********************************************************** SI/USGS Weekly Volcanic Activity Report 3-9 December 2008 ********************************************************** Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Barren Island, Andaman Islands (Indian Ocean) | Kliuchevskoi, Central Kamchatka (Russia) | Nevado del Huila, Colombia | Soufrière Hills, Montserrat Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Colima, México | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Rabaul, New Britain (SW Pacific) | Shiveluch, Central Kamchatka (Russia) | Tongariro, New Zealand | Tungurahua, Ecuador 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 BARREN ISLAND Andaman Islands (Indian Ocean) 12.278°N, 93.858°E; summit elev. 354 m The Darwin VAAC reported that during 7-8 December pilots observed lava flows on Barren Island; ash plumes were not present. Thermal anomalies were detected on satellite imagery. Geologic Summary. Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit of volcano that rises from a depth of about 2,250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with walls 250-350 m high. The caldera, which is open to the sea on the W, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic-flow and -surge deposits. The morphology of a fresh pyroclastic cone that was constructed in the center of the caldera has varied during the course of historical eruptions. Lava flows fill much of the caldera floor and have reached the sea along the western coast during historical eruptions. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m KVERT reported that seismic activity at Kliuchevskoi was above background levels during 28 November-10 December; Strombolian activity ejected bombs 500 m above the crater and lava effusion on the NW flank continued. Analysis of satellite imagery revealed a large daily thermal anomaly in the crater. During 27-29 November, and 2 and 4 December, gas-and-steam plumes with little ash content rose to altitudes of 6-6.2 km (19,700-20,300 ft) a.s.l. and drifted 40-115 km NE, E, SE, and SW. During 4-5 December, the ash content in plumes increased. On 8 December, phreatic bursts occurred where the lava flow front contacted the Erman Glacier. On 9 December, a 50-km-wide ash plume drifted about 550 km ENE. The Level of Concern Color Code was raised to Red. KVERT warned that the activity was dangerous for international and low-flying aircraft. On 10 December, the Level of Concern Color Code was lowered back to Orange because explosive activity decreased. A gas-and-steam plume with a small amount of ash drifted NE. 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. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5365 m INGEOMINAS reported that seismicity from Nevado del Huila continued to be elevated during 2-9 December. On 4 and 6 December overflights were conducted to view the new lava dome at the S flank of Pico Central. The dome elongated towards the SW of Pico Central, following the topography, and measured 400 m in the north-south direction, 150 m in the east-west direction, and was 120 m high. The approximate volume of the dome was 4,500,000 cubic meters. Gas plumes rose 1 km above the dome. New cracks in the glacier were also noted. Geologic Summary. Nevado del Huila, the highest active volcano in Colombia, is an elongated N-S-trending volcanic chain mantled by a glacier icecap. The andesitic-dacitic volcano was constructed within a 10-km-wide caldera. Volcanism at Nevado del Huila has produced six volcanic cones whose ages in general migrated from south to north. Two glacier-free lava domes lie at the southern end of the Huila volcanic complex. The first historical eruption from this little known volcano took place in the 16th century. Two persistent steam columns rise from the central peak, and hot springs are also present. Source: Instituto Colombiano de Geología y Minería (INGEOMINAS) http://www.ingeominas.gov.co// SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m MVO reported a total of four explosive events from the Soufrière Hills lava dome during 2-5 December. The first event was triggered by a small dome collapse on 2 December, occurred without precursory seismicity, and was followed by a pyroclastic flow on the W flank. Resultant ash plumes, accompanied by lightning strikes, rose to an altitude of 12.2 km (40,000 ft) a.s.l. and drifted W. Explosions ejected incandescent blocks up to 1.6 km away from the dome that landed on Gages Mountain (about 1 km WNW), leaving impact craters. The pyroclastic flow also generated multiple pyroclastic surges that traveled S and N, setting fire to trees and bushes. On 3 December another explosion scattered incandescent blocks all over the NW side of Gages Mountain. The third eruptive event, forceful emissions of ash on 4 December, resulted in ash plumes that rose to an altitude of 4.6 km (15,000 ft) a.s.l. The fourth explosive event occurred on 5 December and ejected incandescent blocks that were deposited on the NW side of Gages Mountain. A pyroclastic flow traveled to the W down Gages valley into Plymouth (about 5 km W) and an ash plume drifted NW. On 3, 4, and 5 December small, relatively slow moving pyroclastic flows traveled no more than 3.2 km down the Gages valley. In periods between the events, near-continuous emissions of ash-laden steam were noted. The Hazard Level remained at 3. According to the Washington VAAC, MVO reported eruptions on 6 December. Ash was seen on satellite imagery expanding in multiple directions, then to the E, SE, and W. 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. Sources: Montserrat Volcano Observatory (MVO) http://www.mvo.ms/, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html Ongoing Activity BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m Based on analysis of satellite imagery, the Darwin VAAC reported that during 6-7 December ash plumes from Batu Tara rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted about 55 km NW and SW. 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 CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m Based on observations of satellite imagery, pilot reports, SIGMET notices, and web camera views, the Buenos Aires VAAC reported that during 3-8 December, ash plumes from Chaitén rose to altitudes 1.8-4.6 km (6,000-15,000 ft) a.s.l. and drifted NE, NW, and SW. A thermal anomaly was detected on satellite imagery during 4 and 6-8 December. Geologic Summary. Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m. Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html COLIMA México 19.514°N, 103.62°W; summit elev. 3850 m During 3-8 December, gray plumes from Colima rose to altitudes of 4.2-4.6 km (13,800-15,100 ft) a.s.l. and drifted N and W; a gray plume rose to an altitude of 6.4 km (21,000 ft) a.s.l. on 4 December. White plumes were also observed and, during 4-8 December, rose to a maximum altitude of 4.2 km (13,800 ft) a.s.l. The white plumes drifted SW and SE. Geologic Summary. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4,320 m high point of the complex) on the N and the historically active Volcán de Colima on the S. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the S, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth. Source: Gobierno del Estado de Colima http://www.colima-estado.gob.mx/2006/seguridad/indvolcan.php KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that seismic activity at Karymsky was at background levels during 27-30 November; possible explosions may have generated ash-and-gas plumes to an altitude of 3.7 km (12,100 ft) a.s.l. Analysis of satellite imagery revealed a thermal anomaly in the crater during 27-29 November and 1 December. The Level of Concern Color Code 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. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m HVO reported that during 3-9 December lava flowed SE through a tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex, reaching the Waikupanaha ocean entry. Incandescence was occasionally seen at the TEB vent, and surface flows were noted on and at the base of the pali. On 6 December, a few explosions originated from the ocean entry. Observers reported that a small bench collapse that occurred sometime between 6 and 7 December sent boulders up to 0.5 m in diameter inland about 50-75 m. Earthquakes were variously located beneath and to the S of the caldera, along the SW rift zone, and along the S-flank fault. The vent in Halema'uma'u crater continued to produce a predominantly white plume that drifted mainly SW and deposited small amounts of tephra. Night-time incandescence was rarely seen at the base of the plume, and sounds resembling rockfalls were heard in the vicinity of the crater. During 2-4 December, the plume drifted NW and high concentrations of sulfur dioxide were measured at various locations. On 4 December, hybrid earthquakes were followed by several minutes of dense brown emissions. A vent rim collapse was seen on 5 December after rockfall and booming sounds were heard, and brown ash was emitted. The sulfur dioxide emission rate at the summit was 1,000 and 500 tonnes per day on 4 and 5 December, respectively; the 2003-2007 average rate was 140 tonnes per day. 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/ RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m Based on analysis of satellite imagery and information from RVO, the Darwin VAAC reported that during 3-5, 7, and 9 December ash plumes from Rabaul caldera's Tavurvur cone rose to altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l. and drifted E, NE, NNW, WNW, and W. Geologic Summary. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the E, where its floor is flooded by Blanche Bay.Two major Holocene caldera-forming eruptions at Rabaul took place as recently as 3,500 and 1,400 years ago. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that seismic activity at Shiveluch was above background levels during 28 November-5 December. Based on interpretations of seismic data, ash plumes rose to an altitude of 5.8 km (19,000 ft) a.s.l. According to visual observations, gas-and-steam plumes rose to an altitude of 3.5 km (11,500 ft) a.s.l. during 27 and 29-30 November, and 2 December. Analysis of satellite imagery revealed a daily thermal anomaly on the lava dome. The Level of Concern Color Code 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. During the 1990s, intermittent explosive eruptions took place 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/updates.shtml TONGARIRO New Zealand 39.13°S, 175.642°E; summit elev. 1978 m The Alert Level for Tongariro was lowered to 0 (typical background activity) on 2 December. The number of volcanic earthquakes declined to background levels since mid-2008. In addition, regular measurements of volcanic gas levels and the temperature of the summit gas vent showed no changes over the previous two and a half years. Geologic Summary. Tongariro is a large andesitic volcanic massif, located immediately NE of Ruapehu volcano, that is composed of more than a dozen composite cones constructed over a period of 275,000 years. Vents along a NE-trending zone extending from Saddle Cone (below Ruapehu volcano) to Te Mari crater (including vents at the present-day location of Ngauruhoe) were active during a several hundred year long period around 10,000 years ago, producing the largest known eruptions at the Tongariro complex during the Holocene. The youngest cone of the complex, Ngauruhoe, has grown to become the highest peak of the massif since its birth about 2500 years ago. The symmetrical, steep-sided Ngauruhoe, along with its neighbor Ruapehu to the south, have been New Zealand's most active volcanoes during historical time. Source: GeoNet Data Centre http://www.geonet.org.nz/index.html TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m The IG reported that on 4 December an ash plume from Tungurahua rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted E. Light ashfall was reported in Runtún (6 km NNE) and Pondoa (about 8 km N). Cloud cover prevented visual observations during 5-9 December. Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano. Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/ +++++++++++++++++++++++++++++++++++++ Sally Kuhn Sennert SI/USGS Weekly Volcanic Activity Report Editor Global Volcanism Program http://www.volcano.si.edu/reports/usgs/ Smithsonian Institution, National Museum of Natural History Department of Mineral Sciences, MRC-119 Washington, D.C., 20560 Phone: 202.633.1805 Fax: 202.357.2476 ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
