SI / USGS Weekly VolcanicActivityReport                             Sally Kuhn Sennert - Weekly Report Editor                                 http://www.volcano.si.edu/reports/usgs                                   16 September - 22 September 2009  New Activity/Unrest: | Karymsky, Eastern Kamchatka | Kliuchevskoi, Central Kamchatka (Russia) | Sakar, Northeast of New Guinea (SW Pacific) | Shiveluch, Central Kamchatka (Russia) Ongoing Activity: | Bagana, Bougainville | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Dukono, Halmahera | Kilauea, Hawaii (USA) | Rabaul, New Britain | Reventador, Ecuador | Sakura-jima, Kyushu | Suwanose-jima, Ryukyu Islands (Japan) This page is updated on Wednesdays, please see the GVP Home Page for news of the latest significant activity. 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 _link_s 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 KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m On 22 September, KVERT raised the Level of Concern Color Code for Karymsky to Yellow because seismic activity increased. The seismic network likely detected ash bursts that possibly produced plumes that rose to altitudes less than 2 km (6,600 ft) a.s.l. 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. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Karymsky Information from the Global Volcanism Program KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m KVERT reported that although seismic activity from Kliuchevskoi did not exceed background levels during 11-18 September, weak tremor was detected. Satellite imagery revealed a weak thermal anomaly over the volcano from 13 to 17 September. Strombolian activity that ejected tephra 70 m above the crater was seen at night on 16 and 17 September. The Level of Concern Color Code was raised to Yellow. 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. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Kliuchevskoi Information from the Global Volcanism Program SAKAR Northeast of New Guinea (SW Pacific) 5.414°S, 148.094°E; summit elev. 992 m _base_d on analyses of satellite imagery, the Darwin VAAC reported that on 18 September a possible diffuse ash plume from Sakar rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted 165 km NW. Four hours later images showed that the volcano was clear; the plume may have been smoke from a fire or steam. RVO was unable to confirm that an eruption had or had not occurred. Geologic Summary. Sakar is an incised stratovolcano with a summit crater lake. Deep valleys cut the flanks of the volcano, which is partially surrounded by coral reefs. An older volcano that forms much of the island consists mainly of porphyritic basaltic rocks. A younger andesitic cone with a 1.5-km-wide crater has been constructed within the older volcano's larger crater, whose rim is exposed on the northern and eastern sides. No historical eruptions are known from Sakar, but warm springs are found along the SW coast, and a pyroclastic cone on the southern flank of the 8 x 10 km wide island may be of Holocene age. Map Source: Darwin Volcanic Ash Advisory Centre (VAAC) Sakar Information from the Global Volcanism Program SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that during 11-18 September seismic activity from Shiveluch was above background levels. Analyses of satellite imagery revealed a large daily thermal anomaly over the lava dome. _base_d on interpretations of seismic data, ash plumes possibly rose to an altitude of 7.1 km (23,300 ft) a.s.l. On 13 September, pyroclastic flow deposits 5 km long were seen on the S part of the lava dome. Fumarolic activity was seen during 13 and 16-17 September, and hot avalanches originated from the lava dome were seen at night on 16 and 17 September. The Level of Concern Color Code remained at Orange. _base_d on information from KEMSD, the Tokyo VAAC reported that on 19 September eruptions produced plumes that rose to an altitude of 5.2 km (17,000 ft) a.s.l. 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. Map Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC) Shiveluch Information from the Global Volcanism Program Ongoing Activity BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m _base_d on analyses of satellite imagery, the Darwin VAAC reported that during 17-19 September ash plumes from Bagana rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 25-45 km NW, W, and SW. 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. Map Source: Darwin Volcanic Ash Advisory Centre (VAAC) Bagana Information from the Global Volcanism Program BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m _base_d on analyses of satellite imagery, the Darwin VAAC reported that during 16-19 and 21-22 September ash plumes from Batu Tara rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted 20-65 km W, NW, N, and NE. 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. Map Source: Darwin Volcanic Ash Advisory Centre (VAAC) Batu Tara Information from the Global Volcanism Program CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m During 1-16 September, SERNAGEOMIN reported that Chaitén's Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex continued to grow. The Alert Level remained at Red. _base_d on web camera views, SIGMET notices, and analyses of satellite imagery, the Buenos Aires VAAC reported that during 16 and 20-22 September ash plumes rose to altitudes of
... read more »