Nyiragongo is a stratovolcano with a 1.2 km-wide summit crater containing an active lava lake that has been present since at least 1971. It is located the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo, part of the western branch of the East African Rift System. Typical volcanism includes strong and frequent thermal anomalies, primarily due to the lava lake, incandescence, gas-and-steam plumes, and seismicity. This report updates activity during June through November 2019 with the primary source information from monthly reports by the Observatoire Volcanologique de Goma (OVG) and satellite data.

In the July 2019 monthly report, OVG stated that the lava lake level had dropped during the month, with incandescence only visible at night (figure 68). In addition, the small eruptive cone within the crater, which has been active since 2014, decreased in activity during this timeframe. A MONUSCO (United Nations Stabilization Mission in the Democratic Republic of the Congo) helicopter overflight took photos of the lava lake and observed that the level had begun to rise on 27 July. Seismicity was relatively moderate throughout this reporting period; however, on 9-16 July and 21 August strong seismic swarms were recorded.

Figure 68. Webcam images of Nyiragongo on 20 July 2019 where incandescence is not visible during the day (left) but is observed at night (right). Incandescence is accompanied by gas-and-steam emissions. Courtesy of OVG.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data continued to show frequent and strong thermal anomalies within 5 km of the crater summit through November 2019 (figure 69). Similarly, the MODVOLC algorithm reported almost daily thermal hotspots (more than 600) within the summit crater between June 2019 through November. These data are corroborated with Sentinel-2 thermal satellite imagery and a photo from OVG on 19 December 2019 showing the active lava lake (figures 70 and 71).

Figure 69. Thermal anomalies at Nyiragongo from 3 January through November 2019 as recorded by the MIROVA system (Log Radiative Power) were frequent and strong. Courtesy of MIROVA.

Figure 70. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) showed ongoing thermal activity (bright yellow-orange) at Nyiragongo during June through November 2019. Courtesy of Sentinel Hub Playground.

Figure 71. Photo of the active lava lake in the summit crater at Nyiragongo on 19 December 2019. Incandescence is accompanied by a gas-and-steam plume. Courtesy of OVG via Charles Balagizi.

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

Information Contacts: Observatoire Volcanologique de Goma (OVG), Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo; MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Charles Balagizi (Twitter: @CharlesBalagizi, https://twitter.com/CharlesBalagizi).

Activity at Ebeko includes frequent explosions that have generated ash plumes reaching altitudes of 1.5-6 km over the last several years, with the higher altitudes occurring since mid-2018 (BGVN 43:03, 43:06, 43:12, 44:07). Ash frequently falls in Severo-Kurilsk (7 km ESE), which is monitored by the Kamchatka Volcanic Eruptions Response Team (KVERT). This activity continued during June through November 2019; the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Explosive activity during December 2018 through November 2019 often sent ash plumes to altitudes between 2.2 to 4.5 km, or heights of 1.1 to 3.4 km above the crater (table 8). Eruptions since 1967 have originated from the northern crater of the summit area (figure 20). Webcams occasionally captured ash explosions, as seen on 27 July 2019(figure 21). KVERT often reported the presence of thermal anomalies; particularly on 23 September 2019, a Sentinel-2 thermal satellite image showed a strong thermal signature at the crater summit accompanied by an ash plume (figure 22). Ashfall is relatively frequent in Severo-Kurilsk (7 km ESE) and can drift in different direction based on the wind pattern, which can be seen in satellite imagery on 30 October 2019 deposited NE and SE from the crater(figure 23).

Table 8. Summary of activity at Ebeko, December 2018-November 2019. S-K is Severo-Kurilsk (7 km ESE of the volcano). TA is thermal anomaly in satellite images. Data courtesy of KVERT.

Figure 20. Satellite image showing the summit crater complex at Ebeko, July 2019. Monthly mosaic image for July 2019, copyright 2019 Planet Labs, Inc.

Figure 21. Webcam photo of an explosion and ash plume at Ebeko on 27 July 2019. Videodata by IMGG FEB RAS and KB GS RAS (color adjusted and cropped); courtesy of Institute of Volcanology and Seismology FEB RAS, KVERT.

Figure 22. Satellite images showing an ash explosion from Ebeko on 23 September 2019. Top image is in natural color (bands 4, 3, 2). Bottom image is using "Atmospheric Penetration" rendering (bands 12, 11, 8A) to show a thermal anomaly in the northern crater visible around the rising plume. Courtesy of Sentinel Hub Playground.

Figure 23. A satellite image of Ebeko from Sentinel-2 (LC1 natural color, bands 4, 3, 2) on 30 October 2019 showing previous ashfall deposits on the snow going in multiple directions. Courtesy of Sentinel Hub Playground.

The MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data detected four low-power thermal anomalies during the second half of July, and one each in the months of June, August, and October; no activity was recorded in September or November MODVOLC thermal alerts observed only one thermal anomaly between June through November 2019.

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

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Planet Labs, Inc. (URL: https://www.planet.com/); 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/).

Nevado del Ruiz is a glaciated volcano in Colombia (figure 86). It is known for the 13 November 1985 eruption that produced an ash plume and associated pyroclastic flows onto the glacier, triggering a lahar that approximately 25,000 people in the towns of Armero (46 km west) and Chinchiná (34 km east). Since 1985 activity has intermittently occurred at the Arenas crater. The eruption that began on 18 November 2014 included ash plumes dominantly dispersed to the NW of Arenas crater (BGVN 42:06). This bulletin summarizes activity during January 2016 through December 2017 and is based on reports by Servicio Geologico Colombiano and Observatorio Vulcanológico y Sismológico de Manizales, Washington Volcanic Ash Advisory Center (VAAC) notices, and satellite data.

Figure 86. A satellite image of Nevado del Ruiz showing the location of the active Arenas crater. September 2019 Monthly Mosaic image copyright Planet Labs 2019.

Activity during 2016. Throughout January 2016 ash and steam plumes were observed reaching up to a few kilometers. Significant water vapor and volcanic gases, especially SO₂, were detected throughout the month. Thermal anomalies were detected in the crater on the 27th and 31st. Significant water vapor and volcanic gas plumes, in particular SO₂, were frequently detected by the SCAN DOAS (Differential Optical Absorption Spectroscopy) station and satellite data (figure 87). A M3.2 earthquake was felt in the area on 18 January. Similar activity continued through February with notable ash plumes up to 1 km, and a M3.6 earthquake was felt on the 6th. Ash and gas-and-steam plumes were reported throughout March with a maximum of 3.5 km on the 31st (figure 88). Significant water vapor and gas plumes continued from the Arenas crater throughout the month, and a thermal anomaly was noted on the 28th. An increase in seismicity was reported on the 29th.

Figure 87. Examples of SO2 plumes from Nevado del Ruiz detected by the Aura/OMI instrument on 10, 26, and 31 January 2019. Courtesy of Goddard Space Flight Center.

Figure 88. Ash plumes at Nevado del Ruiz during March. Webcam images courtesy of Servicio Geologico Colombiano, various 2016 reports.

The activity continued into April with a M 3.0 earthquake felt by nearby inhabitants on the 8th, an increase in seismicity reported in the week of 12-18, and another significant increase on the 28th with earthquakes felt around Manizales. Thermal anomalies were noted during 12-18 April with the largest on the 16th. Ash plumes continued through the month as well as significant steam-and-gas plumes. Ashfall was reported in Murillo on the 29th.

The elevated activity continued through May with significant steam plumes up to 1.7 km above the crater during the week of 10-16. Thermal anomalies were reported on the 11th and 12th. Steam, gas, and ash plumes reached 2.5 km above the crater and dispersed to the W and NW. Ashfall was reported in La Florida on the 20th (figure 89) and multiple ash plumes on the 22nd reached 2.5 km and resulted in the closure of the La Nubia airport in Manizales. Ash and gas-and-steam emission continued during June (figure 90).

Figure 89. Ash plumes at Nevado del Ruiz on 17, 18, and 20 May 2016 with fine ash deposited on a car in La Florida, Manizales on the 20th. Webcams located in the NE Guali sector of the volcano, courtesy of Servicio Geologico Colombiano 20 May 2016 report.

Figure 90. Examples of gas-and-steam and ash plumes at Nevado del Ruiz during June and July 2016. Courtesy of Servicio Geologico Colombiano (7 July 2016 report).

Similar activity was reported in July with gas-and-steam and ash plumes often dispersing to the NW and W. Ashfall was reported to the NW on 16 July (figure 91). Drumbeat seismicity was detected on 13, 15, 16, and 17 July, with two hours on the 16th being the longest duration episode do far. Drumbeat seismicity was noted by SGC as indicating dome growth. Significant water vapor and gas emissions continued through August. Ash plumes were reported through the month with plumes up to 1.3 km above the crater on 28 and 2.3 km on 29. Similar activity was reported through September as well as a thermal anomaly and ash deposition apparent in satellite data (figure 92). Drumbeat seismicity was noted again on the 17th.

Figure 91. The location of ashfall resulting from an explosion at Nevado del Ruiz on 16 July 2016 and a sample of the ash under a microscope. The ash is composed of lithics, plagioclase and pyroxene crystals, and minor volcanic glass. Courtesy of Servicio Geologico Colombiano (16 July 2016 report).

Figure 92. This Sentinel-2 thermal infrared satellite image shows elevated temperatures in the Nevado del Ruiz Arenas crater (yellow and orange) on 16 September 2016. Ash deposits are also visible to the NW of the crater. In this image blue is snow and ice. False color (urban) satellite image (bands 12, 11, 4) courtesy of Sentinel Hub Playground.

During the week of 4-10 October it was noted that activity consisting of regular ash plumes had been ongoing for 22 months. Ash plumes continued with reported plumes reaching 2.5 above the crater throughout October (figure 93), accompanied by significant steam and water vapor emissions. A M 4.4 earthquake was felt nearby on the 7th. Similar activity continued through November and December 2016 with plumes consisting of gas and steam, and sometimes ash reaching 2 km above the crater.

Figure 93. An ash plume rising above Nevado del Ruiz on 27 October 2016. Courtesy of Servicio Geologico Colombiano.

Activity during 2017. Significant steam and gas emissions, especially SO₂, continued into early 2017. Ash plumes detected through seismicity were confirmed in webcam images and through local reports; the plumes reached a maximum height of 2.5 km above the volcano on the 6th (figure 94). Drumbeat seismicity was recorded during 3-9, and on 22 January. Inflation was detected early in the month and several thermal anomalies were noted.

Intermittent deformation continued into February. Significant steam-and-gas emissions continued with intermittent ash plumes reaching 1.5-2 km above the volcano. Thermal anomalies were noted throughout the month and there was a significant increase in seismicity during 23-26 February.

Figure 94. Ash plumes at Nevado del Ruiz on 6 January 2017. Courtesy of Servicio Geologico Colombiano.

Thermal anomalies continued to be detected through March. Ash plumes continued to be observed and recorded in seismicity and maximum heights of 2 km above the volcano were noted. Deflation continued after the intermittent inflation the previous month. On 10-11 April a period of short-duration and very low-energy drumbeat seismicity was recorded. Significant gas and steam emission continued through April with intermittent ash plumes reaching 1.5 km above the volcano. Thermal anomalies were detected early in the month.

Unrest continued through May with elevated seismicity, significant steam-and-gas emissions, and ash plumes reaching 1.7 km above the crater. Five episodes of drumbeat seismicity were recorded on 29 May and intermittent deformation continued. There were no available reports for June and July.

Variable seismicity was recorded during August and deflation was measured in the first week. Gas-and-steam plumes were observed rising to 850 m above the crater on the 3rd, and 450 m later in the month. A thermal anomaly was noted on the 14th. There were no available reports for September through December.

On 18 December 2017 the Washington VAAC issued an advisory for an ash plume to 6 km that was moving west and dispersing. The plume was described as a "thin veil of volcanic ash and gasses" that was seen in visible satellite imagery, NOAA/CIMSS, and supported by webcam imagery.

Geologic Background. Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers more than 200 km2. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America's deadliest eruption.

Information Contacts: Servicio Geologico Colombiano (SGC), Diagonal 53 No. 34-53 - Bogotá D.C., Colombia (URL: https://www2.sgc.gov.co/volcanes/index.html); Observatorio Vulcanológico y Sismológico de Manizales (URL: https://www.facebook.com/ovsmanizales); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Sabancaya is an andesitic stratovolcano located in Peru. The most recent eruptive episode began in early November 2016, which is characterized by gas-and-steam and ash emissions, seismicity, and explosive events (BGVN 44:06). The ash plumes are dispersed by wind with a typical radius of 30 km, which occasionally results in ashfall. Current volcanism includes high seismicity, gas-and-steam emissions, ash and SO₂ plumes, numerous thermal anomalies, and explosive events. This report updates information from June through November 2019 using information primarily from the Instituto Geofisico del Peru (IGP) and Observatorio Volcanologico del INGEMMET (Instituto Geológical Minero y Metalúrgico) (OVI-INGEMMET).

Table 5. Summary of eruptive activity at Sabancaya during June-November 2019 based on IGP weekly reports, the Buenos Aires VAAC advisories, the HIGP MODVOLC hotspot monitoring algorithm, and Sentinel-5P/TROPOMI satellite data.

Explosions, ash emissions, thermal signatures, and high concentrations of SO₂ were reported each week during June-November 2019 by IGP, the Buenos Aires Volcanic Ash Advisory Centre (VAAC), HIGP MODVOLC, and Sentinel-2 and Sentinel-5P/TROPOMI satellite data (table 5). Thermal anomalies were visible in the summit crater, even in the presence of meteoric clouds and ash plumes were occasionally visible rising from the summit in clear weather (figure 68). The maximum plume height reached 4.5 km above the crater drifting NW, W, and S the week of 29 July-4 August, according to IGP who used surveillance cameras to visually monitor the plume (figure 69). This ash plume had a radius of 30 km, which resulted in ashfall in Colca (NW) and Huambo (W). On 27 July the SO₂ levels reached a high of 12,814 tons/day, according to INGEMMET. An average of 58 daily explosions occurred in early November, which is the largest average of this reporting period.

Figure 68. Sentinel-2 satellite imagery detected ash plumes, gas-and-steam emissions, and multiple thermal signatures (bright yellow-orange) in the crater at Sabancaya during June-November 2019. Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images courtesy of Sentinel Hub Playground.

Figure 69. A webcam image of an ash plume rising from Sabancaya on 1 August 2019 at least 4 km above the crater. Courtesy of IGP.

Seismicity was also particularly high between August and September 2019, according to INGEMMET. On 14 August, roughly 850 earthquakes were detected. There were 280 earthquakes reported on 15 September, located 6 km NE of the crater. Both seismic events were characterized as seismic swarms. Seismicity decreased afterward but continued through the reporting period.

In February 2017, a lava dome was established inside the crater. Since then, it has been growing slowly, filling the N area of the crater and producing thermal anomalies. On 26 October 2019, OVI-INGEMMET conducted a drone overflight and captured video of the lava dome (figure 70). According to IGP, this lava dome is approximately 4.6 million cubic meters with a growth rate of 0.05 m3/s.

Figure 70. Drone images of the lava dome and degassing inside the crater at Sabancaya on 26 (top) and 27 (bottom) October 2019. Courtesy of INGEMMET (Informe Ténico No A6969).

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows strong, consistent thermal anomalies occurring all throughout June through November 2019 (figure 71). In conjunction with these thermal anomalies, the October 2019 special issue report by INGEMMET showed new hotspots forming along the crater rim in July 2018 and August 2019 (figure 72).

Figure 71. Thermal anomalies at Sabancaya for 3 January through November 2019 as recorded by the MIROVA system (Log Radiative Power) were frequent, strong, and consistent. Courtesy of MIROVA.

Figure 72. Thermal hotspots on the NW section of the crater at Sabancaya using MIROVA images. These images show the progression of the formation of at least two new hotspots between February 2017 to August 2019. Courtesy of INGEMMET, Informe Técnico No A6969.

Sulfur dioxide emissions also persisted at significant levels from June through November 2019, as detected by Sentinel-5P/TROPOMI satellite data (figure 73). The satellite measurements of the SO₂ emissions exceeded 2 DU (Dobson Units) at least 20 days each month during this time. These SO₂ plumes sometimes occurred for multiple consecutive days (figure 74).

Figure 73. Consistent, large SO2 plumes from Sabancaya were seen in TROPOMI instrument satellite data throughout June-November 2019, many of which drifted in different directions based on the prevailing winds. Courtesy of NASA Goddard Space Flight Center.

Figure 74. Persistent SO2 plumes from Sabancaya appeared daily during 13-16 September 2019 in the TROPOMI instrument satellite data. Courtesy of NASA Goddard Space Flight Center.

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

Information Contacts: Instituto Geofisico del Peru (IGP), Calle Badajoz N° 169 Urb. Mayorazgo IV Etapa, Ate, Lima 15012, Perú (URL: https://www.gob.pe/igp); Observatorio Volcanologico del INGEMMET (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa, Peru (URL: http://ovi.ingemmet.gob.pe); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://SO2.gsfc.nasa.gov/); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Karangetang (also known as Api Siau), located on the island of Siau in the Sitaro Regency, North Sulawesi, Indonesia, has experienced more than 40 recorded eruptions since 1675 in addition to many smaller undocumented eruptions. In early February 2019, a lava flow originated from the N crater (Kawah Dua) traveling NNW and reaching a distance over 3 km. Recent monitoring showed a lava flow from the S crater (Kawah Utama, also considered the "Main Crater") traveling toward the Kahetang and Batuawang River drainages on 15 April 2019. Gas-and-steam emissions, ash plumes, moderate seismicity, and thermal anomalies including lava flow activity define this current reporting period for May through November 2019. The primary source of information for this report comes from daily and weekly reports by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM, or the Center of Volcanology and Geological Hazard Mitigation), the Darwin Volcanic Ash Advisory Center (VAAC), and satellite data.

PVMBG reported that white gas-and-steam emissions were visible rising above both craters consistently between May through November 2019 (figures 30 and 31). The maximum altitude for these emissions was 400 m above the Dua Crater on 27 May and 700 m above the Main Crater on 12 June. Throughout the reporting period PVMBG noted that moderate seismicity occurred, which included both shallow and deep volcanic earthquakes.

Figure 30. A Sentinel-2 image of Karangetang showing two active craters producing gas-and-steam emissions with a small amount of ash on 7 August 2019. Courtesy of Sentinel Hub Playground.

Figure 31. Webcam images of gas-and-steam emissions rising from the summit of Karangetang on 14 (top) and 25 (bottom) October 2019. Courtesy of PVMBG via Øystein Lund Andersen.

Activity was relatively low between May and June 2019, consisting mostly of gas-and-steam emissions. On 26-27 May 2019 crater incandescence was observed above the Main Crater; white gas-and-steam emissions were rising from both craters (figures 32 and 33). At 1858 on 20 July, incandescent avalanches of material originating from the Main Crater traveled as far as 1 km W toward the Pangi and Kinali River drainages. By 22 July the incandescent material had traveled another 500 m in the same direction as well as 1 km in the direction of the Nanitu and Beha River drainages. According to a Darwin VAAC report, discreet, intermittent ash eruptions on 30 July resulted in plumes drifting W at 7.6 km altitude and SE at 3 km, as observed in HIMAWARI-8 satellite imagery.

Figure 32. Photograph of summit crater incandescence at Karangetang on 12 May 2019. Courtesy of Dominik Derek.

Figure 33. Photograph of both summit crater incandescence at Karangetang on 12 May 2019 accompanied by gas-and-steam emissions. Courtesy of Dominik Derek.

On 5 August 2019 a minor eruption produced an ash cloud that rose 3 km and drifted E. PVMBG reported in the weekly report for 5-11 August that an incandescent lava flow from the Main Crater was traveling W and SW on the slopes of Karangetang and producing incandescent avalanches (figure 34). During 12 August through 1 September lava continued to effuse from both the Main and Dua craters. Avalanches of material traveled as far as 1.5 km SW toward the Nanitu and Pangi River drainages, 1.4-2 km to the W of Pangi, and 1.8 km down the Sense River drainage. Lava fountaining was observed occurring up to 10 m above the summit on 14-20 August.

Figure 34. Photograph of summit crater incandescence and a lava flow from Karangetang on 7 August 2019. Courtesy of MAGMA Indonesia.

PVMBG reported that during 2-22 September lava continued to effuse from both craters, traveling SW toward the Nanitu, Pangi, and Sense River drainages as far as 1.5 km. On 24 September the lava flow occasionally traveled 0.8-1.5 km toward the West Beha River drainage. The lava flow from the Main Crater continued through at least the end of November, moving SW and W as far as 1.5 km toward the Nanitu, Pangi, and Sense River drainages. In late October and onwards, incandescence from both summit craters was observed at night. The lava flow often traveled as far as 1 km toward the Batang and East Beha River drainage on 12 November, the West Beha River drainage on 15, 22, 24, and 29 November, and the Batang and West Beha River drainages on 25-27 November (figure 35). On 30 November a Strombolian eruption occurred in the Main Crater accompanied by gas-and-steam emissions rising 100 m above the Main Crater and 50 m above the Dua Crater. Lava flows traveled SW and W toward the Nanitu, Sense, and Pangi River drainages as far as 1.5 km, the West Beha and Batang River drainages as far as 1 km, and occasionally the Batu Awang and Kahetang River drainages as far as 2 km. Lava fountaining was reported occurring 10-25 m above the Main Crater and 10 m above the Dua Crater on 6, 8-12, 15, 21-30 November.

Figure 35. Webcam image of gas-and-steam emissions rising from the summit of Karangetang accompanied by incandescence and lava flows at night on 27 November 2019. Courtesy of MAGMA Indonesia via Øystein Lund Andersen.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed consistent and strong thermal anomalies within 5 km of the summit craters from late July through November 2019 (figure 36). Satellite imagery from Sentinel-2 corroborated this data, showing strong thermal anomalies and lava flows originating from both craters during this same timeframe (figure 37). In addition to these lava flows, satellite imagery also captured intermittent gas-and-steam emissions from May through November (figure 38). MODVOLC thermal alerts registered 165 thermal hotspots near Karangetang's summit between May and November.

Figure 36. Frequent and strong thermal anomalies at Karangetang between 3 January through November 2019 as recorded by the MIROVA system (Log Radiative Power) began in late July and were recorded within 5 km of the summit craters. Courtesy of MIROVA.

Figure 37. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) confirmed ongoing thermal activity (bright orange) at Karangetang from July into November 2019. The lava flows traveled dominantly in the W direction from the Main Crater. Courtesy of Sentinel Hub Playground.

Figure 38. Sentinel-2 satellite imagery showing gas-and-steam emissions with a small amount of ash (middle and right) rising from both craters of Karangetang during May through November 2019. Courtesy of Sentinel Hub Playground.

Sentinel-5P/TROPOMI satellite data detected multiple sulfur dioxide plumes between May and November 2019 (figure 39). These emissions occasionally exceeded 2 Dobson Units (DU) and drifted in different directions based on the dominant wind pattern.

Figure 39. SO2 emissions from Karangetang (indicated by the red box) were seen in TROPOMI instrument satellite data during May through November 2019, many of which drifted in different directions based on the prevailing winds. Top left: 27 May 2019. Top middle: 26 July 2019. Top right: 17 August 2019. Bottom left: 27 September 2019. Bottom middle: 3 October 2019. Bottom right: 21 November 2019. Courtesy of NASA Goddard Space Flight Center.

Geologic Background. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, about 125 km NNE of the NE-most point of Sulawesi island. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts have produced pyroclastic flows.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://SO2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Øystein Lund Andersen (Twitter: @OysteinLAnderse, https://twitter.com/OysteinLAnderse, URL: https://www.oysteinlundandersen.com); Dominik Derek (URL: https://www.facebook.com/07dominikderek/).

Ulawun is a basaltic-to-andesitic stratovolcano located in West New Britain, Papua New Guinea, with typical activity consisting of seismicity, gas-and-steam plumes, and ash emissions. The most recent eruption began in late June 2019 involving ash and gas-and-steam emissions, increased seismicity, and a pyroclastic flow (BGVN 44:09). This report includes volcanism from September to October 2019 with primary source information from the Rabaul Volcano Observatory (RVO) and the Darwin Volcanic Ash Advisory Centre (VAAC).

Activity remained low through 26 September 2019, mainly consisting of variable amounts of gas-and-steam emissions and low seismicity. Between 26 and 29 September RVO reported that the seismicity increased slightly and included low-level volcanic tremors and Real-Time Seismic Amplitude Measurement (RSAM) values in the 200-400 range on 19, 20, and 22 September. On 30 September small volcanic earthquakes began around 1000 and continued to increase in frequency; by 1220, they were characterized as a seismic swarm. The Darwin VAAC advisory noted that an ash plume rose to 4.6-6 km altitude, drifting SW and W, based on ground reports.

On 1 October 2019 the seismicity increased, reaching RSAM values up to 10,000 units between 0130 and 0200, according to RVO. These events preceded an eruption which originated from a new vent that opened on the SW flank at 700 m elevation, about three-quarters of the way down the flank from the summit. The eruption started between 0430 and 0500 and was defined by incandescence and lava fountaining to less than 100 m. In addition to lava fountaining, light- to dark-gray ash plumes were visible rising several kilometers above the vent and drifting NW and W (figure 21). On 2 October, as the lava fountaining continued, ash-and-steam plumes rose to variable heights between 2 and 5.2 km (figures 22 and 23), resulting in ashfall to the W in Navo. Seismicity remained high, with RSAM values passing 12,000. A lava flow also emerged during the night which traveled 1-2 km NW. The main summit crater produced white gas-and-steam emissions, but no incandescence or other signs of activity were observed.

Figure 21. Photographs of incandescence and lava fountaining from Ulawun during 1-2 October 2019. A) Lava fountains along with ash plumes that rose several kilometers above the vent. B) Incandescence and lava fountaining seen from offshore. Courtesy of Christopher Lagisa.

Figure 22. Photographs of an ash plume rising from Ulawun on 1 October 2019. In the right photo, lava fountaining is visible. Courtesy of Christopher Lagisa.

Figure 23. Photograph of lava fountaining and an ash plume rising from Ulawun on 1 October 2019. Courtesy of Joe Metto, WNB Provincial Disaster Office (RVO Report 2019100101).

Ash emissions began to decrease by 3 October 2019; satellite imagery and ground observations showed an ash cloud rising to 3 km altitude and drifting N, according to the Darwin VAAC report. RVO reported that the fissure eruption on the SW flank stopped on 4 October, but gas-and-steam emissions and weak incandescence were still visible. The lava flow slowed, advancing 3-5 m/day, while declining seismicity was reflected in RSAM values fluctuating around 1,000. RVO reported that between 23 and 31 October the main summit crater continued to produce variable amounts of white gas-and-steam emissions (figure 24) and that no incandescence was observed after 5 October. Gas-and-steam emissions were also observed around the new SW vent and along the lava flow. Seismicity remained low until 27-29 October; it increased again and peaked on 30 October, reaching an RSAM value of 1,700 before dropping and fluctuating around 1,200-1,500.

Figure 24. Webcam photo of a gas-and-steam plume rising from Ulawun on 30 October 2019. Courtesy of the Rabaul Volcano Observatory (RVO).

In addition to ash plumes, SO₂ plumes were also detected between September and October 2019. Sentinel-5P/TROPOMI data showed SO₂ plumes, some of which exceeded 2 Dobson Units (DU) drifting in different directions (figure 25). MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed strong, frequent thermal anomalies within 5 km of the summit beginning in early October 2019 and throughout the rest of the month (figure 26). Only one thermal anomaly was detected in early December.

Figure 25. Sentinel-5P/TROPOMI data showing a high concentration of SO2 plumes rising from Ulawun between late September-early October 2019. Top left: 11 September 2019. Top right: 1 October 2019. Bottom left: 2 October 2019. Bottom right: 3 October 2019. Courtesy of the NASA Space Goddard Flight Center.

Figure 26. Frequent and strong thermal anomalies at Ulawun for February through December 2019 as recorded by the MIROVA system (Log Radiative Power) began in early October and continued throughout the month. Courtesy of MIROVA.

Activity in November was relatively low, with only a variable amount of white gas-and-steam emissions visible and low (less than 200 RSAM units) seismicity with sporadic volcanic earthquakes. Between 9-22 December, a webcam showed intermittent white gas-and-steam emissions were observed at the main crater, accompanied by some incandescence at night. Some gas-and-steam emissions were also observed rising from the new SW vent along the lava flow.

Geologic Background. The symmetrical basaltic-to-andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. The volcano, also known as the Father, rises above the N coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. The upper 1,000 m is unvegetated. A prominent E-W escarpment on the south may be the result of large-scale slumping. Satellitic cones occupy the NW and E flanks. A steep-walled valley cuts the NW side, and a flank lava-flow complex lies to the south of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.

Information Contacts: Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); 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/); Christopher Lagisa, West New Britain Province, Papua New Guinea (URL: https://www.facebook.com/christopher.lagisa, images posted at https://www.facebook.com/christopher.lagisa/posts/730662937360239 and https://www.facebook.com/christopher.lagisa/posts/730215604071639).

Nyamuragira (also known as Nyamulagira) is a high-potassium basaltic shield volcano located in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo. Previous volcanism consisted of the reappearance of a lava lake in the summit crater in mid-April 2018, lava emissions, and high seismicity (BGVN 44:05). Current activity includes strong thermal signatures, continued inner crater wall collapses, and continued moderate seismicity. The primary source of information for this June-November 2019 report comes from the Observatoire Volcanologique de Goma (OVG) and satellite data and imagery from multiple sources.

OVG reported in the July 2019 monthly that the inner crater wall collapses that were observed in May continued to occur. During this month, there was a sharp decrease in the lava lake level, and it is no longer visible. However, the report stated that lava fountaining was visible from a small cone within this crater, though its activity has also decreased since 2014. In late July, a thermal anomaly and fumaroles were observed originating from this cone (figure 85). Seismicity remained moderate throughout this reporting period.

Figure 85. Photograph showing the small active cone within the crater of Nyamuragira in late July 2019. Fumaroles are also observed within the crater originating from the small cone. Courtesy of Sergio Maguna.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows strong, frequent thermal anomalies within 5 km of the summit between June through November (figure 86). The strength of these thermal anomalies noticeably decreases briefly in September. MODVOLC thermal alerts registered 54 thermal hotspots dominantly near the N area of the crater during June through November 2019. Satellite imagery from Sentinel-2 corroborated this data, showing strong thermal anomalies within the summit crater during this same timeframe (figure 87).

Figure 86. The MIROVA graph of thermal activity (log radiative power) at Nyamuragira during 30 January through November 2019 shows strong, frequent thermal anomalies through November with a brief decrease in activity in late April-early May and early September. Courtesy of MIROVA.

Figure 87. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) confirmed ongoing thermal activity at Nyamuragira into November 2019. Courtesy of Sentinel Hub Playground.

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

Information Contacts: Observatoire Volcanologique de Goma (OVG), Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo; Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sergio Maguna (Facebook: https://www.facebook.com/sergio.maguna.9, images posted at https://www.facebook.com/sergio.maguna.9/posts/1267625096730837).

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

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

Figure 38. Thermal anomalies near the crater summit at Bagana during February-November 2019 as recorded by the MIROVA system (Log Radiative Power) increased in frequency and power in early August. A small cluster was detected in early October after a brief pause in activity in early September. Courtesy of MIROVA.

Figure 39. Sentinel-2 thermal satellite imagery showing small thermal anomalies at Bagana between July-August 2019. Left: A very faint thermal anomaly and a gas-and-steam plume is seen on 7 July 2019. Right: Two small thermal anomalies are faintly seen on 6 August 2019. Both Sentinel-2 satellite images with "Atmospheric penetration" (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

Figure 40. A gas-and-steam plume rising from the summit of Bagana on 18 September 2019. Courtesy of Brendan McCormick Kilbride (University of Manchester).

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

Figure 41. Degassing plumes seen from drone footage 100 m above the summit of Bagana. Top: Zoomed out view of the summit of Bagana degassing. Bottom: Closer perspective of the gases emitted from Bagana. Courtesy of Kieran Wood (University of Bristol) and the Bristol Flight Laboratory.

Figure 42. Photos of gas-and-steam plumes rising from Bagana between 14-19 September 2019. Courtesy of Brendan McCormick Kilbride (University of Manchester).

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

Information Contacts: MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Brendan McCormick Kilbride, University of Manchester, Manchester M13 9PL, United Kingdom (URL: https://www.research.manchester.ac.uk/portal/brendan.mccormickkilbride.html, Twitter: https://twitter.com/BrendanVolc); Kieran Wood, University of Bristol, Bristol BS8 1QU, United Kingdom (URL: http://www.bristol.ac.uk/engineering/people/kieran-t-wood/index.html, Twitter: https://twitter.com/DrKieranWood, video posted at https://www.youtube.com/watch?v=A7Hx645v0eU); University of Bristol Flight Laboratory, Bristol BS8 1QU, United Kingdom (Twitter: https://twitter.com/UOBFlightLab).

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

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

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

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

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

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

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

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

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

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

Figure 32. Photo of Bezymianny showing fumarolic activity on 4 July 2019. Photo by O. Girina (IVS FEB RAS, KVERT); courtesy of KVERT.

Figure 33. Typical infrared satellite images of Bezymianny showing thermal anomalies in the summit crater, including a lava flow to the WNW. Top: 21 August 2019 with SWIR filter (bands 12, 8A, 4). Bottom: 17 September 2019 with Atmospheric Penetration filter (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

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

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

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

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

Figure 49. Sentinel-2 thermal satellite imagery of Mayon between May-October 2019. Small thermal anomalies were recorded in satellite imagery from the summit and some white gas-and-steam plumes are visible. Top left: 30 May 2019. Top right: 9 June 2019. Bottom left: 22 September 2019. Bottom right: 12 October 2019. Sentinel-2 satellite images with "Atmospheric penetration" (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

Figure 50. Small SO2 plumes rising from Mayon during May-September 2019 recorded in DU (Dobson Units). Top left: 28 May 2019. Top right: 26 July 2019. Bottom left: 16 August 2019. Bottom right: 23 September 2019. Courtesy of NASA Goddard Space Flight Center.

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

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

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

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

Figure 79. Merapi volcano is located north of Yogyakarta in Central Java. Photo courtesy of Øystein Lund Andersen.

Figure 80. A view of the Gendol drainage where avalanches and block-and-ash flows are channeled from the active Merapi lava dome. The Gendol drainage is approximately 400 m wide at the summit. Courtesy of Brett Carr, Lamont-Doherty Earth Observatory.

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

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

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

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

Figure 82. The development of the Merapi summit dome from 2 June 2018 to 17 June 2019. Courtesy of Øystein Lund Andersen.

Figure 83. Photos taken of the Merapi summit lava dome in June 2019. Top: This nighttime time-lapse photograph shows incandescence at the south-facing side of the dome on the 16 June. Middle: A closeup of a small rockfall from the dome on 17 June. Bottom: A gas plume accompanying a small rockfall on 17 June. Courtesy of Øystein Lund Andersen.

Figure 84. Blocks from an incandescent rockfall off the Merapi dome reached out to 1 km down the Gendol drainage on 26 June 2019. Courtesy of MAGMA Indonesia.

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

Figure 85. The Merapi dome on 30 July 2019 producing a weak plume. Courtesy of MAGMA Indonesia.

Figure 86. Incandescent rocks from the hot lava dome at the summit of Merapi form rockfalls down the Gendol drainage on 14 July 2019. Courtesy of Øystein Lund Andersen.

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

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

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

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

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

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

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

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

Ahyi seamount is one of a long string of submarine seamounts at the northern edge of the Northern Mariana Islands, part of the Mariana Back-arc segment of the Izu-Bonin trench in the western Pacific Ocean. The remote location of the seamount has made eruptions difficult to document, but seismic stations installed in the region confirmed an eruption in the vicinity in 2001. No further activity was reported until a new eruption was detected by seismic stations and felt by divers in the immediate area in April 2014. Volcanic activity in the Commonwealth of the Northern Mariana Islands is monitored by the US Geological Survey's Volcano Hazards Program, and observations are sometimes gathered by NOAA (National Oceanic and Atmospheric Administration) expeditions. The 2014 eruption and follow-up observations from December 2014 are summarized here.

The eruption at Ahyi seamount between 24 April and 17 May 2014 (BGVN 39:02; Haney et al., 2014) was first recorded as T-phase signals that were detected by various seismometers in the Mariana Islands. Submarine explosions were also heard and felt by NOAA scuba divers conducting coral reef research on the SE coastline of Farallon de Pajaros (Uracas) Island, about 20 km NW of Ahyi. In the same area, the NOAA crew reported sighting mats of orange-yellow bubbles on the water surface that extended up to 1 km from the shoreline. T-phase seismic signals registered across the Northern Mariana Islands (NMI) seismic network at a rate of approximately 10 per hour until 8 May, and then sporadically until 17 May (Haney et al., 2014).

During mid-May, the NOAA ship Hi'ialakai gathered multibeam sonar bathymetry and took three water-column CTD casts (Conductivity, Temperature, and Depth sensor; it gives scientists a precise and comprehensive charting of the distribution and variation of water temperature, salinity, and density). The May 2014 bathymetry revealed that the minimum depth to the summit was about 90 m, notably deeper than the 60 m measured during a 2003 survey. In addition a new crater about 100 m deep had formed at the summit, replacing the summit cone. Also, a distinct landslide chute descended the SE slope 2,300 m, removing material from the head and depositing debris at the base (see figure 4, BGVN 39:02). Significant particle plumes were detected with all three CTD casts, indicating ongoing hydrothermal activity. Plumes with optical anomalies up to 0.4 NTU (nephelometric turbidity units) were found S and W of Ahyi at 100-175 m water depth, corresponding to the depth of the new summit crater. NTU's are light backscattering measurements done by optical sensors in sea water to determine the presence of hydrothermal plumes in the water column.

On 4 December 2014, the NOAA Expedition "Submarine Ring of Fire 2014 – Ironman" visited Ahyi, and again used a CTD sensor to assess the hydrothermal status of the volcano. EM122 multibeam bathymetry data imaged CO₂ gas bubbles rising from the summit (figure 5), and clearly revealed the new summit crater. When the CTD sensor and sampling package was lowered into the water, it measured a thick plume of particles indicating ongoing hydrothermal activity near 150 m depth, close to the base of the new crater that formed during the eruption in April-May 2014.

Figure 5. Three-dimensional image of the summit of Ahyi submarine volcano gathered on 4 December 2014 with the mid-water data shown above the new crater created by the April 2014 eruption. The summit crater is ~100 m deep. CO2 bubbles (in green) can be seen rising from most of the summit, suggesting that there is more than one source of venting. This image shows an area 850 m across with depths ranging from 78 (red) to 400 m (blue). No vertical exaggeration. Image courtesy of Submarine Ring of Fire 2014 - Ironman, NSF/NOAA (http://oceanexplorer.noaa.gov/explorations/ 14fire/logs/december04/media/ahyi.html).

References: Haney, M. M., Chadwick, W., Merle, S. G., Buck, N. J., Butterfield, D. A., Coombs, M. L., Evers, L. G., Heaney, K. D., Lyons, J. J., Searcy, C. K., Walker, S. L., Young, C., and Embley, R. W., The 2014 Submarine Eruption of Ahyi Volcano, Northern Mariana Islands, American Geophysical Union, Fall Meeting 2014, abstract V11B-4727.

Geologic Background. Ahyi seamount is a large conical submarine volcano that rises to within 75 m of the sea surface about 18 km SE of the island of Farallon de Pajaros (Uracas) in the northern Marianas. Water discoloration has been observed there, and in 1979 the crew of a fishing boat felt shocks over the summit area of the seamount, followed by upwelling of sulfur-bearing water. On 24-25 April 2001 an explosive eruption was detected seismically by a station on Rangiroa Atoll, Tuamotu Archipelago. The event was well constrained (+/- 15 km) at a location near the southern base of Ahyi. An eruption in April-May 2014 was detected by NOAA divers, hydroacoustic sensors, and seismic stations.

Information Contacts: National Oceanic and Atmospheric Administration (NOAA), Office of Ocean Exploration and Research, 1315 East-West Highway, Silver Spring, Maryland, USA (URL: http://oceanexplorer.noaa.gov/welcome.html); US Geological Survey, Volcano Hazards Program (USGS-VHP), 12201 Sunrise Valley Drive, Reston, VA, USA (URL: https://volcanoes.usgs.gov/index.html).

Russia's Alaid volcano, located just off the southern tip of the Kamchatka Peninsula, is the northernmost of the chain of volcanoes that comprise the Kuril archipelago. A number of strong explosive eruptions have been recorded there in the last 200 years, including VEI 4 explosions in 1790 and 1981. The last eruption occurred between 5 October and 12 December 2012 when repeated thermal anomalies and ash plumes from the summit crater were observed. A new eruption was first reported on 29 September 2015 by the Tokyo Volcanic Ash Advisory Center (VAAC) (BGVN 41:06). Alaid is monitored by the Kamchatka Volcanic Eruptions Response Team (KVERT); valuable information about this remote site is also gathered from satellite thermal infrared data reported by both the University of Hawai'i's MODVOLC system and the Italian MIROVA system.

A new eruption at Alaid was reported on 29 September 2015. It was characterized by strong thermal anomalies and intermittent gas-and-ash plumes. The thermal anomalies were interpreted by KVERT as Strombolian eruptions and lava flows. The first episode of the eruption exhibited strong thermal anomalies with only two reports of ash, and lasted until 4 January 2016. The second episode began with the reappearance of a strong thermal anomaly and an ash plume on 20 February 2016. This was followed by a series of low-level ash plumes in March and April, and ongoing strong thermal anomalies through early May. The anomalies decreased during mid-May and June, but then a large spike of intense anomalies in the first week of July was accompanied by ash plumes and observations by KVERT of Strombolian eruptions at the summit crater and a lava flow down the SW flank. Thermal activity decreased substantially following this spike, and tapered off completely by the second week of August 2016.

The Tokyo VAAC reported an eruption at Alaid at 2120 UTC on 28 September (0720 on 29 September local time) 2015. They reported it as below 6.1 km altitude, and volcanic ash was not identifiable in satellite images. KVERT raised the Aviation Color Code from Green to Yellow early on 2 October 2015 (local time) based on an intense thermal anomaly observed during the night that they interpreted to be the beginning of a new Strombolian eruption. The first thermal anomalies identified by MIROVA (Middle InfraRed Observation of Volcanic Activity) also appear during the first two days of October (figure 5). MODVOLC thermal alerts first appeared on 5 October and were essentially continuous with no more than a few days break until 4 January 2016. The MIROVA signal remained steady until about the same date when it abruptly decreased. KVERT reported consistent and usually intense thermal anomalies, when the volcano was not obscured by clouds, until 4 January. They observed anomalies in satellite images with decreasing frequency and intensity during the rest of January and into early February.

Figure 5. MIROVA thermal anomaly data for Alaid from 5 April 2015 through 13 January 2017. The first thermal anomaly is visible on 1 or 2 October 2015. The signal remained consistently in the Moderate to High range until the first week of January when it abruptly stopped. It reappeared during the third week of February and was consistently 'High' until mid-May when it decreased to 'Low' values. A sudden spike to near 'Very High' values during the first week of July corresponded with KVERT reports of Strombolian eruptions from the summit crater and a lava flow down the SW flank. Courtesy of MIROVA.

The first report of observed gas-and-steam activity (after the Tokyo VAAC report on 29 September) was by KVERT on 16 December. Visual observations from nearby Paramushir Island (45 km SE) noted a small amount of ash in the steam-and-gas plumes on 28 and 29 December. The Tokyo VAAC also reported a plume of volcanic ash at 4.6 km altitude on 29 December drifting SW. On 5 February 2016 local time KVERT lowered the Aviation Color Code (ACC) to Green, noting decreased thermal activity and only moderate continuing fumarole activity during the previous weeks. A break in the thermal activity between early January and late February is also recorded in the MIROVA data (figure 5).

Another eruptive episode began with the appearance of a strong thermal anomaly and a weak ash emission sending a plume 50 km E on 20 February UTC, leading KVERT to raise the ACC back to Yellow. Renewed MIROVA thermal anomalies appeared on 16 or 17 February (figure 5). The first MODVOLC thermal alert was reported 23 February, and they were essentially continuous (except for probable cloudy days) until 5 May 2016. MIROVA thermal anomalies values remained consistently in the 'High' (VRP of 10⁸-10⁹ Watts) range until the second week of May when they dropped back to 'Low' (VRP of 10⁶-10⁷ Watts).

KVERT reported gas-and-steam plumes containing a small amount of ash on 20 and 24 February 2016. Minor ashfall (less than 1 mm) was reported on 24 February in Severo-Kurilsk, 45 km SE on Paramushir Island. The Tokyo VAAC also reported a possible eruption that day with a plume to 3 km altitude extending NE. An ash plume was reported by KVERT and the Tokyo VAAC on 3 March 2016 at 3 km altitude drifting 52 km WSW. This prompted KVERT to raise the ACC to Orange. Ash emissions continued for the next two days, rising to 3.4-3.9 km and drifting S and SW, according to the Tokyo VAAC. KVERT reported visual data from Paramushir Island confirming an ash plume extending SW on 6 March, and satellite data showing the plume 90 km SW that same day.

Possible eruptions were again reported on 11 and 12 March 2016 by the Tokyo VAAC under 3 km altitude, and on 12 and 14 March by KVERT as visual observations from Paramushir extending 85 km E. Weak ash emissions were reported several more times in March and April rising to between 3 and 4.3 km altitude and drifting in various directions (some as far as 90 km) on 22, 26, and 30-31 March, and 1, 9, 14, 18, 21, and 24 April. KVERT noted that on 21 and 23 April the ash plumes extended about 260 km SE. Moderate thermal anomalies were reported by KVERT from mid-May through the beginning of July, and MIROVA anomalies registered in the 'Low' range during this time. KVERT reported on 12 May that satellite data showed a lava flow on the SW flank. They noted continuing thermal anomalies over the volcano during clear weather throughout May and June, but no ash plumes were reported.

KVERT and the Tokyo VAAC once again noted ash plumes that drifted 150 km SW during 3-4 July. This is consistent with an Aura/OMI image of an SO₂ plume drifting SW from Alaid on 4 July (figure 6). On 7 July, KVERT reported Strombolian activity from a new cinder cone in the summit crater and a lava flow effusing down the SW flank. A sudden spike in the MIROVA data with values rising to 10⁹ W of Radiative Power during 3-7 July (figure 5) corroborates the KVERT observation of the lava flow; the MODVOLC data also shows a strong signal between 3 and 7 July, including several alert pixels on the SW flank of the volcano (figure 7).

Figure 6. SO2 plume drifting SW from Alaid captured on 4 July 2016 by the Aura instrument on the OMI satellite. Courtesy NASA/GSFC.

Figure 7. MODVOLC thermal alert pixel data for Alaid during 3-7 July 2016 showing a multi-pixel alert at the summit likely from Strombolian activity and alert pixels on the SW flank described by KVERT as a lava flow. Green grid lines represent 0.05 decimal degrees. Courtesy of MODVOLC.

The last ash plume was observed by the Tokyo VAAC on 3 July 2016. The final thermal alert was recorded by MODVOLC on 7 July. MIROVA anomalies continued steadily, however, at low levels through the first week in August before ceasing. Two additional MIROVA anomalies appeared briefly in the first and last weeks of September. KVERT reported thermal anomalies continuing until early August. They also noted a gas-and-steam plume extending 155 km NE on 26 July. In their VONA (Volcano Observatory Notice for Aviation) issued on 11 August 2016 at 2305 UTC (1105 on 12 August KST), KVERT lowered the ACC to Yellow based on decreasing intensity of thermal anomalies, and no additional ash plumes since 4 July; they lowered it again to Green on 19 August (local time) citing no further evidence for volcanic activity since the last thermal anomaly on 11 August.

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: 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), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); 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/, http://modis.higp.hawaii.edu/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).

Large lava flows descend the flanks of Alaska's Cleveland volcano, located on Chuginadak Island in the Aleutians, slightly over 1,500 km SW of Anchorage (figure 18). However, dome growth and destruction by frequent small ash explosions have been more typical behavior in recent years; historical activity, including three large (VEI 3) eruptions, is recorded back to 1893. The Alaska Volcano Observatory (AVO) and the Anchorage Volcanic Ash Advisory Center (VAAC) are responsible for monitoring activity and notifying air traffic of aviation hazards associated with Cleveland. This report summarizes activity between July 2011 and June 2014, and provides details of activity from June 2014 through February 2017.

Figure 18. Morning sunlight illuminates the southeast-facing slopes of the Islands of the Four Mountains on 15 November 2013 in this photograph taken from the International Space Station (ISS). The islands, part of the Aleutian Island chain, are the upper slopes of volcanoes rising from the sea floor: Carlisle, Cleveland, Herbert, and Tana. Carlisle and Herbert volcanoes are distinct cones and form separate islands. Cleveland and the Tana volcanic complex form the eastern and western ends respectively of Chuginadak Island; clouds obscure the connecting land area. Astronaut photograph ISS038-E-3612 acquired with a Nikon D3S digital camera using a 400 mm lens, provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 38 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. Caption by William L. Stefanov, Jacobs at NASA-JSC. Courtesy of NASA Earth Observatory ( http://earthobservatory.nasa.gov/IOTD/view.php?id=82588).

Summary of activity during July 2011-June 2014. Dome growth and destruction characterized activity at Cleveland during 2011-2014. Eruptive episodes are challenging to determine due to weather conditions and the remoteness of the volcano; detectible ash plumes are intermittent, and thermal anomalies caused by dome growth are often obscured in satellite imagery. Seismic and infrasound data on explosions often provide valuable information. Dome growth was clearly documented between late July and October 2011 (BGVN 36:08, 37:01). An ash cloud observed on 29 December 2011 was followed by observations of dome growth in satellite data on 30 January 2012. Significant ash explosions occurred during April and June 2012 (BGVN 38:10). AVO also reported ash plumes on 12 July and 20 August 2012. Another small ash cloud was noted by AVO on 10 Nov 2012.

Details of the 2013 activity are provided in Dixon et al. (2015) and summarized here. Elevated temperatures in mid-January 2013 were followed by observations of a new lava dome that measured 100 m in diameter on 30 January 2013, and a second lava extrusion on 9 February. Elevated surface temperatures were intermittently observed until the next ash explosion on 4 May 2013, which was followed by a larger series of explosions on 6 May that filled the crater with tephra and created flowage deposits on the NE, E, and SE flanks. On 26 July, analysis of a satellite images suggested a new lava flow within the summit crater.

From August through 28 December 2013 the infrasound and seismic networks detected a number of additional explosions and periods of infrasonic tremor (see table 8 in Dixon et al., 2015). Most of these events did not have an accompanying ash signal in AVHRR satellite images, suggesting minor to no ash emissions. A detectible ash cloud on 30 December 2013 was preceded by strongly elevated surface temperature readings in the summit area on 28 December (BVGN 39:08). Ash plumes were again detected at the summit on 2 January, 25 February, and 6 March 2014. Cleveland was quiet for almost three months until an explosion on 5 June with a weak ash signal was detected.

Summary of activity during June 2014-February 2017. The growth and explosive destruction of six lava domes at Cleveland were recorded between June 2014 and February 2017. Although an explosion on 5 June 2014 was the last recorded explosion with confirmed ash until 14 June 2015, thermal and visual satellite evidence suggested dome growth activity during July-September and late November 2014. Weakly elevated surface temperatures at the summit were intermittent through February 2015. Minor ash deposits on the flanks were observed on 14 June 2015 in addition to stronger elevated surface temperatures, suggesting a new dome growth episode. An explosion on 21 July 2015 was thought to have destroyed the dome, and strongly elevated surface temperatures indicating new dome growth continued through July and August.

Moderately-elevated surface temperatures were detected at the summit in satellite data from January through 16 April 2016 when a new explosion was recorded. Satellite views in late April indicated that the August 2015 lava dome had been replaced with a small cinder cone within the summit crater. Explosions with no ash reported occurred twice in May, before the extrusion of a small amount of lava forming a new lava dome was observed on 17 May 2016, and which continued to grow for about one week. Moderately-elevated surface temperatures reappeared in mid-July, and field crews observed incandescence in a vent at the summit in late July. Satellite thermal anomalies were persistent from mid-May through September 2016. A new explosion on 24 October 2016 destroyed the dome emplaced in May; satellite views in November showed a deep pit within the summit crater. Weakly elevated surface temperatures reappeared in early December 2016. Moderately-elevated surface temperatures reappeared on 31 January 2017, [followed on 3 February by satellite observations that indicated] a new dome of similar size to earlier ones was once again filling the summit crater.

Activity during June 2014-February 2015. An ash-bearing explosion occurred in the late evening hours of 5 June 2014, resulting in a detached cloud with a weak ash signal observed in a satellite image that rapidly dissipated; no additional ash explosions were observed over the next 12 months. Weakly elevated surface temperatures were observed in satellite data on 7 July, and a vigorous steam-and-gas plume was observed on 8 and 9 July. Typical steam-and-gas emissions and persistent elevated surface temperatures in the summit crater were noted in satellite observations during clear periods through July and August, but AVO received no reports from pilots or mariners of any eruptive activity. Scientists working on the island in early August noted incandescence and puffing activity of steam and gas at the summit, and witnessed several small rockfall events. A newly installed webcam and other geophysical equipment at station CLCO near Concord Point on the SE coast of Chuginadak Island, about 15 km E of the volcano's summit, became operational in September 2014. In mid-September several rockfall signals were detected by the new local seismic network, and indicated the continued instability of volcanic debris on the steep upper flanks of the volcano.

Elevated surface temperatures were observed at the summit on clear days with occasional minor steaming visible in webcam images from late September to late October 2014. On 14 November AVO reported that vigorous steaming from the summit crater was observed in webcam images during the prior week, although they remarked that steam emissions are routinely observed at Cleveland and do not necessarily indicate an increase in unrest. On 28 November, they noted that a small mound of lava in the crater was observed in clear satellite views earlier that week that may have corresponded with the appearance of a faint thermal signal in the satellite data; the lava possibly extruded around 24 November. Satellite views on 19 December 2014 showed weakly elevated surface temperatures at the summit vent.

Low-density gas emissions and weakly elevated surface temperatures in the summit region were observed on 1 January 2015, and during clear weather up to 9 January. After this, nothing of note was observed in satellite or webcam images, and no significant activity was detected in seismic or infrasound (air pressure) data until weakly elevated surface temperatures were again detected in satellite data on 25 February. A low-level steam-and-gas plume emanated from the summit on 24 February, and again was identified in multiple satellite images on 28 February. During March, April, and May 2015, no significant activity, except for occasional steaming from the summit crater, was observed during periods of clear weather, causing AVO to downgrade both the Aviation Color Code (ACC) and the Volcano Alert Level (VAL) to Unassigned on 28 May 2015.

Activity during June 2015-March 2016. AVO issued a new VONA (Volcano Observatory Notice for Aviation) on 17 June 2015 returning the Aviation Color Code to Yellow (Yellow is 2nd lowest on a 4-color scale), and the Volcano Alert Level to Advisory (also 2nd lowest on a 4-level scale). This was based on satellite detection of elevated surface temperatures at the summit and an image from 14 June showing very minor ash deposits on the upper flanks. They interpreted the increase in temperature as consistent with renewed growth of the small lava dome within the crater. Elevated summit surface temperatures were again observed on 30 June, and during three clear days in early July. On 21 July AVO detected an explosion in both infrasound and seismic data, and raised the ACC to Orange and the VAL to WATCH. Satellite views were obscured by clouds, though a dusting of ash on the upper flanks was noted by a nearby field crew and recorded by the webcam later in the day. The explosion destroyed the dome that had formed in November 2014. Strongly elevated surface temperatures were recorded at the summit during the last week of July, including a thermal alert pixel from the MODVOLC system on 31 July.

Slightly elevated surface temperatures were recorded at the summit during the first week of August 2015. On 4 August, a field crew working in the area reported a small amount of lava covering the crater floor. Surface temperatures of the cooling lava measured by the crew were in the range of 550-600°C. Minor ash-and-gas emissions were also observed. A small explosion occurred on 6 August at 2203 AKDT, but no ash cloud was identified. Strongly elevated surface temperatures suggestive of lava effusion were noted in satellite data through 18 August, and weakly elevated temperatures were recorded for the rest of August and September. A small swarm of earthquakes was detected on 29 August.

AVO lowered the ACC to Yellow and the VAL to ADVISORY on 14 October 2015, citing the likely cessation of lava effusion, while minor steaming, weakly elevated surface temperatures, and slightly above-background seismicity continued through November 2015. Exceptionally clear weather during late November allowed many views of the volcano, showing only modest steaming from the summit. Elevated surface temperatures were detected twice during December, and an increase in frequency of small VT (Volcano-Tectonic) events was noted on 22 and 23 December, but otherwise no significant seismicity or emissions (other than steam plumes) were detected.

Moderately-elevated surface temperatures were detected at the beginning of the second week in January 2016, followed by several small earthquakes per day during the third week, and weakly elevated temperatures. Low-level seismicity and elevated surface temperatures were next observed during the last week of February; a brief burst of small local earthquakes was recorded on 28 February followed by weakly elevated surface temperatures during the first week of March. Moderately-elevated surface temperatures were again observed during the last week of March.

Activity during April-September 2016. A new explosion on 16 April 2016 was detected in both infrasound and seismic data, but satellite views were obscured by clouds. AVO raised the ACC to Orange until 29 April, when they noted that recent satellite imagery indicated that the August 2015 lava dome had been replaced with a small cinder cone within the summit crater; seismic activity remained lower after the explosion. Another explosion on 5 May at 1844 local time led AVO to raise the ACC back to Orange, although no ash emissions were observed above the cloud deck. A brief explosive event on 10 May was detected by pressure sensors near the volcano, and again no ash was reported.

A small volume of lava was extruded from the summit on 17 or 18 May, as confirmed in satellite data. The low-relief, 50-m-diameter dome was similar in size and shape to the ten domes observed since 2011, the most recent of which was extruded and destroyed earlier in May. During the week of 20 May, this lava dome enlarged to about 60 m in diameter. Dome growth appeared to have paused or ceased by 23 May. Weakly elevated surface temperatures were observed in mostly clear views by satellite on 25 and 26 May, which is consistent with the presence of the new lava dome. The Aviation Color Code was lowered from Orange to Yellow by AVO on 3 June when no other signs of eruptive activity were observed. Occasional clear satellite views detected weakly elevated surface temperatures that AVO interpreted as consistent with cooling lava during June 2016.

The MIROVA infrared data suggests ongoing thermal anomalies from late May through September 2016 (figure 19). AVO reported weakly-to-moderately-elevated surface temperatures reappearing during the second and third weeks of July. Field crews conducted an overflight during the last week of July and observed incandescence from a vent in the summit crater. Low-level steam plumes and minor degassing were observed a number of times during August. A small swarm of earthquakes occurred on 29 August; owing to the small number of telemetered seismometers on Cleveland, the locations and magnitudes of the earthquakes could not be determined precisely. Thermal anomalies were observed in satellite data during the last week of August and slightly elevated surface temperatures were observed on clear satellite images a number of times in September.

Figure 19. MIROVA data from 18 January 2016 to 18 January 2017 showing a persistent thermal anomaly from Cleveland starting about the time of the observation of the new lava dome (17 or 18 May) through late September 2016. A new thermal anomaly appears in late December 2016. AVO reported elevated surface temperatures on 6 January 2017. Courtesy of MIROVA.

Activity during October 2016-February 2017. AVO detected an explosion at 1310 local time on 24 October 2016 that was heard by residents in Nikolski (75 km E), prompting AVO to raise the ACC to Orange and the VAL to WATCH. No evidence of an eruption cloud was detected above the weather cloud present at 8.5 km altitude, and no ashfall was reported in Nikolski. However, clear post-explosion webcam views of the volcano showed a darkened area around the summit crater which may have been the result of minor ash fallout. Narrow dark streaks were also observed extending down the upper snow-covered part of the edifice, which according to AVO may have been produced by small flows of meltwater and ash. They lowered the ACC back to Yellow on 4 November 2016. Satellite views from early November indicated that the lava dome emplaced in late May was mostly destroyed in the 24 October explosion, and was replaced with a deep pit within the summit crater. Minor steaming was observed from the summit during a few periods of clear weather in November.

Observations of weakly-elevated surface temperatures returned 8 and 9 December, with minor steaming at the summit observed on clear days. A MIROVA thermal anomaly signal reappeared around 25 December. This was followed by AVO's observation of weak-to-moderate elevated surface temperatures during first week of January 2017. Low-level steam plumes were seen on clear days later in the month. Moderately-elevated surface temperatures appeared in satellite data on 31 January. [On 3 February 2017 the appearance of a new dome] led AVO to raise the ACC to Orange. Satellite observations indicated that a new lava dome had been extruded and was partially filling the summit crater. The new dome was about 70 m in diameter and similar in size to previous lava domes that have developed on the floor of the crater.

References: Dixon, J.P., Cameron, C., McGimsey R.G., Neal, D.A., and Waythomas, C., 2015, 2013 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2015-5110, 92 p., http://dx.doi.org/10.3133/sir20155110 .

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, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://www.dggs.alaska.gov/); Anchorage Volcanic Ash Advisory Center (VAAC), Alaska Aviation Weather Unit, NWS NOAA US Dept of Commerce, 6930 Sand Lake Road, Anchorage, AK 99502-1845(URL: http://www.ssd.noaa.gov/); 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/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/).

Recent activity at Copahue through January 2016 (BGVN 41:03) consisted of gas and steam plumes with minor amounts of ash. This report, based on information obtained from the Buenos Aires Volcanic Ash Advisory Center (VAAC), the Southern Andes Volcanological Observatory (OVDAS), and the Servicio Nacional de Geología y Minería (National Geology and Mining Service) (SERNAGEOMIN), covers similar activity from mid-January through December 2016. Volcano Alert Levels were maintained by SERNAGEOMIN (on a four-color scale) and by the Chilean Oficina Nacional de Emergencia del Ministerio del Interior (National Office of Emergency of the Interior Ministry) (ONEMI), on a three-color scale), for alerts to individual communes in the region.

Reports from the Buenos Aires VAAC between 13 January and 26 March 2016, based on Significant Meteorological Information (SIGMET) notices, satellites, and webcam views, indicated continuous gas-and-steam plumes containing minor amounts of ash. The plumes rose as high as 3.3-4.3 km altitude (during 24-25 and 28 February) and drifted as far as 160 km (trending SE and SW) between 28 January and 2 February, and more generally as far as 150 km in a variety of directions.

The Buenos Aires VAAC next reported steam-and-gas emissions, possibly containing minor amounts of ash on 11 June, based on webcam recordings. OVDAS-SERNAGEOMIN reported an eruption during 16-30 June characterized by phreato-magmatic explosions and Strombolian activity. During an overflight on 3 July, SERNAGEOMIN scientists observed Strombolian activity from a pyroclastic cone that was forming on the floor of El Agrio crater (figure 17).

Figure 17. Photo taken during an overflight of Copahue on 3 July 2016 showing Strombolian activity from a pyroclastic cone on the floor of El Agrio crater. Courtesy of SERNAGEOMIN.

Based on webcam and satellite views, the Buenos Aires VAAC reported that during 7-8 July diffuse gas-and-steam plumes with minor amounts of ash rose to an altitude of 3 km and drifted E and SE. The Alert Level remained at Yellow (second highest level on a four-color scale).

Activity renewed in September and lasted through December 2016. Based on satellite and webcam images, notices from the Buenos Aires VAAC after 23 September described gas and water vapor plumes with minor ash content rising above the summit. The plumes rose as high as 5.2 km a.s.l. (during 23-25 and 27-29 November) and drifted based on wind direction SW, S, SSE, ESE, SE, E, ENE, NE, and N. On 2 December OVDAS-SERNAGEOMIN reported that activity continued to be dominated by weak Strombolian explosions, likely from a pyroclastic cone forming on the floor of El Agrio crater. The last VAAC reports of activity during 2016 were for gas-and-ash emissions to altitudes of 3.6-3.9 km drifting in S and E directions.

The only MODVOLC thermal anomaly during the entire reporting period was on 26 October 2016 (1 pixel). The MIROVA volcano hotspot detection system, also based on analysis of MODIS data, detected low level thermal anomalies that became more frequent during the latter part of June through early July 2016 and thereafter occurred less often. The last anomalies recorded by MIROVA (as of early April 2017) were in about the third week of December 2016 (figure 18).

Figure 18. Plot of thermal anomalies at Copahue as recorded by the MIROVA system (Log Radiative Power), April 2016-March 2017. Courtesy of MIROVA.

At some point after the December 2016 activity, SERNAGEOMIN lowered the Alert Level to Green, the lowest of the four levels. No additional reports of activity were issued from any agency through March 2017.

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

Information Contacts: Servicio Nacional de Geología y Minería, (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile ( URL: http://www.sernageomin.cl/); Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI), Beaucheff 1637/1671, Santiago, Chile (URL: http://www.onemi.cl/); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php?lang=es); 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/).

Daikoku seamount lies in the Northern Seamount Province of the Mariana Arc, and is about 850 km due N of Guam in the western Pacific Ocean. The summit is about 325 m below sea level and was first shown to be hydrothermally active in 2003 (figure 3). NOAA (National Oceanic and Atmospheric Administration) has conducted four expeditions to the Northern Mariana Islands in 2003, 2004, 2006, and 2014 under their Ocean Explorer program, specifically to study the volcanoes and the marine life they support. A comparison of the bathymetry recorded in 2003 and 2014 suggests that an explosion may have occurred at Daikoku during that interval, and both geochemical data and rock sampling indicate ongoing hydrothermal activity. In 2016, a research cruise conducted by the Schmidt Ocean Institute included a visit to Daikoku that revealed sulfur chimney formation.

Figure 3. Bathymetry and other data gathered on the 2003 NOAA Ocean Explorer Program's 'Submarine Ring of Fire 2003' expedition at the Mariana Arc between 9 February and 5 March 2003. The stars indicate submarine volcanoes where evidence of hydrothermal activity was found. The volcanoes were mapped in high resolution, and sampled with a CTD, as indicated by the open black circles on the tracklines. The red dots represent the location of the deployed hydrophones and the red line represents the location of the back-arc spreading center. Daikoku is located in the Northern Seamount Province of the Mariana Arc. Courtesy of NOAA's 'Submarine Ring of Fire 2003' expedition.

Geochemical sampling of the seawater is carried out with an instrument package that measures conductivity, temperature, and depth, commonly referred to as a CTD. Turbidity of the water, which estimates the concentration of particulate matter suspended in the plumes, is also measured. The CTD carries bottles for seawater sampling which is then geochemically analyzed.

On 15 April 2004 the NOAA 'Submarine Ring of Fire 2004' expedition made a single dive at Daikoku and noted warm water present over large areas of sandy sediment deposits near the summit, and small flatfish in great abundance in the venting areas. The 'Submarine Ring of Fire 2006' expedition again visited Daikoku on 4 May 2006 and discovered a "cauldron" of molten sulfur (BGVN 31:05). They also observed extensive sulfur crusts in the vicinity of the cauldron, suggesting past emissions of liquid sulfur; they were able to sample a large piece of sulfur crust (figure 4). At that time, they also mapped two large craters on the summit. One pit was reported as over 100 m deep and about 80 m in diameter, and a large plume of white fluid was observed rising out of it.

Figure 4. Sulfur crusts near the Diakoku "cauldron" were observed insitu as well as sampled by the ROV. Upper Image: Sulfur crusts in the vicinity of the sulfur cauldron (BGVN 31:05) imply past emissions of liquid sulfur at Daikoku. Lower Image: The Jason remotely operated vehicle (ROV) holds up a large piece of the sulfur crust that was sampled at Daikoku on 4 May 2006. The lasers- two red dots in the images- are 10 cm apart. Courtesy of Submarine Ring of Fire 2006 expedition, NOAA Ocean Explorer Program.

Researchers from the NOAA Ocean Explorer program visited Daikoku again on 14 December 2014 during its 'Submarine Ring of Fire 2014 – Ironman' expedition, which was conducted from the R/V (Research Vessel) Revelle between 29 November and 22 December 2014. They gathered geochemical and bathymetric data which they were able to compare with 2003 data. The CTD information gathered in 2014 showed very strong plumes coming from the top of the seamount. The plumes had high turbidity, low pH, strong anomalies in reduced chemicals, and very high levels of hydrogen (figure 5).

Figure 5. Cross-section over the top of Daikoku seamount measured on 14 December 2014 with the results from a CTD tow (black line), showing turbidity anomalies (warm colors indicate high particle concentrations) in the plume. Courtesy of 'Submarine Ring of Fire 2014 – Ironman' expedition, NOAA/PMEL, NSF.

The 2014 bathymetry data revealed two summit craters; the larger one measured 150 m across and 100 m deep on the N side of the summit with a crater floor depth of 452 m below sea level, and the smaller one, about 50 m across on the NE flank, had a crater floor depth of 443 m below sea level. The bathymetry data from 2003 show only one small crater on the N side of the summit about 50 m across with a floor depth of 400 m below sea level (figure 6). The larger pit appeared to be about 70 m wider in 2014 than in 2006.

Figure 6. Bathymetric comparison of data collected at the Daikoku summit during the 2014 expedition (top) and in 2003 (bottom). The summit crater was significantly larger, and confirmed to be hydrothermally active by the CTD tow and midwater data collected by the 2014 expedition. A second crater has also appeared on the NE flank of the volcano. Arrows with numbers represent the depth below sea level (Z) in meters. Courtesy of 'Submarine Ring of Fire 2014 – Ironman' expedition, NSF/NOAA.

On 3 and 4 December 2016, the Schmidt Ocean Institute Research Vessel R/V Falkor traveled to the Mariana back-arc with a multidisciplinary team of scientists to gather evidence of active hydrothermal vents and the life they support. They were able to make two ROV (Remotely Operated Vehicle) dives at Daikoku and collected data on the seamount and sea life living there. On their first dive they observed (and sampled) a fissure with a sulfur chimney caked with yellow sulfur, emitting white bubbles and particulates in 70°C water (figure 7).

Figure 7. An active sulfur chimney at Daikoku on 3 December 2016 was videoed and sampled by the Schmidt Ocean Institute expedition. Upper Image: A fissure at Daikoku on 3 December 2016 with a yellow sulfur-caked chimney emitting white bubbles and particulates in 70°C water. Lower Image: The sulfur chimney was sampled by the ROV SuBastian for chemical analysis. Courtesy of Schmidt Ocean Institute, Expedition FK161129.

On their second dive on 4 December 2016, they collected tube worms and crabs, and recorded the formation of "sulfur needles," tadpole-shaped fragments of sulfur that were previously observed in sampled sediments and seen floating in the water column. They appear to form when gas bubbles (probably CO₂) rise through molten sulfur, forming a coating of sulfur around the bubble before the gas escapes (figure 8). Their video shows a sulfur chimney caked with yellow sulfur emitting yellow, white, and orange droplets of sulfur.

Figure 8. Tadpole shaped "sulfur needles" coat the side of a sulfur chimney at Daikoku on 4 December 2016 as gas bubbles coated with sulfur rise through the chimney and drip residue around the sides. A video recording was also made of the chimney emitting bubbles (https://schmidtocean.org/cruise-log-post/daikoku-dive-2-sulfur-good/). Courtesy of Schmidt Ocean Institute, Expedition FK161129.

The cruise scientists used the ship's EM302/710 multibeam echosounder to get a 2-m-resolution image of the summit crater, which they combined with water column data to create an image showing both the bathymetry of the volcano and the shape of the hydrothermal plume emitting from the summit (figure 9).

Figure 9. Multibeam echosounder data reveals the topography of the summit at Daikoku on 4 December 2016 as well as the shape of the hydrothermal plume emitting from the summit. Courtesy of Schmidt Ocean Institute, Expedition FK161129.

Geologic Background. The conical summit of Daikoku seamount lies along an elongated E-W ridge SE of Eifuku submarine volcano and rises to within 323 m of the sea surface. It is one of about a dozen displaying hydrothermal activity in the southern part of the Izu-Marianas chain. A steep-walled, 50-m-wide cylindrical crater on the north flank, about 75 m below the summit, is at least 135 m deep and was observed to emit cloudy hydrothermal fluid. During a NOAA expedition in 2006, scientists observed a convecting, black pool of liquid sulfur with a partly solidified, undulating sulfur crust at a depth of 420 m below the summit. Gases, particulate with the appearance of smoke, and liquid sulfur were bubbling up from the back edge of the sulfur pool.

Information Contacts: Office of Ocean Exploration and Research, National Oceanic and Atmospheric Administration (NOAA), 1315 East-West Highway, Silver Spring, MD 20910, USA (URL: http://oceanexplorer.noaa.gov/, Cruise logs at: http://oceanexplorer.noaa.gov/explorations/03fire/logs/summary/summary.html, http://oceanexplorer.noaa.gov/explorations/04fire/logs/april15/april15.html, http://oceanexplorer.noaa.gov/explorations/06fire/logs/may4/may4.html, http://oceanexplorer.noaa.gov/explorations/14fire/logs/december14/december14.html); Schmidt Ocean Institute, 555 Bryant Street #374, Palo Alto, CA 94301, USA (URL: https://schmidtocean.org/, https://schmidtocean.org/cruise/searching-life-mariana-back-arc/).

After an eruption in April 2009 (BGVN 34:12), Kerinci was quiet until it erupted again in December 2011. The Indonesian agency responsible for volcano monitoring is the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), also known as the Center for Volcanology and Geological Hazard Mitigation (CVGHM). Since mid-December 2011 there have been four instances where there was an emission of ash, qualifying the event as an eruption. These took place in December 2011, June 2013, and twice in 2016. The eruptions in 2016 were separated by five months, so are treated as distinct eruptions.

PVMBG mentioned in its 2015 reports on Kerinci that an eruption on 15 December 2011 generated an ash plume that rose about 600 m above the summit (summit elevation is 3.8 km). No other details were given.

A brief eruption was reported by PVMBG on 2 June 2013, from 0843 to 0848, that generated an ash plume 1 km above the crater. Ashfall as thick as 5 mm was reported in areas to the E, including Tangkil (7.5 km SE). In a Jakarta Post story, a resident of Sungai Rumpun village (about 10 km SE) reported hearing a loud bang and black plumes with a sulfur odor. The article noted that several villages in Gunung Tujuh district (an area that includes the SE flank of the volcano) received heavy ashfall, but it was washed off the crops by rain.

Although PVMBG reported white plumes during 1 February-12 July 2015 that rose 50-300 m and drifted E and W, no clear eruptive activity was noted. Seismicity during this period was dominated by signals indicating emissions and shallow volcanic earthquakes. Climbers who reached the summit around this time (exact dates not reported, images uploaded 17 January 2016) photographed steam plumes (figure 1) and solid lava flows (figure 2) in the crater.

Figure 1. Photo of a steam plume rising from the Kerinci summit crater. Date not reported; uploaded 17 January 2016. Courtesy of Bernhard Huber.

Figure 2. Photo of the crater floor at Kerinci showing solidified lava flows and steam. Date not reported; uploaded 17 January 2016. Courtesy of Bernhard Huber.

Based on satellite images and ground reports from PVMBG, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 15 days between 31 March and 9 June 2016 ash plumes rose to altitudes of 4.0-4.9 km and drifted N, NW, NE, E, and WSW. On 29 April an ash plume rose to an altitude of 6.1 km.

Figure 3. Photo of Kerinci showing a plume rising from the summit crater on 9 June 2016. Courtesy of Luke Mackin.

Ash plumes were again reported on 15-19, and 21 November 2016 based on observations of satellite data by the Darwin VAAC. The plumes rose to altitudes of 4.3-4.6 km and drifted NE, ENE, SE, and S. On 15 and 17 November they drifted almost 30 km downwind. The Alert Level remained at 2 (on a scale of 1-4), where it has been since September 2007, and PVMBG advised residents and visitors not to enter an area within 3 km of the summit.

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

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Bernhard Huber (URL: https://www.flickr.com/photos/97278656@N08/, https://creativecommons.org/licenses/by-nc-nd/2.0/); Luke Mackin (URL: https://www.flickr.com/photos/wildsumatra/, https://creativecommons.org/licenses/by-nc-sa/2.0/); Jakarta Post (URL: http://www.thejakartapost.com/news/2013/06/02/mt-kerinci-erupts.html).

Klyuchevskoy has been quite active for many decades, with eruptive periods alternating with less active times (BGVN 35:06, 38:07, and 39:10). Recent eruptions took place during August-December 2013, with another period of activity beginning in January 2015 and continuing at least into March 2015 (BGVN 39:10). MODVOLC thermal alert pixels, based on MODIS satellite data, were frequent starting on 3 January but had stopped after 26 February 2015. Moderate activity continued until 10 May 2015, when the eruption that began in January ended. Eruptive activity was again observed in late August 2015, and fluctuating activity has continued through March 2017. The Kamchatkan Volcanic Eruption Response Team (KVERT) is responsible for monitoring this volcano, and is the primary source of information. Times are in UTC (local time is UTC + 12 hours).

Activity during April-July 2015. KVERT lowered the Aviation Color Code (ACC) to Green, the lowest of four levels, on 6 April 2015, although moderate gas-and-steam activity continued. On 13 April, gas-and-steam emissions increased at 0840, and continued at least through 1215 on 14 April, with incandescence at the summit possibly indicative of renewed Strombolian activity. KVERT raised the ACC from Green to Yellow. Strong gas-and-steam activity continued through the rest of April; the plumes sometimes contained small amounts of ash. Satellite data showed a weak thermal anomaly when not obscured by clouds, and incandescence at the summit was occasionally observed. On 18 April, KVERT reported that Strombolian activity was continuing, and that a webcam had recorded a narrow ash plume rising 1-2 km and drifting 100 km SE; the ACC was raised to Orange. Satellite images showed a weak thermal anomaly during 16-17 and 23 April; a gas plume containing a small amount of ash drifted 147 km E on 21 April. On 26 April the ACC was lowered to Yellow; KVERT noted that gas-and-steam activity and tremor continued.

Satellite data showed ash-bearing plumes during 2-5 May that drifted more than 450 km SE, and moderate activity continued through 9 May. The ACC was briefly raised to Orange before again being set at Yellow on 12 May. Moderate activity prevailed though the rest of the month. Satellite data showed occasional gas-and-steam plumes, sometimes containing small amounts of ash; weak thermal anomalies were often observed over the volcano when clouds did not obscure viewing.

On 22 May, KVERT described activity as weak. This remained the case through 27 August 2015. Gas-and-steam emissions continued, and satellite data often showed a thermal anomaly when the volcano was not obscured by clouds. Gas-steam plumes drifted 20 km SE on 26-27 May. On 20 July, the ACC was lowered to Green.

Activity during August 2015-March 2016. On 27 August, KVERT reported that a moderate Strombolian explosion had occurred, which continued into 28 August. At 1544 UTC on 27 August, incandescence of the crater was observed. The ACC was raised to Yellow.

Thereafter, through 17 September 2015, KVERT described activity as moderate, with moderate gas-steam activity. Strombolian explosions occurred on 27-28 August and 8-10 September. Satellite data showed occasional weak thermal anomalies when the volcano was not obscured by clouds. On 13-14 September, a diffuse ash plume rose to about 1.5 km and drifted E.

During 24 September-30 November 2015, KVERT described the activity as a "weak explosive eruption." According to video data, moderate gas-and-steam activity continued and a weak thermal anomaly was sometimes observed when the volcano was not obscured by clouds. Occasionally, incandescence of the summit volcanic crater was noted.

KVERT again described activity as moderate during December 2015-March 2016, with strong gas-steam emissions, although the volcano was usually either quiet or obscured by clouds. KVERT reported thermal anomalies each month, ranging from two during December 2015 to 12 during both January and February 2016. Video often recorded incandescence at the summit during the latter part of December.

Activity during April 2016-November 2016. On 3 April 2016, activity increased with Strombolian explosions. Detection of very frequent thermal anomalies by the MODVOLC system began again on 8 April and continued being reported almost daily through 2 November 2016. Thermal data identified by the MIROVA system showed strong anomalies over the same time period (figure 18). The MIROVA data also indicated a steady increase in radiative power beginning in the second half of May 2016.

Figure 18. Plots of MODIS thermal data detected at Klyuchevskoy during the year ending on 23 March 2017. The data analyzed by the MIROVA system is presented as radiative power (top) and log radiative power (bottom). Courtesy of MIROVA.

Strong gas-steam emissions continued, and plumes extended to about 100 km SE on 10 April and about 55 km NE on 14-15 April. Satellite data by KVERT through June showed persistent intense thermal anomalies when not obscured by clouds. On 24 April, activity increased again. According to video and satellite data, a lava flow began to effuse on the S and SE flank of the volcano (along Apakhonchich chute). An ash plume drifted about 500 km SW on 23-24 April. The ACC was raised to Orange.

The explosive-effusive eruption continued from May through September 2016. Lava continued to effuse along the SE flank. Satellite data showed an ash plume extending 88 km SE on 2 May, up to 80 km E and SE on 13 May and 16 May, 47 km W on 13 June, about 30 km E on 18 June, and 60 km W and E on 27-28 June. Gas-steam plumes drifted about 60 km W and E on 27 and 28 June. On 24 June, at 2115 and 2350 UTC, video data showed two rock collapses into the Apakhonchich chute and ash plumes drifted W, then NW. According to video and satellite data, Strombolian activity of the summit crater continued on 24 June.

According to video data, the eruption intensified on 6 July. Strong explosions sent ash to an altitude of 7.5 km and the plumes drifted about 350 km SW, S, and SE. A large bright thermal anomaly was observed all that week. On 6-7 July, dense ash plumes drifted about 400 km SE and E, and numerous ash plumes were observed thereafter through September. Bursts of volcanic bombs shot up to 200-300 m above the summit crater and up to 50 m above the cinder cone into the Apakhonchich chute along the SE flank. Lava continued to flow on the SE flank along the chute (figure 19). Strong gas-steam activity within two volcanic centers emitted various amounts of ash. On 10, 13 and 15 September, explosions shot ash up to an altitude of 7 km and ash plumes extended for about 50 km SE and NE.

Figure 19. Photo of Klyuchevskoy on 25 August 2016 with ash-containing emissions and lava streaming from the cone into the Apakhonchich chute. Courtesy of Denis Bud'kov/Bernard Duick.

During the second week of September, KVERT reported that lava began to effuse on the E and SW flanks. Explosions sent ash up to an altitude of 7.5 km and ash plumes extended for about 530 km in various directions. Small ash layers were observed over Koryaksky and Avachinsky volcanoes on 8 September. On 10, 13, 15, and 20-22 September, explosions sent ash up to an altitude of 6-7 km and ash plumes extended for up to 165 km in various directions. In their 29 September and 6 October reports, KVERT noted that bursts of volcanic ash that rose above the summit crater and cinder cone fell into Apakhonchich chute.

Explosions during the first week of October sent ash to an altitude of 5-6 km and plumes extended about 260 km E. On 7-8 October, gas-steam plumes containing ash drifted about 390 km E and SE. By 13 October, activity had apparently diminished, with moderate gas-steam emissions containing some ash. A weak thermal anomaly was noted on 7 and 12 October.

By 20 October the explosive-effusive activity had returned with a lava flow on the E flank, a large strong thermal anomaly, and strong gas-steam emissions containing various amounts of ash. Explosions sent ash to 5-6 km altitude and plumes extended for about 300 km E, SE, and NW on 14 and 18-19 October. On 20-21 and 23-27 October explosions sent ash up to an altitude of 5-7 km; gas-steam plumes containing ash extended for about 335 km in various directions. On 30-31 October and 1-3 November, explosions sent ash up to an altitude of 5-8 km and gas-steam plumes containing ash extended for about 277 km E and SE. Strong thermal anomalies detected from satellite by the MODIS instrument decreased significantly in strength after 2 November.

On 3-5 November, ash plumes extended up to 116 km E. KVERT's report on 10 November noted that activity had decreased significantly during the previous week. Lava effusion onto the flanks was last noted on 3 November; the next day the thermal anomaly was weaker. Ash plumes were last detected in satellite images during 3-4 November. The ACC was lowered to Yellow on 7 November. However, moderate activity continued and thermal anomalies and Strombolian activity could still be observed. Strong gas-and-steam emissions continued. On 16 November, an ash plume extended up to 85 km NW. KVERT reported a daily thermal anomaly visible in satellite images during 18-25 November.

Activity during December 2016-March 2017. Thermal anomaly data after early November 2016 was not sufficient to cause alerts on MODVOLC, and was seen to be very weak and fluctuating in MIROVA plots before ending completely in mid-February 2017 (see figure 19). On 26 December KVERT reported that a weak thermal anomaly had been detected and that gas-and-steam plumes sometimes contained small amounts of ash. Over the next few months the ACC was frequently changed between Yellwo and Orange, depending on the ash plume hazard to aviation.

Explosions on 1 January 2017 generated ash plumes that rose to an altitude of 5 km and drifted 114 km SE, resulting in KVERT raising the ACC to Orange. Daily satellite imagery showed a thermal anomaly over the volcano during 2-6 January. Gas-and-steam emissions sometimes with minor ash, along with thermal anomalies, continued through 20 January. During 9-10 January ash plumes drifted 160 km ESE, and on 22 January an ash plume rose to 5-5.5 km and drifted 45 km E.

KVERT reported that a thermal anomaly was identified in satellite data during 25 February and 1-3, 5, and 8-9 March. At 1340 on 2 March a gas, steam, and ash plume recorded by the webcam rose to altitudes of 8-9 km and drifted 110 km NE and NW. Explosions on 8 March produced ash plumes that rose to 5.5 km altitude and drifted about 20 km NW. As of 24 March gas-and-steam emissions continued to rise from the crater, and a weak thermal anomaly was sometimes identified in satellite images, but no explosions had been detected since 8 March. On 24 March the ACC was lowered to Green.

A gas, steam, and ash plume identified in satellite data on 28 March rose to altitudes of 5-6 km and drifted 108 km ENE, resulting in the ACC being raised to Yellow. Another ash plume the next day that rose to as high as 7.5 km altitude and drifted 75 km SW prompted an Orange ACC status. Additional explosions during 27-30 March generated ash plumes to an altitude of 7 km that drifted 300 km in multiple directions.

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 East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/); 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/).

Guatemala's Pacaya volcano has a 450-year record of observations of frequent activity, in addition to confirmed radiocarbon dating of eruptions over the last 1,500 years. Its location, approximately 30 km south of the capital of Guatemala City, makes it both a popular tourist attraction as a national park, and a hazard to the several million people that live within 50 km. Activity during the last 50 years has been characterized by extensive lava flows, bomb-laden Strombolian explosions, and large and small ash plumes that have dispersed ash to cities and towns across the region.

This report summarizes activity at Pacaya during the long-lived 2004-2010 eruptive episode, and continues with the details of activity during the next eruption between March 2013 and April 2014. Most of the information is provided by the Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), the Coordinadora Nacional para la Reducción de Desastres (CONRED) of Guatemala, and the Washington Volcanic Ash Advisory Center (VAAC), which provides air traffic advisories. Information is also gathered from remote sensing satellite data provided through the University of Hawai'i's MODVOLC program and from Google Earth images.

Renewed Strombolian activity was observed on 19 July 2004 after two years of mostly steam emissions, and again in early December 2004. Intermittent Strombolian explosions accompanied near-continuous lava flows down most flanks of MacKenney Cone from December until 11 September 2005. An explosion on 9 March 2006 was the beginning of a new, lengthy episode characterized by extensive lava flows and few significant ash plumes. Multiple strong thermal anomalies were recorded every month from March 2006 through June 2010, excepting December 2006. It climaxed with a major explosion of ash and lava flows during 27- 28 May 2010, and ended with the last Strombolian explosions recorded on 26 October 2010. After two and a half years of quiet, a new period of Strombolian activity began on 5 March 2013, which included intermittent lava flows. This continued until an outbreak of more extensive lava flows during the second half of January 2014. After a final burst of lava flows in early March, a small ash plume on 10 April 2014 was the last reported activity for four months.

Activity during June 2004-September 2005. Renewed periods of near-continuous tremor and frequent long-period earthquakes were recorded during June- August 2004, after the end of visible incandescence from a long-lived lava lake in June 2001. Incandescence was first reported on 14 June 2004, followed by ejection of lava fragments from a vent at the bottom of the central crater of MacKenney Cone on 19 July (BGVN 30:10). Incandescence was observed during the next few months, and tephra was expelled from the cone during 7-9 December 2004.

A sequence of substantial lava flows was first observed by INSIVUMEH in January 2005; strong thermal signatures were initially captured by MODVOLC beginning on 24 December 2004 and persisted until 28 August 2005. During this period, most of the lava flows covered the NW, N, and NE flanks of the central crater, but some extended up to 300 m down the W and SW flanks (figure 62). An INSIVUMEH report from 2008 noted that in March and April 2005 the growth of N-S oriented cracks on the MacKenney Crater created a new vent on the cone's ENE side. In just a few days, the flow field from this vent grew to about 800 m long and curved westward down the N flank, filling much of the depression formed by the cracks in the subsequent months (BGVN 33:08).

Figure 62. Two MODVOLC images of Pacaya showing locations of lava flows during 2005. Upper image shows lava flows during 1-15 April 2005. Flows are located NW, N, and NE of MacKenney Cone as well as to the W in a longer flow. During August 2005 (lower image), active flows were concentrated NE and E of the cone with residual cooling observed to the W and SW. Courtesy of HIGP MODVOLC Thermal Alerts System.

Strombolian explosions reached 100 m above the crater, and avalanches of ejected incandescent blocks produced small ash clouds to low levels during much of 2005. Thermal anomalies ceased at Pacaya after 28 August 2005, although observations by INSIVUMEH of occasional Strombolian activity and ejected bombs were made until 11 September. After that, only weak incandescence was reported in early November and January 2006; a new Strombolian explosion occurred on 9 March 2006.

Activity during 2006-2009. The Strombolian explosions that began on 9 March 2006 ejected material tens of meters above the volcano in pulses of activity lasting 10-30 seconds; on 12 March material rose 250 m above MacKenney Cone. Significant lava flows began in late March, advancing about 150 m from the S and SW edges of the crater. A new flow on 13 April was reported by INSIVUMEH as issuing from a parasitic cone, at the ENE base of the main cone, and was 125 m long by 17 April. During the rest of 2006, lava flows from this vent reached lengths of more than 800 m NW of the summit cone and covered an area N, NE, and NW of the cone, known as the 'meseta' (plateau) popular with visitors to the Park (see figures 39, 40, and 41, BGVN 33:08). The Washington VAAC issued only one ash advisory in 2006, on 28 August, and noted possible ash emissions at 3 km altitude drifting 16 km W.

Throughout 2007, 2008, and 2009, multiple vigorous lava flows traveled in different directions from MacKenney Cone. The new lava flows that emerged from a vent on the ENE flank during March and April 2006 also continued to flow NE and N, and then curved to the W in multiple branches, covering large areas of the plateau between the active cone and the three older cones (Cerro Grande, Cerro Chiquito and Cerro Chino) to the N. These flows were most active through November 2008 (figure 63). Flows down the S and SW flanks continued intermittently and reached lengths of several hundred meters. They were most active between August 2008 and the end of 2009; reaching 800 m long in December 2008. Lava flow volume and explosive activity increased during April 2009; the flows traveled down the S and SW flanks for distances up to 400 m. During July, they traveled as far as 600 m down the flanks, and remained vigorous throughout the rest of the year.

Figure 63. Location and extent of thermal anomalies from lava flows and Strombolian activity at Pacaya during April and November 2008. Upper image: Thermal anomalies suggest that lava flows during the first half of April 2008 were primarily issuing from a vent on the NE flank and flowing N, NW, and NE, and not originating from MacKenney Cone. Lower image: By November 2008, there were extensive flows from the summit crater flowing W and SW, as well as to areas N of the cone. Courtesy of HIGP MODVOLC Thermal Alerts System.

Strombolian explosions were intermittent during this three year period, only reported a handful of times in January, June, and December 2007, February, May, and July 2008, and March and April 2009, with explosions of material to a few tens of meters above the summit cone. These explosions often created gas plumes reported by INSIVUMEH to altitudes of 2-3 km. They reported that material from explosions in March 2009 enlarged the cones in the summit crater, and vigorous degassing contributed to substantial noise. A small spatter cone, 4 m high, was detected in the S part of the crater in late April.

There were only three series of VAAC reports during 2007-2009, two in 2007 and one in 2008. A small ash plume was observed on 6 April 2007 at 4.6 km altitude that drifted less than 10 km SSE before dissipating. On 17 November 2007 a narrow plume was observed in satellite imagery extending 15-25 km NW of the summit at an altitude of 4.3 km. A brief emission of gas and possible ash was reported on 2 November 2008, but dissipated within three hours.

Activity during 2010. During January 2010, the lava flows that had descended the S, SW, and W flanks of MacKenney Cone since 2006 ceased flowing. Strombolian explosions were observed again in early February and new flows originating from a depression on the NE flank of the cone traveled 400 m down the E and NE flanks toward the meseta. Avalanches of blocks from the flow fronts set fire to local vegetation. Significant tephra explosions reached up to 150 m high in late February and lava flows traveled 800 m E (figure 64). Multiple lava flows on the SW flank of MacKenney cone on 20 May 2010 traveled 1.6 km, farther than previously recorded flows.

Figure 64. Significant new lava flows at Pacaya can be identified moving E from the NE flank of MacKenney Cone beginning in February 2010 on this map of MODVOLC thermal alerts. The flows that had been active through January to the W and SW were cooling but still produced a thermal signature visible in this MODVOLC image from the second half of March 2010. Courtesy of HIGP MODVOLC Thermal Alerts System.

This increasing activity culminated in a large Strombolian eruption on 27 and 28 May 2010. On 29 May a 90-m-wide lava flow traveled SSE down the flank at an estimated rate of 100 m per hour and burned three houses on the Pacaya Grande ranch (see details in BGVN 39:05). The eruption was characterized in a report from CONRED as having constant explosions that ejected material 500 m into the air. INSIVUMEH reported a continuing series of explosions 5-10 seconds apart that ejected black ash up to 1 km above the crater on 28 May.

Numerous weather clouds prevented the Washington VAAC from determining an altitude of the ash plume until late on 28 May, when it was visible in satellite imagery at about 13 km altitude. Ash plumes drifted 20-30 km NW, causing ashfall as thick as 10 cm in areas downwind, including in Guatemala City, about 30 km NNE. INSIVUMEH reported 5-7 mm of ashfall during 27-28 May at the Aurora International Airport. CONRED reported on 28 May that about 1,600 people had been evacuated from six towns 3-4 km W, NNW, N, and NNE, and that the airport was closed. According to a map posted by CONRED, blocks fell in areas as far as 12 km NE, and ash was reported in areas E of Chinautla, 37 km NNE. Reuters News Agency reported that one person (a reporter) died and three children were missing.

The lava flow moving down the SSE flank of MacKenney Cone was shown by MODVOLC thermal alert pixels that persisted through much of June 2010 (figure 65). The lava flowed to within 450 m of several properties including El Chupadero, located 2-2.5 km S of the crater, and disrupted an access road from El Caracol (3 km SW) and Los Pocitos (5.5 km S).

Figure 65. Thermal alert pixels seen in MODVOLC data show the area of lava flows at Pacaya extending down the SSE flank of MacKenney Cone from the summit and from a vent on the SSE side of the cone during June 2010, damaging property in its path. Courtesy of HIGP MODVOLC Thermal Alerts System.

Intermittent Strombolian activity continued into June 2010, with tephra ejected as high as 700 m above the crater. The lava flows on the SE flank remained active through mid-June and had traveled as far as 3.5 km before cooling. By late June, the cone was primarily emitting white and blue fumarolic plumes to several hundred meters. Significant ash emissions and small pyroclastic flows were again reported during the last two weeks of July, causing an evacuation of 150 people from nearby areas. A Washington VAAC report on 22 July noted a plume at an altitude of 4.1 km drifting N, that produced ashfall within 10 km. Strombolian explosions on 24 and 25 July were strong enough to cause a MODVOLC thermal alert pixel at the summit, and to eject tephra blocks onto the flanks.

The last eruptive events of this multi-year eruption were ash plumes emitted in August and Strombolian activity in October 2010. Small ash plumes rose to 800 m above the crater causing ashfall 5 km away on 2 and 3 August. This was followed by a burst of Strombolian explosions during 21-22 and 26 October. After this, only fumarolic emissions of primarily water vapor were reported at Pacaya until a plume of ash-and-gas was reported by INSIVUMEH on 5 March 2013.

A comparison of a geologic map prepared by INSIVUMEH's Rudiger Escobar Wolf in 2010 (also published in BGVN 39:05) and a Google Earth image from December 2010 readily shows the impact of the extensive flows at Pacaya during the 2006-2010 eruptive episode (figure 66).

Figure 66. Comparison of 2010 geologic map (also published in BGVN 39:05) and a Google Earth image dated 12 December 2010 showing the impact of the lava flows at Pacaya from the 2006-2010 eruption. Geologic map from INSIVUMEH, imagery from Google Earth.

Activity during March 2013-August 2014. Pacaya remained quiet between October 2010 and March 2013 except for intermittent pulses of seismicity and minor water vapor and gas emissions. An increase in explosions was noted beginning late in 2012, but only steam plumes were observed rising less than 500 m above the summit during January and February 2013. A single MODVOLC thermal alert pixel captured on 2 Feb 2013 to the SE of MacKenney Cone is likely the result of agricultural, not volcanic, activity.

The first report of renewed activity was on 5 March 2013 when INSIVUMEH noted that a thin plume of brown ash accompanied the fumarolic plumes, and dispersed to the S. Weak gas-and-ash plumes recurred several more times during March. On 24 April tephra was ejected 25 m high by weak explosions; incandescence and explosions were detected the next day and again on 29 April. Incandescence was regularly observed during May, and more substantial Strombolian activity started on 20 May and carried through to the end of the month. Tephra ejections rose to 25 m above the crater, and continuous explosions a few minutes apart that ejected bombs and generated rumbles, were heard 4 km away. An explosion on 30 May ejected ash and lapilli 200 m above the crater that was then deposited within 400 m of the crater.

Strombolian activity on 27 June 2013 again ejected small amounts of tephra that were deposited on the W flank. An investigation of the summit crater of MacKenney Cone during June determined that a 15 m high cone had been the source of the most recent explosive activity. An increase in seismicity in late July indicated the continued growth of the pyroclastic cone which had risen to 4 m above the crater rim by 24 July, doubling its total height from June to more than 30 m high. Weak explosions and incandescence were observed the next night, and a Strombolian eruption on 30 July lasted for four hours and ejected material 250 m above the cone. A diffuse ash plume drifted 2 km N, causing ashfall in areas downwind, and another ash plume drifted 5 km S. A prominent hot spot at the summit was reported by the Washington VAAC.

During 9 and 10 August seismicity increased again and Strombolian explosions ejected tephra 200 m above MacKenney Crater and onto the flanks, 400 m from the crater, causing small avalanches on the flanks. Another explosion during the night of 14-15 August produced a 300-m-long lava flow that traveled W from MacKenney Crater; new emissions of ash and gases to 500 m above the crater were reported by the Washington VAAC the next day. Tremors and explosions of incandescent material continued through August and the first half of September ejecting material and sending small ash plumes a few kilometers above the cone. Incandescence was reported as visible from the capital to the N by mid-September. Two MODVOLC thermal anomaly pixels were recorded on 30 August and 3 September confirming the increased thermal activity reported by INSIVUMEH.

In late November 2013 INSIVUMEH reported that activity remained unchanged with weak explosions, gas emissions and tephra ejections continuing. Pilots reported that ash plumes rose to 2.7 km and drifted 10 km SW. This continued into early January 2014 when activity at the main crater increased; seismographs recorded constant tremor, and beginning on 11 January, INSIVUMEH observed tephra explosions to 100 m, gas plumes to 600 m, and new craters on the E, S, and W flanks that produced extensive new lava flows. These flows emitted strong thermal anomaly signatures that were captured by MODVOLC for the next two weeks (figure 67).

Figure 67. MODVOLC thermal alert images from Pacaya on individual days during January 2014 show the extent of new lava from multiple vents on the E, S, and W flanks of MacKenney Cone. The green dot is the summit crater at MacKenney Cone. Clockwise from top left: a) 11 January, thermal signatures N and SW of the summit crater; b) 13 January, the strongest signals are from the SW and SW flanks; c) 19 January, fewer signals suggest a pause in the flows; d) 20 January, renewed flows on the S flank. Courtesy of HIGP MODVOLC Thermal Alerts System.

At the beginning of this event (on 11 January) CONRED reported evacuations from Villa Canales (14 km NW), El Chupadero (2-2.5 km S), and San Vicente Pacaya (5 km NW). Lava flows had reached 3 km by 13 January. A report on 21 January noted that the S-flank lava flow was 3.6 km long and continued to slowly advance, burning vegetation (figure 68) between the Rodeo and Los Pocitos roads.

Figure 68. An a'a lava flow at Pacaya burning its way through a forest on 11 January 2014. Courtesy of CONRED.

Volcanologists observed that the cone in MacKenney Crater had been completely destroyed during the January events, leaving a deep crater that produced fumarolic activity. The Washington VAAC noted an ash plume on 11 January that rose to 3.4 km and extended 55 km SSW from the summit. After that, a prominent hot spot was visible but there was no further indication of ash in satellite imagery. Separate Google Earth images captured in December 2013 and April 2014 show the extent of the new lava flows on the S flank of MacKenney Cone (figure 69) during January 2014.

Figure 69. Two Google Earth images of the S flank of MacKenney Cone at Pacaya before and after lava flows during January 2014. Upper image is dated 30 December 2013. Lower image is dated 9 April 2014. An image dated 30 March also shows the new flows, but was much hazier. Note that the location of MODVOLC thermal alerts in figure 67d matches the location of January 2014 lava flows. Courtesy of Google Earth.

The next episode of activity began with increased gas-and-vapor plumes during 27-28 February 2014 and included ejection of fine pyroclastic material 600 m S and SW from the crater. INSIVUMEH and CONRED noted increased activity on 2 March; at 0515 Strombolian activity at MacKenney Crater ejected material as high as 800 m and lava flows descended the W flank (figure 70). Explosions produced dense ash plumes that initially rose 2.5 km and drifted 15 km S, SW, and W. Ashfall was reported in El Rodeo (4 km WSW), Patrocinio (about 5 km W), and Francisco de Sales (5 km N). By the next day, activity had decreased, but lava flows traveled up to 1.3 km S and ejected tephra drifted 600 m S and SW. Small explosions and lava flows continued to be active for the next week. MODVOLC thermal alerts were captured around the summit on 2 and 3 March, but no additional thermal alerts were recorded in 2014. The Washington VAAC also noted emissions of gas and volcanic ash on 2 March that rose to 4.9 km altitude and extended over 200 km W before the end of the day. By 3 March an area of light ash remained 370 km W of the volcano off the southern Mexico coast and dissipated during the day.

Figure 70. The eruption of Pacaya on 2 March 2014. The lava fountain (reddish) can be seen at the summit vent. Courtesy of CONRED.

After INSIVUMEH reported a small ash plume on 10 April 2014, only minor episodes of increased seismicity and steam plumes rising a few tens of meters above the summit were observed through August.

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); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/, archive at: http://www.ssd.noaa.gov/VAAC/archive.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/); Google Earth (URL: https://www.google.com/earth/); Reuters News Agency (URL: http://www.reuters.com/article/us-guatemala-volcano-idUSTRE64R11M20100528?pageNumber=2).

Mount Rokatenda, or Paluweh, on the island of Palu'e, lies north of the primary volcanic arc that cuts across Flores Island in Indonesia's Lesser Sunda Islands, and has seen infrequent activity in modern times. The previous eruption in 1985 from a summit lava dome spread 3 cm of ash over villages on the W side of the island. This report is a summary of the October 2012 to August 2013 eruption, and an update through 2016 that includes information provided by Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), the Darwin Volcanic Ash Advisory Center (VAAC), and the University of Hawai'i's MODVOLC thermal alert reporting system. Numerous news reports also covered the major explosions during 2013.

Two brief periods of increased seismicity in April 2009 and January 2012 were the only recorded activity at Paluweh since 1985, prior to an eruption that began in October 2012 and continued through August 2013. PVMBG noted the beginning of lava dome growth on 8 October. A substantial number of MODVOLC thermal alert pixels from MODIS satellite data were first recorded on 11 October 2012 and recurred regularly through 20 July 2013. The first ash plumes were reported by the Darwin VAAC on 11 November 2012 and continued several times each month through May 2013, and then again in late June and during 10-12 August. Plumes generally rose to 2-3 km and drifted between 50 and 100 km in various directions, although a large ash plume on 3 February 2013 rose to higher than 13 km and drifted over 500 km SE, S and SW, briefly impacting air travel in NW Australia. A major explosion on 10 August 2013 created a large pyroclastic flow to the NW from the summit that killed five people on the beach. No further explosions were specifically dated after 12 August 2013, and seismicity gradually decreased over the next several months.

Activity during October 2012-April 2013. PVMBG noted lava dome growth, incandescent avalanches, pyroclastic flows, and ash plumes during October 2012 through January 2013. Ejecta as large as 6 cm in diameter was deposited up to 3 km from the summit, and ashfall affected the entire island, averaging 2 cm thick in places; lahars and ash damaged homes and infrastructure on the island (BGVN 39:01). A large eruption on 2 February 2013, which produced a 13-km-high ash plume the next day, generated a substantial SO2 signature, pyroclastic flows to the S and SW, and avalanches. Residents of eight villages were evacuated and significant ashfall was reported up to 1 mm thick in Ende (60 km S on East Nusa Tenggara Island). Thick ashfall was also reported in Ona (SE part of the island) and thin deposits were reported in other areas of the island to the W, N, and E. During a field expedition on 7 February, PVMBG staff observed that about 25% of the S portion of the dome was lost; the lava-dome volume had been an estimated 5.1 million cubic meters on 13 January, prior to the explosion.

After the large early February 2013 explosion, many intermittent low-level ash emissions continued through the last week in May, with over 175 VAAC reports issued from the Darwin VAAC during the period. NASA's Earth Observatory (EO) identified an ash plume in MODIS satellite images drifting over 440 km SW on 24 March 2013, and discoloration of the seawater from ash W of the island (figure 7).

Figure 7. NASA image acquired 24 March 2013 with the MODIS instrument shows an ash plume from Paluweh drifting over 440 km SW across Flores Island. Light-colored ash coats the southern third of Paluweh Island, and the ocean to the W of the island is colored turquoise from ash floating near the water's surface. Image posted at http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=80737. Courtesy of NASA, GSFC.

Another NASA-EO image captured on 19 April 2013 shows the extent of ash deposits covering areas of the S and E sides of the summit where the plumes most commonly drift. A delta extending S into the Flores Sea, which was visible in imagery on 12 February and likely created by a pyroclastic flow during the large 2-3 February explosion (figure 8), was also visible.

Figure 8. NASA-EO image of Paluweh captured 19 April 2013. Note the extent of ash covering the area of the island on the S and E sides of the summit where the plumes usually drift. It also shows a delta extending S into the Flores Sea, also visible in imagery on 12 February (http://earthobservatory.nasa.gov/IOTD/view.php?id=80422 ) and likely created by a pyroclastic flow during the large 2-3 February explosion. Courtesy of NASA Earth Observatory (ihttp://earthobservatory.nasa.gov/NaturalHazards/view.php?id=80987).

Activity during May-August 2013. There was a three-week break in reported ash plumes between 25 May and 19 June when a low level plume rising to 2.4 km was observed drifting 37 km SE. After this, no further activity was reported until 10 August. A large and deadly explosion took place on 10 August, producing an ash plume that rose to 4.3 km and drifted 130 km W. Details of the explosion are given in BGVN 39:01 and additional information is provided in this report. According to PVMBG, a substantial pyroclastic flow traveled NW from the summit down the Ojaubi drainage towards a village on the beach and killed five fisherman. Rescuers noted that the ground was hot and covered with 10-20 cm of ash. NASA-EO captured images before and after the 10 August 2013 eruption where the path of the pyroclastic flow to the NW is clearly visible (figure 9).

Figure 9. NASA-EO images of Paluweh (Mt. Rokatenda) on 3 August and 4 September 2013, before and after a large eruption with a deadly pyroclastic flow that traveled NW from the summit to the ocean, killing 5 people at the beach on 10 August. The delta on the S of the island was created during an earlier eruption and pyroclastic flow on 2-3 February 2013. Courtesy of NASA Earth Observatory ( http://earthobservatory.nasa.gov/IOTD/view.php?id=81986).

Activity during 2014-2016. In April 2014, PVMBG noted that the last major explosion had been on 10 August 2013. The last 2013 ash plume recorded by the Darwin VAAC was on 12 August 2013. Visual observations of occasional eruptive activity were noted until November 2013; small explosion earthquakes were also reported as being last recorded in November. No changes were observed in the lava dome between September 2013 and March 2014. PVMBG lowered the Alert level from III to II (on a scale of 1-4) on 7 April 2014.

No additional reports of activity at Paluweh appeared until late 2015, when PVMBG noted that steam plumes rising 75-200 m above the summit were common between August and October 2015. Seismicity remained low but variable during this time as well. From November 2015 through January 2016, steam plume heights ranged from 5-150 m. Seismicity remained low; earthquakes indicating rock avalanches and fumarolic emissions were the most common type recorded (figure 10). Paluweh remained quiet throughout 2016, although in February 2017 it was still listed by PVMBG at Alert Level II, with a potential for eruptive activity.

Figure 10. Seismic activity at Paluweh between 1 January 2015 and 13 January 2016. Vertical Axis represents daily number of events for all graphs. Guguran are avalanche events, Hembusan are emission-related events, Vulkanik Dangkal (VB) are shallow volcanic events, Vulkanik Dalam (VA) are deep volcanic events, Tektonik Local are local tectonic events, and Tektonik Jauh are distant tectonic events. Courtesy of PVMBG (Paluweh report, 18 January 2016).

Geologic Background. Paluweh volcano, also known as Rokatenda, forms the 8-km-wide island of Palu'e north of the volcanic arc that cuts across Flores Island. The broad irregular summit region contains overlapping craters up to 900 m wide and several lava domes. Several flank vents occur along a NW-trending fissure. The largest historical eruption occurred in 1928, when strong explosive activity was accompanied by landslide-induced tsunamis and lava dome emplacement. Pyroclastic flows in August 2013 resulted in 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/); 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/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/).

A brief eruption that began on 23 October 2013 was the first reported activity at Zhupanovsky since 1959 (BGVN 39:09). After another eight months of quiet, eruptive activity began again in early June 2014 that was characterized by periods of frequent, moderate, ash-generating explosions that continued through the end of that year (BGVN 39:09). As described below, similar activity continued from January 2015 through 24 March 2016, with periods of strong explosions generating ash plumes as high as 10 km altitude. Another long period of eight months without observed activity was broken by a large eruption on 20 November 2016. No additional activity was reported through March 2017. Most of the data comes from Kamchatka Volcanic Eruption Response Team (KVERT) reports. Often, the volcano is obscured by clouds. All reported dates are UTC unless otherwise noted (local = -12 hours).

Activity during 2015. According to KVERT, the moderate eruption with explosions generating ash plumes continued into 2015 (table 1). The Aviation Color Code remained Orange (third level on a four-color scale) between 1 January and 15 May 2015. After an explosion on 3 April, explosive activity waned and KVERT lowered the Aviation Color Code from Orange to Yellow (second level on a four-color scale) on 16 May. On 9 June 2015, activity increased again, with webcam and satellite images showing an ash plume rising to an altitude of 6 km. The Aviation Color Code was raised on 8 June to Orange.

During an overflight on 16 July, volcanologists observed fresh deposits at the foot of the volcano from collapses of the S section of the active Priemysh Crater that likely occurred on 12 July (figures 7 and 8). Moderate activity at the crater continued through 17 July; the Aviation Color Code was lowered to Yellow on 18 June and to Green on 23 July.

Figure 7. Photo of the summit area of Zhupanovsky showing the collapse deposits from the Priemysh cone, 16 July 2015. Photo credit to A. Plechova and V.I. Vernadsky, IGAC RAS. Courtesy of Institute of Volcanology and Seismology FEB RAS, KVERT.

Figure 8. Photo of the southern side of Zhupanovsky showing the collapse deposits from the Priemysh cone, 16 July 2015. Photo credit to A. Plechova and V.I. Vernadsky, IGAC RAS. Courtesy of Institute of Volcanology and Seismology FEB RAS, KVERT.

On 7 August KVERT reported that explosive activity had ended, but collapses of the S part of the active crater continued. On 6 August ash plumes rose to an altitude of 5 km and drifted 25-60 km SW, triggering KVERT to raise the Aviation Color Code to Yellow. The code was lowered back to Green on 13 August.

KVERT indicated that activity remained low until 27 November 2015 when, based on satellite images, ash plumes rose to altitudes of 5-6 km and drifted 285 km E. The Aviation Color Code was raised to Orange. IVS FED RAS (Institute Volcanology and Seismology Far East Division of the Russian Academy of Sciences) observers noted an ash explosion at 0356 on 30 November (UTC); the Tokyo Volcanic Ash Advisory Center (VAAC) reported that the resulting ash plume rose to an altitude of 9 km. Pyroclastic flow deposits 15.5 km long were observed on the S flank after the 30 November event.

According to KVERT, activity decreased after a partial collapse of the S central sector on 27 and 30 November 2015. Satellite images detected a very weak thermal anomaly over the volcano on 4 and 7 December. Moderate levels of fumarolic activity continued. On 10 December the Aviation Color Code was lowered to Yellow. By early-to-mid December 2015, only moderate levels of fumarolic activity were observed. On 17 December the Aviation Color Code was lowered to Green.

KVERT reported that thermal anomalies occurred frequently during the reporting period; often they were obscured by clouds. The only MODVOLC thermal alerts, based on MODIS anomalies, during the reporting period were during March-June 2015: on 7 March, 8 March (2 pixels), 15 March (2 pixels), 21 March (2 pixels), 20 May, and 16 June.

Table 1. Summary of reported activity at Zhupanosky, January 2015-March 2016. Data is from webcam images, satellite images, and visual observations. On many days, clouds obscured visibility. Courtesy of KVERT and Tokyo VAAC.

Activity during 2016. The eruption pattern of fluctuating activity levels continued into 2016. Based on visual observations, KVERT reported that at 1636 on 19 January 2016 (UTC), an explosion generated an ash plume that rose to an altitude of 7-8 km and drifted 20 km E (figure 9). The Aviation Color Code was raised to Orange.

Figure 9. Photo of the ash column rising from Zhupanovsky, 19 January 2016. Still image taken from webcam video. Courtesy of Institute of Volcanology and Seismology FEB RAS, KVERT.

Moderate steam-and-gas activity continued during 5 February-18 March. An explosion at 2029 on 12 February (UTC) was recorded by a video camera and generated an ash plume that rose to an altitude of 7 km and drifted E. A larger explosion visually observed a minute later generated an ash plume that rose to an altitude of 10 km and drifted 50 km SE. The Aviation Color Code was raised to Red for several hours. In a report issued at 2334 (UTC), KVERT noted that only moderate amounts of gas and steam rose from the volcano; the Aviation Color Code was lowered to Orange. Ash from the earlier explosions drifted E over Kronotsky Bay and NW. A few hours later, an ash plume was detected in satellite images rising 1 km above the volcano and drifting 288 km E.

The Tokyo VAAC recorded an explosion at 1320 on 24 March (UTC) that generated an ash plume which rose to an altitude of 8 km. After the explosion, no further activity was observed. A very weak thermal anomaly was detected over the volcano in satellite images on 1 and 10 April. The Aviation Color Code was thus lowered to Yellow on 13 April. The last thermal anomaly detection in a satellite image was on 10 April. However, moderate fumarolic activity continued. The Aviation Color Code was lowered to Green on 16 June.

At 1429 on 20 November 2016 a webcam recorded ash plumes rising to altitudes of 6-8 km and drifting 73 km E (figure 10); the Aviation Color Code was raised from Green to Orange. No further activity was observed, and on 22 November the Aviation Color Code was lowered to Yellow.

Figure 10. Photo of the ash column rising from Zhupanovsky and extending E, 20 November 2016. Still image taken from webcam video. Courtesy of Institute of Volcanology and Seismology FEB RAS, KVERT.

Geologic Background. The Zhupanovsky volcanic massif consists of four overlapping stratovolcanoes along a WNW-trending ridge. The elongated volcanic complex was constructed within a Pliocene-early Pleistocene caldera whose rim is exposed only on the eastern side. Three of the stratovolcanoes were built during the Pleistocene, the fourth is Holocene in age and was the source of all of Zhupanovsky's historical eruptions. An early Holocene stage of frequent moderate and weak eruptions from 7000 to 5000 years before present (BP) was succeeded by a period of infrequent larger eruptions that produced pyroclastic flows. The last major eruption took place about 800-900 years BP. Historical eruptions have consisted of relatively minor explosions from the third cone.

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/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences, (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).

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.

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.

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.

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 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 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 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.

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/).