.ldeo.columbia.edu/user/bcarr).


Manam (Papua New Guinea) — October 2019 Citation iconCite this Report

Manam

Papua New Guinea

4.08°S, 145.037°E; summit elev. 1807 m

All times are local (unless otherwise noted)


Significant eruption on 28 June produced an ash plume up to 15.2 km and pyroclastic flows

Manam is a frequently active volcano forming an island approximately 10 km wide, located 13 km north of the main island of Papua New Guinea. At the summit are the Main Crater and South Crater, with four valleys down the NE, SE, SW, and NW flanks (figure 57). Recent activity has occurred at both summit craters and has included gas and ash plumes, lava flows, and pyroclastic flows. Activity in December 2018 prompted the evacuation of nearby villages and the last reported activity for 2018 was ashfall on 8 December. Activity from January through September 2019 summarized below is based on information from the Rabaul Volcano Observatory (RVO), the Darwin Volcanic Ash Advisory Center (VAAC), the University of Hawai'i's MODVOLC thermal alert system, Sentinel-5P/TROPOMI and NASA Aqua/AIRS SO2 data, MIROVA thermal data, Sentinel-2 satellite images, and observations by visiting scientists. A significant eruption in June resulted in evacuations, airport closure, and damage to local crops and infrastructure.

Figure (see Caption) Figure 57. A PlanetScope image of Manam showing the two active craters with a plume emanating from the South Crater and the four valleys at the summit on 29 August 2019. Image copyright 2019 Planet Labs, Inc.

Activity during January-May 2019. Several explosive eruptions occurred during January 2019 according to Darwin VAAC reports, including an ash plume that rose to around 15 km and dispersed to the W on the 7th. RVO reported that an increase in seismic activity triggered the warning system shortly before the eruption commenced (figure 58). Small explosions were observed through to the next day with ongoing activity from the Main Crater and a lava flow in the NE valley observed from around 0400. Intermittent explosions ejected scoria after 0600, depositing ejecta up to 2 cm in diameter in two villages on the SE side of the island. Incandescence at both summit craters and hot deposits at the terminus of the NE valley are visible in Sentinel-2 TIR data acquired on the 10th (figure 59).

Figure (see Caption) Figure 58. Real-Time Seismic-Amplitude Measurement graph representing seismicity at Manam over 7-9 January 2019, showing the increase during the 7-8 January event. Courtesy of RVO.
Figure (see Caption) Figure 59. Sentinel-2 thermal infrared (TIR) imagery shows incandescence in the two Manam summit craters and at the terminus of the NE valley near the shoreline on 10 January 2019. Courtesy of Sentinel-Hub Playground.

Another explosion generated an ash plume to around 15 km on the 11th that dispersed to the SW. An explosive eruption occurred around 4 pm on the 23rd with the Darwin VAAC reporting an ash plume to around 16.5 km altitude, dispersing to the E. Activity continued into the following day, with satellites detecting SO2 plumes on both 23 and 24 January (figure 60). Activity declined by February with one ash plume reported up to 4.9 km altitude on 15 February.

Figure (see Caption) Figure 60. SO2 plumes originating from Manam detected by NASA Aqua/AIRS (top) on 23 January 2019 and by Sentinel-5P/TROPOMI on 24 January (bottom). Images courtesy of Simon Carn, Michigan Technological University.

Ash plumes rose up to 3 km between 1 and 5 March, and dispersed to the SE, ESE, and E. During 5-6 March the plumes moved E, and the events were accompanied by elevated seismicity and significant thermal anomalies detected in satellite data. During 19-22 March explosions produced ash plumes up to 4.6 km altitude, which dispersed to the E and SE. Simon Carn of the Michigan Technological University noted a plume in Aqua/AIRS data at around 15 km altitude at 0400 UTC on 23 January with approximately 13 kt measured, similar to other recent eruptions. Additional ash plumes were detected on 29 March, reaching 2.4-3 km and drifting to the E, NE, and N. Multiple SO2 plumes were detected throughout April (figure 61).

Figure (see Caption) Figure 61. Examples of elevated SO2 (sulfur dioxide) emissions from Manam during April 2019, on 9 April (top left), 21 April (top right), 22 April (bottom left), 28 April (bottom right). Courtesy of the NASA Space Goddard Flight Center.

During 19-28 May the Deep Carbon Observatory ABOVE (Aerial-based Observations of Volcanic Emissions) scientific team observed activity at Manam and collected gas data using drone technology. They recorded degassing from the South Crater and Main Crater (figure 63 and 64), which was also detected in Sentinel-5P/TROPOMI data (figure 65). Later in the day the plumes rose vertically up to 3-4 km above sea level and appeared stronger due to condensation. Incandescence was observed each night at the South Crater (figure 66). The Darwin VAAC reported an ash plume on 10 May, reaching 5.5 km altitude and drifting to the NE. Smaller plumes up to 2.4 km were noted on the 11th.

Figure (see Caption) Figure 62. Degassing plumes from the South Crater of Manam, seen from Baliau village on the northern coast on 24 May 2019. Courtesy of Emma Liu, University College London.
Figure (see Caption) Figure 63. A strong gas-and-steam plume from Manam was observed moving tens of kilometers downwind on 19 May 2019, viewed here form the SSW at dusk. Photo courtesy of Julian Rüdiger, Johannes Gutenberg University Mainz.
Figure (see Caption) Figure 64. Sentinel-5P/TROPOMI SO2 data acquired on 22 May 2019 during the field observations of the Deep Carbon Observatory ABOVE team. Image courtesy of Simon Carn, Michigan Technological University.
Figure (see Caption) Figure 65. Incandescence at the South Crater of Manam was visible during 19-21 May 2019 from the Baliau village on the northern coast of the island. Photos courtesy of Tobias Fischer, University of New Mexico (top) and Matthew Wordell (bottom).

Activity during June 2019. Ash plumes rose to 4.3 km and drifted SW on 7-8 June, and up to 3-3.7 km and towards the E and NE on 18 June. Sentinel-2 thermal satellite data show hot material around the Main Crater on 24 June (figure 66). On 27 June RVO reported that RSAM (Real-time Seismic Amplitude Measurement, a measure of seismic activity through time) increased from 540 to over 1,400 in 30 minutes. "Thundering noise" was noted by locals at around 0100 on the 28th. An ash plume drifting SW was visible in satellite images acquired after 0620, coinciding with reported sightings by nearby residents (figure 67). The Darwin VAAC noted that by 0910 the ash plume had reached 15.2 km altitude and was drifting SW. When seen in satellite imagery at 1700 that day the large ash plume had detached and remained visible extending SW. There were 267 lightning strokes detected within 75 km during the event (figure 68) and pyroclastic flows were generated down the NE and W flanks. At 0745 on 29 June an ash plume reached up to 4.8 km.

Villages including Dugulava, Yassa, Budua, Madauri, Waia, Dangale, and Bokure were impacted by ashfall and approximately 3,775 people had evacuated to care centers. Homes and crops were reportedly damaged due to falling ash and scoria. Flights through Madang airport were also disrupted due to the ash until they resumed on the 30th. The Office of the Resident Coordinator in Papua New Guinea reported that as many as 455 homes and gardens were destroyed. Humanitarian resources were strained due to another significant eruption at nearby Ulawun that began on 26 June.

Figure (see Caption) Figure 66. Sentinel-2 thermal satellite data show hot material around the Main Crater and a plume dispersing SE through light cloud cover on 24 June 2019. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 67. Himawari-8 satellite image showing the ash plume rising above Manam and drifting SW at 0840 on 28 June. Satellite image courtesy of NCIT ScienceCloud.
Figure (see Caption) Figure 68. There were 267 lightning strokes detected within 75 km of Manam between 0729 on 27 June and 0100 on 29 June 2019. Sixty of these occurred within the final two hours of this observation period, reflecting increased activity. Red dots are cloud to ground lightning strokes and black dots are in-cloud strokes. Courtesy of Chris Vagasky, Vaisala Inc.

Activity during July-September 2019. Activity was reduced through July and September. The Darwin VAAC reported an ash plume to approximately 6 km altitude on 6 July that drifted W and NW, another plume that day to 3.7 km that drifted N, and a plume on the 21st that rose to 4.3 km and drifted SW and W. Diffuse plumes rose to 2.4-2.7 km and drifted towards the W on 29 September. Thermal anomalies in the South Crater persisted through September.

Fresh deposits from recent events are visible in satellite deposits, notably in the NE after the January activity (figure 69). Satellite TIR data reflected elevated activity with increased energy detected in March and June-July in MODVOLC and MIROVA data (figure 70).

Figure (see Caption) Figure 69. Sentinel-2 thermal infrared images acquired on 12 October 2018, 20 May 2019, and 12 September 2019 show the eruption deposits that accumulated during this time. A thermal anomaly is visible in the South Crater in the May and September images. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 70. MIROVA log radiative power plot of MODIS thermal infrared at Manam during February through September 2019. Increases in activity were detected in March and June-July. Courtesy of MIROVA.

Geologic Background. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys" channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Information Contacts: Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea; 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); 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/); Office of the Resident Coordinator, United Nations, Port Moresby, National Capital District, Papua New Guinea (URL: https://papuanewguinea.un.org/en/about/about-the-resident-coordinator-office, https://reliefweb.int/report/papua-new-guinea/papua-new-guinea-volcanic-activity-office-resident-coordinator-flash-2); Himawari-8 Real-time Web, developed by the NICT Science Cloud project in NICT (National Institute of Information and Communications Technology), Japan, in collaboration with JMA (Japan Meteorological Agency) and CEReS (Center of Environmental Remote Sensing, Chiba University) (URL: https://himawari8.nict.go.jp/); Simon Carn, Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA (URL: http://www.volcarno.com/, Twitter: @simoncarn); Chris Vagasky, Vaisala Inc., Louisville, Colorado, USA (URL: https://www.vaisala.com/en?type=1, Twitter: @COweatherman, URL: https://twitter.com/COweatherman); Emma Liu, University College London Earth Sciences, London WC1E 6BS (URL: https://www.ucl.ac.uk/earth-sciences/people/academic/dr-emma-liu); Matthew Wordell, Boise, ID, USA (URL: https://www.matthhew.com/biocontact); Julian Rüdiger, Johannes Gutenberg University Mainz, Saarstr. 21, 55122 Mainz, Germany (URL: https://www.uni-mainz.de/).


Tangkuban Parahu (Indonesia) — October 2019 Citation iconCite this Report

Tangkuban Parahu

Indonesia

6.77°S, 107.6°E; summit elev. 2084 m

All times are local (unless otherwise noted)


Phreatic eruption on 27 July followed by intermittent explosions through to 17 September 2019

Tangkuban is located in the West Bandung and Subang Regencies in the West Java Province and has two main summit craters, Ratu and Upas (figure 3). Recent activity has largely consisted of phreatic explosions and gas-and-steam plumes at the Ratu crater. Prior to July 2019, the most recent activity occurred in 2012-2013, ending with a phreatic eruption on 5 October 2013 (BGVN 40:04). Background activity includes geothermal activity in the Ratu crater consisting of gas and steam emission (figure 4). This area is a tourist destination with infrastructure, and often people, overlooking the active crater. This report summarizes activity during 2014 through September 2019 and is based on official agency reports. Monitoring is the responsibility of Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM).

Figure (see Caption) Figure 3. Map of Tangkuban Parahu showing the Sunda Caldera rim and the Ratu, Upas, and Domas craters. Basemap is the August 2019 mosaic, copyright 2019 Planet Labs, Inc.
Figure (see Caption) Figure 4. Background activity at the Ratu crater of Tangkuban Parahu is shown in these images from 1 May 2012. The top image is an overview of the crater and the bottom four images show typical geothermal activity. Copyrighted photos by Øystein Lund Andersen, used with permission.

The first reported activity in 2014 consisted of gas-and-steam plumes during October-December, prompting PVMBG to increase the alert level from I to II on 31 December 2014. These white plumes reached a maximum of 50 m above the Ratu crater (figure 5) and were accompanied by elevated seismicity and deformation. This prompted the implementation of an exclusion zone with a radius of 1.5 km around the crater. The activity decreased and the alert level was lowered back to I on 8 January 2015. There was no further reported activity from January 2015 through mid-2019.

Figure (see Caption) Figure 5. Changes at the Ratu crater of Tangkuban Parahu during 25 December 2014 to 8 January 2015. Rain water accumulated in the crater in December and intermittent gas-and-steam plumes were observed. Courtesy of PVMBG (8 January 2015 report).

From 27 June 2019 an increase in activity was recorded in seismicity, deformation, gas chemistry, and visual observations. By 24 July the responsible government agencies had communicated that the volcano could erupt at any time. At 1548 on 26 July a phreatic (steam-driven) explosion ejected an ash plume that reached 200 m; a steam-rich plume rose to 600 m above the Ratu crater (figures 6, and 7). People were on the crater rim at the time and videos show a white plume rising from the crater followed by rapid jets of ash and sediment erupting through the first plume. Deposition of eruption material was 5-7 cm thick and concentrated within a 500 m radius from the point between the Rata and Upas craters, and wider deposition occurred within 2 km of the crater (figures 8 and 9). According to seismic data, the eruption lasted around 5 minutes and 30 seconds (figure 10). Videos show several pulses of ash that fell back into the crater, followed by an ash plume moving laterally towards the viewers.

Figure (see Caption) Figure 6. These screenshots are from a video taken from the Ratu crater rim at Tangkuban Parahu on 26 July 2019. Initially there is a white gas-and-steam plume rising from the crater, then a high-velocity black jet of ash and sediment rises through the plume. This video was widely shared across multiple social media platforms, but the original source could not be identified.
Figure (see Caption) Figure 7. The ash plume at Tangkuban Parahu on 26 July 2019. Courtesy of BNPB.
Figure (see Caption) Figure 8. Volcanic ash and lapilli was deposited around the Ratu crater of Tangkuban Parahu during a phreatic eruption on 26 July 2019. Note that the deposits have slumped down the window and are thicker than the actual ashfall. Courtesy of BNPB.
Figure (see Caption) Figure 9. Ash was deposited on buildings that line the Ratu crater at Tangkuban Parahu during a phreatic eruption on 26 July 2019. Photo courtesy of Novrian Arbi/via Reuters.
Figure (see Caption) Figure 10. A seismogram showing the onset of the 26 July 2019 eruption of Tangkuban Parahu and the elevated seismicity following the event. Courtesy of PVMBG via Øystein Lund Andersen.

On 27 July, the day after the eruption, Øystein Lund Andersen observed the volcano using a drone camera, operated from outside the restricted zone. Over a period of two hours the crater produced a small steam plume; ashfall and small blocks from the initial eruption are visible in and around the crater (figure 11). The ashfall is also visible in satellite imagery, which shows that deposition was restricted to the immediate vicinity to the SW of the crater (figure 12).

Figure (see Caption) Figure 11. Photos of the Ratu crater of Tangkuban Parahu on 27 July 2019, the day after a phreatic eruption. A small steam plume continued through the day. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 12. PlanetScope satellite images showing the Ratu crater of Tangkuban Parahu before (17 July 2019) and after (28 July 2019) the explosion that took place on 26 July 2019. Natural color PlanetScope Imagery, copyright 2019 Planet Labs, Inc.

Another eruption occurred at 2046 on 1 August 2019 and lasted around 11 minutes, producing a plume up to 180 m above the vent. Additional explosions occurred at 0043 on 2 August, lasting around 3 minutes according to seismic data, but were not observed. Explosions continued to be recorded at 0145, 0357, and 0406 at the time of the PVMBG report when the last explosion was ongoing, and a photo shows an explosion at 0608 (figure 13). The explosions produced plumes that reached between 20 and 200 m above the vent. Due to elevated activity the Alert Level was increased to II on 2 August. Ash emission continued through the 4th. During 5-11 August events ejecting ash continued to produce plumes up to 80 m, and gas-and-steam plumes up to 200 m above the vent. Ashfall was localized around Ratu crater. The following week, 12-18 August, activity continued with ash and gas-and-steam plumes reaching 100-200 m above the vent. During 19-25 August, similar activity sent ash to 50-180 m, and gas-and-steam plumes to 200 m. A larger phreatic explosion occurred at 0930 on 31 August with an ash plume reaching 300 m, and a gas-and-steam plume reaching 600 m above the vent, depositing ash and sediment around the crater.

Figure (see Caption) Figure 13. A small ash plume below a white gas-and-steam plume erupting from the Ratu crater of Tangkuban Parahu on 2 August 2019 at 0608. Courtesy of PVBMG (2 August 2019 report).

In early September activity consisted of gas-and-steam plumes up to 100-180 m above the vent with some ash plumes observed (figure 14). Two larger explosions occurred at 1657 and 1709 on 7 September with ash reaching 180 m, and gas-and-steam up to 200 m above the vent. Ash and sediment deposited around the crater. Due to strong winds to the SSW, the smell of sulfur was reported around Cimahi City in West Bandung, although there was no detected increase in sulfur emissions. A phreatic explosion on 17 September produced an ash plume to 40 m and a steam plume to 200 m above the crater. Weak gas-and-steam emissions reaching 200 m above the vent continued through to the end of September.

Figure (see Caption) Figure 14. A phreatic explosion at Tangkuban Parahu in the Ratu crater at 0724 on 4 September 2019, lasting nearly one minute. The darker ash plume reached around 100 m above the vent. Courtesy of PVGHM (4 September 2019 report).

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

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/); Øystein Lund Andersen (Twitter: @OysteinLAnderse, https://twitter.com/OysteinLAnderse, URL: https://www.oysteinlundandersen.com/tangkuban-prahu/tangkuban-prahu-volcano-west-java-one-day-after-the-26th-july-phreatic-eruption/); Reuters (URL: https://www.reuters.com/news/picture/editors-choice-pictures-idUSRTX71F3E).


Sheveluch (Russia) — November 2019 Citation iconCite this Report

Sheveluch

Russia

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

All times are local (unless otherwise noted)


Frequent ash explosions and lava dome growth continue through October 2019

After a lull in activity at Sheveluch, levels intensified again in mid-December 2018 and remained high through April 2019, with lava dome growth, strong explosions that produced ash plumes, incandescent lava flows, hot avalanches, numerous thermal anomalies, and strong fumarolic activity (BGVN 44:05). This report summarizes activity between May and October 2019. The volcano is monitored by the Kamchatka Volcanic Eruptions Response Team (KVERT).

According to KVERT, explosive activity continued to generate ash plumes during May-October 2019 (table 13). Strong fumarolic activity, incandescence and growth of the lava dome, and hot avalanches accompanied this process. There were also reports of plumes caused by re-suspended ash rather than new explosions. Plumes frequently extended a few hundred kilometers downwind, with the longest ones remaining visible in imagery as much as 1,000-1,400 km away. One of the larger explosions, on 1 October (figure 52), also generated a pyroclastic flow. Some of the stronger explosions sent the plume to an altitude of 10-11 km, or more than 7 km above the summit. The Aviation Color Code remained at Orange (the second highest level on a four-color scale) throughout the reporting period, except for several hours on 6 October when it was raised to Red (the highest level).

Table 13. Explosions and ash plumes at Sheveluch during May-October 2019. Dates and times are UTC, not local. Data courtesy of KVERT.

Dates Plume altitude (km) Drift Distance and Direction Remarks
30 Apr-02 May 2019 -- 200 km SE Resuspended ash.
03-10 May 2019 -- 50 km SE, SW Gas-and-steam plumes containing some ash.
13 May 2019 -- 16 km SE Resuspended ash.
11-12 Jun 2019 -- 60 km WNW Explosions and hot avalanches seen in video and satellite images.
24, 27 Jun 2019 4.5 E, W Ash plumes.
05 Aug 2019 2.5 40 km NW Diffuse ash plume.
25 Aug 2019 4.5-5 500 km NW Ash plumes.
29 Aug 2019 10 Various; 550 km N Explosions at 1510 produced ash plumes.
30 Aug 2019 7-7.5 50 km SSE Explosions at 1957 produced ash plumes.
03 Sep 2019 5.5 SE --
02-03, 05 Sep 2019 10 660 km SE Ash plumes seen in satellite images.
05 Sep 2019 -- -- Resuspended ash.
11-12 Sep 2019 -- 250 km ESE Resuspended ash plumes. Satellite and webcam data recorded ash emissions and a gas-and-steam plume with some ash drifting 50 km ESE on 12 Sep.
12-15, 17, 19 Sep 2019 -- 200 km SW, SE, NE Ash plumes.
20-21, 23, 26 Sep 2019 7 580 km ESE Explosions produced ash plumes.
29 Sep, 01-02 Oct 2019 9 1,400 km SE, E Explosions produced ash plumes. Notable pyroclastic flow traveled SE on 1 Oct.
04 Oct 2019 -- 170 km E Resuspended ash.
06 Oct 2019 10 430 km NE; 1,080 km ENE Ash plumes. Aviation Color Code raised to Red for several hours.
08 Oct 2019 -- 170 km E Resuspended ash.
06, 09 Oct 2019 6.5-11 1,100 km E --
11-13, 15 Oct 2019 6.5-7 620 km E, SE Explosions produced ash plumes.
16-17 Oct 2019 -- 125 km E Resuspended ash.
19-20 Oct 2019 -- 110 km SE Resuspended ash.
21 Oct 2019 10-11 1,300 km SE Explosions produced ash plumes.
Figure (see Caption) Figure 52. An explosion of Sheveluch on 1 October 2019. A pyroclastic flow was also reported by KVERT this day. Courtesy of Yu. Demyanchuk, IVS FEB RAS, KVERT.

Numerous thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were observed every month. Consistent with this, the MIROVA (Middle InfraRed Observation of Volcanic Activity) system recorded thermal anomalies almost daily. According to KVERT, a thermal anomaly over Sheveluch was identified in satellite images during the entire reporting period, although cloudy weather sometimes obscured observations.

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

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).


Piton de la Fournaise (France) — November 2019 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)


Three brief eruptive events in July, August, and October 2019

Short pulses of intermittent eruptive activity have been common at Piton de la Fournaise, the large basaltic shield volcano on La Réunion Island in the western Indian Ocean, for several thousand years. Over the last 20 years effusive basaltic eruptions have occurred on average twice per year. The activity is characterized by lava fountains and lava flows, and occasional explosive eruptions that shower blocks over the summit area and produce ash plumes. Almost all of the recent activity has occurred within the Enclos Fouqué caldera around the flanks of the central cone which has the Dolomieu Crater at its summit, although past eruptions in 1977, 1986, and 1998 have occurred at vents outside the caldera. Two eruptive episodes were reported during January-June 2019; from 18 February to 10 March, and from 11 to 13 June (BGVN 44:07). Three episodes during July-October 2019 are covered in this report, with information provided primarily by the Observatoire Volcanologique du Piton de la Fournaise (OVPF) as well as satellite instruments.

Three brief eruptive episodes took place during July-October 2019. In each case, slow ground inflation in the weeks leading up to the eruption was followed by sudden inflation at the time of the fissure opening and lava flow event. This was followed by a resumption of inflation days or weeks later. The first event took place during 29-30 July and consisted of three fissures opening on the N flank of the Dolomieu cone. It lasted for less than 24 hours, and the maximum flow length was about 730 m. The second event began on 11 August with two fissures opening on the S flank of the Dolomieu cone. The flows traveled downhill almost 3 km; activity ended on 15 August. Two new fissures opened during 25-27 October on the SSE flank of the cone; one was active only briefly while the second created a 3.6-km-long flow that stopped a few hundred meters before the major highway. The sudden surges of thermal energy from the eruptions are clearly visible in the MIROVA thermal data (figure 182). Each of the eruptive episodes was also accompanied by SO2 emissions that were detected by satellite instruments (figure 183).

Figure (see Caption) Figure 182. Three eruptive events took place at Piton de la Fournaise during July-October 2019 and appear as spikes in thermal activity during 29-30 July, 11-15 August, and 25-27 October. Additional events in late February-early March and mid-June are also visible in this MIROVA graph of thermal energy from 12 December 2018 through October 2019. Courtesy of MIROVA.
Figure (see Caption) Figure 183. Sulfur dioxide emissions were measured from Piton de la Fournaise during each of the eruptive events that occurred in July (top left), August (top right and bottom left), and October (bottom right) 2019. Courtesy of NASA Goddard Space Flight Center.

Activity during July 2019. The last eruption, a series of flows from several fissures on the SSE flank of Dolomieu Crater near the crater rim (at the center of the Enclos Fouqué caldera), lasted from 11 to 13 June 2019 (figure 184). Ground deformation after the eruption indicated renewed inflation of the edifice which had been ongoing since May. OVPF reported an increase in seismicity beginning on 21 June which continued throughout July; the earthquakes were located near the NW rim of the Dolomieu Crater and on its NW flank. Four centimeters of elongation were recorded between two GNSS stations within the Enclos during late June and July prior to the next eruption. The next short-lived eruption took place during 29-30 July, near the location of the seismicity on the NW flank of the Dolomieu cone about 600 m E of the Formica Leo cone. The onset of the eruption was accompanied by rapid ground deformation of about 12-13 cm, recorded at a station that is located west of the Dolomieu Crater (figure 185).

Figure (see Caption) Figure 184. Location maps of lava flows formed during the 11-13 June 2019 (left) and 29-30 July 2019 (right) eruptions at Piton de la Fournaise. Information derived from satellite data via the OI2 platform and aerial photos. Lava flows from June are shown as red polygons and eruptive fissures are shown as white lines. For the July event, the flows are shown in white. Courtesy of OVPF, OI2 and Université Clermont Auvergne (Monthly bulletins of the Piton de la Fournaise Volcanological Observatory, June and July 2019).
Figure (see Caption) Figure 185. Horizontal surface displacements indicating inflation of Piton de la Fournaise of about four centimeters were gradual between 14 June and 28 July 2019 (left). Just prior to and at the onset of the eruption on 29 July, a much greater displacement of about 12 cm occurred, associated with the subsurface ascent of magma (right). Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, July 2019).

The late July eruption began around 1200 local time on 29 July 2019 with the opening of three fissures over a distance of about 450 m on the N flank of Dolomieu cone, close to the tourist trail to the summit (figure 186). Lava fountains 20-30 m high were reported. Thermal measurements indicated flow temperatures of about 1,100°C at the base of the lava fountains; samples were collected for analysis (figure 187). Average discharge rates of 11.6 m3s were estimated for the eruption which ended less than 24 hours later, around 0430 on 30 July. The maximum flow length was about 730 m.

Figure (see Caption) Figure 186. Three fissures opened at Piton de la Fournaise on 29 July 2019 and flows traveled 730 m downslope before stopping the next day. The fissures were located on the N flank of Dolomieu cone. Courtesy of OVPF-IPGP, Imaz PressRéunion, and Réunion La 1ère (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, July 2019).
Figure (see Caption) Figure 187. Samples were collected for analysis by OVPF from the 29 July 2019 flow at Piton de la Fournaise. Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, July 2019).

Eruption of 11-15 August 2019. During 1-10 August there were 33 shallow volcano-tectonic (VT) earthquakes located under the SE flank of Dolomieu cone; a new eruption began over this area on 11 August (figure 188). Two centimeters of inflation were recorded between the 29-30 July eruption and the 11-15 August event; this was followed by a rapid burst of inflation (tens of centimeters) at the onset of the eruption. Inflation resumed shortly after the eruption ended. The eruption began around 1620 local time on 11 August. Two fissures opened, one at 1,700 m elevation, and one at 1,500 m elevation on the SE flank, about 1,400 m apart (figure 189). Due to the steep slopes in the area, the lava flow quickly reached the "Grande Pentes" area before slowing down at the flatter "Piton Tremblet" area. The farthest traveled flow was cooling at an elevation of about 560 m, about 2 km from the National Road (RN2) on 14 August. The maximum effusion rate was measured at 9 m3/s. The eruption stopped on 15 August 2019 at 2200 local time after more than 6 hours of "piston gas" activity, and a brief pause in flow activity earlier in the day. About 3 million m3of lava were emitted, according to OVPF-IPGP. The flows from the 1,700 m and 1500 m altitude fissures reached maximum lengths of 2.9 and 2.7 km, respectively.

Figure (see Caption) Figure 188. Locations of eruptive fissures that opened on 11 August 2019 on the SE flank of Dolomieu cone at Piton de la Fournaise, and the approximate locations of the associated flows. Courtesy of IVPF-IPGP / OPGC-LMV (Bulletin d'activité du mercredi 14 août 2019 à 15h30, Heure locale).
Figure (see Caption) Figure 189. Lava flows from the Piton de la Fournaise eruption of 11-15 August 2019 emerged from two fissures on the SE flank of Dolomieu cone. The flows were both active on 13 August (left) at around 0930 local time. Visual and thermal images of the lava flows on 14 August at around 2100 local time (center and right) showed them continuing down the steep slope of the cone and spreading out over the shallower area below. Courtesy of OVPF-IPGP, LMV-OPGC (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, August 2019).

Activity during September-October 2019. Very little activity was reported during September 2019. Seismicity remained low with only 32 earthquakes reported during the month, and inflation, which had continued after the 11-15 August eruption, stopped at the beginning of September. Inflation resumed on 11 October. Two seismic swarms were recorded during October 2019. The first, on 21 October (207 events), lasted for about 40 minutes, and did not result in an eruption. The second began on 25 October and consisted of 827 events. It was followed by an eruption during 25-27 October located on the SSE flank of the Dolomieu cone. Deformation followed a similar pattern as it had during and prior to the eruptive events of July and August. Inflation of a few centimeters between 11 and 24 October was followed by rapid inflation of about 10 cm at the onset of the new eruption. Inflation resumed again after this eruption as well.

Two fissures opened during the 25-27 October eruption, one at 1,060 m elevation and one at 990 m. The first fissure was no longer active when viewed during an overflight 2.5 hours after it had opened. The flows moved rapidly until reaching the lower slope areas of the Grand Brule about 1.5-2 km downstream of the "Piton Tremblet" area. On 26 October only one vent was active with fountains 10-20 m high (figure 190). The lava discharge rates during the eruption averaged about 14 m3/s. The eruption ended at 1630 local time on 27 October after one hour of "gas piston" activity (figure 191). A total of about 1.8 million m3 of lava was emitted. The flows from the 990 m elevation site reached a maximum length of 3.6 km, and the lava flow front stopped about 230 m before reaching the RN2 National road (figure 192).

Figure (see Caption) Figure 190. On 25 October 2019 the front of the active flow at Piton de la Fournaise had reached the level of the Piton Tremblet by 1700 local time (left). Image by PGHM (Bulletin d'activité du 25 octobre 2019 à 18h00, Heure locale). The following day, the active vent had lava fountains 10-20 m high (right) (Bulletin d'activité du samedi 26 octobre 2019 à 11h00, Heure locale). Courtesy of OVPF/IPGP.
Figure (see Caption) Figure 191. The eruptive site of the 25-27 October 2019 eruption at Piton de la Fournaise had one flow still active on 27 October with 10-20 m high lava fountains (left). The flow front stopped that day a few hundred meters before the National Road (right). Courtesy of OVPF/IPGP (Bulletin d'activité du dimanche 27 octobre 2019 à 12h00, Heure locale).
Figure (see Caption) Figure 192. The location of the 25-27 October 2019 lava flow at Piton de la Fournaise started at the very base of the SSE flank of Dolomieu cone and traveled 3.6 km E towards the Highway and the coast. Basemap from Google Earth, fissures (red) and flows (in white) derived from aerial photos. Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, October 2019).

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

Information Contacts: Observatoire Volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris (OVPF-IPGP), 14 route nationale 3, 27 ème km, 97418 La Plaine des Cafres, La Réunion, France (URL: http://www.ipgp.fr/fr); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); 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/).


Agung (Indonesia) — November 2019 Citation iconCite this Report

Agung

Indonesia

8.343°S, 115.508°E; summit elev. 2997 m

All times are local (unless otherwise noted)


Quiet returns after explosions on 10 and 13 June 2019

After a large, deadly explosive and effusive eruption during 1963-64, Indonesia's Mount Agung on Bali remained quiet until a new eruption began in November 2017 (BGVN 43:01). Activity continued throughout 2018 with explosions that produced ash plumes rising multiple kilometers above the summit, and the slow effusion of the lava within the summit crater. Increasingly frequent and intense explosions with ash emissions and incandescent ejecta characterized activity during February through May 2019 (BGVN 44:06). Two more explosions in June 2019 produced significant ash plumes; no further explosive activity occurred through October 2019. Information about Agung comes from Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), also known as the Indonesian Center for Volcanology and Geological Hazard Mitigation (CVGHM), the Darwin Volcanic Ash Advisory Center (VAAC), and multiple sources of satellite data. This report covers the end of the eruption in June and observations through October 2019.

After a large explosion on 31 May 2019, a smaller event occurred on 10 June. Another large explosion with an ash plume that rose to 9.1 km altitude was recorded on 13 June (local time). It drifted hundreds of kilometers before dissipating. No further explosive activity was reported through October 2019, only diffuse white steam plumes rising at most a few hundred meters above the summit. The Alert Level remained at III (of four levels) throughout the period. The record of thermal activity showed an increase during the explosive events of late May and June, but then decreased significantly (figure 57). There was no obvious thermal signature in satellite images that explained the small increase in thermal energy recorded by the MIROVA data at the end of August 2019.

Figure (see Caption) Figure 57. The thermal energy at Agung increased significantly during the explosive events of late May and early June 2019, and then decreased substantially as seen in this MIROVA graph from 23 January through October 2019. There was no obvious satellite thermal signature to explain the brief increase in thermal energy in late August. Courtesy of MIROVA.

On 31 May 2019 a large explosion produced an ash plume that rose more than 2 km above the summit (BGVN 44:06, figure 56). The Darwin VAAC reported that it split into two plumes, one drifted E at 8.2 km and the other ESE at 6.1 km altitude, dissipating after about 20 hours early on 1 June. A small eruption with an ash plume that rose to 3.9 km altitude was reported the next day by the Darwin VAAC. It was detected in the webcam and pilot reports confirmed that it drifted E for a few hours before dissipating. PVMBG reported gray emissions to 300 m above the peak on 1 June and 100 m above the summit on 2 June. By 6 June the emissions were white, rising only 50 m above the summit. For several subsequent days, the summit was covered in fog with no observations of emissions.

On 10 June 2019 an explosion lasting 90 seconds was reported at 1212 local time; PVMBG noted a gray ash plume 1,000 m above the summit (figure 58). The Darwin VAAC confirmed the emission in satellite imagery and by pilot report; it was moving SW at 4.3 km altitude and then drifted S before dissipating by the end of the day. Early on 13 June local time (12 June UTC) a new explosion that was clearly visible in the webcam produced a large ash plume that drifted W and SW (figure 59). The explosion was recorded on the seismogram for almost four minutes and sent incandescent ejecta in all directions up to 700 m from the summit. The first satellite imagery of the plume reported by the Darwin VAAC suggested the altitude to be 9.1 km. A secondary plume was drifting W from the summit at 5.5 km altitude a few hours later. By six hours after the eruption, the 9.1 km altitude plume was about 90 km SSW of the Denpassar airport and the 5.5 km altitude plume was about 110 km W of the airport. By the time the higher altitude plume dissipated after about 14 hours, it had reached 300 km S of the airport. For the remainder of June, only diffuse white steam plumes were reported, rising generally 30-50 m above the summit, with brief pulses to 150-200 m during 27-29 June.

Figure (see Caption) Figure 58. An ash plume rose 1,000 m above the summit of Agung on 10 June 2019. Top image courtesy of Rita Bauer (Volcano Verse), bottom image courtesy of PVMBG (Information on G. Agung Eruption, 10 June 2019).
Figure (see Caption) Figure 59. A large eruption at Agung at 0138 local time on 13 June 2019 sent an ash plume to 9.1 km altitude and incandescent ejecta 700 m in all directions. Courtesy of Jaime S. Sincioco, screenshot from volcano YT webcam.

Although no further surface activity was reported at Agung during July through October 2019, PVMBG kept the Alert Level at III throughout the period. Only steam plumes were reported from the summit usually rising 50 m before dissipating. Steam emissions rose to 150 m a few times each month. Plumes were reported at 300 m above the summit on 6 July and 15 August. No thermal anomalies were visible in Sentinel 2 satellite images during the period.

Geologic Background. Symmetrical Agung stratovolcano, Bali's highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means "Paramount," rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities.

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/); 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/); Rita Bauer, Volcano Verse (Twitter @wischweg, URL: https://twitter.com/wischweg/status/1137956367258570752); Jamie S. Sincioco, Philippines (Twitter @jaimessincioco, URL: https://twitter.com/jaimessincioco/status/1139109685796020224).


Copahue (Chile-Argentina) — November 2019 Citation iconCite this Report

Copahue

Chile-Argentina

37.856°S, 71.183°W; summit elev. 2953 m

All times are local (unless otherwise noted)


New ash emissions begin in early August; intermittent and ongoing through October 2019

Most of the large edifice of Copahue lies high in the central Chilean Andes, but the active, acidic-lake filled El Agrio crater lies on the Argentinian side of the border at the W edge of the Pliocene Caviahue caldera. Infrequent mild-to-moderate explosive eruptions have been recorded since the 18th century. The most recent eruptive episode with ash plumes lasted from early June 2017 to early December 2018. After 8 months of quiet, renewed phreatic explosions and ash emissions began in August 2019 and were ongoing through October 2019. This report summarizes activity from January through October 2019 and is based on reports issued by Servicio Nacional de Geología y Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur (OVDAS), Buenos Aires Volcanic Ash Advisory Center (VAAC), satellite data, and photographs from nearby residents.

Intermittent steam plumes were reported from the El Agrio crater at the summit during January-July 2019, but no ash emissions were seen. An increase in seismicity and changes in the crater lake level during March led SERNAGEOMIN to increase the Alert Level from Green to Yellow at the beginning of April. Fluctuating tremor signals in the first week of August coincided with satellite imagery that showed the appearance of dark material, possibly ash, on the snow around the summit crater. The first thermal anomaly appeared on 3 September and the first clear ash explosions were recorded on 11 September. Eruptive activity was intermittent through the end of the month; a series of larger explosions beginning on 30 September caused SERNAGEOMIN to raise the Alert Level from Yellow to Orange. A period of more intense explosive activity lasted through the first week of October. The larger explosions then ceased, but during the rest of October there were continuing observations of seismicity, ash emissions, and incandescent ejecta, along with multiple thermal anomalies in the summit area.

Observations during January-April 2019. Copahue remained at Alert Level Yellow with a 1-km exclusion radius during January 2019 after ash emission in December 2018. Ongoing degassing was reported with white plumes from El Agrio crater rising to 355 m (figure 25). The Alert Level was lowered to Green at the end of the month, and the exclusion radius was reduced to 500 m, although intermittent low-level seismicity in the region continued. SERNAGEOMIN reported a M 3.2 earthquake about 10 km NE of the summit, 2 km deep, on 29 January 2019. The acidic lake inside El Agrio crater was quiet at the end of the month (figure 26).

Figure (see Caption) Figure 25. Degassing of steam from Copahue on 10 and 17 (inset) January 2019. Courtesy of OPTIC Neuquén (10 January) and SERNAGEOMIN (17 January).
Figure (see Caption) Figure 26. El Agrio crater at Copahue on 31 January 2019. Courtesy of Valentina Sepulveda, Hotel Caviahue.

Steam plumes occasionally rose to 180 m above the crater during February 2019. A swarm of 117 volcano-tectonic (VT) seismic events on 22-23 February 2019 was located about 14 km NE of the volcano, with the largest events around a M 3.5. Steam plumes rose to about 280 m above the crater during March. SERNAGEOMIN noted an increase in seismicity during the month, and a decrease in the lake level within El Agrio crater. This led them to increase the Alert Level to Yellow (second on a four-level scale) at the beginning of April. Emissions remained minimal during April (figure 27); an 80 m high steam plume was reported on 4 April. The lake level continued to fall, based on satellite imagery, and a M 3.1 earthquake was reported on 29 April located about 10 km NE of the summit about 10 km deep.

Figure (see Caption) Figure 27. Clear skies revealed no activity from the summit of Copahue on 7 or April 2019. The volcano was quiet throughout the month, although the Alert Level remained at Yellow. Image taken near Caviahue, 10 km E in Argentina. Courtesy of Valentina Sepulveda, Hotel Caviahue.

Observations during May-July 2019. Sporadic episodes of low-altitude steam plume degassing were noted during May 2019, but otherwise very little surface activity was reported (figure 28). On 13 May, a steam plume reached 160 m above the crater rim, and on 28 May, the tallest plume rose 200 m above the crater. Hybrid-type earthquakes were recorded early in the month, followed by a slow increase in the amplitude of the tremor signal. Seismicity increased slightly during the second half of the month with activity concentrated closer to the summit crater. A weak SO2 plume was recorded by satellite instruments on 23 May. The level of the lake began increasing during the second half of the month.

Figure (see Caption) Figure 28. No surface activity was visible at Copahue on 5 May 2019, but seismicity increased slowly during the month. Image taken near Caviahue. Courtesy of Valentina Sepulveda, Hotel Caviahue.

SERNAGEOMIN reported tremor signals with fluctuating amplitude throughout June 2019. Repeated episodes of low-altitude white degassing occurred around the El Agrio crater. On 7 June, a 300 m plume was observed above the crater; the level of the crater lake was variable. On 17 June a 400-m-tall white plume was observed above the crater. Seismicity, although low, increased during the second half of the month. Multiple episodes of low-altitude white degassing occurred around the active crater all during July 2019 (figure 29). On 9 July a plume rose about 450 m above the crater. On 16 July a white plume rose 250 m above the crater. SENAGEOMIN noted a rise in the rate of seismicity during the first half of the month; the tremor signal continued with fluctuating amplitude. Satellite instruments detected small SO2 plumes on 4 and 9 July (figure 30).

Figure (see Caption) Figure 29. A steam plume rose a few hundred meters above the summit of Copahue on 23 July 2019. Courtesy of Valentina Sepulveda, Hotel Caviahue.
Figure (see Caption) Figure 30. The TROPOMI instrument on the Sentinel-5P satellite detected small SO2 plumes at Copahue on 4 and 9 July 2019. Courtesy of NASA Goddard Space Flight Center.

Activity during August-October 2019. Sentinel-2 satellite imagery from 2, 4, 7, and 9 August suggested the ejection of particulate material (figure 31), with dark streaks in the snow extending a few hundred meters E and SE from the crater. Images from the community of Caviahue on 3 and 4 August show distinct discoloration of the snow around the E side of the summit crater (figures 32 and 33). Small but discernible SO2 plumes were detected by satellite instruments on 2, 3, 16, 19, 30, and 31 August. Fluctuating tremor signals continued during August with several episodes of low-altitude white degassing from the El Agrio crater; a white plume on 5 August rose 380 m above the crater. The lake level continued to drop and the Alert Level remained at Yellow.

Figure (see Caption) Figure 31. Sentinel 2 satellite imagery of Copahue from late July and early August 2019 show fresh dark material deposited over the fresh winter snow, suggesting recent ejecta from the El Agrio crater. Top left: The summit was covered with fresh snow on 25 July 2019. Top right: A dark streak extends E then N from the El Agrio crater on 2 August. Bottom left: A streak of dark material trends SE from the crater over the snow on 4 August. Bottom Right: On 7 August a different streak extends E from the crater while fresh snow has covered the earlier streak. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 32. At sunset on 3 August 2019, darker material was visible on the snow on the E side of the summit of Copahue; a dense steam plume rose from El Agrio crater. Courtesy of Valentina Sepulveda, Hotel Caviahue.
Figure (see Caption) Figure 33. Particulates covered the fresh snow near the summit of Copahue on 4 August 2019, as seen from the community of Caviahue, about 10 km E. A steam plume rose from El Agrio crater. Courtesy of Valentina Sepulveda, Hotel Caviahue.

Distinct SO2 plumes were again captured by satellite instruments on 1, 3, and 5-7 September 2019 (figure 34). The first thermal signature in nine months also appeared in Sentinel-2 satellite imagery on 3 September (figure 35). Midday on 9 September, seismometers recorded an increase in the amplitude of a continuous tremor. High clouds prevented clear views of the crater and no ash emissions were observed. Beginning on 11 September, low-energy long-period (LP) events were associated with infrasound signals and low-energy explosions that produced small ash plumes. The largest explosion produced a plume 250 m above the crater. Incandescence and high-temperature ejecta were observed around the emission point. The ash drifted ESE about 3 km. Ten explosions were reported between 11 and 12 September, associated with low-intensity acoustic signals and ash emissions. Plumes reached 430 m above the crater rim on 12 September. Ash deposits on the snow were visible in in Sentinel-2 images on 11 and 13 September, extending about 6 km E from El Agrio crater (figure 35). Images from the ground on 12 September indicated fresh ash on the E flank (figure 36).

Figure (see Caption) Figure 34. Small but distinct SO2 plumes from Copahue were measured by the TROPOMI instrument on the Sentinel 5P satellite on 1 and 3 September 2019, and additionally on 5-7 September. Courtesy of NASA Goddard Space Center.
Figure (see Caption) Figure 35. Sentinel-2 satellite images indicated thermal activity and ash emissions at Copahue on 3, 11, and 13 September 2019. Left: The first thermal anomaly in nine months appeared on 3 September. Middle: An ash streak trended E across the snow from El Agrio crater on 11 September. On 13 September, the streak was a wider cone that extended ESE for about 6 km. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 36. Ash deposits coated snow on the E flank of Copahue on 12 September 2019, while a steam plume drifted SE from the crater, as seen from the community of Caviahue about 10 km E in Argentina. Courtesy of Valentina Sepulveda, Hotel Caviahue.

Although fresh snow had covered any ash deposits by 16 September 2019 (figure 37), small thermal anomalies appeared in Sentinel-2 imagery on 16 and 21 September. SO2 plumes were measured by satellite instruments on 21 and 25 September. Photos from Caviahue on 25 September showed ash on the E flank and a steam-and-ash plume drifting NE (figure 38). Ashfall on the snow was visible in satellite imagery on 26 September, and covered a larger area on 28 September; there was also a substantial thermal anomaly that day (figure 39).

Figure (see Caption) Figure 37. Fresh snow had covered over recent ash emissions at Copahue by 16 September 2019; thermal anomalies were detected in satellite data from the summit crater the same day. Courtesy of Valentina Sepulveda, Hotel Caviahue.
Figure (see Caption) Figure 38. On a clear 25 September 2019 fresh ash covered snow on the E flank of Copahue, and an ash and steam plume was drifting NE from the El Agrio crater. The mountains are reflected in Lago Caviahue located about 12 km E in Argentina. Courtesy of Valentina Sepulveda, Hotel Caviahue.
Figure (see Caption) Figure 39. Sentinel-2 imagery of Copahue on 28 September showed ashfall in a large area around the summit and a small ash plume (left); a substantial thermal anomaly was also visible within the El Agrio crater (right). Courtesy of Sentinel Hub Playground.

During the late afternoon of 30 September, three high-energy LP earthquakes were reported located 5.8 km NE of the El Agrio crater. They were accompanied by abundant lower energy earthquakes in the same area. The VT earthquakes were equivalent to a M 3.5. Inhabitants of Caviahue (12 km E) reported feeling several of the events; atmospheric conditions prevented observation of the summit. This sudden increase in seismicity prompted SERNGEOMIN to raise the Alert Level to Orange and increase the radius of the area of potential impact to 5 km. Seismicity (VT, LP and tremor earthquakes) continued at a high rate into 1 October. Argentina's geologic hazards and mining agency, Servicio Geologico Minero Argentino (SEGEMAR) also issued a notice of the increased warning level on 30 September (figure 40).

Figure (see Caption) Figure 40. A dense steam plume rises from the active crater at Copahue in this image looking due E towards Caviahue and Lago Caviahue, 12 km E. The rim of the Caviahue caldera is in the distance. Argentina's SEGEMAR posted this photograph (undated) with their notice of the increase in warning level on 30 September 2019. Courtesy of SEGEMAR.

Cameras near the volcano detected ash plumes associated with explosions around the crater at 0945 on 1 October 2019 which continued throughout the first week of the month. Satellite imagery showed streaks of dark ash over snow trending SE and E and from the summit on 1 and 8 October (figure 41). Five separate explosions were recorded during 1-2 October. Persistent degassing was accompanied by episodes of ash emissions and incandescence at night. Seismicity continued during 2-3 October, but poor weather mostly obscured visual evidence of activity; a few pulses of white and gray emissions were observed. Seismic events were located 5-7 km NE at a depths of 0.7-1.7 km, and continued for several days. Clearer skies on 4 October revealed steam plumes and pulses of ash rising from El Agrio crater. Incandescence was visible at night. A ground-based image showed ash covering the E flank and an ash plume drifting NE down the flank (figure 42). The Buenos Aires VAAC reported weak ash emissions on 4 October moving NE at 3.4 km altitude. The webcam showed continuous ash emission from the summit during 4-5 October.

Figure (see Caption) Figure 41. Sentinel-2 satellite imagery of Copahue showed dark streaks trending SE and E from the summit in early October. On 1 October 2019 (left) there was a narrow streak of ash to the SE and a steam plume drifting the same direction. On 8 Octobe0r (right), a wide cone of ashfall covered the E flank, and a plume of gray ash drifted NE over the edge of the deposit. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 42. Gray ash covered areas of Copahue's E flank on 4 October 2019 and an ash plume drifted NE down the flank. Image from Caviahue, about 10 km E. Courtesy of Valentina Sepulveda, Hotel Caviahue.

White steam plumes with pulses of ash and incandescence at night were observed on 5 and 6 October. Seismic activity decreased on 6 October. The following day, SERNAGEOMIN lowered the Alert Level to Yellow and reduced the restricted zone to 1,000 m around the summit crater. While seismicity had decreased, ash emissions continued from low-level pulsating explosions which produced ash plumes that drifted E (figure 43). They observed that the total area to that date affected by ashfall was about 24.5 km2, extending up to 5 km W and 6 km E from the summit. They also noted that a pyroclastic cone about 130 m across had appeared inside the crater. Ash emissions and explosions with incandescent ejecta continued during the second week of October (figure 44). A change in wind direction created a several-kilometer-long streak of ash trending SW from the summit by 13 October; a strong thermal anomaly that day indicated continued activity (figure 45). SO2 plumes were recorded by satellite instruments on 1, 3, 4, and 13 October.

Figure (see Caption) Figure 43. Ash and steam drifted E from the summit of Copahue on 7 October 2019, the day that SERNAGEOMIN lowered the Alert Level from Orange to Yellow. Courtesy of SEGEMAR.
Figure (see Caption) Figure 44. Incandescent ejecta was visible at the summit of Copahue overnight on 11 October 2019 in the image from a local webcam. Courtesy of Culture Volcan.
Figure (see Caption) Figure 45. A new dark streak of ash on snow trended SW from the El Agrio crater at Cophahue on 13 October 2019. The strong thermal anomaly the same day indicated the level of eruptive activity was still high. Natural color image based on bands 4,3, and 2; Atmospheric penetration rendering based on bands 12, 11, and 8a. Courtesy of Sentinel Hub Playground.

Seismicity continued for the rest of October, but no explosions were recorded. Sulfur dioxide emissions were recorded by satellite instruments on 18, 22, 23, and 30 October (figure 46). When weather permitted, constant degassing with episodes of ash emissions from the crater were visible during the day and incandescence appeared at night. Satellite imagery on 18, 23, and 28 October showed substantial ash plumes drifting in different directions from the summit. A large area around the summit crater was covered with dark ash on 18 and 23 October. Fresh snowfall had covered most of the area by 28 October, and the narrow dark streak trending SE underneath the ongoing ash plume was the only surface covered with material (figure 47). Distinct thermal anomalies appeared in satellite images on 16, 18, 23, and 31 October. A number of thermal alerts were recorded by the MIROVA system as well during the second half of the month.

Figure (see Caption) Figure 46. The TROPOMI instrument on the Sentinel-5P satellite recorded SO2 emissions from Copahue on 18, 22, 23, and 30 October 2019. Satellite imagery on also showed ash plumes on 18 and 23 October. Courtesy of NASA Goddard Space Flight Center.
Figure (see Caption) Figure 47. Distinct ash plumes and dark ashfall over snow on 18, 23, and 28 October 2019 at Copahue indicated ongoing eruptive activity (top row) through the end of the month. The large area of ash-covered snow visible on 18 and 23 October was covered with fresh snowfall by 28 October when the dense ash plume drifting SE left only a narrow dark trail of ashfall in the fresh snow underneath (right). Strong thermal anomalies were apparent on 18 and 23 October but obscured by dense ash on 28 October (bottom row). Natural color image based on bands 4, 3, and 2; atmospheric penetration rendering based on bands 12, 11, and 8a. Courtesy of Sentinel Hub Playground.

The highest plume noted by SERNAGEOMIN during the second half of the month rose 1,200 m above the crater on 22 October 2019 (figure 48). The Buenos Aires VAAC reported ash emissions from the summit visible in webcams almost every day in October. On 16 October, an ash plume was seen in satellite imagery moving SE at 3.4 km altitude under mostly clear skies; the webcam showed continuous ash emission. A faint plume was barely seen moving S in satellite imagery at 3.4 km altitude on 18 October; the webcam revealed continuous emission of gases and possible dilute volcanic ash. The VAAC reported ash emissions daily from 18-25 October. Drift directions varied from SE, moving to NE on 21-23 October, and back to E and SE the following days. The altitudes ranged from 3.0 to 4.3 km. On 20 October, the plume extended about 80 km SE. The ash appeared as pulses moving NE on 22 and 23 October at 4.3 km altitude. Emissions reappeared in satellite imagery on 28 and 30-31 October, drifting SE and NE at 3.4-3.7 km altitude; incandescence was visible overnight on 30-31 October from the webcam.

Figure (see Caption) Figure 48. A plume of ash and steam from Copahue rose 1,200 m above the summit on 22 October 2019 and drifted NE. It was clearly visible from 25 km SW of the volcano in the El Barco Indigenous community of Alto Biobío, Chile, along with ash-covered snow on the SW flank. Courtesy of EveLyN.

Geologic Background. Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.

Information Contacts: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); OPTIC Neuquén, Oficina Provincial de Tecnologías de la Información y la Comunicación- Gobierno de la Provincia del Neuquén, Neuquén, Argentina (URL: https://www.neuqueninforma.gob.ar/tag/optic/, Twitter: @OPTIC_Nqn, https://twitter.com/OPTIC_Nqn); 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); Valentina Sepulveda, Hotel Caviahue, Caviahue, Argentina (URL: https://twitter.com/valecaviahue, Twitter:@valecaviahue); Cultur Volcan, Journal d'un volcanophile, (URL: https://laculturevolcan.blogspot.com, Twitter: @CulturVolcan); EveLyn, Twitter: @EveCaCid (URL: https://twitter.com/EveCaCid/status/1186663015271321601).


Turrialba (Costa Rica) — November 2019 Citation iconCite this Report

Turrialba

Costa Rica

10.025°N, 83.767°W; summit elev. 3340 m

All times are local (unless otherwise noted)


Activity diminishes during March-October 2019, but small ash emissions continue

This report summarizes activity at Turrialba during March-October 2019. Typical activity similar to that reported in late 2018 and early 2019 (BGVN 44:04) included periodic weak ash explosions and numerous emissions containing some ash. However, during this period activity appeared to diminish with time. Data were provided by weekly reports by the Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA).

According to OVSICORI-UNA, only highly diluted ash emissions were recorded from 22 April to 27 May (note that no reports were available online from the last week of March until 22 April). Weak ash explosions were again noted on 28 July, 4 August, and possibly on 20 October. OVSICORI-UNA reported more explosions or emissions containing ash on 25 and 28 October (table 9).

Table 9. Summary of reported activity at Turrialba, March-October 2019. Cloudy weather sometimes obscured observations. Maximum plume height is above the crater rim. Information courtesy of OVSICORI-UNA.

Date Time Max plume height Plume drift Remarks
01 Mar 2019 0444 200 m NE --
02-04 Mar 2019 -- 200-300 m -- Continuous emissions with minor amounts of ash.
09-12 Mar 2019 -- 1,000 m -- Gas plumes containing minor amounts of ash.
16-17 Mar 2019 -- -- -- Frequent and discontinuous emissions, but no visual confirmation due to poor visibility.
20-22 Mar 2019 -- 300 m W, SW Continuous emissions of steam with periodic pulses of diffuse ash; sulfur odor noted in Tierra Blanca de Cartago on 22 March.
23-26 Mar 2019 -- -- -- Steam plumes with low concentration of magmatic gases.
24 Mar 2019 0503 500 m -- Series of four pulses with ash.
31 Mar 2019 0735 -- -- Explosion followed by passive emissions with low concentration of magmatic gases. Seismicity dominated by low-frequency events.
08 Apr 2019 -- -- -- Minor ash emissions.
24 Apr 2019 -- -- -- Diffuse ash emission.
26 Apr 2019 -- -- N Emission with low ash content.
27 Apr 2019 0722 below 100 m -- Weak, brief explosion with ash plume.
04 May 2019 0524 -- -- Emission of very diluted ash.
12-19 May 2019 -- -- -- Passive, short-duration emissions with small amounts of ash occurred sporadically.
19-20 May 2019 -- -- -- Prolonged and intermittent periods of emissions with minor amounts of ash.
28 Jul 2019 1441 -- -- Weak explosion and ash emission after 30 minutes of heavy rain. Inclement weather prevented visual confirmation. Ashfall in La Picada (N) and El Retiro farms.
03-04 Aug 2019 -- -- -- Two small explosions, with some ash in the second.
11 Aug 2019 -- -- -- Weak emission during night, identified by its seismic signal. No ash emission observed.
05 Aug-19 Oct 2019 -- -- -- No ash detected.
20 Oct 2019 2100 -- -- Explosion identified with seismicity; weather conditions prevented visual observation. No ashfall reported.
25 Oct 2019 0400, 0700 -- -- Weak explosion at 0400, with ash. Ash at 0700 not associated with seismic signal, so could be a small intra-crater collapse.
28 Oct 2019 1500 -- -- Weak emission containing ash.

A report from Red Sismologica Nacional (RSN) about the 28 October ash explosion noted that it occurred at 1501 local time and lasted about 5 minutes. There were no reports of ashfall, but the crater webcam captured the small plume rising from the active vent. Incandescence in the active crater continued to be seen on the monitoring cameras.

Geologic Background. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive edifice covers an area of 500 km2. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

Information Contacts: Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica (URL: http://www.ovsicori.una.ac.cr/); Red Sismologica Nacional (RSN) a collaboration between a) the Sección de Sismología, Vulcanología y Exploración Geofísica de la Escuela Centroamericana de Geología de la Universidad de Costa Rica (UCR), and b) the Área de Amenazas y Auscultación Sismológica y Volcánica del Instituto Costarricense de Electricidad (ICE), Costa Rica (URL: https://rsn.ucr.ac.cr/).

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Bulletin of the Global Volcanism Network - Volume 37, Number 04 (April 2012)

Managing Editor: Richard Wunderman

Galeras (Colombia)

Frequent seismic swarms, elevated SO2; ash explosions begin in May 2012

Galunggung (Indonesia)

One possible 2008 ash plume, crater lake anomalies in 2011-2012

Gamkonora (Indonesia)

Instability followed by confusing news claims of minor June 2012 eruption

Iliamna (United States)

Rockfalls and fumarolic activity continue with spike in early 2012

Masaya (Nicaragua)

Continuous monitoring of emissions and new investigations from collaborators

Semeru (Indonesia)

Increased seismicity with lava flows and pyroclastic flows during February-April 2012

Soputan (Indonesia)

Alert level raised in May 2012 based on increased seismic activity



Galeras (Colombia) — April 2012 Citation iconCite this Report

Galeras

Colombia

1.22°N, 77.37°W; summit elev. 4276 m

All times are local (unless otherwise noted)


Frequent seismic swarms, elevated SO2; ash explosions begin in May 2012

Our last report focused on the VEI 2 eruption of August 2010 as well as results from regular monitoring through May 2011 by the Instituto Colombiano de Geología y Minería (INGEOMINAS) based in Pasto, the provincial capital located ~10 km E of Galeras. Here we discuss the continuing efforts to monitor Galeras from June 2011 through April 2012. We highlight regular measurements from telemetered tiltmeter data, SO2 flux values, and earthquake cataloging and analysis. Additional monitoring activities, including radon gas assessments and thermal measurements, were conducted by INGEOMINAS and reported in weekly and monthly reports online. We briefly mention ash explosions that began on 13 May 2012.

April 2011-April 2012 Seismicity. During this reporting period, INGEOMINAS characterized five types of earthquake events: volcano-tectonic (VT), long-period (LP), tremor (TRE), hybrid (HYB), and tornillo (TOR). This data is available in online reports on the INGEOMINAS website for various years.

Earthquakes during this time were rarely deeper than 20 km and clustered ~2 km below the summit, and at times, ranging 5-8 km (table 13). Seismicity was dominated by hybrid events, signals characterizing fracturing and fluid movement. Tremor frequently occurred from May-July 2011 and December 2011-January 2012. From January-March 2012, the duration of tremor was longer than 800 minutes/month (table 13). LP events occurred most frequently in April 2011 and February 2012; VT events primarily appeared in March and April 2012. Tornillo events had been rare in 2011 but were the cause for alarm in November 2011 when INGEOMINAS detected 18 events. The seismic pattern of "tornillo-type" earthquakes has been associated with pre-eruptive conditions - in particular, explosive activity in 1992 and 2010 was preceded by episodes of tornillos (BGVN 34:12). The Alert Level was raised in November (to Orange, on a four-color scale) but lowered again in December (to Yellow) when these signals disappeared from the records; only two events were recorded in December 2011, then again in February 2012.

Figure (see Caption) Table 13. Seismicity at Galeras from April 2011 through April 2012. Earthquake counts for five types of events: volcano-tectonic (VT), long-period (LP), tremor (TRE), hybrid (HYB), and tornillos (TOR). The Alert Level was raised to Orange in November (highlighted in red). Tornillos occurred rarely during this reporting period; "-" indicates events were not reported. Courtesy of INGEOMINAS.

June 2011. INGEOMINAS reported that seismic energy was relatively low this month compared to May 2011. Inflation and deformation events were recorded by two tilt stations (Cráter and Calabazo); other stations, however, were stable (see figure 116 for monitoring station locations). The most proximal tilt station, Cráter, recorded the largest changes in deformation, and especially the radial component (often an order of magnitude larger than the tangential component). During this reporting period, INGEOMINAS frequently included data from the two component tiltmeters and calculated the vectors for Cráter (see INGEOMINAS online reports).

Figure (see Caption) Figure 116. Map of station locations for the INGEOMINAS Pasto monitoring network (from the April 2012 online monthly report). Instrumentation includes: seismometers (SP = short period, BB = broadband), tiltmeters, acoustic flow, ScanDOAS, electromagnetic potential, and Global Positioning System (GPS) stations, as indicated in the legend. This map does not include all monitoring sites, for example fixed stations for Radon and EDM are also part of the network with results posted online. Courtesy of INGEOMINAS.

Large amounts of steam and gas rose from Galeras' crater in June; a plume was frequently observed with a height up to 400 m above the crater. The plume was primarily water vapor, and measurements of SO2 flux showed high variability. INGEOMINAS reported values from ScanDOAS and MobileDOAS ranging from 41-1,455 tons/day; a total of 22 measurements with wind direction and velocity were taken between 1-30 June. The maximum measurement of SO2 flux was made by ScanDOAS from the Santa Bárbara station located 7.0 km NNW from the summit. The minimum value was measured along a traverse with MobileDOAS between the towns La Buitrera and Sandoná (see figure 116 for locations, La Buitera is beyond the map).

July 2011. Seismic energy was 75% higher in July compared with calculations in June. A low-energy seismic swarm of LP events was recorded during 18-19 July. Seismic swarms have occurred periodically at Galeras, the last episode was recorded in early April 2011; this was also the last time tornillo earthquakes were detected (table 13). Deformation continued with fluctuations, however, fieldwork was necessary to reinstall the Cráter tiltmeter (located 0.8 km E of the main crater and at 4,060 m above sea level) when it was disrupted by electric storms on 11 July 2011; the tiltmeter was back online on 20 July.

During clear conditions, a steam plume was visible from Galeras which reached a maximum of 1.5 km above the crater. The maximum SO2 flux for July was 1,080 tons/day which was obtained on 11 July at the Santa Bárbara station with ScanDOAS. A total of 15 measurements with wind direction and velocity were taken between 6 and 23 July. The minimum measurement of SO2 flux was made on 19 July by ScanDOAS, also from the Santa Bárbara station (stations Alto Jiménez and Alto Tinajillas were also recording values).

August 2011. An hour-long seismic swarm was recorded starting at 1800 on 24 August. INGEOMINAS classified these earthquakes as primarily long-period, suggesting that hydrothermal processes were active beneath Galeras. Three of the tiltmeters (Cráter, Huairatola, and Calabozo) indicated deformation and two stations (Peladitos and Cobanegra) showed no change.

Emissions continued to be visible from the crater; a white plume was frequently observed that rose 800 m above the crater rim. SO2 levels were significantly low in August; INGEOMINAS calculated the maximum SO2 flux as 185 tons/day from the Santa Bárbara station on 3 August. A total of 26 measurements were recorded from 1 to 31 August. The lowest value, 25 tons/day, was recorded during a traverse along the northeastern route (between the towns of Genoy and Nariño) on 9 August with MobileDOAS.

September 2011. Seismicity continued at low levels and few earthquakes were large enough to locate (table 13). On 6 September a swarm of hybrid earthquakes was recorded; this was a small episode that occurred between 0600 and 0800. Tilt stations Cráter and Huairatola recorded fluctuations while Calabozo, Peladitos, and Cobanegra showed no significant changes.

The summit was visible for much of September; the plume rose typically less than 500 m above the crater. According to INGEOMINAS, SO2 levels were low in September. A total of 16 measurements were recorded by ScanDOAS from one fixed station (Santa Bárbara station), flux ranged from 51-225 tons/day.

October 2011. INGEOMINAS reported that an earthquake swarm occurred during 25-30 October. Events were characterized as hybrids, suggesting fluid movement and hydrothermal processes; hypocenters were very shallow, less than 2 km beneath the crater. Tilt stations Cráter, Huairatola, and Calabozo recorded fluctuations while Peladitos and Urcunina showed no significant changes.

In October, conditions were favorable for observing the summit area of Galeras. A column of white vapor was visible during most of the month; the plume rose to a height of 800 m above the rim. SO2 flux was relatively low; 19 values were recorded between 1-31 October. The maximum value was 340 tons/day as recorded on 1 October by the Alto Jiménez station (located 10.8 km NW of the summit). The lowest value, 32 tons/day, was recorded at the Santa Bárbara station on 10 October.

November 2011.INGEOMINAS continued registering swarms of shallow VT earthquakes. These events were primarily located at depths less than 1 km from the crater with magnitudes

Figure (see Caption) Figure 117. Seismogram, energy peaks, and spectrogram of the frequency of a tornillo event recorded on 14 November 2011 at 2328 from Galeras. Courtesy of INGEOMINAS.

Several overflights of the crater were conducted in November by INGEOMINAS along with the Colombian Air Force (figure 118). During these flights, staff observed conditions within the crater and noted a strong sulfur odor. Thermal anomalies were detected with a forward-looking infrared (FLIR) camera; on 2 and 26 November, investigators recorded maximum temperatures around 200°C.

Figure (see Caption) Figure 118. An aerial view of Galeras looking S toward a police station and towers on the crater rim. Photo taken during reconnaissance by INGEOMINAS on 2 November 2011.

INGEOMINAS reported significant changes in tilt from the Cráter station (figure 119). Between 7 September and 30 November, there were variations between 3,720 and 920 µrad with increasing and decreasing trends for tangential and radial components, respectively. Trends were also recorded from stations: Peladitos, Huairatola, and Cobanegra. Stations Calabozo and Urcunina showed small fluctuations and were considered stable.

Figure (see Caption) Figure 119. Galeras tiltmeter data (Radial and Tangential components are 'C.Rad' and 'C.Tang', respectively) from stations Cráter, Peladitos, Huairatola, and Cobanegra from April through November 2011. Courtesy of INGEOMINAS.

INGEOMINAS reported that SO2 flux in November ranged from 5 to 178 tons/day. The highest values were recorded by stations implementing ScanDOAS; the Alto Jiménez station recorded the maximum on 5 November. The lowest value was from a MobileDOAS traverse along the Sandoná route on 30 November.

December 2011. The Alert Level was lowered from Orange to Yellow on 6 December due to reduced seismicity; tornillo events were no longer recorded. The tilt station Cráter continued to register changes. INGEOMINAS determined that the NE sector of the volcano exhibited deflation from 7 September to 24 November (figure 119) and beginning on 24 November a change occurred and inflation began. The records suggested that the Huairatola station was detecting deflation of the NE sector from 6 August to 31 December. Data from Cobanegra, from 28 February to 31 December, was also consistent with showing changes in the NE. The Peladitos, Urcunina, and Cóndor stations showed small variations and were considered stable.

In collaboration with the Colombian Air Force, INGEOMINAS conducted an overflight of the crater on 6 December. Several thermal images were taken with a FLIR camera (figure 120). The highest temperature recorded was 200°C.

Figure (see Caption) Figure 120. On 6 December 2012 INGEOMINAS retrieved thermal images of Galeras. In the FLIR image on the right, three maximum temperatures were captured: 116.8°C, 98.7°C, and 74.4°C. Courtesy of INGEOMINAS.

Increased degassing was noted from two sites on the N edge of the crater, Paisita and Chavas (for a crater location map, see figure 87 in BGVN 23:01). SO2 flux was measured by three fixed ScanDOAS stations; a total of 12 measurements were recorded during 1-22 December. Emissions were low and ranging from 21 to 310 tons/day. INGEOMINAS recorded the maximum value from Alto Tinajillas (located 13.3 km W of the crater, figure 116) on 14 December; the minimum was from Santa Bárbara on 9 December.

January 2012. On 31 January, INGEOMINAS reported that a seismic swarm dominated by short-period VT events was recorded. Deformation detected by the Cráter station suggested three unique episodes where radial tilt was increasing, stabilized, and decreased. The tangential component exhibited an inversion of this trend: decreasing, stabilization, and increasing. INGEOMINAS calculated 657 µrad of inflation within the central crater, followed by stabilization and later, deflation measured as 264 µrad.

Steam continued to rise from Paisita and Chavas craters. A white plume was typically visible low over the crater however, on 5, 11, and 21 January, the plume height varied between 500 and 800 m. INGEOMINAS reported that SO2 flux continued at low levels, ranging from 32-259 tons/day. A total of 12 values were obtained from fixed ScanDOAS stations. The maximum value was recorded at the Santa Bárbara station on 27 January.

February 2012. Seismic swarms occurred in February consisting primarily of small, shallow events. At 2148 on 27 February the short-period seismic station Anganoy (located 0.8 km E of the crater, figure 116) recorded an event INGEOMINAS characterized as a 'pseudo-Tornillo'; this event had a dominant frequency of 4.1 Hz and a duration of 36 seconds.

Pseudo-tornillos appeared to be rare events and had occurred previously in November 2011. These have much shorter codas (tails) compared to those of the tornillo signals. The latter last up to several minutes, have small amplitudes compared to duration, and generally decay progressively so their seismic traces appear screw-like in appearance (tornillos is Spanish for screw). These features and various other subtypes and their diagnostic signal characteristics and names are discussed in Narváez and others (1997).

Deformation measured by the Cráter station recorded 774 µrad of deflation in the central crater. The Cobanegra station registered decreasing trends; the stations Peladitos, Urcunina, and Cóndor were considered stable.

A white plume from the crater was visible by webcameras and reached heights less than 800 m above the rim. SO2 flux in February remained low and ranged from 8 to 498 tons/day. A total of 27 values were recorded from fixed ScanDOAS and MobileDOAS measurements. The maximum flux was recorded on 22 February at the Alto Jiménez station.

March 2012. In March, seismic energy decreased by 89.1% compared to February, and few earthquakes were located. However, tremor continued (table 13). The Cráter tiltmeter recorded variability in early March, and from 22 to 31 March, 1,440 µrad of inflation was recorded within the central crater. The Cobanegra station recorded decreasing trends with both components while the stations Peladitos, Urcunina, Cóndor, Calabozo, and Arlés were considered stable.

A white plume was visible during most of the month except for four days. Plume height was maintained below 1.9 km. On 2 March, the National Park reported strong sulfur odors and also received alerts from the municipal committee of Sandoná that gas was noticeable.

Based on fixed and mobile detectors, INGEOMINAS reported that SO2 flux increased dramatically in March. A maximum of 3,390 tons/day was recorded by the Alto Jiménez station on 15 March. The lowest value recorded was 305 tons/day during a traverse along the Consaca-Sandoná route on 30 March. A total of 33 measurements were collected from 1 to 31 March.

April 2012. INGEOMINAS reported that seismic swarms occurred during 5-8 and 11-16 April consisting primarily of small, shallow VT events. The Cráter and Huairatola tilt stations registered variability suggesting inflation in the W sector of Galeras, an area known for high seismicity. The Cobanegra station recorded decreasing trends from both components between 85 and 430 µrad. The other stations were considered stable.

A white plume was frequently visible above the crater in April. Webcameras and observers recorded a maximum height of 2,000 m. On 16 April, the local committee for the prevention of disasters (CLOPAD) of the provincial capital, Pasto, received reports from inhabitants near the N flank of Galeras; gas emissions were visible and people could hear noises from the crater.

SO2 flux continued at elevated levels in April. INGEOMINAS recorded 33 measurements during April. A maximum of 1,477 tons/day was recorded at the Alto Jiménez station on 2 April. The highest levels of SO2 emissions were recorded within the first week of April, averaging 1,012 tons/day. The lowest value was recorded on 13 April, 10 tons/day, along the La Florida-Sandoná route with MobileDOAS.

Editor's Note: INGEOMINAS and the Washington Volcanic Ash Advisory Center (VAAC) reported that ash emissions were detected in early May 2012 (figure 121) and continued into early June.

Figure (see Caption) Figure 121. An ash explosion from Galeras was captured by the "Barranco" webcamera on 27 May 2012. This high-resolution camera was located on the NW rim of the crater. Timing of photo sequence: A. 09:37:53; B. 09:39:08; C. 09:40:15; D. 09:41:40. Courtesy of INGEOMINAS.

Reference. Narváez, L.M., Torres, R.A., Gómez, D.M., Cortez, G.P., Cepeda, H.V., and Stix, J., 1997. 'Tornillo'-type seismic signals at Galeras volcano, Colombia, 1992-1993, Journal of Volcanology and Geothermal Research, 77: 159-171.

Geologic Background. Galeras, a stratovolcano with a large breached caldera located immediately west of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Long-term extensive hydrothermal alteration has contributed to large-scale edifice collapse on at least three occasions, producing debris avalanches that swept to the west and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid-Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.

Information Contacts: Instituto Colombiano de Geologia y Mineria (INGEOMINAS), Observatorio Vulcanológico y Sismológico de Pasto, Pasto, Colombia (URL: https://www2.sgc.gov.co/volcanes/index.html); 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/).


Galunggung (Indonesia) — April 2012 Citation iconCite this Report

Galunggung

Indonesia

7.25°S, 108.058°E; summit elev. 2168 m

All times are local (unless otherwise noted)


One possible 2008 ash plume, crater lake anomalies in 2011-2012

This report mentions a possible ash plume from Galunggung volcano in July 2008 and various other anomalies, including discolored crater lake water during parts of 2011 and 2012. Our last report on Galunggung was in 1984 (SEAN 09:02), following a deadly eruption that began in mid-1982 and ended in early 1983.

The following background information on the volcano was provided in 13 February and 28 May 2012 reports from the Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM). According to the latest report from CVGHM, the present-day lake in the conical crater of Galunggung volcano has a diameter of 1 km and a typical depth of 11 m. In the middle of the lake sits a small, 30 m high, 250 x 165 m scoria cone which was produced during the final stage of the 1982-83 eruption. Galunggung's hazards include phreatic and phreatomagmatic eruptions capable of draining the lake and producing mud flows.

As further background, some of the historical eruptions were explosive, centered at the volcano's crater lake. These eruptions occurred four times, in 1822, 1894, 1918, and 1982-1983. The eruption of 1982-1983 occurred over a period of 21 months, from 5 April 1982-8 January 1984 (SEAN 07:04, 07:06, 07:07, 07:08, 07:09, 07:10, 07:11, and 07:12). In late June 1982, a British Airways jumbo jet encountered an ash cloud that stalled all four of its engines and abraded its windshield and wing surfaces. The aircraft lost 7.5 km of altitude before the engines could be restarted, but it landed safely in Jakarta (SEAN 07:06).

Incorrect report of 2002 eruption; questionable one in 2008. Based on erroneous information from a pilot report, the Darwin Volcanic Ash Advisory Centre (VAAC) stated that an eruption occurred at Galunggung at 1748 hr on 23 August 2002. It produced a W-drifting low-level plume. No ash was visible on satellite imagery. Subsequently, Dali Ahmad of CVGHM had advised Dan Shackelford (amateur volcanist, now deceased) that the report of an eruption on 23 August 2002 was incorrect. It turned out that the likely cause of the incident was a bushfire near the volcano that led observers to believe that an eruption was occurring.

Based on a pilot report and inconclusive observations of satellite imagery, the Darwin VAAC reported that on 17 July 2008 a possible ash plume from Galunggung rose to an altitude of 5.5 km and drifted SW. However, CVGHM did not report eruptive activity and advised that the volcanic activity status was "normal" at that time.

2011-2012 observations. CVGHM reported that from September 2011 to 8 February 2012 the crater lake water at Galunggung was discolored. In addition, a sudden increase in water temperature was measured, from 27° C on 5 February to 40° C on 8 February. Based on seismic data and crater lake observations, CVGHM raised the Alert Level from 1 to 2 (on a scale of 1-4) on 12 February and recommended that people stay at least 500 m away from the lake shore.

CVGHM reported that after the Alert Level was raised, seismic activity at Galunggung decreased drastically through 27 May 2012. Moreover, on 27 April, plants around the crater area looked green and lush, small fish were swimming in the water, and insects around the crater were active. Based on seismic data, crater lake water temperature and pH data, and visual observations, CVGHM lowered the Alert Level from 2 to 1 on 28 May 2012.

MODVOLC satellite thermal alerts were absent at Galunggung during 2011-2012 (and at least since 2000). CVCHM noted in its 28 May 2012 report that throughout the first half of 2012 Galunggung volcano was often covered in mist.

Geologic Background. The forested slopes Galunggung in western Java are cut by a large horseshoe-shaped caldera breached to the SE that has served to channel the products of recent eruptions in that direction. The "Ten Thousand Hills of Tasikmalaya" dotting the plain below the volcano are debris-avalanche hummocks from the collapse that formed the breached caldera about 4200 years ago. Although historical eruptions, restricted to the central vent near the caldera headwall, have been infrequent, they have caused much devastation. The first historical eruption in 1822 produced pyroclastic flows and lahars that killed over 4000 people. More recently, a strong explosive eruption during 1982-1983 caused severe economic disruption to populated areas near the volcano.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM) (URL: http://www.vsi.esdm.go.id); Darwin Volcanic Ash Advisory Centre (VAAC) (URL: http://www.noaa.gov/VAAC/OTH/AU/messages.html).


Gamkonora (Indonesia) — April 2012 Citation iconCite this Report

Gamkonora

Indonesia

1.38°N, 127.53°E; summit elev. 1635 m

All times are local (unless otherwise noted)


Instability followed by confusing news claims of minor June 2012 eruption

Previous Bulletin reports on Gamkonora highlighted an eruption in 1981, minor explosions in April 1987 (SEAN 06:07), and a phreatic eruption in early July 2007 (BGVN 32:10). Reports by the Center of Volcanology and Geological Hazard Mitigation (CVGHM) noted tiny diffuse white plumes in 2009 and again in 2011 when the observatory recorded an average of 2 volcanic earthquakes per day. During mid-2011 through mid-2012, in addition to intervals with several shallow volcanic earthquakes per day, instruments also recorded increasing tremor and hundreds of signals of inferred emissions described as hot-air blasts. The hazard status rose accordingly and remained elevated as this report goes to press on 29 June 2012 at Alert Level 3 (on a scale of 1-4).

As this report goes to press a potentially inaccurate news report indicated an eruption starting 13 June 2012 (see subsection below). That behavior remained unconfirmed by CVGHM or the Darwin Volcanic Ash Advisory Centre (VAAC) as discussed further in a subsection below.

Figures 2-4 provide broad regional context on Gamkonora near the northern margin of Indonesia. A previous map (figure 1 in BGVN 32:10) shows Gamkonora and other Holocene volcanoes on a map of Halmahera and adjacent islands.

Figure (see Caption) Figure 2. Indonesian volcanoes with eruptions since 1900 A.D. as compiled from Simkin and Siebert (1994) by Lyn Topinka (USGS-Cascades Volcano Observatory). Halmahera island and Gamkonora volcano appear in the upper (N) part of the map (see figures 3 and 4). Courtesy of the USGS.
Figure (see Caption) Figure 3. Gamkonora and the situation there associated with unrest in July 2007 (BGVN 32:10). Note the globe showing Indonesia at upper right. On the main map, most of the unshaded and unlabeled islands situated NW of Gamkonora belong to the Philippines. Courtesy of Relief Web.
Figure (see Caption) Figure 4. A UNOSAT product made 12 July 2007 addressing Gamkonora's crisis around that time. The scale and details highlight the local setting; the box at upper left mentions 2004 population estimates and notes that there were 35,000 residents within 20 km of the volcano. Courtesy of UNOSAT.

CVGHM reports were scarce during 1982-2011. One report noted that seismic activity increased somewhat on 24 March 2008. The increase included an episode of continuous tremor.

On 23 March 2009, CVGHM lowered the Alert Level from 2 to 1 based on visual observations and decreased seismicity since January. Diffuse white plumes rose 50-150 m above the crater. Residents and visitors were reminded not to approach or climb into the crater.

CVGHM reported that during January-April 2011, diffuse white plumes rose 25-100 m above Gamkonora's crater rim. Seismicity increased during 29 April-3 May 2011.

On 1 May, white plumes rose 150 m above the crater rim. The next day, white plumes were observed rising 300 m above the crater rim and observers saw incandescence from the crater. Residents near the volcano's base noted a sulfur smell. On 3 May 2011 the Alert level was raised to 2.

Various types of earthquakes were noted during January to April 2011. They included shallow volcanic earthquakes (2 per day average), deep volcanic earthquakes (once per day average), local tectonic earthquakes (1-7 per day average), and far tectonic earthquakes (4 per day average).

A 13 June 2012 CVGHM report noted that during May and June 2012 the emissions were sparsely to medium white in color and rising 75 to 200 m above the crater rim. Absent were sulfurous smells, open flames, eruptive noises, and other similar anomalous symptoms.

The same CVGHM report noted that seismic signals since 3 May 2010 included emission signals (hot-air blasts, averaging 10-12 daily), harmonic tremor (averaging 10-15 events daily), shallow volcanic earthquakes (averaging 2 daily, but for the one specific case given, during the interval 31 May to 11 June 2012, only 1 occurred), and distant tectonic earthquakes (averaging 4 daily). Table 1 presents a breakdown of the interpreted seismic signals during 1 May to 12 June 2012.

Table 1. Seismic data released on 13 June 2012 for Gamkonora. The entries represent total events during specified intervals during May and early June 2012 ("--" signifies absence of data). Courtesy of CVGHM.

Dates Tremor Events (amplitude range) Emission signals Deep volcanic Distant tectonic Local tectonic
01 May-10 May 2012 125 (2-14 mm) 22 18 49 --
11 May-20 May 2012 186 (1.5-10 mm) 81 4 54 --
21 May-30 May 2012 233 (2-13 mm) 209 2 48 95
31 May-11 Jun 2012 246 (2-7 mm) 183 8 49 --
12 Jun 2012 38 (2-5 mm) 2 -- 1 2

The authors of the 13 June report made no further comment about the air-blast signals that had become common at the volcano (table 1). They did note that since the beginning of May 2012, tremor had increased. They interpreted this and the overall seismicity as due to magma intruding upward and approaching shallow depths within the volcano. The authors noted that intrusions could lead to increased pressure within the volcano, although they viewed this pressure as yet relatively small.

As previously noted, starting on 3 May 2011, the volcano's hazard status rose to Alert Level 2. On 3 May 2012 it rose to Level 3, where it remained at least as late as 29 June 2012. The Level 3 status excluded residents, visitors, and tourists from approaching closer than 3 km from the summit. The report also prompted local governments to coordinate with the volcano's monitoring post, which is located in the village of Gamsungi (or with CVGHM's main office in Bandung).

News claims of eruption on 13 June 2012. The English language version of Antara News released a report (edited by Ella Syafputri) at 1913 on 13 June stating that Gamakonora had erupted that afternoon. The eruption, if it did occur, escaped clear mention in available CVGHM reports. The news report said that the eruption sent a plume of undisclosed type or color 3 km "into the sky" (a term that could imply a plume to 3 km altitude or could mean a plume 3 km over the ~1.6 km summit, in effect to ~4.6 km altitude). The news report said the event had the effect of "forcing hundreds of residents living on the volcano's slope to evacuate to safer areas."

Despite the headline "Mount Gamkonora erupts" and directly under that, the sentence "The volcanic ash spread to as far as Tobelo, the capital of North Halmahera district", the two quotes referred to events at two separate volcanoes. In the 5th paragraph of the article the topic shifted to Dukono, another volcano in the region, which turned out to have been the source of the ash (not Gamkonora).

The news report spawned no fewer than 10-20 English-language reports on as many websites. Some of these derivative reports continued to mistakenly attribute Dukono ashfall to Gamkonora, and in some cases they added further errors.

Reference. Simkin, T. and Siebert, L., 1994, Volcanoes of the World: a Regional Directory, Gazetteer, and Chronology of Volcanism During the Last 10,000 Years. (2nd ed.) Geoscience Press, Tucson, 368 pp.

Geologic Background. The shifting of eruption centers on Gamkonora, the highest peak of Halmahera, has produced an elongated series of summit craters along a N-S trending rift. Youthful-looking lava flows originate near the cones of Gunung Alon and Popolojo, south of Gamkonora. Since its first recorded eruption in the 16th century, typical activity has been small-to-moderate explosive eruptions. Its largest historical eruption, in 1673, was accompanied by tsunamis that inundated villages.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Lyn Topinka, United States Geological Survey, 1300 SE Cardinal Court, Bldg. 10, Suite 100, Vancouver, WA, 98683; UNOSAT (URL: https://unitar.org/unosat/); 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/); Antara News (URL: http://www.antaranews.com/en/news/).


Iliamna (United States) — April 2012 Citation iconCite this Report

Iliamna

United States

60.032°N, 153.09°W; summit elev. 3053 m

All times are local (unless otherwise noted)


Rockfalls and fumarolic activity continue with spike in early 2012

Iliamna was last discussed in September 1997 (BGVN 22:09). This report is largely based on seismic data extracted from Alaska Volcano Observatory (AVO) yearly reports for 1997 to 2011, with the exception of an increase of seismicity during early 2012 that was reported by various sources. From the start of 2012, both rockfalls and seismicity progressively increased; this prompted AVO to increase the Alert Level to Advisory in March 2012. A map showing the location of Iliamna in relation to nearby volcanoes and communities is depicted in figure 1. Figures 2 and 3 are topographic maps showing Iliamna's known debris avalanches and rockfall deposits.

Figure (see Caption) Figure 1. Map of Iliamna and nearby volcanoes and communities. Iliamna is in SW Alaska near the mouth of the Cook Inlet, and W of the Kenai Peninsula. Courtesy of AVO.
Figure (see Caption) Figure 2. Iliamna topographic mapping of known debris-avalanche and rockfall deposits. As indicated in the explanation (bottom), red triangles indicate debris avalanches associated with Iliamna, pale orange triangles indicate debris avalanches associated with Iliamna that have been reworked by glaciers, green triangles indicate debris avalanches not associated with Iliamna, green and red dashed lines indicate the maximum likely extent of debris avalanches with relatively long and short runouts, respectively, potential pathways of debris avalanches are indicated by red arrows, and orange shaded areas indicate the generalized extent of rockfall debris on glacier surfaces. Courtesy of Waythomas (1999).
Figure (see Caption) Figure 3. View of the SE flank of Iliamna Volcano showing debris-avalanche deposits from 1997 (solid red line), the fumarole zone near the summit (yellow dashed line), and the older avalanche scar at the head of Red Glacier (red dashed line). Photo undated; courtesy of Waythomas (1999).

Most of the upper edifice exposes highly altered, unstable rock and shows scars from mass wasting. The E scar has been the source of frequent non-volcanic gravitational collapses producing mixed avalanches of ice, snow, rock, and mud that typically extend several kilometers downslope. Some are large enough to be visible from the Kenai Peninsula (Neal and others, 1995; McGimsey and Wallace, 1999).

Reports on Iliamna's seismicity since early 1997 are sparse. According to AVO, a pilot reported a fresh deposit of mud and rock on the upper NE flank on 6 July 1999. However, spring and summer avalanches are common on the glacier-dominated summit.

On 25 July 2003, an avalanche of snow, ice, and rock occurred. The event lasted four minutes and was recorded by seismometers located 75 km away on Augustine volcano. The avalanche presumably originated from the same vicinity as in previous years, a steep portion of the SE flank adjacent to an extensive permanent fumarolic zone above a debris-avalanche deposit (figure 3; Neal and others, 1995; McGimsey and Wallace, 1999; McGimsey and others, 2004).

On 15 May 2005, AVO seismologists noted a swarm of unusual seismic activity at Iliamna. The events were emergent and prolonged (the longest lasted 5-8 minutes) and were strongest at seismic station ILS, located on the S flank of South Twin (figure 4). The activity began at about 1250 UTC and tapered off at 1718 UTC. Analysis revealed that the signals most likely were caused by a surficial process, such as a snow avalanche (a common occurrence on Iliamna), but this particular event lacked the usual precursory seismicity preceding other Iliamna snow and ice avalanches ( Caplan-Auerbach and others, 2004; J. Caplan-Auerbach, written commun., 2005; Caplan-Auerbach and Huggel, 2007).

Figure (see Caption) Figure 4. Iliamna volcano topographic map showing the location of the 15 May 2005 rockslide as a thick black line on the S flank of South Twin and the seismic station ILS as a red dot. Lake Clark National Park boundary shown as a thin black line. Base map provided by C. Waythomas, AVO/USGS; courtesy of McGimsey (2008).

During an overflight on 16 May 2005, Lee Fink of Lake Clark National Park observed a large, fresh rock slide (not a snow or ice avalanche) SE of Iliamna that began at ~1,980 m elevation on the SE flank of South Twin, and ran down to ~365 m elevation (figure 5a). Along the lengthy ridge extending S of Iliamna (including both South Twin, North Twin, and a large unnamed massif) are steep, exposed sections of bedrock. The 15 May rockfall occurred below the ridge (figure 5b).

Figure (see Caption) Figure 5. (a) Rock avalanche on SE flank of S Twin (topographic high at upper center) beginning at ~2 km elevation and running down to ~0.37 km elevation. Photo by Page Spencer, Lake Clark National Park, 16 May 2005. (b) Iliamna from the E captured on 12 July 2006. The arrows mark the location of the 15 May 2005 rock avalanche. Photo by Christinia Neal, AVO/USGS. Courtesy of McGimsey (2008).

During Iliamna's mid-May 2005 rock slide, earthquakes at Augustine volcano, ~100 km SSW of Iliamna in the Cook Inlet, increased from 2 per day in April to 70 per day by the end of the year (McGimsey, 2008). However, no evidence exists that this increase disturbed Iliamna. Other factors such as temperature changes, ice and snow mass (and other conditions) would have contributed to the weakening of the summit material at Iliamna.

According to AVO, earthquake numbers increased significantly between 2008-2009, but returned to near-normal levels in 2010 (table 1).

Table 1. Numbers and types of earthquakes at Iliamna between 2008 and 2010. Key: VT, volcanic tremor; LF, low frequency; Mc, magnitude of completion (lowest magnitude detectable); and '--', not reported. Courtesy of AVO.

Year Total Earthquakes Volcanic Tremor Low-frequency Other Magnitude of completion (lowest magnitude detectable)
2008 102 -- -- -- --
2009 173 159 13 1 0.3
2010 76 61 15 0 0.2

Early 2012 elevated seismicity. AVO reported that during December 2011-February 2012, earthquake activity steadily increased. During the first week of March 2012, numerous earthquakes occurred that varied in number and magnitude. According to a press account (Alaskan Dispatch), on 8 March, a moderate M 4.1 earthquake struck the region. On 9 March, AVO increased the Alert Level to Advisory and the Aviation Color Code to Yellow. AVO reported that the increased activity was a significant change, but also noted that a similarly energetic episode of seismic unrest from September 1996 to February 1997 did not lead to an eruption.

Between 9 March through at least 3 April 2012, seismicity remained above background levels. Satellite images acquired during 9-16 March showed a plume drifting 56 km downwind that was likely water vapor. An AVO report noted that long-lived fumaroles at the summit of Iliamna frequently produced visible plumes, but the current plume appeared to be more robust than usual. Scientists aboard an overflight on 17 March observed vigorous and plentiful fumaroles at the summit, consistent with elevated gas emissions. Gas measurements indicated that the volcano was emitting elevated levels of SO2 and CO2, consistent with a magmatic source. During the overflight, scientists did not observe obvious signs of recent rockfalls, such as large areas of newly exposed bedrock or unusual disturbance of the glacial ice. Some deformation of the ice at the headwall of the Red Glacier on the E side of the summit was observed, but it is not clear that this was related to the current volcanic unrest; glacier avalanching is common on this very steep area and was last seen in 2008. During 25-27 March, activity declined somewhat to just above background levels. When not obscured by clouds, satellite and web camera views showed nothing unusual.

References. Caplan-Auerbach, J., Prejean, S.G., and Power, J.A., 2004, Seismic recordings of ice and debris avalanches of Iliamna Volcano (Alaska): Acta Vulcanologica, v. 16, n. 1-2, p. 9-20.

Caplan-Auerbach, J., and Huggel, C., 2007, Precursory seismicity associated with frequent, large ice avalanches on Iliamna volcano, Alaska, USA: Journal of Glaciology, v. 53, n. 180, p. 128-140.

Detterman, R.L., and Hartsock, J.K., 1966, Geology of the Iniskin-Tuxedni region, Alaska: U.S. Geological Survey Professional Paper 512, 78 p.

Dixon, J.P., and Stihler, S.D., 2009, Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2008: U.S. Geological Survey Data Series 467, 88 p. Available at http://pubs.usgs.gov/ds/467/

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, 84 p. Available online at http://pubs.usgs.gov/ds/531/

McGimsey, R.G., and Wallace, K.L., 1999, 1997 volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 99-0448, 42 p.

McGimsey, R.G., Neal, C.A., and Girina, O., 2004, 1999 Volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 2004-1033, 49 p.

McGimsey, R.G., Neal, C.A., Dixon, J.P., and Ushakov, S., 2008, 2005 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 2007-5269, 94 p.

Neal, C.A., Doukas, M.P., and McGimsey, R.G., 1995, 1994 volcanic activity in Alaska-Summary of events and response of Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 95-271, 18 p. [Iliamna, p. 4-5].

Waythomas, C.F. and Miller, T.P., 1999, Preliminary Volcano-Hazard Assessment for Iliamna Volcano, U.S. Geological Survey Open-File Report OF 99-373.

Geologic Background. Iliamna is a prominentglacier-covered stratovolcano in Lake Clark National Park on the western side of Cook Inlet, about 225 km SW of Anchorage. Its flat-topped summit is flanked on the south, along a 5-km-long ridge, by the prominent North and South Twin Peaks, satellitic lava dome complexes. The Johnson Glacier dome complex lies on the NE flank. Steep headwalls on the S and E flanks expose an inaccessible cross-section of the volcano. Major glaciers radiate from the summit, and valleys below the summit contain debris-avalanche and lahar deposits. Only a few major Holocene explosive eruptions have occurred from the deeply dissected volcano, which lacks a distinct crater. Most of the reports of historical eruptions may represent plumes from vigorous fumaroles E and SE of the summit, which are often mistaken for eruption columns (Miller et al., 1998). Eruptions producing pyroclastic flows have been dated at as recent as about 300 and 140 years ago, and elevated seismicity accompanying dike emplacement beneath the volcano was recorded in 1996.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: http://www.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://www.dggs.alaska.gov/); Alaskan Dispatch (URL: http://www.alaskadispatch.com/).


Masaya (Nicaragua) — April 2012 Citation iconCite this Report

Masaya

Nicaragua

11.984°N, 86.161°W; summit elev. 635 m

All times are local (unless otherwise noted)


Continuous monitoring of emissions and new investigations from collaborators

In our last report on Masaya volcano, we reviewed field investigations and gas measurements from 2008-2011 including the attempt to launch a small Zeppelin as an experiment to measure gas emissions in March 2011 (BGVN 36:11). Here we present results from monitoring efforts focused on the elevated activity that has continued from Masaya's Santiago crater, one of the nested summit craters in Nindirí cone (figure 30). New gas measurements and field observations have become available from the Instituto Nicaragüense de Estudios Territoriales (INETER) from November 2011 through March 2012. Reports were also available for Masaya's Comalito cinder cone, a site of continuous gas emissions and elevated temperatures. In February 2012, INETER met with collaborators from both Simon Fraser University (Canada) and The Open University (UK). We highlight some of the results from these collaborators including mapping and modeling of Masaya's hydrothermal complex, results from long-term SO2 flux monitoring, and a conceptual model that links magma chamber dynamics with intermittent explosive activity.

Figure (see Caption) Figure 30. In this false-color image, Masaya caldera is well-defined. Landsat bands 4,3,2 emphasize vegetation (red) and soil (brown to yellow) and the panchromatic analysis improved the distinction between dark rock (lava) and water (Masaya lake, at the E edge of the caldera) (NASA Landsat Program, 2007). Annotation is based on sketch maps by Mooser and others (1958) and Girard and van Wyk de Vries (2005); image processed by GVP.

The false-color image of Masaya (figure 30) and the surrounding area is a standard composite image (bands 4,3,2) captured by Landsat on 25 March 2001, during Nicaragua's dry season (November through April). Here, vegetation appears in shades of red (darker in areas with denser vegetation), urban areas are cyan blue, and soils vary from dark to light browns. Located just 500 m E of Santiago crater, Masaya crater is distinguished by older deposits, last active around 150 AD, and contains a ring of vegetation (which appears as a pale pink circle). Masaya's recent lava flows have been contained within the larger caldera except for those dating from 1670 when lava ponded along the northern caldera rim and spilled over to cover more than 1 km2 outside the caldera.

In November 2011, INETER recorded little activity from Masaya. No field visits were made and no earthquakes were large enough to locate hypocenters. Seismicity that month was low, at 50 RSAM units.

On 12 December 2011, INETER conducted site visits to Masaya's active crater (Santiago) and Comalito cinder cone. With an infrared thermometer, temperatures were measured from vents within Santiago crater; the highest temperatures measured were 42 and 45°C. The field investigators learned from National Park personnel that, recently during a 2-hour period, booming noises were heard from Santiago crater. INETER suggested that the noise resulted from strong gas release from deep within the crater - no visible material was ejected during the episodes. Areas of gas release could be visually identified within the crater; these were also locations where debris had been shed from the S and SW walls. Rockfalls from these locations were likely affecting gas emissions.

Additional visits to Comalito cone (figure 30), a satellite cone located less than 2 km NE of Santiago crater, allowed in situ measurements of fumarole temperatures. Four sites were measured; the highest temperature was 79°C, the lowest was 75°C (fumaroles 4 and 1 respectively). These temperatures were considered typical compared to others during 2011 (as compiled by INETER; figure 31). The lowest temperatures of the year 2011 were recorded in May and July with some values as low as 60-65°C.

Figure (see Caption) Figure 31. Temperature measurements made by INETER during 2011 at Masaya's Comalito cone. Four fumaroles were measured consistently throughout the year. Courtesy of INETER.

To quantify SO2 gas emissions, INETER used a mobile Mini DOAS throughout the year transported on two different routes. The road between Ticuantepe and San Juan de la Concepción was the closest route available when the plume trended SW. An additional route, at a greater distance (figure 25 from BGVN 36:11) was available between Las Quatro Esquinas and El Crucero. On 13 December, cloud cover limited the number of successful traverses; however, an average SO2 flux of 648 metric tons per day (t/d) was calculated from three of the six traverses. This was a significant increase compared to values obtained in October 2011 when 13 successful traverses that month yielded an average of 153 t/d. These values (and others in this report) have not been corrected for meteorological conditions and error calculations were not available during this reporting period.

On 23 January 2012 INETER conducted traverses below Masaya's plume with a Mini DOAS. Measurements along both routes, proximal (Ticuantepe and San Juan de la Concepción) and distal (Las Quatro Esquinas and El Crucero) were attempted. From 10 calculations, SO2 flux from the proximal route yielded 801 t/d. From the distal route, the average flux rate was 543 t/d.

INETER conducted fieldwork during 30-31 January 2012, visiting Santiago crater and Comalito cone. Temperatures from fumarole sites on Comalito had maximum temperatures of 70°C (fumarole 4) and 78°C (fumarole 2) on 30 January. The maximum temperature measured from Santiago crater had increased to 95°C.

On 1 February 2012, INETER visited Comalito cone and reported fumarole temperatures. The highest temperature was 97°C (fumarole 1); on 23 February the highest temperature was 86°C (fumarole 2). Fieldwork also included visits to Santiago crater; temperatures within the crater were relatively low, 75 and 70°C (from 1 February and 23 February, respectively). SO2 flux from Mini DOAS from the closest route (Ticuantepe and San Juan de la Concepción) yielded an average of 943 t/d based on 12 traverses, continuing the trend of increased SO2 emissions since December 2011.

In March 2012, National Park personnel reported that acoustic noise from the crater was less frequent compared to the previous month. Also, visible gas emissions appeared concentrated at the SW and innermost portions of Santiago crater. On 12 March 2012, INETER visited Masaya and measured temperatures from Santiago crater. A wide range of values was recorded: 100°C to 43°C. Relatively stable temperatures were measured from Comalito cone: 73°C to 76°C. The highest temperatures were measured at fumaroles 3 and 4.

On 20 March INETER conducted Mini DOAS traverses beneath Masaya's SW-trending gas plume. On the proximal route, 12 traverses were successful and determined an average SO2 flux of 1002 t/d suggesting the increasing trend that began in early December 2011 was continuing. Without error calculations and assessing meteorological conditions, however, this trend could not be directly interpreted.

Geohydrology. Long-term interest in diffuse CO2 gas emissions spurred recent investigations into Masaya's hydrothermal system. Mauri and others (2012) found active hydrothermal anomalies under many of the cinder cones and investigated these conditions with field measurements of soil CO2 concentration, self-potential (SP), soil temperatures, and flow-path modeling (figure 32). Self potential methods make observations "of the static natural voltage existing between sets of points on the ground (Sheriff, 1982)". From Comalito cone, Nindirí cone, and the lower slopes of Masaya, CO2 gas concentrations ranged from 26 to 43 ppm (mean values). During a 5-year investigation, the authors collected SP geophysical data over extensive transects within the caldera. The datasets yielded significant correlations between high CO2 soil concentrations and SP anomalies. Water depths were determined by processing the SP data with mathematical techniques (wavelets from the Poisson kernel family). They concluded that interconnected structures (ring faults, fissures, and dikes) serve as flow paths for gas, fluids, and heat. These structures also have the potential to block groundwater flow, a conclusion suggested by their models of groundwater contributions to Masaya Lake (Laguna de Masaya) (figure 32).

Figure (see Caption) Figure 32. Groundwater flow model for Masaya volcano taken from Mauri and others (2012). (a) A map indicating key geographic and geologic features including groundwater flow. (b,c) Two vertical profiles with a legend at the bottom. The groundwater was mapped using two geo-electrical prospecting techniques. The self-potential (SP) technique yielded data processed with multi-scale wavelet tomography (MWT). The second technique was the transient electromagnetic method (TEM) (see key and text).

In Figure 32a, we see the spatial localization of uprising fluids associated with hydrothermal activity (green diamonds) and gravitational water flow (blue squares) within Masaya caldera for which depths have been determined. The names of volcanic cones are in blue; crater names and ground structures are in dark red; dark green dashed lines are the fissure vent structures; solid red lines represent the inferred structures (faults, fissures) based on previous work by Crenshaw and others (1982) and Harris (2009). The red dashed lines are the hypothetical structures (faults, fissures) (Crenshaw and others, 1982). The black dashed line is the inferred limit of the caldera.

The three segments traced in Figure 32a correspond to cross-sections along A-D-B (figure 32b) and C-D-B (figure 32c). Cross-section A-D-B represents the water flow direction across the caldera while the cross-section along profile C-D-B represents the water flow direction through the active Santiago crater and across the caldera. The dashed red lines represent underground structures in cases where the dip orientation is unknown and are based on the work of Williams (1983) and Crenshaw and others (1982). Blue lines with a single dot above the center represent water flow having a flow direction different than the cross-section view. Solid arrows represent the flow direction inferred from the self potential/elevation gradient. Elevations of the shallow flow direction (blue and solid green arrows) were estimated from multi-scale wavelet tomography (MWT). MWT is a signal processing method based on waves that allow for location of dipole and monopole sources which correspond to the electrical anomalies generated by water flow through bedrock. The dashed grey line and dashed blue arrows are deep hypothetical flows from the transient electromagnetic method (TEM) results (MacNeil and others, 2007). TEM results were considered in this study because they offered a different level of sensitivity to SP method and, at the time of the study, direct well data was not available to correlate results, making it difficult to determine which model (MWT or TEM) best represented the true water depth.

Long-term SO2 fluxes and windspeed-induced errors. Nadeau and Williams-Jones (2009) consolidated data spanning three decades (figure 33) and assessed current methods for constraining uncertainties in SO2 data collected on traverses with UV correlation spectrometers (COSPEC/DOAS/FLYSPEC). The authors agreed with previous investigators that the following factors contribute to uncertainties: variable local windspeed, emission rate, dry deposition of sulfur from the plume, and conversion of SO2 to sulfate aerosols within the plume. Of these factors, the authors stressed that for low-lying volcanoes such as Masaya, the local wind patterns cause the largest errors. "One must be wary of using one blanket plume speed value for all data collected at different locations, as it can result in misleading variations within the SO2 flux dataset (Nadeau and Williams-Jones, 2009)." At Masaya, this led to as much a 50% apparent decrease in measured SO2 flux between the proximal and distal routes.

Figure (see Caption) Figure 33. Mean SO2 fluxes grouped by month from numerous field campaigns at Masaya. Error bars represent 1 standard deviation of 1 month of measurements. Note the break in the x-axis. Data from Nadeau and Williams-Jones (2009), which expanded on previous work by numerous investigators listed in that publication.

Modeling Masaya's magma system. Glyn Williams-Jones from Simon Fraser University visited Masaya with student researchers on 21 February 2012. At the National Park facilities, this group presented recent research and results from the 8-year-long collaborative effort between Simon Fraser University, The Open University, and INETER. Williams-Jones reviewed the primary monitoring techniques applied to Masaya and preliminary results regarding the environmental impact of the persistent degassing. In particular, gravity measurements, GPS, and DOAS/FLYSPEC have been used to characterize activity. SO2 flux and air quality measurements have been part of an additional effort to characterize environmental impacts related to resident's health. The varying trend in the SO2 flux observed since 1976 has been interpreted as being related to varying rates of magma convection in the volcanic plumbing system, as opposed to models invoking intermittent magma supply (Williams-Jones and others, 2003; Stix, 2007).

The model invoking convection within the system links Masaya's periodic explosive activity with intense, long-term degassing (Williams-Jones and others, 2003; Stix, 2007). The accumulation of a gas-rich magma within a shallow reservoir could develop a buoyant, pressurized foam. This setting would be susceptible to disruptions (by convection cells or structural adjustments, for example) and could be destabilized, leading to explosive activity.

References. Crenshaw, W.B., Williams, S.N., and Stoiber, R.E., 1982, Fault location by radon and mercury detection at an active volcano in Nicaragua, Nature, 300: 345?346.

Harris, A.J.L., 2009, The pit-craters and pit-crater-filling lavas of Masaya volcano, Bulletin of Volcanology, 71(5): 541?558.

MacNeil, R.E., Sanford, W.E., Connor, C.B., Sandberg, S.K., and Diez, M., 2007, Investigation of the groundwater system at Masaya Caldera, Nicaragua, using transient electromagnetics and numerical simulation, Journal of Volcanology and Geothermal Research, 166(3?4): 216?232.

Mauri, G., Williams-Jones, G., Saracco, G., and Zurek, J.M., 2012, A geochemical and geophysical investigation of the hydrothermal complex of Masaya volcano, Nicaragua, Journal of Volcanology and Geothermal Research, 227?228: 15?31.

Nadeau, P.A. and Williams-Jones, G., 2009, Apparent downwind depletion of volcanic SO2 flux-lessons from Masaya Volcano, Nicaragua, Bulletin of Volcanology, 71: 389?400.

NASA Landsat Program, 2007, Landsat ETM+ scene 7dx20010325, Orthorectified, USGS, Sioux Falls, Mar. 25, 2001.

Sheriff, R.E., 1982, Encyclopedic Dictionary of Exploration Geophysics, Eighth Edition, Society of Exploration Geophysicists, Tulsa, OK, 266 pp.

Stix, J., 2007, Stability and instability of quiescently active volcanoes: the case of Masaya, Nicaragua. Geology, 35(6):535?538.

Williams, S.N., 1983, Geology and eruptive mechanisms of Masaya Caldera complex, Nicaragua [PhD Thesis]: Hanover, New Hampshire, Dartmouth College, 169 p.

Williams-Jones, G., Rymer, H., and Rothery, D.A., 2003, Gravity changes and passive SO2 degassing at the Masaya caldera complex, Nicaragua, Journal of Volcanology and Geothermal Research, 123: 137?160.

Geologic Background. Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras pyroclastic shield volcano and is 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 twin volcanoes of Nindirí and Masaya, 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 6500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. 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 cause health hazards and crop damage.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); Glyn Williams-Jones, Department of Earth Sciences, Simon Fraser University, Burnaby, Canada (URL: http://www.sfu.ca/earth-sciences.html); Hazel Rymer, Department of Environment, Earth and Ecosystems, The Open University, Milton Keynes, UK (URL: http://www8.open.ac.uk/science/environment-earth-ecosystems/).


Semeru (Indonesia) — April 2012 Citation iconCite this Report

Semeru

Indonesia

8.108°S, 112.922°E; summit elev. 3657 m

All times are local (unless otherwise noted)


Increased seismicity with lava flows and pyroclastic flows during February-April 2012

Semeru is one of the most active volcanoes worldwide and is of special concern because the drainage area is heavily populated. The volcano has a steep canyon that extends from the summit to the SE, which has funneled pyroclastic flows and lahars into populated areas. The decades-long seismicity from Semeru has typically included mildly explosive Strombolian style eruptions, earthquakes and tremor, ash plumes, and occasional pyroclastic flows (BGVN 32:03, 34:05, and 35:08). See the location of Semeru with respect to the regional setting in figure 17.

Figure (see Caption) Figure 17. Index map of Semeru (red triangle) with respect to other Holocene regional volcanoes (black triangles). Courtesy of CVGHM and VDAP.

According to reporting by the Center of Volcanology and Geological Hazard Mitigation (CVGHM) and the USGS Volcano Disaster Assistance Program (VDAP), six large explosions between 1981 and 2002 resulted in many fatalities. They noted that since 1995, pyroclastic flows have been restricted to S drainages such as Kali Kembar; however, a small proportion of recent flows have entered the headwaters of Kali Koboan on the SE, which leads to heavily populated areas, including Sumberrejo and Candipuro (figure 18). This report discusses activity between February 2010 (the end of the previous report) and 2 May 2012.

Figure (see Caption) Figure 18. 2010 map of Semeru and adjacent area, showing drainage channels from the summit and nearby population centers. Note the location of the 2012 lava flows just S and SE of the volcano. The area around the SE quadrant is heavily populated with a Volcano Population Index (VPI10) of 7,000. In previous eruptions, lahars reached as far as 30 km from the summit. Should similar lahars occur in the future, as many as 150,000 more inhabitants along major drainages could be affected. Based in part on a summary of activity by CVGHM and VDAP. Modified from Siswowidjoyo and others (1997) and Thouret and others (2007); VPI10 was calulated using LandScan 2010.

On 4 November 2010, CVGHM reported that from August to October 2010 seismic activity at Semeru had increased, and "smoke" and occasional gas plumes rose 400-500 m above the crater. During September incandescent avalanches traveled 400 m SE into the Besuk Kembar drainage on three occasions. Incandescence from the crater was observed in October. Incandescent avalanches traveled 600 m into Besuk Kembar on 2 November. Two days later, they reached 4 km into the Besuk Kembar and Besuk Bang (S) drainages (figure 18). CVGHM noted that the lava dome in the Jonggring Saloko crater was growing. The Alert Level remained at 2 (on a scale of 1-4).

According to the Darwin Volcanic Ash Advisory Centre (VAAC), during 18-19 November 2010, ash plumes rose to an altitude of 4.6 km and drifted 75-110 km N and NW. Sulfur dioxide gas was detected 75 km SW.

According to Volcano Discovery, the group observed 2-3 small-to-medium ash explosions per day during a photo expedition in May 2011, but noted that activity had increased during the past weeks.

In an account posted online by Volcano Discovery on 15 September 2011, the group visited the volcano and noted that an active lava dome was growing inside the crater and that 3-4 eruptions occurred daily. They inferred that the size and frequency of the eruptions had apparently increased in the past days (figure 19).

Figure (see Caption) Figure 19. Photo of Semeru's crater on 1 September 2011, with a lava dome. Courtesy of Volcano Discovery.

CVGHM reported that on 29 December 2011, both earthquakes and tremor increased, and dense white-and-gray plumes rose as high as 600 m above the active crater. During January 2012, crater incandescence was observed, and avalanches carried incandescent material 200-400 m away from the crater. According to a 4 January 2012 article in the Jakara Globe, a government official indicated that authorities had closed the trail to the peak of Semeru because of heavy rain and an increased danger of landslides.

On 2 February 2012 a large explosion was reported and incandescent material fell up to 2.5 km from the crater. Tables 20 and 21 indicate the types and numbers of earthquakes and other seismic events reported by CVGHM for February to April 2012. Based on the increased seismic activity and visual observations, CVGHM raised the Alert Level from 2 to 3 on 2 February 2012.

Table 20. Types and numbers of earthquakes and plumes observed at Semeru during February-April 2012. Courtesy of CVGHM.

Month Deep Shallow Long-distance Local Eruptive Explosive Harmonic Tremor Pyroclastic Flow
Feb 2012 4 1 61 -- 80 2336 116 430
Mar 2012 17 5 60 23 -- 1665 610 40
Apr 2012 7 2 44 -- -- 3447 66 4

Table 21. Observed Semeru plumes during February-April 2012. Data from CVGHM. The only other plume noted by the Darwin VAAC between February 2010 and May 2012 was on 18-19 November 2010; this plume was noted in the text. Courtesy of CVGHM.

Month Number of observed plumes Plume height above crater
Feb 2012 22 100-500 m
Mar 2012 9 100-400 m
Apr 2012 155 100-500 m

CVGHM reported that during 1-29 February 2012 multiple pyroclastic flows from Semeru traveled 500 and 2,500 m into the Besuk Kembar and Besuk Kobokan rivers (on the S flank), respectively. Government officials set up an exclusion zone on the SE flank where pyroclastic flows had occurred.

During 1 February-30 April 2012, dense gray-to-white plumes rose 100-500 m above Jongring Seloko crater and drifted W and N. Incandescence was visible up to 50 m above the crater during 1 February-31 March. Seismicity decreased toward the end of April, although the lava dome grew that month.

According to a news account (People's Daily Online) on 1 March 2012, seismic activity had increased from 28 to 38 tremors per day. According to the news account, Dr. Surono, head of CVGHM, stated that the volcano was erupting daily, emitting ash plumes, and tremor occurred every 15-30 minutes. He also noted that the volcanic dome was increasing in size.

According to Volcano Discovery, an expedition leader visiting Semeru observed frequent explosions every few minutes on 27 March 2012, with many powerful enough to eject glowing bombs that produced small glowing avalanches down the S flank.

According to CVGHM and VDAP, a new lava dome started to extrude in late 2011 directly over a dome formed in 2010. The new dome probably will not completely fill the summit crater because it is being drained by two new lava flows, both flowing SE. The longer of the two lava flows extended about 1.9 km from the summit vent. Pyroclastic flows are being generated by collapse of the steep termini of the lava flows, and their deposits extend to 3.2 km from the summit, i.e. 0.7 km from the front shown in figure 18. In addition, the collapsing lava flow fronts are resulting in high levels of avalanche and rockfall activity. According to CVGHM and VDAP, the closest villages in the highest-risk areas on the S and SE flanks are about 10 km from the summit.

On 2 May 2012 CVGHM lowered the Alert Level to 2, but reminded the public not to approach the crater within a 4-km radius.

Geologic Background. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Volcano Disaster Assistance Program (VDAP), US Geological Survey (USGS), 1300 SE Cardinal Court, Bldg. 10, Suite 100, Vancouver, WA 98683; 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); Jakarta Globe (URL: http://www.thejakartaglobe.com); People’s Daily Online (URL: english.peopledaily.com; Volcano Discovery (URL: http://mobile.volcanodiscovery.com).


Soputan (Indonesia) — April 2012 Citation iconCite this Report

Soputan

Indonesia

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

All times are local (unless otherwise noted)


Alert level raised in May 2012 based on increased seismic activity

Our previous report of Soputan volcano chronicled activity during July-September 2011 (BGVN 36:11). Table 9 gives a brief history of activity and highlights activity through early May 2012. The data sources are the Darwin Volcanic Ash Advisory Centre (VAAC) for satellite monitoring of ash plumes and the Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM) for seismic monitoring and assignment of alert levels. According to a 28 May 2012 report by CVGHM, Soputan's activities are characterized by the growth of lava domes that have been accreting steadily since 1991. The accretion of these lava domes has been frequently accompanied by ash/cinder eruptions.

Table 9. Summary of volcanic ash observations and other activity at Soputan volcano from late June 2011 through mid-2012. 'VA' refers to volcanic ash. Courtesy of Darwin VAAC and CVGHM.

Date Observations Remarks
21 Jun-02 Jul 2011 Seismic activity increased --
02 Jul 2011 -- Alert Level 2 to 3
03 Jul-04 Jul 2011 Explosive eruption of incandescent material with pyroclastic flow 4 km to W; VA plume to 4.6-14 km extending 407 km W --
04 Jul 2011 High-level eruption has ceased, dissipating --
19 Jul 2011 -- Alert Level 3 to 2
14 Aug 2011 Two eruptions; VA plume to 3.7 km extending 107 km W Alert Level 2 to 3; VA not identifiable on satellite imagery
14 Aug-07 Sep 2011 Seismic Activity significantly decreased after eruption --
08 Sep 2011 Hot air blasts of smoke from the mass of the lava dome Alert Level 3 to 2
28 May 2012 Seismic activity significantly increased Alert Level 2 to 3

On 28 May 2012, CVGHM raised the Alert Level of Soputan from 2 to 3 (on a scale of 1-4) following increasing sesimic activity. According to CVGHM, increasing activity had been observed from 21-27 May, when the volcano spewed out white smoke to heights of between 50 to 150 m above the summit. Seismicity increased significantly on 25 May.

CVGHM called on local residents to stay beyond a 6 km radius from the volcano's summit. It also warned residents of the threat of a lahar, urging people living near Ranowangko, Pentu, Lawian and Popang rivers to remain alert and aware.

MODVOLC Thermal Alerts. MODVOLC satellite thermal alerts were measured at Soputan on 2-3 July, 9 July, and 14-15 August 2011, all on the volcano's W flank. These were the first such measurements since the volcano's last eruption, during late October to early November 2008 (BGVN 33:09). Since 8 August 2011 to early March 2012, no alerts have been measured.

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: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Volcanological Survey of Indonesia (VSI), Jalan Diponegoro 57 Bandung, Jawa Barat 40122, Indonesia (URL: http://vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac); MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Jakarta Post (URL: http://www.thejakartapost.com).

Atmospheric Effects

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

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

Special Announcements

Special announcements of various kinds and obituaries.

Special Announcements

Additional Reports

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

Kermadec Islands


Floating Pumice (Kermadec Islands)

1986 Submarine Explosion


Tonga Islands


Floating Pumice (Tonga)


Fiji Islands


Floating Pumice (Fiji)


Andaman Islands


False Report of Andaman Islands Eruptions


Sangihe Islands


1968 Northern Celebes Earthquake


Southeast Asia


Pumice Raft (South China Sea)

Land Subsidence near Ham Rong


Ryukyu Islands and Kyushu


Pumice Rafts (Ryukyu Islands)


Izu, Volcano, and Mariana Islands


Acoustic Signals in 1996 from Unknown Source

Acoustic Signals in 1999-2000 from Unknown Source


Kuril Islands


Possible 1988 Eruption Plume


Aleutian Islands


Possible 1986 Eruption Plume


Mexico


False Report of New Volcano


Nicaragua


Apoyo


Colombia


La Lorenza Mud Volcano


Pacific Ocean (Chilean Islands)


False Report of Submarine Volcanism


Central Chile and Argentina


Estero de Parraguirre


West Indies


Mid-Cayman Spreading Center


Atlantic Ocean (northern)


Northern Reykjanes Ridge


Azores


Azores-Gibraltar Fracture Zone


Antarctica and South Sandwich Islands


Jun Jaegyu

East Scotia Ridge


Additional Reports (database)

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

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

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

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

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

UFO adherent claims new volcano in Sea of Marmara

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

Fumaroles and minor seismicity since October 2002

12/2005 (BGVN 30:12) Elgon

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



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

False Report of Mount Pinokis Eruption

Philippines

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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


False Report of Somalia Eruption (Somalia) — December 1997

False Report of Somalia Eruption

Somalia

3.25°N, 41.667°E; summit elev. 500 m

All times are local (unless otherwise noted)


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

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

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

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

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


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

False Report of Sea of Marmara Eruption

Turkey

40.683°N, 29.1°E; summit elev. 0 m

All times are local (unless otherwise noted)


UFO adherent claims new volcano in Sea of Marmara

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Information Contacts: Erol Erkmen, Tuvpo Project Alp.


Har-Togoo (Mongolia) — May 2003

Har-Togoo

Mongolia

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

All times are local (unless otherwise noted)


Fumaroles and minor seismicity since October 2002

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


Elgon (Uganda) — December 2005

Elgon

Uganda

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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