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SI/USGS Weekly Volcanic Activity Report 11-17 August 2010
From: "Sally Kuhn Sennert" <KUHNS@xxxxxx>
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SI/USGS Weekly Volcanic Activity Report
11-17 August 2010
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Kilauea, Hawaii (USA) | Manam, Northeast of New Guinea (SW Pacific) | San Miguel, El Salvador
Ongoing Activity: | Bagana, Bougainville | Batu Tara, Komba Island (Indonesia) | Dukono, Halmahera | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Kliuchevskoi, Central Kamchatka (Russia) | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Turrialba, Costa Rica | Ulawun, New Britain
The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.
New Activity/Unrest
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 11-17 August HVO reported that activity at Kilauea continued from the summit caldera and the east rift zone. At the summit caldera, the level of the lava-pool surface in the deep pit within the floor of Halema'uma'u crater remained mostly stable; glow from the vent was also visible at night. A plume from the vent mainly drifted SW, dropping small amounts of ash downwind. At Pu'u 'O'o crater, a small incandescent vent on the N floor that occasionally extruded lava flows was observed to be a hornito. At the east rift zone, lava that flowed through the TEB lava-tube system fed occasional surface flows at the base of the pali and on the coastal plain WNW and W of Kalapana Gardens, as well as the Puhi-o-Kalaikini ocean entry.
Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/
MANAM Northeast of New Guinea (SW Pacific) 4.080°S, 145.037°E; summit elev. 1807 m
RVO reported that incandescence from Manam's South Crater was visible at 4-5 minute intervals on 10 August. The next day diffuse black ash plumes rose a few hundred meters above the rim. Steady incandescence was accompanied by periodic ejections of lava fragments ejected 400-500 m above the rim. Main Crater emitted diffuse white vapor. Based on analysis of satellite imagery, the Darwin VAAC reported that on 14 August ash plumes rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 55 km NW.
Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE avalanche valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded at Manam since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.
Sources: Rabaul Volcano Observatory (RVO),
Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
SAN MIGUEL El Salvador 13.434°N, 88.269°W; summit elev. 2130 m
On 13 August, Servicio Nacional de Estudios Territoriales (SNET) reported that seismicity remained above background levels after an increase was detected on 1 August. Average background RSAM values ranged from 15 to 50 units per day. During 12-13 August, RSAM values ranged between 433 and 465. Over the next few days, seismicity decreased significantly; from 14 August to 16 August, RSAM values decreased from 188 to 132. Access to areas within a 2-km-radius remained restricted.
Geologic Summary. The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. A broad, deep crater that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit of the towering volcano, which is also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic volcano have fed a series of fresh lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the N, W, and SE sides. The SE-flank lava flows are the largest and form broad sparsely vegetated lava fields.
Source: Servicio Nacional de Estudios Territoriales (SNET) http://www.snet.gob.sv/
Ongoing Activity
BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 13-15 August ash plumes from Bagana rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 75 km SW and W.
Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is 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 volcano's flanks on all sides.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 13-17 August ash plumes from Batu Tara drifted 35-95 km NW and W at altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l.
Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 12-17 August ash plumes from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 25-95 km W, NW, and SW.
Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m
During 12-17 August, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.7 km (13,500-15,400 ft) a.s.l. and drifted W and NW. Rumbling and "degassing" sounds were associated with the explosions. At night during 15-16 August explosions ejected incandescent material 100 m above the crater. On 17 August blocks descended the S flanks.
Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that during 6-13 August seismic activity from Karymsky was above background levels and suggested that possible ash plumes rose to an altitude of 2.5 km (8,200 ft) a.s.l. A thermal anomaly over the volcano was detected in satellite imagery during 7-8 and 10-11 August. Based on analyses of satellite imagery and information from KVERT, the Tokyo VAAC reported an eruption on 16 August. A subsequent notice stated that ash had dissipated. The Aviation Color Code level remained at Orange.
Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 6-13 August seismic activity from Kliuchevskoi was above background levels and lava flowed down the SW flank. Strombolian activity and gas-and-ash emissions were observed during 6 and 8-12 August. Cloud cover prevented observations the other days. Satellite imagery analysis showed a large and intense daily thermal anomaly on the volcano. Based on analyses of satellite imagery, the Tokyo VAAC reported a possible eruption on 16 August. A subsequent notice stated that ash had dissipated. The Aviation Color Code level remained at Orange.
Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 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 major explosive and effusive events from flank craters.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 6-13 August seismic activity from Shiveluch was above background levels, suggesting that possible ash plumes rose to an altitude of 6.5 km (21,300 ft) a.s.l. on 9 August and to an altitude of 4 km (13,100 ft) a.s.l. the other days. Cloud cover prevented visual observations. Satellite imagery analysis showed a daily thermal anomaly on the volcano and an ash plume that drifted 55 km NW on 10 August. The Aviation Color Code level remained at Orange.
Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that mild ash-and-steam venting from Soufrière Hills as well as rockfalls were seen during 6-13 August. Most of the activity was focused in the collapse scar and above the Gages valley to the W. On 6 August a small ash plume rose 1 km above the lava dome, and on 8 August a pyroclastic flow descended Gages valley. The Hazard Level remained at 3.
Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.
Source: Montserrat Volcano Observatory (MVO) http://www.mvo.ms/
TURRIALBA Costa Rica 10.025°N, 83.767°W; summit elev. 3340 m
The Washington VAAC reported that on 15 August ash emissions from Turrialba were seen through an OVSICORI-UNA web camera, about 600 m E of the active crater. Satellite imagery showed an approximately 10-km-wide ash plume drifting 15 km W.
Geologic Summary. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m wide summit depression that is breached to the NE. Most activity at Turrialba originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred at Turrialba during the past 3500 years. Turrialba has been quiescent since a series of explosive eruptions during the 19th century that were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.
Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
ULAWUN New Britain 5.05°S, 151.33°E; summit elev. 2334 m
RVO reported that white and gray-to-brown plumes rose no more than 300 m above Ulawun during 6-12 August, and fine ash fell on the NW and W flanks. Seismicity decreased as compared to previous weeks.
Geologic Summary. 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. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S 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.
Source: Rabaul Volcano Observatory (RVO)
11-17 August 2010
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Kilauea, Hawaii (USA) | Manam, Northeast of New Guinea (SW Pacific) | San Miguel, El Salvador
Ongoing Activity: | Bagana, Bougainville | Batu Tara, Komba Island (Indonesia) | Dukono, Halmahera | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Kliuchevskoi, Central Kamchatka (Russia) | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Turrialba, Costa Rica | Ulawun, New Britain
The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.
New Activity/Unrest
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 11-17 August HVO reported that activity at Kilauea continued from the summit caldera and the east rift zone. At the summit caldera, the level of the lava-pool surface in the deep pit within the floor of Halema'uma'u crater remained mostly stable; glow from the vent was also visible at night. A plume from the vent mainly drifted SW, dropping small amounts of ash downwind. At Pu'u 'O'o crater, a small incandescent vent on the N floor that occasionally extruded lava flows was observed to be a hornito. At the east rift zone, lava that flowed through the TEB lava-tube system fed occasional surface flows at the base of the pali and on the coastal plain WNW and W of Kalapana Gardens, as well as the Puhi-o-Kalaikini ocean entry.
Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/
MANAM Northeast of New Guinea (SW Pacific) 4.080°S, 145.037°E; summit elev. 1807 m
RVO reported that incandescence from Manam's South Crater was visible at 4-5 minute intervals on 10 August. The next day diffuse black ash plumes rose a few hundred meters above the rim. Steady incandescence was accompanied by periodic ejections of lava fragments ejected 400-500 m above the rim. Main Crater emitted diffuse white vapor. Based on analysis of satellite imagery, the Darwin VAAC reported that on 14 August ash plumes rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 55 km NW.
Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE avalanche valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded at Manam since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.
Sources: Rabaul Volcano Observatory (RVO),
Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
SAN MIGUEL El Salvador 13.434°N, 88.269°W; summit elev. 2130 m
On 13 August, Servicio Nacional de Estudios Territoriales (SNET) reported that seismicity remained above background levels after an increase was detected on 1 August. Average background RSAM values ranged from 15 to 50 units per day. During 12-13 August, RSAM values ranged between 433 and 465. Over the next few days, seismicity decreased significantly; from 14 August to 16 August, RSAM values decreased from 188 to 132. Access to areas within a 2-km-radius remained restricted.
Geologic Summary. The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. A broad, deep crater that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit of the towering volcano, which is also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic volcano have fed a series of fresh lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the N, W, and SE sides. The SE-flank lava flows are the largest and form broad sparsely vegetated lava fields.
Source: Servicio Nacional de Estudios Territoriales (SNET) http://www.snet.gob.sv/
Ongoing Activity
BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 13-15 August ash plumes from Bagana rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 75 km SW and W.
Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is 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 volcano's flanks on all sides.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 13-17 August ash plumes from Batu Tara drifted 35-95 km NW and W at altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l.
Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 12-17 August ash plumes from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 25-95 km W, NW, and SW.
Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m
During 12-17 August, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.7 km (13,500-15,400 ft) a.s.l. and drifted W and NW. Rumbling and "degassing" sounds were associated with the explosions. At night during 15-16 August explosions ejected incandescent material 100 m above the crater. On 17 August blocks descended the S flanks.
Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that during 6-13 August seismic activity from Karymsky was above background levels and suggested that possible ash plumes rose to an altitude of 2.5 km (8,200 ft) a.s.l. A thermal anomaly over the volcano was detected in satellite imagery during 7-8 and 10-11 August. Based on analyses of satellite imagery and information from KVERT, the Tokyo VAAC reported an eruption on 16 August. A subsequent notice stated that ash had dissipated. The Aviation Color Code level remained at Orange.
Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 6-13 August seismic activity from Kliuchevskoi was above background levels and lava flowed down the SW flank. Strombolian activity and gas-and-ash emissions were observed during 6 and 8-12 August. Cloud cover prevented observations the other days. Satellite imagery analysis showed a large and intense daily thermal anomaly on the volcano. Based on analyses of satellite imagery, the Tokyo VAAC reported a possible eruption on 16 August. A subsequent notice stated that ash had dissipated. The Aviation Color Code level remained at Orange.
Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 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 major explosive and effusive events from flank craters.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 6-13 August seismic activity from Shiveluch was above background levels, suggesting that possible ash plumes rose to an altitude of 6.5 km (21,300 ft) a.s.l. on 9 August and to an altitude of 4 km (13,100 ft) a.s.l. the other days. Cloud cover prevented visual observations. Satellite imagery analysis showed a daily thermal anomaly on the volcano and an ash plume that drifted 55 km NW on 10 August. The Aviation Color Code level remained at Orange.
Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that mild ash-and-steam venting from Soufrière Hills as well as rockfalls were seen during 6-13 August. Most of the activity was focused in the collapse scar and above the Gages valley to the W. On 6 August a small ash plume rose 1 km above the lava dome, and on 8 August a pyroclastic flow descended Gages valley. The Hazard Level remained at 3.
Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.
Source: Montserrat Volcano Observatory (MVO) http://www.mvo.ms/
TURRIALBA Costa Rica 10.025°N, 83.767°W; summit elev. 3340 m
The Washington VAAC reported that on 15 August ash emissions from Turrialba were seen through an OVSICORI-UNA web camera, about 600 m E of the active crater. Satellite imagery showed an approximately 10-km-wide ash plume drifting 15 km W.
Geologic Summary. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m wide summit depression that is breached to the NE. Most activity at Turrialba originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred at Turrialba during the past 3500 years. Turrialba has been quiescent since a series of explosive eruptions during the 19th century that were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.
Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
ULAWUN New Britain 5.05°S, 151.33°E; summit elev. 2334 m
RVO reported that white and gray-to-brown plumes rose no more than 300 m above Ulawun during 6-12 August, and fine ash fell on the NW and W flanks. Seismicity decreased as compared to previous weeks.
Geologic Summary. 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. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S 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.
Source: Rabaul Volcano Observatory (RVO)
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