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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

Pacaya (Guatemala) Lava flows and Strombolian explosions continued during February-July 2019

Colima (Mexico) Renewed volcanism after two years of quiet; explosion on 11 May 2019

Masaya (Nicaragua) Lava lake activity declined during March-July 2019

Rincon de la Vieja (Costa Rica) Occasional weak phreatic explosions during March-July 2019

Aira (Japan) Explosions with ejecta and ash plumes continue weekly during January-June 2019

Agung (Indonesia) Continued explosions with ash plumes and incandescent ejecta, February-May 2019

Kerinci (Indonesia) Intermittent explosions with ash plumes, February-May 2019

Suwanosejima (Japan) Small ash plumes continued during January through June 2019

Great Sitkin (United States) Small steam explosions in early June 2019

Ibu (Indonesia) Frequent ash plumes and small lava flows active in the crater through June 2019

Ebeko (Russia) Continuing frequent moderate explosions though May 2019; ashfall in Severo-Kurilsk

Klyuchevskoy (Russia) Weak thermal anomalies and moderate Strombolian-type eruptions in September 2018-June 2019



Pacaya (Guatemala) — August 2019 Citation iconCite this Report

Pacaya

Guatemala

14.382°N, 90.601°W; summit elev. 2569 m

All times are local (unless otherwise noted)


Lava flows and Strombolian explosions continued during February-July 2019

Pacaya is one of the most active volcanoes in Guatemala, with activity largely consisting of frequent lava flows and Strombolian activity at the Mackenney crater. This report summarizes continued activity during February through July 2019 based on reports by Guatemala's Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH) and Sistema de la Coordinadora Nacional para la Reducción de Desastres (CONRED), visiting scientists, and satellite data.

At the beginning of February activity included Strombolian explosions ejecting material up to 5 to 30 m above the Mackenney crater and a degassing plume up to 300 m. Multiple lava flows were observed throughout the month on the N, NW, and W flanks, reaching 350 m from the crater and resulting in avalanches from the flow fronts. Strombolian activity continued with sporadic to continuous explosions ejecting material 5-75 m above the Mackenney crater. Degassing produced plumes up to 300 m above the crater, and incandescence from the crater and lava flows were seen at night. Daniel Sturgess of Bristol University observed activity on the 24th, noting a 70-m-long lava flow with individual blocks from the front of the flow rolling down the flanks (figure 108). He reported that mild Strombolian explosions occurred every 10-20 minutes and ejected blocks, up to approximately 4 m in diameter, as high as 5-30 m above the crater and towards the northern flank.

Figure (see Caption) Figure 108. An active lava flow on the NW flank of Pacaya on 24 February 2019 with incandescence visible in lower light conditions. Courtesy of Daniel Sturgess, University of Bristol.

Similar activity continued through March with multiple lava flows reaching a maximum of 200 m N and NW, and avalanches descending from the flow fronts. Ongoing Strombolian explosions expelled material up to 75 m above the Mackenney crater. Degassing produced a white-blue plume to a maximum of 900 m above the crater (figure 109) and incandescence was noted some nights.

Figure (see Caption) Figure 109. A degassing plume at Pacaya reaching 350 m above the crater and dispersing to the S on 19 March 2019. Courtesy of CONRED.

During April lava flows continued on the N and NW flanks, reaching a maximum length of 300 m, with avalanches forming from the flow fronts. Degassing formed plumes up to 600 m above the crater that dispersed with various wind directions. Strombolian activity continued with explosions ejecting material up to 40 m above the crater. On the 2nd and 3rd weak rumbles were heard at distances of 4-5 km. Similar activity continued through May with lava flows reaching 300 m to the N, degassing producing plumes up to 600 m above the crater, and Strombolian explosions ejecting material up to 15 m above the crater.

Lava flows continued out to 300 m in length to the N and NW during June (figures 110 and 111). Strombolian activity ejected material up to 30 m above the crater and degassing resulted in plumes that reached 300 m. During July there were multiple active lava flows that reached a maximum of 300 m in length on the N and NW flanks (figure 112). Avalanches generated by the collapse of material at the front of the lava flows were accompanied by explosions ejecting material up to 30 m above the crater.

Figure (see Caption) Figure 110. An active lava flow on Pacaya on 9 June 2019 with incandescent blocks rolling down the flank from the flow front. Courtesy of Paul Wallace, University of Liverpool.
Figure (see Caption) Figure 111. Activity at Pacaya on 22 June 2019 with a degassing plume dispersed to the W and a 300-m-long lava flow. Photos by Miguel Morales, courtesy of CONRED.
Figure (see Caption) Figure 112. Two lava flows were active to the N and NW at Pacaya on 20 July 2019. Photos courtesy of CONRED.

During February through July multiple lava flows and crater activity were detected in Sentinel-2 satellite thermal images (figures 113 and 114) and relatively constant thermal energy was detected by the MIROVA system with a slight decrease in the energy and frequency of anomalies during June (figure 115). The thermal anomalies detected by the MODVOLC system for each month from February through July spanned 6-30, with six during June and 30 during April.

Figure (see Caption) Figure 113. Sentinel-2 thermal satellite images of Pacaya show lava flows to the N and NW during February through April 2019. There was a reduction in visible activity in early March. False color (urban) satellite images (bands 12, 11, 4) courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 114. Sentinel-2 thermal satellite images of Pacaya showing lava flow and hot avalanche activity during June and July 2019. False color (urban) satellite images (bands 12, 11, 4) courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 115. MIROVA log radiative power plot of MODIS thermal infrared at Pacaya during October 2018 through July 2019. Detected thermal energy is relatively stable with a decrease through June and subsequent increase during July. Courtesy of MIROVA.

Geologic Background. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.

Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/); Coordinadora Nacional para la Reducción de Desastres (CONRED), Av. Hincapié 21-72, Zona 13, Guatemala City, Guatemala (URL: http://conred.gob.gt/www/index.php); 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/); Daniel Sturgess, School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, United Kingdom (URL: http://www.bristol.ac.uk/earthsciences/); Paul Wallace, Department of Earth, Ocean and Ecological Sciences, University of Liverpool, 4 Brownlow Street, Liverpool L69 3GP, United Kingdom (URL: https://www.liverpool.ac.uk/environmental-sciences/staff/paul-wallace/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Colima (Mexico) — August 2019 Citation iconCite this Report

Colima

Mexico

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

All times are local (unless otherwise noted)


Renewed volcanism after two years of quiet; explosion on 11 May 2019

Frequent historical eruptions at Volcán de Colima date back to the 16th century and include explosive activity, lava flows, and large debris avalanches. The most recent eruptive episode began in January 2013 and continued through March 2017. Previous reports have covered activity involving ash plumes with extensive ashfall, lava flows, lahars, and pyroclastic flows (BGVN 41:01 and 42:08). In late April 2019, increased seismicity related to volcanic activity began again. This report covers activity through July 2019. The primary source of information was the Centro Universitario de Estudios e Investigaciones de Vulcanologia, Universidad de Colima (CUEIV-UdC).

On 11 May 2019, CUEIV-UdC reported an explosion that was recorded by several monitoring stations. A thermal camera located south of Colima captured thermal anomalies associated with the explosion as well as intermittent degassing, which mainly consisted of water vapor (figure 131). A report from the Unidad Estatal de Protección Civil de Colima (UEPCC), and seismic and infrasound network data from CUEIV-UdC, recorded about 60 high-frequency events, 16 landslides, and 14 low-magnitude explosions occurring on the NE side of the crater during 11-24 May. Drone imagery showed fumarolic activity occurring on the inner wall of this crater on 22 May (figure 132).

Figure (see Caption) Figure 131. Gas emissions from Colima during the 11 May 2019 eruption as seen from the Naranjal station. Courtesy of CUEIV-UdC (Boletin Seminal de la Actividad del Volcan de Colima 17 mayo 2019 no 121).
Figure (see Caption) Figure 132. A drone photo showing fumarolic activity occurring within the NE wall of the crater at Colima on 22 May 2019. Courtesy of CUEIV-UdC (Boletin Seminal de la Actividad del Volcan de Colima 24 mayo 2019 no 122).

Small explosions and gas-and-steam emissions continued intermittently through mid-July 2019 concentrated on the NE side of the crater. An overflight on 9 July 2019 revealed that subsidence from the consistent activity slightly increased the diameter of the vent; other areas within the crater also showed evidence of subsidence and some collapsed material on the outer W wall (figure 133). During the weeks of 19 and 26 July 2019, monitoring cameras and seismic data recorded eight lahars.

Figure (see Caption) Figure 133. A drone photo of the crater at Colima on 8 July 2019 shows continuing fumarolic activity and evidence of a collapsed wall on the W exterior side. Courtesy of CUEIV-UdC (Boletin Seminal de la Actividad del Volcan de Colima 12 julio 2019 no 129).

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

Information Contacts: Centro Universitario de Estudios e Investigaciones de Vulcanologia, Universidad de Colima (CUEIV-UdC), Colima, Col. 28045, Mexico; Centro Universitario de Estudios Vulcanologicos y Facultad de Ciencias de la Universidad de Colima, Avenida Universidad 333, Colima, Col. 28045, Mexico (URL: http://portal.ucol.mx/cueiv/); Unidad Estatal de Protección Civil, Colima, Roberto Esperón No. 1170 Col. de los Trabajadores, C.P. 28020, Mexico (URL: http://www.proteccioncivil.col.gob.mx/).


Masaya (Nicaragua) — August 2019 Citation iconCite this Report

Masaya

Nicaragua

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

All times are local (unless otherwise noted)


Lava lake activity declined during March-July 2019

Masaya, in Nicaragua, contains a lava lake found in the Santiago Crater which has remained active since its return in December 2015 (BGVN 41:08). In addition to this lava lake, previous volcanism included explosive eruptions, lava flows, and gas emissions. Activity generally decreased during March-July 2019, including the number and frequency of thermal anomalies, lava lake levels, and gas emissions. The primary source of information for this report comes from the Instituto Nicareguense de Estudios Territoriales (INETER).

On 21 July 2019 a small explosion in the Santiago Crater resulted in some gas emissions and an ash cloud drifting WNW. In addition to the active lava lake (figure 77), monthly reports from INETER noted that thermal activity and gas emissions (figure 78) were decreasing.

Figure (see Caption) Figure 77. Active lava lake visible in the Santiago Crater at Masaya on 27 June 2019. Photo by Sheila DeForest (Creative Commons BY-SA license).
Figure (see Caption) Figure 78. Gas emissions coming from the Santiago Crater at Masaya on 29 June 2019. Photo by Sheila DeForest (Creative Commons BY-SA license).

On 15 May and 22 July 2019, INETER scientists used a FLIR SC620 thermal infrared camera to measure temperatures of fumaroles on the Santiago Crater. In May 2019 the temperature of fumaroles had decreased by 48°C since the previous month. Between May and July 2019 fumarole temperatures continued to decline; temperatures ranged from 90° to 136°C (figure 79). Compared to May 2019 these temperatures are 3°C lower. INETER reports that the level of the lava lake has been slowly dropping during this reporting period.

Figure (see Caption) Figure 79. FLIR (forward-looking infrared) and visible images of the Santiago Crater at Masaya showing fumarole temperatures ranging from 90° to 136°C. The scale in the center shows the range of temperatures in the FLIR image. Courtesy of INETER (March 2019 report).

According to MIROVA (Middle InfraRed Observation of Volcanic Activity) data from MODIS satellite instruments, frequent thermal anomalies were recorded from mid-March through early May 2019, with little to no activity from mid-May to July 2019 (figure 80). Sentinel-2 thermal images show high temperatures in the active lava lake on 10 March 2019 (figure 81). Thermal energy detected by the MODVOLC algorithm showed 14 hotspot pixels with the most number of hotspots (7) occurring in March 2019.

Figure (see Caption) Figure 80. Thermal anomalies were relatively constant at Masaya from early September 2018 through early May 2019 and then abruptly decreased until mid-June 2019 as recorded by MIROVA. Courtesy of MIROVA.
Figure (see Caption) Figure 81. Sentinel-2 thermal satellite image showing a detected heat signature from the active lava lake at Masaya on 10 March 2019. The lava lake is visible (bright yellow-orange). Approximate diameter of the crater containing the lava lake is 500 m. Thermal (urban) satellite image (bands 12, 11, 4) courtesy of Sentinel Hub Playground.

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/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Sheila DeForest (URL: https://www.facebook.com/sheila.deforest).


Rincon de la Vieja (Costa Rica) — August 2019 Citation iconCite this Report

Rincon de la Vieja

Costa Rica

10.83°N, 85.324°W; summit elev. 1916 m

All times are local (unless otherwise noted)


Occasional weak phreatic explosions during March-July 2019

The acid lake of Rincón de la Vieja's active crater has generated intermittent weak phreatic explosions regularly since 2011, continuing during the past year through at least August 2019. The volcano is monitored by the Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA), and the information below comes from its weekly bulletins between 4 March and 2 September 2019. Clouds often prevented webcam and satellite views. The current report describes activity from March through July 2019.

OVSICORI-UNA reported that weak events occurred on 19 March at 1851 and on 29 March 2019 at 2043. A two-minute-long phreatic explosion on 1 April at 0802 produced a plume that rose 600 m above the crater rim. Continuous emissions were visible during 3-4 April, rising 200 m above the crater rim. On 3 April, at 1437, a small explosion was detected. An explosion on 10 April at 0617 produced a gas-and-steam plume that rose 1 km above the crater rim and drifted SE. On 12 April at 0643, a plume rose 500 m. Another event took place at 0700 on 13 April, although poor weather conditions prevented visual observations. On 14 April, OVSICORI-UNA noted that aerial photographs showed a milky-gray acid lake at a relatively low water level with convection cells of several tens meters of diameter in the center and eastern parts of the lake.

According to an OVSICORI-UNA bulletin, a small phreatic explosion occurred on 1 May. Another explosion on 11 May at 0720 produced a white gas-and-steam plume that rose 600 m above the crater rim. Phreatic explosions were recorded on 14 May at 1703 and on 17 May at 0357, though dense fog prevented visual confirmation of both events with webcams. On 15 May a local observer noted a diffuse plume of steam and gas, material rising from the crater, and photographed milky-gray deposits on the N part of the crater rim ejected from the event the day before. A major explosion occurred on 24 May.

OVSICORI-UNA recorded a significant phreatic 10-minute-long explosion that began on 11 June at 0343, but plumes were not visible due to weather conditions. No further phreatic events were reported in July.

Seismic activity was very low during the reporting period, and there was no significant deformation. Short tremors were frequent toward the end of April, but were only periodic in May and June; tremor almost disappeared in July. A few long-period earthquakes were recorded, and volcano-tectonic earthquakes were even less frequent.

Geologic Background. Rincón de la Vieja, the largest volcano in NW Costa Rica, is a remote volcanic complex in the Guanacaste Range. The volcano consists of an elongated, arcuate NW-SE-trending ridge that was constructed within the 15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on the south side. Sometimes known as the "Colossus of Guanacaste," it has an estimated volume of 130 km3 and contains at least nine major eruptive centers. Activity has migrated to the SE, where the youngest-looking craters are located. The twin cone of 1916-m-high Santa María volcano, the highest peak of the complex, is located at the eastern end of a smaller, 5-km-wide caldera and has a 500-m-wide crater. A plinian eruption producing the 0.25 km3 Río Blanca tephra about 3500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous historical eruptions possibly dating back to the 16th century, have been from the prominent active crater containing a 500-m-wide acid lake located ENE of Von Seebach crater.

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/, https://www.facebook.com/OVSICORI/).


Aira (Japan) — July 2019 Citation iconCite this Report

Aira

Japan

31.593°N, 130.657°E; summit elev. 1117 m

All times are local (unless otherwise noted)


Explosions with ejecta and ash plumes continue weekly during January-June 2019

Sakurajima rises from Kagoshima Bay, which fills the Aira Caldera near the southern tip of Japan's Kyushu Island. Frequent explosive and occasional effusive activity has been ongoing for centuries. The Minamidake summit cone has been the location of persistent activity since 1955; the Showa crater on its E flank has also been intermittently active since 2006. Numerous explosions and ash-bearing emissions have been occurring each month at either Minamidake or Showa crater since the latest eruptive episode began in late March 2017. This report covers ongoing activity from January through June 2019; the Japan Meteorological Agency (JMA) provides regular reports on activity, and the Tokyo VAAC (Volcanic Ash Advisory Center) issues tens of reports each month about the frequent ash plumes.

From January to June 2019, ash plumes and explosions were usually reported multiple times each week. The quietest month was June with only five eruptive events; the most active was March with 29 (table 21). Ash plumes rose from a few hundred meters to 3,500 m above the summit during the period. Large blocks of incandescent ejecta traveled as far as 1,700 m from the Minamidake crater during explosions in February and April. All the activity originated in the Minamidake crater; the adjacent Showa crater only had a mild thermal anomaly and fumarole throughout the period. Satellite imagery identified thermal anomalies inside the Minamidake crater several times each month.

Table 21. Monthly summary of eruptive events recorded at Sakurajima's Minamidake crater in Aira caldera, January-June 2019. The number of events that were explosive in nature are in parentheses. No events were recorded at the Showa crater during this time. Data courtesy of JMA (January to June 2019 monthly reports).

Month Ash emissions (explosive) Max. plume height above crater Max. ejecta distance from crater
Jan 2019 8 (6) 2.1 km 1.1 km
Feb 2019 15 (11) 2.3 km 1.7 km
Mar 2019 29 (12) 3.5 km 1.3 km
Apr 2019 10 (5) 2.2 km 1.7 km
May 2019 15 (9) 2.9 km 1.3 km
Jun 2019 5 (2) 2.2 km 1.3 km

There were eight eruptive events reported by JMA during January 2019 at the Minamidake summit crater of Sakurajima. They occurred on 3, 6, 7, 9, 17, and 19 January (figure 76). Ash plume heights ranged from 600 to 2,100 m above the summit. The largest explosion, on 9 January, generated an ash plume that rose 2,100 m above the summit crater and drifted E. In addition, incandescent ejecta was sent 800-1,100 m from the summit. Incandescence was visible at the summit on most clear nights. During an overflight on 18 January no significant changes were noted at the crater (figure 77). Infrared thermal imaging done on 29 January indicated a weak thermal anomaly in the vicinity of the Showa crater on the SE side of Minamidake crater. The Kagoshima Regional Meteorological Observatory (KRMO) (11 km WSW) recorded ashfall there during four days of the month. Satellite imagery indicated thermal anomalies inside Minamidake on 7 and 27 January (figure 77).

Figure (see Caption) Figure 76. Incandescent ejecta and ash emissions characterized activity from Sakurajima volcano at Aira during January 2019. Left: A webcam image showed incandescent ejecta on the flanks on 9 January 2019, courtesy of JMA (Explanation of volcanic activity in Sakurajima, January 2019). Right: An ash plume rose hundreds of meters above the summit, likely also on 9 January, posted on 10 January 2019, courtesy of Mike Day.
Figure (see Caption) Figure 77. The summit of Sakurajima consists of the larger Minamidake crater and the smaller Showa crater on the E flank. Left: The Minamidake crater at the summit of Sakurajima volcano at Aira on 18 January 2019 seen in an overflight courtesy of JMA (Explanation of volcanic activity in Sakurajima, March 2019). Right: Two areas of thermal anomaly were visible in Sentinel-2 satellite imagery on 27 January 2019. "Geology" rendering (bands 12, 4, and 2) courtesy of Sentinel Hub Playground.

Activity increased during February 2019, with 15 eruptive events reported on days 1, 3, 7, 8, 10, 13, 14, 17, 22, 24, and 27. Ash plume heights ranged from 600-2,300 m above the summit, and ejecta was reported 300 to 1,700 m from the crater in various events (figure 78). KRMO reported two days of ashfall during February. Satellite imagery identified thermal anomalies at the crater on 6 and 26 February, and ash plumes on 21 and 26 February (figure 79).

Figure (see Caption) Figure 78. An explosion from Sakurajima at Aira on 7 February 2019 sent ejecta up to 1,700 m from the Minamidake summit crater. Courtesy of JMA (Explanation of volcanic activity in Sakurajima, February 2019).
Figure (see Caption) Figure 79. Thermal anomalies and ash emissions were captured in Sentinel-2 satellite imagery on 6, 21, and 26 February 2019 originating from Sakurajima volcano at Aira. Top: Thermal anomalies within the summit crater were visible underneath steam and ash plumes on 6 and 26 February (closeup of bottom right photo). Bottom: Ash emissions on 21 and 26 February drifted SE from the volcano. "Geology" rendering (bands 12, 4, and 2) courtesy of Sentinel Hub Playground.

The number of eruptive events continued to increase during March 2019; there were 29 events reported on numerous days (figures 80 and 81). An explosion on 14 March produced an ash plume that rose 3,500 m above the summit and drifted E. It also produced ejecta that landed 800-1,100 m from the crater. During an overflight on 26 March a fumarole was the only activity in Showa crater. KRMO reported 14 days of ashfall during the month. Satellite imagery identified an ash plume on 13 March and a thermal anomaly on 18 March (figure 82).

Figure (see Caption) Figure 80. A large ash emission from Sakurajima volcano at Aira was photographed by a tourist on the W flank and posted on 1 March 2019. Courtesy of Kratü.
Figure (see Caption) Figure 81. An ash plume from Sakurajima volcano at Aira on 18 March 2019 produced enough ashfall to disrupt the trains in the nearby city of Kagoshima according to the photographer. Image taken from about 20 km away. Courtesy of Tim Board.
Figure (see Caption) Figure 82. An ash plume drifted SE from the summit of Sakurajima volcano at Aira on 13 March (left) and a thermal anomaly was visible inside the Minamidake crater on 18 March 2019 (right). "Geology" rendering (bands 12, 4, and 2) courtesy of Sentinel Hub Playground.

A decline in activity to only ten eruptive events on days 7, 13, 17, 22, and 25 was reported by JMA for April 2019. An explosion on 7 April sent ejecta up to 1,700 m from the crater. Another explosion on 13 April produced an ash plume that rose 2,200 m above the summit. Most of the eruptive events at Sakurajima last for less than 30 minutes; on 22 April two events lasted for almost an hour each producing ash plumes that rose 1,400 m above the summit. Ashfall at KRMO was reported during seven days in April. Two distinct thermal anomalies were visible inside the Minamidake crater on both 12 and 27 April (figure 83).

Figure (see Caption) Figure 83. Two thermal anomalies were present inside Minamidake crater at the summit of Sakurajima volcano at Aira on 12 (left) and 27 (right) April 2019. "Geology" rendering (bands 12, 4, and 2) courtesy of Sentinel Hub Playground.

There were 15 eruptive events during May 2019. An event that lasted for two hours on 12 May produced an ash plume that rose 2,900 m from the summit and drifted NE (figure 84). The Meteorological Observatory reported 14 days with ashfall during the month. Two thermal anomalies were present in satellite imagery in the Minamidake crater on both 17 and 22 May.

Figure (see Caption) Figure 84. An ash plume rose 2,900 m above the summit of Sakurajima at Aira on 12 May 2019 (left); incandescent ejecta went 1,300 m from the summit crater on 13 May. Courtesy of JMA (Explanation of volcanic activity in Sakurajima, May 2019).

During June 2019 five eruptive events were reported, on 11, 13, and 24 June; the event on 11 June lasted for almost two hours, sent ash 2,200 m above the summit, and produced ejecta that landed up to 1,100 m from the crater (figure 85). Five days of ashfall were reported by KRMO.

Figure (see Caption) Figure 85. A large ash plume on 11 June 2019 rose 2,200 m above the summit of Sakurajima volcano at Aira. Courtesy of Aone Wakatsuki.

Geologic Background. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Mike Day, Minnesota, Twitter (URL: https://twitter.com/MikeDaySMM, photo at https://twitter.com/MikeDaySMM/status/1083489400451989505/photo/1); Kratü, Twitter (URL: https://twitter.com/TalesOfKratue, photo at https://twitter.com/TalesOfKratue/status/1101469595414589441/photo/1); Tim Board, Japan, Twitter (URL: https://twitter.com/Hawkworld_, photo at https://twitter.com/Hawkworld_/status/1107789108754038789); Aone Wakatsuke, Twitter (URL: https://twitter.com/AoneWakatsuki, photo at https://twitter.com/AoneWakatsuki/status/1138420031258210305/photo/3).


Agung (Indonesia) — June 2019 Citation iconCite this Report

Agung

Indonesia

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

All times are local (unless otherwise noted)


Continued explosions with ash plumes and incandescent ejecta, February-May 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). Lava emerged into the summit crater at the end of November and intermittent ash plumes rose as high as 3 km above the summit through the end of the year. 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 (BGVN 43:08, 44:02). Information about the ongoing eruptive episode 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 ongoing eruption from February through May 2019.

Intermittent but increasingly frequent and intense explosions with ash emissions and incandescent ejecta characterized activity at Agung during February through May 2019. During February, explosions were reported three times; events on seven days in March were documented with ash plumes and ashfall in surrounding villages. Five significant events occurred during April; two involved incandescent ejecta that traveled several kilometers from the summit, and ashfall tens of kilometers from the volcano. Most of the five significant events reported in May involved incandescent ejecta and ashfall in adjacent villages; air traffic was disrupted during the 24 May event. Ash plumes in May reached altitudes over 7 km multiple times. Thermal activity increased steadily during the period, according to both the MIROVA project (figure 44) and MODVOLC thermal alert data. MAGMA Indonesia reported at the end of May 2019 that the volume of lava within the summit crater remained at about 25 million m3; satellite information indicated continued thermal activity within the crater. Alert Level III (of four levels) remained in effect throughout the period with a 4 km exclusion radius around the volcano.

Figure (see Caption) Figure 44. Thermal activity at Agung from 4 September 2018 through May 2019 was variable. The increasing frequency and intensity of thermal events was apparent from February-May. Courtesy of MIROVA.

Steam plumes rose 30-300 m high daily during February 2019. The Agung Volcano Observatory (AVO) and PVMBG issued a VONA on 7 February (UTC) reporting an ash plume, although it was not visible due to meteoric cloud cover. Incandescence, however, was observed at the summit from webcams in both Rendang and Karangasem City (16 km SE). The seismic event associated with the explosion lasted for 97 seconds. A similar event on 13 February was also obscured by clouds but produced a seismic event that lasted for 3 minutes and 40 seconds, and ashfall was reported in the village of Bugbug, about 20 km SE. On 22 February a gray ash plume rose 700 m from the summit during a seismic event that lasted for 6 minutes and 20 seconds (figure 45). The Darwin VAAC reported the plume visible in satellite imagery moving W at 4.3 km altitude. It dissipated after a few hours, but a hotspot remained visible about 10 hours later.

Figure (see Caption) Figure 45. An ash plume rose from the summit of Agung on 22 February 2019, viewed from the Besakih temple, 7 km SW of the summit. Courtesy of PunapiBali.

Persistent steam plumes rose 50-500 m from the summit during March 2019. An explosion on 4 March was recorded for just under three minutes and produced ashfall in Besakih (7 km SW); no ash plume was observed due to fog. A short-lived ash plume rose to 3.7 km altitude and drifted SE on 8 March (UTC) 2019. The seismic event lasted for just under 4 minutes. Ash emissions were reported on 15 and 17 March to 4.3 and 3.7 km altitude, respectively, drifting W (figure 46). Ashfall from the 15 March event spread NNW and was reported in the villages of Kubu (6 km N), Tianyar (14 km NNW), Ban, Kadundung, and Sukadana. MAGMA Indonesia noted that two explosions on the morning of 17 March (local time) produced gray plumes; the first sent a plume to 500 m above the summit drifting E and lasted for about 40 seconds, while the second plume a few hours later rose 600 m above the crater and lasted for 1 minute and 16 seconds. On 18 March an ash plume rose 1 km and drifted W and NW. An event on 20 March was measured only seismically by PVMBG because fog prevented observations. An eruption on 28 March produced an ash plume 2 km high that drifted W and NW. The seismic signal for this event lasted for about two and a half minutes. The Darwin VAAC reported the ash plume at 5.5 km altitude, dissipating quickly to the NW. No ash was visible four hours later, but a thermal anomaly remained at the summit (figure 47). Ashfall was reported in nearby villages.

Figure (see Caption) Figure 46. Ash plumes from Agung on 15 (left) and 17 (right) March 2019 resulted in ashfall in communities 10-20 km from the volcano. Courtesy of PVMBG and MAGMA Indonesia (Information on G. Agung Eruption, 15 March 2019 and Gunung Agung Eruption Press Release March 17, 2019).
Figure (see Caption) Figure 47. A thermal anomaly was visible through thick cloud cover at the summit of Agung on 29 March 2019 less than 24 hours after a gray ash plume was reported 2,000 m above the summit. "Atmospheric Penetration" rendering (bands 12, 11, and 8A) courtesy of Sentinel Hub Playground.

The first explosion of April 2019 occurred on the 3rd (UTC); PVMBG reported the dense gray ash plume 2 km above the summit drifting W. A few hours later the Darwin VAAC raised the altitude to 6.1 km based on infrared temperatures in satellite imagery. The seismic signal lasted for three and a half minutes and the explosion was heard at the PGA Post in Rendang (12 km SW). Incandescent material fell within a radius of 2-3 km, mainly on the S flank (figure 48). Ashfall was reported in the villages of Telungbuana, Badeg, Besakih, Pempatan, Teges, and Puregai on the W and S flanks (figure 49). An explosion on 11 April also produced a dense gray ash plume that rose 2 km above the summit and drifted W. A hotspot remained about six hours later after the ash dissipated.

Figure (see Caption) Figure 48. Incandescent ejecta appeared on the flanks of Agung after an eruption on 4 April 2019 (local time) as viewed from the observation post in Rendang (8 km SW). Courtesy of Jamie Sincioco.
Figure (see Caption) Figure 49. Ashfall in a nearby town dusted mustard plants on 4 April 2019 from an explosion at Agung the previous day. Courtesy of Pantau.com (Photo: Antara / Nyoman Hendra).

PVMBG reported an eruption visible in the webcam early on 21 April (local time) that rose to 5.5 km altitude and drifted SW. The ash spread W and S and ash fell around Besakih (7 km SW), Rendang (8 km SW), Klungkung (25 km S), Gianyar (20 km WSW), Bangli (17 km WNW), Tabanan (50 km WSW), and at the Ngurah Rai-Denpasar Airport (60 km SW). About 15 hours later a new explosion produced a dense gray ash plume that rose to 3 km above the summit and produced incandescent ejecta in all directions as far as 3 km away (figure 50). The ash spread to the S and ashfall was reported in Besakih, Rendang, Sebudi (6 km SW), and Selat (12 km SSW). Both of the explosions were heard in Rendang and Batulompeh. The incandescent ejecta from the explosions remained within the 4-km exclusion zone. A satellite image on 23 April showed multiple thermal anomalies within the summit crater (figure 51). A dense gray plume drifted E from Agung on 29 April (30 April local time) at 4.6 km altitude. It was initially reported by ground observers, but was also visible in multispectral satellite imagery for about six hours before dissipating.

Figure (see Caption) Figure 50. An explosion at Agung on 21 April 2019 sent incandescent eject 3,000 m from the summit. Courtesy of MAGMA Indonesia (Gunung Agung Eruption Press Release April 21, 2019).
Figure (see Caption) Figure 51. Multiple thermal anomalies were still present within the summit crater of Agung on 23 April 2019 after two substantial explosions produced ash and incandescent ejecta around the summit two days earlier. "Atmospheric Penetration" rendering (bands 12, 11, and 8A) courtesy of Sentinel Hub Playground.

PVMBG reported an eruption on 3 May 2019 that was recorded on a seismogram with a signal that lasted for about a minute. Satellite imagery reported by the Darwin VAAC showed a growing hotspot and possible ash near the summit at 4.3 km altitude moving NE. A few days later, on 6 May, a gray ash plume rose to 5.2 km altitude and drifted slowly W before dissipating; it was accompanied by a seismic signal that lasted for about two minutes. Explosions on 12 and 18 May produced significant amounts of incandescent ejecta (figure 52). The seismic signal for the 12 May event lasted for about two minutes; no plume was observed due to fog, but incandescent ejecta was visible on the flanks and the explosion was heard at Rendang. The Darwin VAAC reported an ash plume from the explosion on 17 May (18 May local time) at 6.1 km altitude in satellite imagery moving E. They revised the altitude a short while later to 7.6 km based on IR temperature and movement; the plume drifted N, NE, and E in light and variable winds. A few hours after that it was moving NE at 7.6 km altitude and SE at 5.5 km altitude; this lasted for about 12 hours until it dissipated. Ashfall was reported in villages downwind including Cutcut, Tongtongan, Bonyoh (20 km WNW), and Temakung.

Figure (see Caption) Figure 52. Explosions on 12 (left) and 18 (right) May (local time) 2019 produced substantial ejecta on the flanks of Agung visible from a distance of 10 km or more in PVMBG webcams. The ash plume from the 18 May event resulted in ashfall in numerous communities downwind. Courtesy of PVMBG (Information Eruption G. Agung, May 13, 2019, Information Eruption G. Agung, May 18, 2019).

The initial explosion on 18 May was captured by a webcam at a nearby resort and sent incandescent ejecta hundreds of meters down the NE flank within 20 seconds (figure 53). Satellite imagery on 3, 8, 13, and 18 May indicated multiple thermal anomalies growing stronger at the summit. All of the images were captured within 24 hours of an explosive event reported by PVMBG (figure 54).

Figure (see Caption) Figure 53. The 18 May 2019 explosion at Agung produced an ash plume that rose to over 7 km altitude and large bombs of incandescent material that traveled hundreds of meters down the NE flank within the first 20 seconds of the explosion. Images taken from a private webcam located 12 km NE. Courtesy of Volcanoverse, used with permission.
Figure (see Caption) Figure 54. Satellite images from 3, 8, 13, and 18 May 2019 at Agung showed persistent and increasing thermal anomalies within the summit crater. All images were captured within 24 hours of explosions reported by PVMBG. "Atmospheric Penetration" rendering (bands 12, 11, and 8A) courtesy of Sentinel Hub Playground.

PVMBG issued a VONA on 24 May 2019 reporting a new ash emission. They indicated that incandescent fragments were ejected 2.5-3 km in all directions from the summit, and the seismic signal lasted for four and a half minutes (figure 55). A dense gray ash plume was observed from Tulamben on the NE flank rising 2 km above the summit. Satellite imagery indicated that the plume drifted SW and ashfall was reported in the villages of Besakih, Pempatan, Menanga, Sebudi, Muncan, Amerta Bhuana, Nongan, Rendang, and at the Ngurah Rai Airport in Denpassar. Additionally, ashfall was reported in the districts of Tembuku, Bangli, and Susut (20 km SW). The Darwin VAAC reported an ash plume visible in satellite imagery at 4.6 km altitude along with a thermal anomaly and incandescent lava visible in webcam imagery. The remains of the ash plume were about 170 km S of the airport in Denpasar (60 km SW) and had nearly dissipated 18 hours after the event. According to a news article several flights to and from Australia were cancelled or diverted, though the International Gusti Ngurah Rai (IGNR) airport was not closed. On 31 May another large explosion produced the largest ash plume of the report period, rising more than 2 km above the summit (figure 56). The Darwin VAAC reported its altitude as 8.2 km drifting ESE visible in satellite data. 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.

Figure (see Caption) Figure 55. A large explosion at Agung on 24 May 2019 produced incandescent ejecta that covered all the flanks and dispersed ash to many communities to the SW. Courtesy of PVMBG (Gunung Agung Eruption Press Release 24 May 2019 20:38 WIB, Kasbani, Ir., M.Sc.).
Figure (see Caption) Figure 56. An explosion at Agung on 31 May 2019 sent an ash plume to 8.2 km altitude, the highest for the report period. Courtesy of Sutopo Purwo Nugroho, BNPB.

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/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); The Jakarta Post, Mount Agung eruption disrupts Australian flights, (URL: https://www.thejakartapost.com/news/2019/05/25/mount-agung-eruption-disrupts-australian-flights.html); PunapiBali (URL: http://punapibali.com/, Twitter: https://twitter.com/punapibali, image at https://twitter.com/punapibali/status/1098869352588288000/photo/1); Jamie S. Sincioco, Phillipines (URL: Twitter: https://twitter.com/jaimessincioco. Image at https://twitter.com/jaimessincioco/status/1113765842557104130/photo/1); Pantau.com (URL: https://www.pantau.com/berita/erupsi-gunung-agung-sebagian-wilayah-bali-terpapar-hujan-abu?utm_source=dlvr.it&utm_medium=twitter); Volcanoverse (URL: https://www.youtube.com/channel/UCi3T_esus8Sr9I-3W5teVQQ); Sutopo Purwo Nugroho, BNPB (Twitter: @Sutopo_PN, URL: https://twitter.com/Sutopo_PN ).


Kerinci (Indonesia) — June 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 explosions with ash plumes, February-May 2019

Frequently active, Indonesia's Mount Kerinci on Sumatra has been the source of numerous moderate explosive eruptions since its first recorded eruption in 1838. Intermittent explosions with ash plumes, usually multiple times per month, have characterized activity since April 2018. Similar activity continued during February-May 2019, the period covered in this report with information provided primarily by the Indonesian volcano monitoring agency, Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), MAGMA Indonesia, notices from the Darwin Volcano Ash Advisory Center (Darwin VAAC), and satellite data. PVMBG has maintained an Alert Level II (of 4) at Kerinci for several years.

On 13 February 2019 the Kerinci Volcano Observatory (KVO), part of PVMBG, noted a brownish-white ash emission that was drifting NE about 400 m above the summit. The seismicity during the event was dominated by continuous volcanic tremor. A brown ash emission was reported on 7 March 2019 that rose to 3.9 km altitude and drifted NE. Ash also drifted 1,300 m down the SE flank. Another ash plume the next morning drifted W at 4.5 km altitude, according to KVO. On 10, 11, and 13 March KVO reported brown ash plumes drifting NE from the summit at about 4.0-4.3 km altitude. The Darwin VAAC observed continuous ash emissions in satellite imagery on 15 March drifting W at 4.3 m altitude that dissipated after about 3 hours (figure 10). A gray ash emission was reported on 19 March about 600 m above the summit drifting NE; local news media noted that residents of Kayo Aro reported emissions on both 18 and 19 March (figure 11). An ash emission appeared in satellite imagery on 25 March (figure 10). On 30 March the observatory reported two ash plumes; a brown emission at 0351 UTC and a gray emission at 0746 UTC that both drifted NE at about 4.4 km altitude and dissipated within a few hours. PVMBG reported another gray ash plume the following day at a similar altitude.

Figure (see Caption) Figure 10. Sentinel-2 satellite imagery of Kerinci from 15 (left) and 25 (right) March 2019 showed evidence of ash plumes rising from the summit. Kerinci's summit crater is about 500 m wide. "Geology" rendering (bands 12, 4, 2), courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 11. Dense ash plumes from Kerinci were reported by local news media on 18 and 19 March 2019. Courtesy of Nusana Jambi.

Activity continued during April with a brown ash emission reported on 3 April by several different agencies; the Darwin VAAC and PVMBG daily reports noted that the plume was about 500 m above the summit (4.3 km altitude) drifting NE. KVO observed two brown ash emissions on 13 April (UTC) that rose to 4.2 km altitude and drifted NE. Satellite imagery showed minor ash emissions from the summit on 14 April; steam plumes 100-500 m above the summit characterized activity for the remainder of April (figure 12).

Figure (see Caption) Figure 12. A dilute ash emission rose from the summit of Kerinci on 14 April 2019 (left); only steam emissions were present on a clear 29 April in Sentinel-2 imagery (right). "Geology" rendering (bands 12, 4, 2), courtesy of Sentinel Hub Playground.

Ashfall on the NE and S flanks within 7 km of the volcano was reported on 2 May 2019. According to a news article, at least five villages were affected late on 2 May, including Tanjung Bungo, Sangir, Sangir Tengah, Sungai Rumpun, and Bendung Air (figures 13 and 14). The smell of sulfur was apparent in the villages. Brown ash emissions were observed on 3 and 4 May that rose to 4.6 and 4.1 km altitude and drifted SE. The Darwin VAAC reported an emission on 5 May, based on a pilot report, that rose to 6.7 km altitude and drifted NE for about an hour before dissipating. A brown ash emission on 10 May rose 700 m above the summit and drifted SE. Satellite imagery captured ash emissions from the summit on 14 and 24 May (figure 15). For the remainder of the month, 300-700-m-high dense steam plumes were noted daily until PVMBG reported white and brown plumes on 26 and 27 May rising 500-1,000 m above the summit. Although thermal anomalies were not reported during the period, persistent weak SO2 emissions were identified in TROPOMI instrument satellite data multiple times per month (figure 16).

Figure (see Caption) Figure 13. Ashfall was reported from five villages on the flanks of Kerinci on 2 May 2019. Courtesy of Uzone.
Figure (see Caption) Figure 14. An ash plume at Kerinci rose hundreds of meters on 2 May 2019; ashfall was reported in several nearby villages. Courtesy of Kerinci Time.
Figure (see Caption) Figure 15. Ash emissions from Kerinci were captured in Sentinel-2 satellite imagery on 14 (left) and 24 (right) May 2019. The summit crater is about 500 m wide. "Geology" rendering (bands 12, 4, 2), courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 16. Weak SO2 anomalies from Kerinci emissions were captured by the TROPOMI instrument on the Sentinel-5P satellite multiple times each month from February to May 2019. Courtesy of NASA Goddard Space Flight Center.

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/); 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); 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/); Nuansa Jambi, Informasi Utama Jambi: (URL: https://nuansajambi.com/2019/03/20/gunung-kerinci-semburkan-asap-tebal/); Kerinci Time (URL: https://kerincitime.co.id/gunung-kerinci-semburkan-abu-vulkanik.html); Uzone.id (URL: https://news.uzone.id/gunung-kerinci-erupsi-5-desa-tertutup-abu-tebal).


Suwanosejima (Japan) — July 2019 Citation iconCite this Report

Suwanosejima

Japan

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

All times are local (unless otherwise noted)


Small ash plumes continued during January through June 2019

Suwanosejima is an active volcanic island south of Japan in the Ryuku islands with recent activity centered at Otake crater. The current eruption began in October 2004 and activity has mostly consisted of small ash plumes, ballistic ejecta, and visible incandescence at night. This report summarizes activity during January through June 2019 and is based on reports by the Japan Meteorological Agency (JMA), and various satellite data.

Thermal activity recorded by the MIROVA system was low through January and February after a decline in November (figure 36), shown in Sentined-2 thermal infrared imagery as originating at a vent in the Otake crater (figure 37). During January an explosive event was observed at 1727 on the 3rd, producing a gray plume that rose 600 m above the crater. A white gas-and-steam plume rose to 1.5 km above the crater and nighttime incandescence was observed throughout the month. Reduced activity continued through February with no reported explosive eruptions and light gray plumes up to 900 m above the crater. Incandescence continued to be recorded at night using a sensitive surveillance camera.

Figure (see Caption) Figure 36. MIROVA log radiative power plot of MODIS thermal infrared data at Suwanosejima during September 2018 through June 2019. There was reduced activity in 2019 with periods of more frequent anomalies during March and June. Courtesy of MIROVA.
Figure (see Caption) Figure 37. A Sentinel-2 thermal satellite image shows Suwanosejima with the active Otake crater in the center with elevated temperatures shown as bright orange/yellow. There is a light area next to the vent that may be a gas plume. False color (urban) satellite image (bands 12, 11, 4) courtesy of Sentinel Hub Playground.

There was an increase in thermal energy detected by the MIROVA system in mid-March and there was a MODVOLC thermal alert on the 15th. Occasional small explosions occurred but no larger explosive events were recorded. A white plume was noted on the 27th rising to 900 m above the crater and an event at 1048 on the 30th produced a light-gray plume that rose to 800 m. Incandescence was only observed using a sensitive camera at night (figure 38).

Figure (see Caption) Figure 38. Incandescence from the Suwanosejima Otake crater reflecting in clouds above the volcano. Courtesy of JMA (Volcanic activity of Suwanosejima March 2019).

No explosive events were observed through April. A white gas-and-steam plume rose to 1,200 m above the crater on the 19th and incandescence continued intermittently. Minor explosions were recorded on 5, 30, and 31 May, but no larger explosive events were observed during the month. The event on the 30th produced ash plume that reached 1.1 km above the crater. Similar activity continued through June with one explosive event occurring on the 2nd. Overall, there was a reduction in the number of ash plumes erupted during this period compared to previous months (figure 39).

Figure (see Caption) Figure 39. Observed activity at Suwanosejima for the year ending in July 2019. The black vertical bars represent steam, gas, or ash plume heights (scale in meters on the left axis), yellow diamonds represent incandescence observed in webcams, gray volcano symbols along the top are explosions accompanied by ash plumes, red volcano symbols represent large explosions with ash plumes. Courtesy of JMA (Volcanic activity of Suwanosejima June 2019).

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

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Great Sitkin (United States) — July 2019 Citation iconCite this Report

Great Sitkin

United States

52.076°N, 176.13°W; summit elev. 1740 m

All times are local (unless otherwise noted)


Small steam explosions in early June 2019

The Great Sitkin volcano is located about 40 km NE of Adak Island in the Aleutian Islands and has had a few short-lived eruptions over the past 100 years. Prior to the latest activity in early June 2019 described below, small phreatic explosions occurred in June and August 2018 (BGVN 43:09). An eruption in 1974 produced a lava dome in the center of the crater. The Alaska Volcano Observatory (AVO) is the primary source of information for this September 2018-June 2019 reporting period.

Low-level unrest occurred from September 2018 through February 2019 with slightly elevated seismic activity (figure 6). Small explosions were seismically detected by AVO on 30 October, 5 and 16 November, and 11 December 2018, but they were not seen in regional infrasound data and satellite data did not show an ash cloud.

On 1, 7, and 9 June 2019, AVO reported small steam explosions as well as slightly elevated seismic activity. Steam plumes and surficial evidence of an explosion were not observed during these events. On 18 June 2019 weakly elevated surface temperatures were recorded, field crews working on Adak observed some steam emissions, and a gas flight was conducted. Elevated concentrations of carbon dioxide detected above the lava dome were likely associated with the steam explosions earlier in the month (figures 7 and 8). From 23 June through the end of the month seismicity began to decline back to background levels.

Figure (see Caption) Figure 6. A steam plume was seen at the summit of Great Sitkin on 7 December 2018. Photo by Andy Lewis and Bob Boyd; courtesy of AVO/USGS.
Figure (see Caption) Figure 7. Some degassing was observed on the southern flank of the Great Sitkin during an overflight on 18 June 2019. Photo by Laura Clor; image courtesy of AVO/USGS.
Figure (see Caption) Figure 8. View of Great Sitkin with white plumes rising from the summit on 20 June 2019. Photo by Laura Clor, courtesy of AVO/USGS.

Geologic Background. The Great Sitkin volcano forms much of the northern side of Great Sitkin Island. A younger parasitic volcano capped by a small, 0.8 x 1.2 km ice-filled summit caldera was constructed within a large late-Pleistocene or early Holocene scarp formed by massive edifice failure that truncated an ancestral volcano and produced a submarine debris avalanche. Deposits from this and an older debris avalanche from a source to the south cover a broad area of the ocean floor north of the volcano. The summit lies along the eastern rim of the younger collapse scarp. Deposits from an earlier caldera-forming eruption of unknown age cover the flanks of the island to a depth up to 6 m. The small younger caldera was partially filled by lava domes emplaced in 1945 and 1974, and five small older flank lava domes, two of which lie on the coastline, were constructed along northwest- and NNW-trending lines. Hot springs, mud pots, and fumaroles occur near the head of Big Fox Creek, south of the volcano. Historical eruptions have been recorded since the late-19th century.

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


Ibu (Indonesia) — July 2019 Citation iconCite this Report

Ibu

Indonesia

1.488°N, 127.63°E; summit elev. 1325 m

All times are local (unless otherwise noted)


Frequent ash plumes and small lava flows active in the crater through June 2019

Ibu volcano on Halmahera island in Indonesia began the current eruption episode on 5 April 2008. Since then, activity has largely consisted of small ash plumes with less frequent lava flows, lava dome growth, avalanches, and larger ash plumes up to 5.5 km above the crater. This report summarizes activity during December 2018 through June 2019 and is based on Volcano Observatory Notice for Aviation (VONA) reports by MAGMA Indonesia, reports by Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and Badan Nasional Penanggulangan Bencana (BNPB), and various satellite data.

During December PVMBG reported ash plumes ranging from 200 to 800 m above the crater. There were 11 MODVOLC thermal alerts that registered during 1-12 December. An explosion on 12 January 2019 produced an ash plume that reached 800 m above the crater and dispersed to the S (figure 15). A report released for this event by Sutopo at BNPB said that Ibu had erupted almost every day over the past three months; an example given was of activity on 10 January consisting of 80 explosions. There were four MODVOLC thermal alerts through the month.

Figure (see Caption) Figure 15. An eruption at Ibu at 1712 on 21 January 2019 produced an ash plume that rose to 800 m above the crater. Courtesy of BNPB (color adjusted).

Throughout February explosions frequently produced ash plumes as high as 800 m above the crater, and nine MODVOLC thermal alerts were issued. Daily reports showed variable plume heights of 200-800 m most days throughout the month. Wind directions varied and dispersed the plumes in all directions. A VONA released at 1850 on 6 February reported an ash plume that rose to 1,925 m altitude (around 600 m above the summit) and dispersed S. Activity continued through March with the Darwin VAAC and PVMBG reporting explosions producing ash plumes to heights of 200-800 m above the crater and dispersing in various directions. There were ten MODVOLC alerts through the month.

Similar activity continued through April, May, and June, with ash plumes reaching 200-800 m above the crater. There were 12, 6, and 15 MODVOLC Alerts in April, May, and June, respectively.

Planet Scope satellite images show activity at a two vents near the center of the crater that were producing small lava flows from February through June (figure 16). Thermal anomalies were frequent during December 2018 through June 2019 across MODVOLC, MIROVA, and Sentinel-2 infrared data (figures 17 and 18). Sentinel-2 data showed minor variation in the location of thermal anomalies within the crater, possibly indicating lava flow activity, and MIROVA data showed relatively constant activity with a few reductions in thermal activity during January and February.

Figure (see Caption) Figure 16. Planet Scope natural color satellite images showing activity in the Ibu crater during January through June 2019, with white arrows indicating sites of activity. One vent is visible in the 21 February image, and a 330-m-long (from the far side of the vent) lava flow with flow ridges had developed by 24 March. A second vent was active by 12 May with a new lava flow reaching a maximum length of 520 m. Activity was centered back at the previous vent by 23-27 June. Natural color Planet Scope Imagery, copyright 2019 Planet Labs, Inc.
Figure (see Caption) Figure 17. Examples of thermal activity in the Ibu crater during January through May 2019. These Sentinel-2 satellite images show variations in hot areas in the crater due to a vent producing a small lava flow. Sentinel-2 false color (urban) images (bands 12, 11, 4) courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 18. MIROVA log radiative power plot of MODIS thermal infrared at Ibu from September 2018 through June 2019. The registered energy was relatively stable through December, with breaks in January and February. Regular thermal anomalies continued with slight variation through to the end of June. Courtesy of MIROVA.

Geologic Background. The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, contained several small crater lakes through much of historical time. The outer crater, 1.2 km wide, is breached on the north side, creating a steep-walled valley. A large parasitic cone is located ENE of the summit. A smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. Only a few eruptions have been recorded in historical time, the first a small explosive eruption from the summit crater in 1911. An eruption producing a lava dome that eventually covered much of the floor of the inner summit crater began in December 1998.

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/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Planet Labs, Inc. (URL: https://www.planet.com/).


Ebeko (Russia) — July 2019 Citation iconCite this Report

Ebeko

Russia

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

All times are local (unless otherwise noted)


Continuing frequent moderate explosions though May 2019; ashfall in Severo-Kurilsk

The Ebeko volcano, located on the northern end of the Paramushir Island in the Kuril Islands, consists of many craters, lakes, and thermal features and has been frequently erupting since late February 2017. Typical activity includes ash plumes, explosive eruptions, and gas-and-steam activity. The previous report through November 2018 (BGVN 43:12) described frequent ash explosions that sometimes caused ashfall in Severo-Kurilsk (7 km E). The primary source of information is the Kamchatka Volcanic Eruptions Response Team (KVERT). This report updates the volcanic activity at Ebeko for December 2018 through May 2019.

Frequent moderate explosive activity continued after November 2018. Volcanologists in Severo-Kurilsk observed explosions sending up ash, which drifted N, NE, and E, resulting in ash falls on Severo-Kurilsk on 28 different days between December 2018 and March 2019. On 25 December 2018 an explosion sent ash up to a maximum altitude of 4.5 km and then drifted N for about 5 km. Explosions occurring on 8-10 March 2019 sent ash up to an altitude of 4 km, resulting in ashfall on Severo-Kurilsk on 9-10 March 2019. An ash plume from these explosions rose to a height of 2.5 km and drifted to a maximum distance of 30 km ENE.

Satellite data analyzed by KVERT registered 12 thermal anomalies from December 2018 through May 2019. According to satellite data analyzed by MIROVA (Middle InfraRed Observation of Volcanic Activity), only one thermal anomaly was recorded from December 2018-May 2019, and no hotspot pixels were recognized using satellite thermal data from the MODVOLC algorithm.

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

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


Klyuchevskoy (Russia) — July 2019 Citation iconCite this Report

Klyuchevskoy

Russia

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

All times are local (unless otherwise noted)


Weak thermal anomalies and moderate Strombolian-type eruptions in September 2018-June 2019

Klyuchevskoy has had alternating eruptive and less active periods since August 2015. Activity has included lava flows, a growing cinder cone, thermal anomalies, gas-and-steam plumes, and ash explosions. Though some eruptions occur near the summit crater, major explosive and effusive eruptions have also occurred from flank craters (BGVN 42:04 and 43:05). Intermittent moderate gas-and-steam and ash emissions were previously reported from mid-February to mid-August 2018. The Kamchatka Volcanic Eruptions Response Team (KVERT) is the primary source of information for this September 2018-June 2019 reporting period.

KVERT reported that moderate gas-and-steam activity, some of which contained a small amount of ash, and weak thermal anomalies occurred intermittently from the beginning of September 2018 through mid-April 2019. On 21-22 April 2019 webcam data showed a gas-and-steam plume extending about 160 km SE (figure 31). Moderate Strombolian-type volcanism began late April 2019 and continued intermittently through June 2019. On 11-12 June webcam data showed explosions that sent ash up to a maximum altitude of 6 km, with the resulting ash plume extending about 200 km WNW.

Figure (see Caption) Figure 31. Gas-and-steam plume containing some amount of ash rising from the summit of Klyuchevskoy on 22 April 2019. Photo by A. Klimova, courtesy of Institute of Volcanology and Seismology (IVS FEB RAS).

Thermal anomalies were noted by KVERT during two days in September 2018, six days in April 2019, eleven days in May 2019, and six days in June 2019. MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed infrequent weak thermal anomalies December 2018 through early May 2019.

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

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).

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Bulletin of the Global Volcanism Network - Volume 38, Number 10 (October 2013)

Managing Editor: Richard Wunderman

Alaid (Russia)

Minor ash plumes on 17 and 23 October and 8 November 2012

Apoyeque (Nicaragua)

Seismic swarms in 2009 and 2012

Barren Island (India)

Ash plume drifted up to 220 km SW in February 2013

Cleveland (United States)

Dome growth and destruction during 2012-2013

Karymsky (Russia)

Seismicity and ash plumes, September 2010-December 2013

Negro, Cerro (Nicaragua)

Seismic swarm in 2013

Rabaul (Papua New Guinea)

Variable but often modest eruptions during mid-2011 through 2013



Alaid (Russia) — October 2013 Citation iconCite this Report

Alaid

Russia

50.861°N, 155.565°E; summit elev. 2285 m

All times are local (unless otherwise noted)


Minor ash plumes on 17 and 23 October and 8 November 2012

Our previous report noted weak seismicity from Alaid during November 2003, although seismologists determined it was not related to volcanic activity (BGVN 28:11). This report discusses activity from December 2003 to January 2014. Emissions were observed in May 2010 and October 2012, but ash was not detected in the plumes until 23 October 2012. The last thermal anomaly was detected in December 2012.

Alaid volcano is located on Atlasova island off the southern tip of Russia's Kamchatka peninsula and represents the northernmost Holocene volcano in the Kuril Islands (figures 2 and 3). Other names for the volcano and island include Araido, Atlasova, Oyakoba, and Uyakhuzhach (Ukviggen, 2013). Despite the islands small size, its summit (2,339 m elevation) is the highest in the Kuriles. The volcano also plays a large and colorful role in the region's folklore (Ukviggen, 2013; Svalova, 1999).

Figure (see Caption) Figure 2. A regional map showing Alaid volcano, located S of the Kamchatka Peninsula (K), S of the city Petropavlovsk-Kamchatsky (P-K), and W of Paramushir and Shumshu Islands. Alaid (red triangle) is located at Atlasora Island. The original map was in Russian with authorship information at lower right. Courtesy of Kamchatka Volcanic Eruption Response Team (KVERT).
Figure (see Caption) Figure 3. A simple map with S towards the top, illustrating Alaid on Atlasov island and some of the adjacent Holocene volcanoes in the Kuriles. Volcanoes on Kamchatka are omitted. Taken from Volcano World.

On 5 October 2012, (KVERT) changed the Aviation Color Code from Green to Yellow due to "signs of elevated unrest above known background levels." A Volcano Observatory Notification to Aviation (VONA) noted that a possible explosive eruption could produce an ash column height of 10-15 km. Because Alaid is located near many flight routes, an eruption poses hazards to aviation (Girina and others, 2013).

On 23 May a gas-and-steam plume from Alaid was seen in satellite imagery drifting 11 km ESE. No other signs of possible increasing activity were seen in imagery or noted by observers on Paramushir Island during 21-28 May. During 2012, thermal anomalies were detected on 6, 12, 14-17, 19, 23, 27-28 and 30-31 October, 1, 4, 6-9, 12, 14, 20 and 24 November, and 4 and 12 December. At times, satellites could not detect thermal anomalies over Alaid volcano because of cloud cover, for example during the end of December 2012 and the beginning of January 2013. Visual observations from the adjacent Paramushir and Shumshu islands reported steam activity on 5, 11, 16, 17, 23, 26 and 27 October 2012; steam plumes rose 200 m on 5 October and 3 km on 23 October. (KVERT) and Institute of Volcanology and Seismology (IVS) FED RAS photographs showed fumarole activity on 6, 11, 12, 16, 25 and 27 October and 29 November 2012.

Several ash plumes erupting from Alaid volcano were reported in October and November 2012. (KVERT) and (IVS) FED RAS photographs from 17 and 23 October showed steam plumes containing ash rising 700 m. During this time, a small cinder cone grew in the larger summit crater. The volcano and its summit crater can be observed during an interval of inactivity on figure 4. Observers on 8 November 2012 noted that the volcanic cone was covered by ash.

Figure (see Caption) Figure 4. Photograph of Alaid during clear viewing conditions taken by the International Space Station's Expedition 31 crew on 18 May 2012. The silver-gray appearance on the sea surface surrounding much of the volcano results from strongly reflected sunlight bounced off the sea surface (sunglint). The image was provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center (Photo ID, ISS031-E-41959). Courtesy of the International Space Station, the Image Science & Analysis Laboratory at Johnson Space Center, and William L. Stefanov (Jacobs/ESCG at NASA-JSC).

Because of mechanical problems, seismicity could not be monitored for the majority of the time Alaid was at Aviation Color Code Yellow; seismic data was unavailable from January 2009 until November 2012. The seismic station was repaired on 16 November 2012, and KVERT noted moderate seismic activity. During early December, the amplitude of volcanic tremor was in the range 12.1-18.7 μm/s. After 11 December 2012, technical reasons again prevented further seismic data acquisition.

On 8 January 2013 the Aviation Color Code was reduced to Green, meaning that "volcanic activity was considered to have ceased, and the volcano reverted to its normal, non-eruptive state" (KVERT).

References: Svalova, VB, 1999, Geothermal Legends through History in Russia and the Former USSR: A Bridge to the Past, Geothermal Resources Council Transactions, v. 22 p.235-239. PDF file. (URL: http://pubs.geothermal-library.org/lib/grc/1015911.pdf)

Ukviggen, 2013, Alaid: Part 1–the Banished Beauty, Volcano Cafe, 24 April 2013. Accessed online 13 January 2014. (URL: http://volcanocafe.wordpress.com/2013/04/24/alaid-part-1-the-banished-beauty/)

Girina,O., Manevich, A., Melnikov, D., Nuzhdaev,A., Demyanchuk, Y., and Petrova, E., 2013, Explosive Eruptions of Kamchatkan Volcanoes in 2012 and Danger to Aviation, EGU General Assembly, (abstract), 2013 meeting in Vienna, Austria. (URL: http://adsabs.harvard.edu/abs/2013EGUGA..15.6760G).

Geologic Background. The highest and northernmost volcano of the Kuril Islands, 2285-m-high Alaid is a symmetrical stratovolcano when viewed from the north, but has a 1.5-km-wide summit crater that is breached widely to the south. Alaid is the northernmost of a chain of volcanoes constructed west of the main Kuril archipelago. Numerous pyroclastic cones dot the lower flanks of this basaltic to basaltic-andesite volcano, particularly on the NW and SE sides, including an offshore cone formed during the 1933-34 eruption. Strong explosive eruptions have occurred from the summit crater beginning in the 18th century. Reports of eruptions in 1770, 1789, 1821, 1829, 1843, 1848, and 1858 were considered incorrect by Gorshkov (1970). Explosive eruptions in 1790 and 1981 were among the largest in the Kuril Islands during historical time.

Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response Team (KVERT), a cooperative program of the Institute of Volcanic Geology and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia; Volcano World (URL: http://volcano.oregonstate.edu/alaid); and International Space Station, the Image Science & Analysis Laboratory at Nasa's Johnson Space Center, and William L. Stefanov (Jacobs Technology).


Apoyeque (Nicaragua) — October 2013 Citation iconCite this Report

Apoyeque

Nicaragua

12.242°N, 86.342°W; summit elev. 518 m

All times are local (unless otherwise noted)


Seismic swarms in 2009 and 2012

Within the last five years, Instituto Nicaragüense de Estudios Territoriales (INETER) reported at least two seismic swarms at Apoyeque, and between the Chiltepe Peninsula and the city of Managua (~15 km SE) (figure 1). Our last report also highlighted swarms which lasted several hours and days in 2001 and 2007 (BGVN 34:04). Intermittent seismicity was reported within the region during 2009-2012, but events were rarely larger than M 2.5.

Figure (see Caption) Figure 1. Regional maps showing Apoyeque and the tectonic setting. (A) Sketch map highlighting volcanic centers in Central America relative to the active subduction of Cocos Plate beneath the Caribbean Plate. In Nicaragua active volcanism is concentrated inside the Nicaragua Depression (ND). The red box labeled "B" refers to the 50 x 50 km area that includes Apoyeque on the Chiltepe Peninsula. (B) This Landsat 7 image corresponds to the extent of the red box labeled "B" in the sketch map "A"; the Nejapa-Miraflores fault (NMF) marks an offset in the main arc and frequently generates seismicity. (C) Along the NMF, mainly monogenetic volcanoes have formed W of Managua city. Modified from Pardo and others, 2009.

2009 swarm. INETER reported a seismic swarm on 29 September 2009. It began at 1800 local time in an area W of Apoyeque volcano. The main event occurred at 1817 local time, with a ML 3.1 event at a depth of 5 km. The earthquake was felt by the population in Sandino City, ~5 km W of the earthquakes. The seismic swarm lasted until 2 October 2009; the total number of detected earthquakes was not disclosed.

2012 swarm. INETER reported a swarm that began at 1727 local time on 6 September 2012. The National Seismic Network detected and located the series of earthquakes between Apoyeque and the Nejapa-Miraflores fault (figure 1).

More than 20 earthquakes were detected and the two largest had magnitudes of 2.3 and 3.8, with depths of 2.8 and 6 km respectively; the largest event occurred at 1937 (figure 2). None of these earthquakes were reportedly felt by local populations and the event was assigned an Intensity II. The swarm lasted ~2 hours.

Figure (see Caption) Figure 2. Epicenters of the largest earthquakes from the Apoyeque swarm are plotted. INETER detected ~20 earthquakes on 6 September 2012 all within 30 km depth. Courtesy of INETER.

Avellán and others (2012) described the polygenetic Apoyeque volcano as belonging to the Nejapa volcanic field (figure 1), which is bound by the Nejapa fault system. There were 23 eruptions from the field within the last ~30 ka; 13 of these events were explosive (VEI 2). The most recent eruption was dated between 2,130 ± 40 and 1,245 ± 120 years BP. With respect to hazards implications, clear vent migration patterns were seemingly absent for this volcanic field. The authors concluded that there is a high probability of future, similar eruptions, particularly phreatomagmatic ones, within this area of Nicaragua.

References: Avellán, D.R., Macías, J.L., Pardo, N., Scolamacchia, T., and Rodriguez, D., 2012, Stratigraphy, geomorphology, geochemistry and hazard implications of the Nejapa Volcanic Field, western Managua, Nicaragua, Journal of Volcanology and Geothermal Research, 213-214: 51-71.

Pardo, N., Macías, J.L., Giordano, G., Cianfarra, P., Avellán, D.R., and Bellatreccia, F., 2009, The ~1245 yr BP Asososca maar eruption: The youngest event along the Nejapa-Miraflores volcanic fault, Western Managua, Nicaragua, Journal of Volcanology and Geothermal Research, 184: 292-312.

Geologic Background. The Apoyeque volcanic complex occupies the broad Chiltepe Peninsula, which extends into south-central Lake Managua. The peninsula is part of the Chiltepe pyroclastic shield volcano, one of three large ignimbrite shields on the Nicaraguan volcanic front. A 2.8-km wide, 400-m-deep, lake-filled caldera whose floor lies near sea level truncates the low Apoyeque volcano, which rises only about 500 m above the lake shore. The caldera was the source of a thick mantle of dacitic pumice that blankets the surrounding area. The 2.5 x 3 km wide lake-filled Xiloá (Jiloá) maar, is located immediately SE of Apoyeque. The Talpetatl lava dome was constructed between Laguna Xiloá and Lake Managua. Pumiceous pyroclastic flows from Laguna Xiloá were erupted about 6100 years ago and overlie deposits of comparable age from the Masaya plinian eruption.

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


Barren Island (India) — October 2013 Citation iconCite this Report

Barren Island

India

12.278°N, 93.858°E; summit elev. 354 m

All times are local (unless otherwise noted)


Ash plume drifted up to 220 km SW in February 2013

Our last Bulletin report (BGVN 36:06) noted that Barren Island was still erupting during 2011. This report both discusses an April 2010 ash plume that recently came to our attention and reports on activity as late as October 2013. A regional map appears in the last section.

On 19 April 2010, based on analysis of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that a plume from Barren Island rose to an altitude of 2.4 km and drifted 55 km N. Ash, however, could not be identified from the satellite data.

A Twitter posting included the photo in figure 20, an image apparently acquired in December 2010. The Indian Navy (via Twitter) reported seeing "smoke" and lava was also seen on the island from a surveillance plane on 16 October 2013. A large hot spot is visible on recent MODIS satellite data.

Figure (see Caption) Figure 20. A photo of Barren Island emitting a dark ash plume from its main cone. The photo's metadata indicated that it was taken on 10 December 2010. Copyrighted photo by Paul Andrew Johnson and posted on Panoramio photo display website.

VAAC reported that on 16 February 2013 during 1430 to 2000 (UTC date and time) an ash plume from Barren Island reached an altitude of 6.1 km and drifted 220 km SW. Meteorological clouds masked the ash cloud after 2000 UTC and the VAAC warned that ash could still reside at altitude. The 16 February 2013 plume height was derived from a 1530 UTC MTSAT-2 infrared image and an atmospheric sounding at Penang made at 1200 UTC. The VAAC also created a forecast of the plume's movement based on the Hysplit model data.

Darwin VAAC found that on 17 October 2013 an ash plume rose to an altitude of 3.7 km and drifted ~30 km NW. The plume was first seen in imagery at 0732 UTC and last seen at 0932 UTC. Plume height was derived from MTSAT-2 visible wavelength image, observed ash movement, and comparison to winds from both an atmospheric model and a 0600 UTC sounding.

Regional map. A regional map brings together geography and tectonics of the region centered on Barren Island (figure 21).

Figure (see Caption) Figure 21. Location map for Barren Island seen on the digital version of the wall map "This Dynamic Planet" (Simkin and others, 2005). The background image is from ER Mapper. The oceanic bathymetry and on-land topography translate for this gray-scale image, forming two independent series ranging from dark (low) to light (high). Thus, deep ocean and low land are dark, and shallow ocean and high land are light. White triangles with black borders represent Holocene volcanoes (Siebert and Simkin, 2002). Labeled volcanoes are Barren Island, Narcondam (N); Popa (P) and the Singu Plateau (SP) in Myanmar, the Tengchong pyroclastic cones (T) in southern China. The curving white line is the convergent boundary between the Indian Plate and the Eurasian Plate, including the Burma sub-plate (BP) of the Eurasian Plate.

At Barren Island's latitude, the convergent boundary is the subduction zone named the Andaman trench; to the S is the Sumatran trench, and to the N is the continental-collision zone marked by the Indo-Myanmar ranges (IMR) and still farther N and W, the Himalayan front. The large white arrow shows the NNE relative-motion vector of ~60 mm/yr for the Indian Plate and the Eurasian PlateW of Sumatra. The 26 December 2004 Sumatran earthquake (Mw 9.3) is marked by a white dot. Taken from Sanjeev Raghav (2011).

References: Luhr, J. F. and Haldar, D., 2006, Barren Island volcano (NE Indian Ocean): island-arc high-alumina basalts produced by troctolite contamination; J. Volcanol. Geotherm. Res., vol. 149, pp. 177-212.

Ray, J.S, Pande K., Awasthi, N. 2013, A minimum age for the active Barren Island volcano, Andaman Sea, Current Science; Special Section: Earth Sciences, Vol. 104, No. 7, 10 April 2013.

Sanjeev, R. 2011, Barren Volcano- A Pictorial Journey From Recorded Past To Observed Recent Part-I Earth Science India, Open Access e-Journal, Popular Issue, IV (III), July, 2011; (URL: www.earthscienceindia.info ).

Siebert, L. and Simkin, T.,2002, Volcanoes of the world: an illustrated catalog of Holocene volcanoes and their eruptions, Smithsonian Institution Global Volcanism Program, Digital Information Series, GVP-3.

Simkin, T., Tilling, R.I., Vogt, P.R., Kirby, S., Kimberly, P., and Stewart, D.B. This Dynamic Planet: World Map of Volcanoes, Earthquakes, Impact Craters, and Plate Tectonics U.S. Geological Survey (2005).

Geologic Background. Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S volcanic arc extending between Sumatra and Burma (Myanmar). It is the emergent summit of a volcano that rises from a depth of about 2250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with walls 250-350 m high. The caldera, which is open to the sea on the west, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic-flow and -surge deposits. Historical eruptions have changed the morphology of the pyroclastic cone in the center of the caldera, and lava flows that fill much of the caldera floor have reached the sea along the western coast.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina Northern Territory 0811 Australia; Twitter (URL: https://twitter.com/twitter); and VolcanoDiscovery (URL: http://www.volcanodiscovery.com/).


Cleveland (United States) — October 2013 Citation iconCite this Report

Cleveland

United States

52.825°N, 169.944°W; summit elev. 1730 m

All times are local (unless otherwise noted)


Dome growth and destruction during 2012-2013

In the previous Bulletin report (BGVN 37:01) we discussed a cycle of lava-dome growth within the summit crater from late 2011 through early 2012. That cycle of extrusion and destruction of domes continued into 2013. The lava dome observed on 30 January 2013 persisted to the end of this reporting period, September 2013. The dynamic conditions at Cleveland caused the Alaska Volcano Observatory (AVO) to report numerous changes in the Aviation Color Code and Alert Level, fluctuating between Yellow/Advisory and Orange/Watch throughout this time period (table 5).

Table 5. During 2012-2013, AVO announced changes in the Aviation Color Code and Volcano Alert Level for Cleveland. AVO and other US Observatories use a combination color code and alert level system that addresses both airborne and ground-based hazards (Gardner and Guffanti, 2006); the lowest level in this 4-step system is Normal/Green and the highest is Warning/Red. Courtesy of USGS-AVO.

Date of Change Aviation Color Code/ Volcano Alert Level
31 Jan 2012 Orange/Watch
23 Mar 2012 Yellow/Advisory
28 Mar 2012 Orange/Watch
30 May 2012 Yellow/Advisory
19 Jun 2012 Orange/Watch
05 Sep 2012 Yellow/Advisory
10 Nov 2012 Orange/Watch
21 Nov 2012 Yellow/Advisory
06 Feb 2013 Orange/Watch
08 Mar 2013 Yellow/Advisory
04 May 2013 Orange/Watch
04 Jun 2013 Yellow/Advisory

Continued explosions during 2012-2013. Cleveland has a history of frequent, minor ash emissions particularly during 2005-2009 (McGimsey and others, 2007; Neal and others, 2011) and with more frequency during 2011-2013 (Guffanti and Miller, 2013; De Angelis and others, 2012). During 2012-2013, Cleveland remained unmonitored by ground-based seismic instrumentation; volcanic unrest was primarily detected by the seismic network located on nearby Umnak Island (figure 12). Observations were also conducted with satellites that have capabilities of distinguishing ash from meteorological clouds during clear conditions: GOES (Geostationary Operational Environmental Satellite), POES (Polar Operational Environmental Satellite which carries the AVHRR scanner), and the Terra and Aqua satellites that carry MODIS sensors.

Figure (see Caption) Figure 12. Locations of Cleveland volcano (red triangle) and the infrasound stations in Alaska. Black dots are individual infrasound sensors co-located with seismic monitoring stations, yellow dots are infrasound arrays. The inset shows Umnak Island where the Okmok volcano stations are located; this is the closest seismic network to Cleveland. Map modified from De Angelis and others, 2012.

Additional assessments of explosive activity in this period were aided by (1) direct observations from mariners or pilots (PIREPS); (2) near real-time recordings of ground-coupled airwaves that characteristically arrive at seismic stations as extremely slow velocity signals, ~1 order of magnitude smaller than typical seismic velocity in the crust (De Angelis and others, 2012); (3) new infrasound detection capabilities recently expanded to include a station on Akutan (~500 km ENE of Cleveland).

De Angelis and others (2012) determined that 20 explosions were detected between December 2011 and August 2012, particularly by infrasound sensors as far away as 1,827 km from the active vent, as well as ground-coupled acoustic waves recorded at seismic stations across the Aleutian Arc. By retrospectively examining the record of airwaves from Cleveland, those authors determined that many explosions had gone unnoticed in satellite images, likely because of poor weather conditions that obscured the signal or because these explosions were brief, small, and lofted little ash.

Significant ash explosions in April-June 2012 and May 2013. During the 2012-2013reporting period, explosions from Cleveland's summit crater were most frequently detected during April and June 2012 (figure 13). Additional explosions were reported by AVO through July 2013. Relative quiescence (which included minor thermal anomalies visible in satellite images) followed and continued through September 2013.

Figure (see Caption) Figure 13. Satellite image of Cleveland collected on 9 June 2012 by the satellite Worldview-2. Snow persisted on the flanks during this time, but recent, minor ash deposits were visible around the summit crater. In this view, N is at the top of the image and the narrow isthmus connecting Cleveland to the rest of Chuginadak Island is at the R-hand side of the image (although not visible here). Courtesy of USGS-AVO and Digital Globe.

During 2012-2013, at least two explosions were large enough to generate ash plumes that reached >4 km above the summit crater. Both were reported by the Anchorage Volcanic Ash Advisory Center (VAAC) on 7 April 2012 and 4 May 2013. The April event produced a plume that rose ~6 km a.s.l.; AVO reported that ash drifted E at 18 m/s. The 4 May 2013 event (figure 14) generated an ash plume that rose ~4.6 km a.s.l. Based on POES data and AVO observations, the ash drifted SE at ~10 m/s and dissipated within 5 hours.

Figure (see Caption) Figure 14. (A) AVHRR satellite image of Cleveland was taken at 0643 on 4 May 2013. This infrared image shows elevated temperatures that were present at Cleveland's summit and a small, low-level eruption plume containing minor amounts of ash trailed to the E. The thermal anomaly appears as a white dot in the center of the image. Courtesy of USGS-AVO/UAF-GI. (B) True-color Terra MODIS satellite image acquired at 2050 on 4 May 2013 shows an eruption plume from Cleveland. The diffuse ash plume extended from Cleveland's summit and across the SW point of Umnak Island. Courtesy of USGS-AVO and Land Atmosphere Near-real time Capability for EOS (LANCE) system operated by the NASA/GSFC/Earth Science Data and Information System (ESDIS).

During 2012-2013, AVO reported that explosions were frequently attributed to dome destruction. Those events often completely removed the new lava domes from the crater (table 6).

Table 6. Cleveland's lava dome history during 2012-2013 based on a variety of observations of the Cleveland summit crater. Note that an earlier dome was destroyed during 25-29 December 2011 and was confirmed absent by 24 January 2012. Courtesy of USGS-AVO.

New Dome Date Observations
30 Jan 2012 40 m across. Dome was gone by 11 March 2012.
26 Mar 2012 70 m across. Dome was gone by 4 April 2012.
25 Apr 2012 25 m across. Dome was gone some time before 29 April 2012.
03 May 2012 25 m wide. Dome was gone by 6 May 2012.
30 Jan 2013 100 m wide. Dome persisted through September 2013.

More on elevated surface temperatures during 2012-2013. In addition to the case shown in figure 14A, thermal anomalies in the vicinity of Cleveland's summit crater were frequently detected during this reporting period. AVO inferred that these observations reflected a variety of volcanic activity such as fresh, hot tephra from recent explosions, the hot open conduit at the bottom of the summit crater, incandescent rock such as the above mentioned domes (table 6) at the surface, or hot volcaniclastic flow deposits on the flanks (figure 15).

Figure (see Caption) Figure 15. Composite image of the Cleveland summit area compiled from Landsat-8 images acquired on 8 June 2013. N is at the top of the image. Thermal infrared data are overlain onto a visible wavelength image; the extent of lava flows erupted during early May 2013 appears bright with colors corresponding to temperatures in the key (upper-L-hand corner). Temperature values are given in Kelvin, and range from 303-312 K (86-102 °F). The longest lava flows extended to ~715 m downslope from the summit. The summit was also covered by dark ash deposits and is surrounded by a low cloud deck. Courtesy of USGS-AVO.

AVO reported that a satellite-based thermal alarm was triggered on 12 June 2012, attributed to the formation of hot lahars or rubble flows on Cleveland's flanks. While no lava dome was present at that time (see table 6), this was a significant event that transported debris to 700 m elevation on the NW flank (note that Cleveland has a summit elevation of 1,730 m). Other deposits, likely from other lahars, were mobilized on the NNW and NNE flanks. The deposits were mainly confined to drainages; deposits extended >1.5 km in length. Flowage features on the SE and SW flanks reached >1 km in length. AVO scientists also noted that all flanks had shown signs of melted snow but cautioned that the visual effect could also be attributed to non-eruptive remobilization of existing fragmental material on the steep flanks.

Volcaniclastic deposits were also noted based in satellite images on 10 November 2012. These features were located on the E flank and extended ~1 km down the slope.

References: De Angelis, S., Fee, D., Haney, M., and Schneider, D., 2012. Detecting hidden volcanic explosions from Mt. Cleveland Volcano, Alaska with infrasound and ground-coupled airwaves, Geophysical Research Letters, 39, L21312, doi:10.1029/2012GL053635.

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

Guffanti, M., and Miller, T., 2013. A volcanic activity alert-level system for aviation: review of its development and application in Alaska: Natural Hazards, 15 p., doi:0.1007/s11069-013-0761-4.

McGimsey, R.G., Neal, C.A., Dixon, J.P., and Ushakov, Sergey, 2007. 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., available at http://pubs.usgs.gov/sir/2007/5269/.

Neal, C.A., McGimsey, R.G., Dixon, J.P., Cameron, C.E., Nuzhaev, A.A., and Chibisova, Marina, 2011. 2008 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2010-5243, 94 p., available at http://pubs.usgs.gov/sir/2010/5243.

Geologic Background. The beautifully symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited Chuginadak Island. It lies SE across Carlisle Pass strait from Carlisle volcano and NE across Chuginadak Pass strait from Herbert volcano. Joined to the rest of Chuginadak Island by a low isthmus, Cleveland is the highest of the Islands of the Four Mountains group and is one of the most active of the Aleutian Islands. The native name, Chuginadak, refers to the Aleut goddess of fire, who was thought to reside on the volcano. Numerous large lava flows descend the steep-sided flanks. It is possible that some 18th-to-19th century eruptions attributed to Carlisle should be ascribed to Cleveland (Miller et al., 1998). In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.

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 (URL: http://www.gi.alaska.edu/), and c)Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://www.dggs.alaska.gov/); and Anchorage Volcanic Ash Advisory Center (VAAC), 6930 Sand Lake Road, Anchorage, AK 99502, USA (URL: http://vaac.arh.noaa.gov/list_vaas.php).


Karymsky (Russia) — October 2013 Citation iconCite this Report

Karymsky

Russia

54.049°N, 159.443°E; summit elev. 1513 m

All times are local (unless otherwise noted)


Seismicity and ash plumes, September 2010-December 2013

This report summarizes activity at Karymsky from September 2010 to 31 December 2013. This period was characterized by frequent explosions with ash plumes, and persistent thermal anomalies. During this period, explosions catapulted ash to altitudes as high as 6.5 km (and possibly higher). According to Girina and others (2013), Karymsky has been in a state of explosive eruption since 1996.

The Kamchatka Volcanic Eruptions Response Team (KVERT) monitors the volcano by seismic instruments and by satellite. Occasionally, pilots and volcanologists observe the volcano visually; however, the volcano is frequently shrouded by clouds. KVERT does not directly observe ash plumes, but infers their presence and their maximum altitudes based upon seismic data, although sometimes satellite observations are used. Occasionally, plume altitudes and directions are provided by the Tokyo Volcanic Ash Advisory Center (VAAC), based on information from Yelizovo Airport (UHPP). The Aviation Color Code was Orange (the second highest) throughout the reporting period. This report is based on weekly KVERT online reports.

Figures 27 and 28 show Kamchatka and Karymsky in the context of both geography and representative aviation flight paths. Since Karymsky sits directly below a principal flight route and close to many others, tall ash plumes from Karymsky present an acute hazard to aircraft. More than 200 flights per day occurred over the North Pacific region at the end of 2007 (Neal and others, 2007). That translated to over 10,000 passengers and millions of dollars in cargo that flew across the North Pacific every day (Neal and others, 2007).

Figure (see Caption) Figure 27. The Northern Pacific region showing major Holocene volcanoes in red and selected aeronautical flight paths across the Russian Far East and North Pacific. Karymsky lies nearly directly below the major, bidirectional flight path G583. Taken from Neal and others (2009).
Figure (see Caption) Figure 28. A smaller-scale map than the one above, centered on the Kamchataka Peninsula showing major Holocene volcanoes including Karymsky, with a more detailed view of flight routes (arrows show directions of travel). Seismically monitored volcanoes are distinguished from those unmonitored, with about 30 real-time seismometers available in the region as of 2008. Alaid volcano, just S of Kamchatka, is the subject of a separate report in this issue of the Bulletin. Taken from Neal and others (2009).

September 2010-December 2012 activity. During September 2010-December 2010, KVERT weekly reports stated that seismic activity was at or above background levels. During January 2011-December 2012, most reports characterized the seismic activity as moderate. However, KVERT stated that activity was weak and moderate between 23 August-20 September 2012, during the week before 25 October 2012, and during all of December 2012. Activity was weak during the first week of July 2012.

According to KVERT, one or more ash explosions occurred weekly, and ash plumes rose to altitudes of 2-6.5 km, with most weekly values in the altitude range of 2.5-5 km. Explosive activity apparently weakened slightly during April and May 2012, with plume altitudes decreasing to 1.8-2.5 km, and apparently weakened further between mid-July and mid-August 2012, when KVERT did not report any ash plumes.

Figure 29 shows an image captured the MODIS instrument during May 2011. A plume is discernable to the edge of the image, ~140 km ESE. Radiating from the volcano is a pattern of recent ash fall deposits contrasting with broad snow cover.

Figure (see Caption) Figure 29. Satellite image of Karymsky acquired on 7 May 2011. Evidence of frequent eruptions is visible in this natural-color satellite image. Dark gray ash extends away from Karymsky's summit covering sectors of the volcano in radial patterns. A plume of ash extends to the SE, over Kronotskiy Kroniv (Kronotsky Gulf). The image was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite. Courtesy of NASA's Earth Observatory (image by Jeff Schmaltz and original descriptive material by Robert Simmon).

During mid-September 2012, ash plume altitudes reached 5.5-6 km, but had decreased to a more normal 3 km in December 2012. On 11 April 2012, instruments aboard the Terra satellite detected ash deposits about 15 km long on the E flank. According to the Tokyo VAAC, an ash plume rose to an altitude of 7.3 km and drifted N on 13 March 2011, and to an altitude of 5.5-11.9 km and drifted SW on 18 April 2011; the Tokyo VAAC reported several other ash plumes during the reporting period, but the two mentioned here represent the maximum plumes heights recorded during the reporting period.

KVERT reported Stombolian activity during October 2010. A thermal anomaly was reported every week during this period, although clouds often obscured satellite data.

On 20 November 2010, volcanologists aboard a helicopter observed moderate gas-and-steam activity. Slopes near the summit were covered with ash. According to KVERT, volcanologists also visually observed weak gas-and-steam activity on 18 December 2012.

2013 activity. During January through March 2013, seismic activity fluctuated from weak to moderate. During April through mid-August, seismic activity was not recorded for technical reasons. From mid-August through the end of 2013, activity was moderate. When satellite data was included in 2013 KVERT weekly reports (6, 14 March; 11, 18 July; 5, 12, 19 September; 3 October), the volcano was either quiet or obscured by clouds.

KVERT reports from 10 October 2013 through at least 2 January 2014 stated that Strombolian and weak Vulcanian activity probably had occurred, because satellite data sometimes showed a bright thermal anomaly over the volcano along with ash plumes (figure 30). The reports did not mention this activity during earlier portions of the reporting period (September 2010-December 2013), except for mid-October 2010; however, because thermal anomalies persisted throughout the reporting period and ash plumes were common, we suspect that Strombolian and weak Vulcanian activity probably occurred often during this time.

During 2013, ash plumes seldom exceeded an altitude of 3.5 km. However, powerful ash explosions up to an altitude of 6 km were observed on 5 August by a helicopter crew and volcanologists on the flank of nearby Tolbachik volcano.

Figure (see Caption) Figure 30. Photo of Karymsky on 30 November 2013 showing Vulcanian explosion with ash cloud billowing upward. Look direction unknown. Courtesy of Institute of Volcanology and Seismology FEB RAS, KVERT (with credit to Alexander Bichenko. NP VK).

Lopez and others (2012) used "coincident measurements of infrasound, SO2, ash, and thermal radiation collected over a ten day period at Karymsky Volcano in August 2011 to characterize the observed activity and elucidate vent processes. The ultimate goal of this project is to enable different types of volcanic activity to be identified using only infrasound data, which would significantly improve our ability to continuously monitor remote volcanoes. Four types of activity were observed. Type 1 activity is characterized by discrete ash emissions occurring every 1- 5 minutes that either jet or roil out of the vent, by plumes from 500-1500 m (above vent) altitudes, and by impulsive infrasonic onsets. Type 2 activity is characterized by periodic pulses of gas emission, little or no ash, low altitude (100 - 200 m) plumes, and strong audible jetting or roaring. Type 3 activity is characterized by sustained emissions of ash and gas, with multiple pulses lasting from ~1-3 minutes, and by plumes from 300-1500 m. Type 4 activity is characterized by periods of relatively long duration (~30 minutes to >1 hour) quiescence, no visible plume and weak SO2 emissions at or near the detection limit, followed by an explosive, magmatic eruption, producing ash-rich plumes to >2,000 m, and centimeter to meter (or greater) sized pyroclastic bombs that roll down the flanks of the edifice. Eruption onset is accompanied by high-amplitude infrasound and occasionally visible shock-waves, indicating high vent overpressure."

The above meeting abstract ultimately led to the paper Lopez and others (2013). In the abstract for that work, the authors characterized the four types of activity as: (1) ash explosions, (2) pulsatory degassing, (3) gas jetting, and (4) explosive eruption.

Ongoing eruptions, often on a near daily basis, prevailed during January-March 2014, with thermal anomalies on satellite data, ash plumes hundreds of meters over the ~1.5 km summit's elevation. The plumes were visible in imagery for over 100 km downwind (often in the sector NE-E-SE).

References: Girina, O., Manevich, A., Melnikov, D., Nuzhdaev, A., Demyanchuk, Y., and Petrova, E., 2013, Explosive Eruptions of Kamchatkan Volcanoes in 2012 and Danger to Aviation, Geophysical Research Abstracts, Vol. 15, EGU General Assembly 2013 held 7-12 April, 2013 in Vienna, Austria, id. EGU2013-6760.

Lopez, T., Fee, D, and Prata, F., 2012, Characterization of volcanic activity using observations of infrasound, volcanic emissions, and thermal imagery at Karymsky Volcano, Kamchatka, Russia, Geophysical Research Abstracts, Vol. 14, EGU General Assembly 2012, held 22-27 April, 2012 in Vienna, Austria., p.13076.

Lopez, T., D. Fee, F. Prata, and J. Dehn, 2013, Characterization and interpretation of volcanic activity at Karymsky Volcano, Kamchatka, Russia, using observations of infrasound, volcanic emissions, and thermal imagery, Geochem. Geophys. Geosyst., 14, 5106-5127, doi:10.1002/2013GC004817

Neal C, Girina O, Senyukov S, Rybin A, Osiensky J, Izbekov P, Ferguson G, 2009, Russian eruption warning systems for aviation. Natural Hazards, 51(2), p. 245-262

Neal, C, Girina, O, Senyukov, S, Rybin, A, Osiensky, J, Hall, T, Nelson, K, and Izbekov, P, 2007, Eruption Warning Systems for Aviation in Russia: A 2007 Status Report, World Meteorological Organization (WMO), in close collaboration with the International Civil Aviation Organization (ICAO) and the Civil Aviation Authority Of New Zealand, paper at the Fourth International Workshop On Volcanic Ash, Rotorua, New Zealand, 26-30 March 2007 [VAWS/4 WP/03-01] (URL: http://www.caem.wmo.int/moodle/file.php?file=/1/VWS/6_VAWS4WP0301_1_.pdf)

Geologic Background. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed during the early Holocene. The caldera cuts the south side of the Pleistocene Dvor volcano and is located outside the north margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7600-7700 radiocarbon years ago; construction of the stratovolcano began about 2000 years later. The latest eruptive period began about 500 years ago, following a 2300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been vulcanian or vulcanian-strombolian with moderate explosive activity and occasional lava flows from the summit crater.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Kamchatka Branch of Geophysical Survey of RAS (KB GS RAS) (URL: http://www.emsd.ru/); and Jeff Schmaltz and Robert Simmon, NASA Earth Observatory (URL: http://earthobservatory.nasa.gov).


Cerro Negro (Nicaragua) — October 2013 Citation iconCite this Report

Cerro Negro

Nicaragua

12.506°N, 86.702°W; summit elev. 728 m

All times are local (unless otherwise noted)


Seismic swarm in 2013

Since our last report (BGVN 37:01), Instituto Nicaragüense de Estudios Territoriales (INETER) continued to conduct fieldwork at Cerro Negro during 2012-2013 and reported that stable conditions prevailed except for a small seismic swarm detected in 2013.

INETER reported that from Cerro Negro's activity during 2012 was considered normal. Several significant landslides occurred that year, particularly from the S-SW interior rim of the primary crater. Seismicity was variable throughout the year with some interruptions of the signal (table 5).

Table 5.Seismicity was reported in INETER monthly reports during January-June 2012. Note that representative values are presented in the RSAM column (not mathematical averages) whereas the Max RSAM column contains the highest value recorded each month. There was a station outage during part of January. Courtesy of INETER.

Month # Eqs RSAM Max RSAM Tremor (hours/day)
Jan 43 ~20 160 na
Feb 85 ~20 80 3-18
March 76 ~50 255 1-16
April 162 ~20 50 1-15
May 111 12-30 65 some
June 179 10-20 45 1

A gas measurement campaign was conducted within Cerro Negro's main crater in collaboration with the Instituto Tecnologicos de Energias Renovables (ITER) in late 2012. During the course of fieldwork, on 26 and 30 November, and 1 December, the team measured diffuse CO2 emissions from the soil at 219 points. The preliminary results showed normal levels, ~33 tons per day, compared to past results from this area.

Temperature measurements for 2012 were reported based on the four different fumarolic sites within the main crater (figure 20). The range varied between 50 and 325 degrees C.

Figure (see Caption) Figure 20. Temperature measurements from Cerro Negro's crater summarized for 2011-2013. Data were collected December 2011-May 2013. Four different fumaroles were sampled and measured (fumaroles 1, 2, 3, and 6; for locations see figure 21). The data were collected at intervals of days and many are shown here (as in the original INETER plot) connected with line segments. Courtesy of INETER.
Figure (see Caption) Figure 21. The location of the four measured fumaroles located within Cerro Negro's largest crater. The view is approximately to the N. Courtesy of INETER.

Field investigations during March-June 2013 yielded additional observations of rockfalls and slides within the main crater. INETER also measured temperatures from the four fumarolic sites and concluded that steady conditions persisted (figure 20).

INETER reported a seismic swarm on 4 June 2013. RSAM had increased 60 units; 49 earthquakes were detected but were too small to be located. INETER maintained Alert Status Green and released informational statements to the media that described their response to the escalation and they also highlighted the potential of hazardous gas emissions for the area. The Sistema Nacional para Prevención, Mitigación y Atención de Desastres (SINAPRED) suggested that local residents and tourists in the area should be cautious around the flanks of Cerro Negro due to the possibility of rockfalls triggered by seismic events.

As a response to the increased seismicity that month, INETER conducted hot spring sampling and gas measuring campaigns in the area of Cerro Negro during 6-7 June. A team of fieldworkers focused on diffuse CO2 flux from the soil in a fault area on the W side of the Las Pilas-El Hoyo complex (SE of Cerro Negro, figure 15 in BGVN 37:01). The team took measurements 5 m apart at 91 points along a fault scarp, with depths of 11 and 40 cm within the soil; those measurements indicate an average flux of 59-80 ppm/s. No additional seismic unrest was reported during the month.

Geologic Background. Nicaragua's youngest volcano, Cerro Negro, was created following an eruption that began in April 1850 about 2 km NW of the summit of Las Pilas volcano. It is the largest, southernmost, and most recent of a group of four youthful cinder cones constructed along a NNW-SSE-trending line in the central Marrabios Range. Strombolian-to-subplinian eruptions at intervals of a few years to several decades have constructed a roughly 250-m-high basaltic cone and an associated lava field constrained by topography to extend primarily NE and SW. Cone and crater morphology have varied significantly during its short eruptive history. Although it lies in a relatively unpopulated area, occasional heavy ashfalls have damaged crops and buildings.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); Instituto Tecnológico y de Energías Renovables (ITER), 38611 Granadilla, Tenerife, Canary Islands, Spain (URL: http://www.iter.es/); Hoy: El Periodico que yo quiero, Managua, Nicaragua (URL: http://www.hoy.com.ni/2013/06/05/vigilan-al-volcán-cerro-negro/); and Sistema Nacional para Prevención, Mitigación y Atención de Desastres (SINAPRED), Managua, Nicaragua (URL: http://www.sinapred.gob.ni/).


Rabaul (Papua New Guinea) — October 2013 Citation iconCite this Report

Rabaul

Papua New Guinea

4.271°S, 152.203°E; summit elev. 688 m

All times are local (unless otherwise noted)


Variable but often modest eruptions during mid-2011 through 2013

The last Bulletin report on Rabaul Caldera (BGVN 36:07) recorded dozens of explosions in the first week of August 2011. The explosions produced ash-rich clouds that drifted NW and deposited ash in areas from Rabaul Town (3-5 km NW) to Nonga Village (10 km NW) (figure 57). This report covers activity from the end of August 2011 to December 2013, using data primarily compiled from the Rabaul Volcano Observatory (RVO) and the Darwin Volcanic Ash Advisory Center (VAAC). During this time, hundreds of small earthquakes were detected, almost all of which occurred congruently with ash emissions or explosions. One notable development occurred in July 2013, when a new lava dome formed on Tavurvur in the middle of a long period of eruptive activity running from April to September of the same year. Shortly after the dome's formation, strong venting of ash at Tavurvur gave way to explosions on 10 July that continued until 5 September, 2013. A second period of explosive activity began on 13 November, 2013, and terminated at the end of November.

Figure (see Caption) Figure 57. Location maps of Rabaul and Tavurvur Cone (a and b). White boxes in a and b zoom to show maps b and c, respectively. Maps derived from Google Earth Landsat images and modified to show regional reference points in relation to Rabaul's Tavurvur Cone. (c) map of Rabaul caldera derived from work by Almond and McKee and prepared by Lyn Topinka (US Geological Survey 1998).

August 2011 to November 2012. Rabaul Caldera was generally tranquil from 12 August 2011 to November 2012. During this time, only emissions of white vapor were seen rising from the cone, which became denser with the rain and humidity or periods of cool temperatures. Seismicity was low although several high frequency earthquakes NE of Tavurvur were recorded on 6 June 2012. GPS instruments recorded at least 2 cm of inflation (greater than the long-term decadal trend in inflation) and sub-continuous tremor was recorded by four local seismic stations 17-20 September 2011. Diffuse SO2 emissions recorded in late November 2012.

January and February 2013. At 2128 on 19 January 2013, Rabaul town residents and volcanologists at RVO heard loud rumbling and roaring noises from Tavurvur, marking the beginning of a period of activity that lasted until 2 February 2013 (table 12). RVO determined on the morning of 20 January that small discrete explosions had produced ash plumes during the night. Those plumes reached a maximum height of 500 m above the crater, and the prevailing winds pushed them E and SE.

Table 12.Maximum height above the crater, date, direction, and color for plumes from Tavurvur Cone from 19 January, 2013 to 7 February 2013. Seismicity during some of the events is also described. Courtesy of RVO.

DatePlume Height (m)DirectionColorSeismicity
1/19 500 E, SE N/A N/A
1/20 200 E, SE Light Gray N/A
1/22 200 S, SSE Gray N/A
1/22 (2148) 2000 SE, ESE Gray N/A
1/23 2000 SE Light Gray Numerous, associated with ash emissions
1/24 1000 E, ESE Light Gray Numerous, associated with volcanic degassing
1/25 700 E, ESE Light Gray Low, associated with ash emissions
1/26 500 ESE Gray Low, associated with ash emissions
1/27 500 ESE White and Light Gray Low, associated with ash emissions
1/28 500 ESE White and Light Gray Low
1/29 500 E, ESE Light Gray Low
1/30 500 ESE Light Gray Low
2/1 500 E, ESE Light Gray Low
2/2 500 E, ESE Light Gray Low
2/3 2000 E, NE Dark Gray Low, associated with ash emissions
2/4 2000 E, SE Light Gray Low, associated with ash emissions
2/5 2688 E, ENE Pale Gray Low, associated with ash emissions
2/6 2000 NW Pale Gray Low, associated with ash emissions
2/7 2000 NW Pale Gray Low, associated with ash emissions

On 21 January at 0930, RVO noted an increase in emissions from Tavurvur consisting of mostly water vapor and low volumes of ash that created a plume ranging in color from white to light gray. The plume rose to a maximum height of 200 m and drifted SW. These conditions remained constant for the next 24 hours, except for a loud explosion and several minutes of roaring and rumbling at 2335 that night. The vegetation on the north side of South Daughter (also known as Turangunan, see figure 57) turned brown, suggesting the release of SO2 from the volcano.

Further increase in emissions was noted at 0930 on 22 January, and plumes rose to a maximum height of 200m drifting to the SE. That night at 2147 a large explosion ejected both a light gray plume low in ash content and small amounts of incandescent spatter. Explosive noises were heard throughout the night and continued through 23 January. Both diffuse and dense ash plumes drifted SE. RVO remarked that calm meteorological conditions allowed the plume to ascend to a maximum altitude of 2,000 m. Activity at Tavurvur through 7 February was characterized by small-to-moderate explosions producing light-to-dark-gray ash clouds of low ash content and variable plume heights, constant white vapor, and low-to-moderate levels of roaring and rumbling. Ash affected areas downwind; ABC Australia Network News reported that the ash shut down New Britain airports until 31 January.

On 5 February, the Darwin VAAC reported a pale gray plume that rose to 2,000 m a.s.l. and drifted E and ENE.

Ash fell on Turangunan on 3 February. Very fine ash fell in Rabaul Town on 6 and 7 February due to a southeasterly wind blowing the plume NW from Tavurvur. There were no other affected areas.

March 2013. RVO recorded increased ash emissions on 3 March. Those emissions were brown and continued until 7 March. Volcanologists at RVO reported that the emissions increased over time throughout the latter part of 3 March and by 6 March were occurring nearly every minute. At the same time, many small earthquakes associated with ash emissions were detected. Four regional earthquakes were felt on 5 March at 1358, 1606, and 1621, and on 6 March at 1953. These earthquakes ranged from a magnitude of 5.1 to 5.4, originating SSE from Rabaul to the east of Wide Bay (see figure 57 for reference) at depths of 50-60 km. They were felt in Rabaul Town with intensities III - IV. RVO did not report any change in volcanic activity at this time. Earthquakes on 7 March occurred with instances of ash emissions, which had declined in frequency to once every few hours.

Tavurvur remained quiet until 12 March, when an explosion at 1108 expelled a dark gray-to-black billowing ash column for 40 minutes. Afterwards, emissions changed to billowing white ash clouds that rose 300 m and drifted SE.

April 2013 to September 2013. Activity at Tavurvur from 14 April until 9 July was characterized by ongoing roaring, rumbling, and diffuse to dense white plumes, including some occasionally laden with fine ash particles (table 13). Throughout the period, some low intensity earthquakes and some explosions were detected, which ejected ash clouds to variable heights. Many ash plumes were blown to the SE until 30 April, when the wind began blowing to the NW. As a result, downwind areas including Rabaul town experienced ashfall from 30 April to 9 September.

Table 13.Table describes the height, color, direction, and plume densities from Rabaul's Tavurvur cone as well as the areas affected by ash fall from 14 April to 5 September 2013. Note that towns referenced here can be found in figure 57. Courtesy of RVO and Darwin VAAC.

Date Plume Height (m) Ash Color Direction Notes Areas affected by ash fall
4/14 - 4/17 100 White SE diffuse to dense None
4/18 5288 White 35km E   None
4/19 - 4/23 100 White SE diffuse to dense None
4/24 - 4/28 200 White SE diffuse to dense None
4/29 - 5/16 200 White NW diffuse to dense Rabaul Town
5/17 - 6/15 800 White NW to SE diffuse to dense Rabaul Town
6/16 - 6/30 1000 White to Light Gray NW to SE diffuse to dense Rabaul Town
7/1 - 7/9 2000 White to Gray NW diffuse to dense Rabaul Town
7/10 -7/14 2000 Gray NW Moderate to dense Rabaul Town
7/15 - 7/21 2000 Light to Pale Gray E, NNE, NW, W, SW, Energetic explosions, fine ashfall Between Nodup and Rapolo, Rabaul town
7/22 - 7/31 2000 Light to Pale Gray E, NNE, NW, W, SW, Energetic explosions, fine ashfall Between Namanula and Malaguna No. 1, Rabaul Town, Malaguna No. 2, Vulcan Area
8/1 - 8/24 1000 Pale Gray NW Forceful emissions east Old Rabaul, Namanula Hill, Nonga Area, Rabaul Town, Malaguna No. 1
8/29 1800 Pale Gray 150 km NW Forceful emissions east Old Rabaul, Namanula Hill, Nonga Area, Rabaul Town, Malaguna No. 2
8/26 - 8/28 1000 Pale Gray NW Forceful emissions east Old Rabaul, Namanula Hill, Nonga Area, Rabaul Town, Malaguna No. 3
8/29 2100 Pale Gray 40 km NW Forceful emissions east Old Rabaul, Namanula Hill, Nonga Area, Rabaul Town, Malaguna No. 4
8/30 - 8/31 1000 Pale Gray NW Forceful emissions east Old Rabaul, Namanula Hill, Nonga Area, Rabaul Town, Malaguna No. 5
9/1 - 9/5 50 Pale Gray NW Strong winds re-suspended old ash Rabaul Town, exposure low - moderate

On 12 June 2013 a small lava dome, estimated to be 25-30 m high, began forming on the floor of Tavurvur. Photos taken that day appear as figures 58 and 59.

Figure (see Caption) Figure 58. Photo of the new lava dome forming on 12 June 2013. Courtesy of RVO.
Figure (see Caption) Figure 59. A new lava dome in Tavurvur, taken on 12 June 2013 with estimated scale bars. Courtesy of the RVO.

On 26 June, incandescence was observed at a vent on the dome and was associated with strong venting of steam and ash, which continued to 14 July.

A few discrete explosions occurred on 10 July, producing moderate to dense gray ash clouds. This low level eruptive activity persisted until 9 September, with energetic explosions producing mostly light-to-pale-gray ash clouds that drifted NW and affected areas downwind. The eruptions occurred at a varying range of intervals from ten's of seconds to hours.

From 14 April to 14 July, several small low-frequency earthquakes occurred. The majority of these were too small to be located, but time series data suggest that they originated near Tavurvur. In early July, a recently restored seismic station near Tavurvur confirmed that earthquakes were occurring beneath Tavurvur volcano. The station also detected smaller earthquakes that other seismic stations had not recorded. On 15 July, the level of seismicity increased, with events concurrent with ash emissions. On 1 August, seismicity increased and remained elevated until 9 September; seismic events continued to be associated with ash emissions.

Ground deformation during this entire period remained relatively stable, reflecting the long-term trend of uplift. On 11 May, the base station antenna broke, resulting in a loss of GPS data. Ground measurements using water tube tilt meters showed a slight inflation recorded at Matupit Island (see figure 57). Throughout the entire month of August, ground measurements showed slight deflation, but the long term inflation trend resumed beginning on 1 September.

During 1-5 September, RVO stated that "people in Rabaul town reported an odor reflective of chlorine. The substance that caused the odor is normal output of volcanic processes but an uncommon one. Its presence does not represent anything unusual or increase in volcanic activity."

Figure (see Caption) Figure 60. This natural color image of Tavurvur Cone emitting an ash plume on 6 August 2013 was acquired by the Advanced Land Imager (ALI) on the Earth Observing-1 (EO-1) satellite, and posted on the NASA Earth Observatory website. Note scale and N arrow at far left. Courtesy of Jesse Allen and Robert Simmon (Nasa Earth Observatory).

September to November 2013. The Darwin VAAC observed one ash plume on 27 September 2013. The plume rose to an altitude of 2,400 m a.s.l. and drifted 110 km NE and NW. No other activity was recorded until mid- November.

On 13 November 2013, a moderate explosion at Tavurvur produced a dense, gray billowing plume of ash which rose 1000 m and blew NW. More explosions followed at irregular intervals, and continued until 18 November. Ash plumes from those explosions were blown E, SE, and NW at lower altitudes and rose to a maximum height of 1000 m. Between explosions, wisps of white vapor rose from the volcano. Large explosions occurred at 0738, 0851, 1308, and 1903 on 13 November, and the next day at 2044. RVO reported minor inflation at the center of the caldera. There was some roaring and rumbling, but seismicity was low with small low-frequency earthquakes occurring with explosions.

During 19-30 November, Tavurvur produced fewer explosions, accompanied by white to light gray emissions, and small traces of diffuse to dense white vapors were occasionally observed. Those plumes drifted E, SE, and NW at a maximum height of 1,000 m above the crater summit. Two small, high-frequency volcano-tectonic earthquakes were detected during 23-27 November and located NE of Tavurvur.

December 2013. Little activity occurred at Rabaul during December. Minor emissions of mainly diffuse, though occasionally dense, white vapor occurred. A blue tint to the emissions was reported on some days during the reporting periodThere were no audible noises except for two two moderate explosions at 1850 on 15 December and 0732 on 22 December. Neither explosion was ash rich. RVO noted a weak fluctuating glow visible at night on 31 December.

Geologic Background. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor utilized by what was the island's largest city prior to a major eruption in 1994. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the east, where its floor is flooded by Blanche Bay and was formed about 1400 years ago. An earlier caldera-forming eruption about 7100 years ago is now considered to have originated from Tavui caldera, offshore to the north. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city.

Information Contacts: Rabaul Volcano Observatory, Department of Mineral Policy and Geohazards Management, Volcanological Observatory Geohazards Management Division, P.O. Box 386, Kokopo, East New Britain Province, Papua New Guinea; and Darwin Volcanic Ash Advisory Centre (VAAC) (URL: http://www.bom.gov.au/info/vaac/); Nasa Earth Observatory (URL: http://earthobservatory.nasa.gov); and ABC Australia Network News (URL: http://www.abc.net.au/news-01-31/an-png-airport-reopens-after-volcano-forces-closure/4492838).

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/).