********************************************************** SI/USGS Weekly Volcanic Activity Report 7-13 January 2009 ********************************************************** Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Rabaul, New Britain (SW Pacific) | Shishaldin, Fox Islands | Soufrière Hills, Montserrat | Tungurahua, Ecuador | Yasur, Vanuatu (SW Pacific) Ongoing Activity: | Barren Island, Andaman Islands (Indian Ocean) | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Dukono, Halmahera (Indonesia) | Etna, Sicily (Italy) | Fuego, Guatemala | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Llaima, Central Chile | Sakura-jima, Kyushu (Japan) | Shiveluch, Central Kamchatka (Russia) | Suwanose-jima, Ryukyu Islands (Japan) | Ubinas, Perú 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 RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 3-14 January gray ash plumes from Rabaul caldera's Tavurvur cone rose several hundred meters above the crater to 1.7 km (5,600 ft) a.s.l. and drifted SW and SE. Explosions or forceful emissions sometimes ejected incandescent lava fragments that fell back into the crater and occasionally onto the slopes. Ashfall affected areas downwind; Air Niugini suspended all its flights to Tokua airport (about 20 km SE) during 5-9 January. According to a news article, a local shipping company offered to take passengers to a nearby airport in New Ireland Province, an area not affected by the ash plumes. Based on analysis of satellite imagery, the Darwin VAAC reported that during 11-12 January ash plumes rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE, E, and NE. RVO reported that on 11 January two small vents opened on the SW flank of Tavurvur (one-quarter of the way up the flank) and emitted strong fumaroles. During 11-13 January, the vents ejected ash. On 13 January, two explosions produced dull booms and sounds resembling falling rocks. Ash plumes rose 200-500 m above the vents and drifted SE. Later that day, diffuse white plumes were emitted. Air Niugini flights into Tokua airport remained suspended on 13 January. 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. Sources: Ima Itikarai and Steve Saunders, Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html, Australian Broadcasting Corporation http://www.abc.net.au/news/stories/2009/01/09/2462543.htm?section=justin SHISHALDIN Fox Islands 54.756°N, 163.97°W; summit elev. 2857 m AVO reported that thermal anomalies over Shishaldin's summit were detected in satellite imagery during 7-10 January. Clouds prevented observations on 11, 12, and 13 January. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory. Geologic Summary. The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2,857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. Constructed atop an older glacially dissected volcano, Shishaldin is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the W and NE sides at 1,500-1,800 m elevation. Shishaldin contains over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of Strombolian ash eruptions from the small summit crater, sometimes producing lava flows, have been recorded since the 18th century. Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/ SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m MVO reported that during 2-3 January activity from the Soufrière Hills lava dome increased drastically. On 2 January, an energetic pyroclastic flow and associated surge traveled down Tyers Ghaut (NW) and reached the upper part of Belham River. On 3 January, after a period of elevated seismicity, two explosions produced ash plumes to altitudes greater than 10.7 km (35,000 ft) a.s.l. Ashfall affected most of the island at elevations of 1.2 km (4,000 ft) a.s.l. and above. The explosions had significant "jet components" to at least 500 m above the dome. In-column collapses resulted in pyroclastic flows that traveled W and reached Plymouth (about 5 km W). After the second explosion, the level of activity decreased dramatically and remained low through 9 January. The Hazard Level remained at 4. 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 TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m The IG reported that during 7-10 and 12 January steam-and-ash plumes from Tungurahua rose to altitudes of 6-6.5 km (19,700-21,300 ft) a.s.l. and drifted NW, WNW, W, and E. On most days, ash fell within 8 km NW and SW, and roaring, explosions, and "cannon shot" noises were reported. On 7 and 10 January, incandescence blocks ejected from the crater rolled down the flanks. 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/ YASUR Vanuatu (SW Pacific) 19.53°S, 169.442°E; summit elev. 361 m Based on a pilot observation, the Wellington VAAC reported that an ash plume from Yasur rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted SE. Ash was not identified on satellite imagery. Geologic Summary. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous Strombolian and vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Yasur is a mostly unvegetated pyroclastic cone with a nearly circular, 400-m-wide summit crater. Yasur is largely contained within the small Yenkahe caldera in SE Tanna Island. It is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. Active tectonism along the Yenkahe horst accompanying eruptions of Yasur has raised Port Resolution harbor more than 20 m during the past century. Source: Wellington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html Ongoing Activity BARREN ISLAND Andaman Islands (Indian Ocean) 12.278°N, 93.858°E; summit elev. 354 m Based on analysis of satellite imagery, the Darwin VAAC reported that during 7-8 and 10-11 January ash plumes from Barren Island rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted W and SW. 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 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 on 7 January ash plumes from Batu Tara rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted NE and ENE. 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 SERNAGEOMIN reported that during 29 December-9 January Chaitén's Domo Nuevo 2 continued to grow and generate a gas-and-ash plume. The plume rose to altitudes of 2.6-3.1 km (8,500-10,200 ft) a.s.l.; block-and-ash flows from frequent spine collapses tinged the plume reddish brown. On 2 January, observers in Chaitén town reported that a block-and-ash flow traveled E and produced a second plume. An overflight on 9 January revealed that Domo Nuevo 1 and Domo Nuevo 2 filled up the 3-km-wide inner caldera. Activity was concentrated on the S part of Domo Nuevo 2. The Alert Level remained Red. According to a news article, Argentine Airlines resumed flights into Esquel airport (about 120 km E) on 12 January, after suspending operations due to ash during the previous eight months. Based on SIGMET notices and web camera views, the Buenos Aires VAAC reported that on 10 and 12 January ash plumes continuously rose to altitudes 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted NNE and E. 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. Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/, Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html, Infobae http://www.infobae.com/contenidos/424719-100894-0-Reanudan-los-vuelos-Esquel-la-erupci%C3%B3n-del-Volc%C3%A1n-Chait%C3%A9n DUKONO Halmahera (Indonesia) 1.68°N, 127.88°E; summit elev. 1335 m Based on analysis of satellite imagery, the Darwin VAAC reported that on 7 January ash plumes from Dukono rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted E and SE. 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 ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m INGV-CT reported that during 5-11 January activity from Etna's summit craters was observed utilizing surveillance cameras situated in Milo (about 11 km ESE); inclement weather prevented direct inspection of the summit area. Degassing was seen from the NW Bocca Nuova vent, from the walls and floor of Southeast Crater, and along summit fumarolic fields. The NW-SE-trending fissure E of the summit craters continued (since 13 May 2008) to produce active lava flows to the N of the SE end of the fissure, along the W wall of the Valle del Bove. Geologic Summary. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BC. Historical lava flows cover much of the surface of this massive basaltic stratovolcano, the highest and most voluminous in Italy. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater. Flank eruptions, typically with higher effusion rates, occur less frequently and originate from fissures that open progressively downward from near the summit. A period of more intense intermittent explosive eruptions from Etna's summit craters began in 1995. The active volcano is monitored by the Instituto Nazionale di Geofisica e Volcanologia (INGV) in Catania. Source: Istituto Nazionale di Geofisica e Vulcanologia Sezione di Catania (INGV-CT) http://www.ct.ingv.it/ FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m INSIVUMEH reported that during 8-9 January, multiple explosions (3-5 per hour) from Fuego produced ash plumes that rose to altitudes of 4.3-5.4 km (14,100-17,700 ft) a.s.l. and drifted 10-15 km S and SW. The explosions produced rumbling sounds and shock waves that were detected 10-15 km away. Ashfall was reported in areas downwind. Constant avalanches of blocks descended the S and SW flanks. Based on analysis of satellite imagery and information from the Tegucigalpa MWO, the Washington VAAC reported that on 10 January a diffuse plume drifted W. 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. Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that during 2-9 January seismic activity from Karymsky was not evaluated due to technical issues. Analysis of satellite imagery revealed a thermal anomaly in the crater on 7 January; clouds prevented observations on the other days. 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 7-13 January lava flowed SE through a tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex, reaching the Waikupanaha ocean entry. Surface flows were noted on the coastal plain and incandescence was seen at the base of the pali. Explosions at the ocean entry were seen on 6, 8, and 11 January. A lobe of lava called the Prince lobe, to the W of Waikupanaha, advanced to within about 160 m of the coastline. The vent in Halema'uma'u crater continued to produce a predominantly white plume that drifted mainly SW. Tephra production had stopped; rockfalls inside the vent continued. An infrared camera showed that the vent conduit was closed by rubble deep beneath the floor of the crater. The sulfur dioxide emission rate at the summit was 800 tonnes per day on 7 January; above the 2003-2007 average rate of 140 tonnes per day. Variable winds periodically caused sulfur dioxide concentrations in the air to reach unsafe levels and effect nearby communities, and caused the Jaggar Museum to close on 12 January. 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/ 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 1-9 January. Strombolian activity and lava effusion on the NW flank continued. Analysis of satellite imagery revealed a large daily thermal anomaly in the crater. Ashfall was reported in Kozyrevsk village (about 50 km W) on 1 January. Ash plumes drifted 60 km N on 1 January and 35 km SW on 2 January. 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/index_eng.php LLAIMA Central Chile 38.692°S, 71.729°W; summit elev. 3125 m SERNAGEOMIN reported that ash emissions and gas plumes from cones inside Llaima's crater were observed during 30 December-6 January. Geologic Summary. Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other to the SE. The massive 3,125-m-high, glacier-covered stratovolcano has a volume of 400 cu km. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following eruption of the 24 cu km Curacautín Ignimbrite. More than 40 scoria cones dot the volcano's flanks. Following the end of an explosive stage about 7,200 years ago, construction of the present edifice began, characterized by Strombolian, Hawaiian, and infrequent subplinian eruptions. Frequent moderate explosive eruptions with occasional lava flows have been recorded since the 17th century. Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/ SAKURA-JIMA Kyushu (Japan) 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported that on 9 January an eruption from Sakura-jima produced a plume that rose to an altitude of more than 2.4 km (8,000 ft) a.s.l. and drifted SE. Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76. Source: 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 seismic activity at Shiveluch was above background levels during 2-9 January. Based on interpretations of seismic data, ash plumes rose to an altitude of 8.8 km (28,900 ft) a.s.l. on 7 January and to an altitude of 5.7 km (18,700 ft) a.s.l. on the other days during the reporting period. Analysis of satellite imagery revealed a large daily thermal anomaly on the lava dome and an ash plume that drifted 25 km W on 6 January. Gas-and-steam emissions were seen on 2, 4, and 6 January. Ash deposits were noted in areas about 10 km SW on 7 January. 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/index_eng.php SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m Based on information from JMA, the Tokyo VAAC reported an explosion from Suwanose-jima on 9 January. Geologic Summary. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent Strombolian activity from On-take, the NE summit crater, that began in 1949 and lasted nearly a half century. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, after which the island was uninhabited for about 70 years. The SW crater produced lava flows that reached the western coast in 1813, and lava flows reached the eastern coast of the island in 1884. Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html UBINAS Perú 16.355°S, 70.903°W; summit elev. 5672 m Based on a SIGMET notice, the Buenos Aires VAAC reported that on 11 January an ash plume from Ubinas rose to an altitude of 7.3 km (24,000 ft) a.s.l. and drifted NE. Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives it a truncated appearance. Ubinas is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank of Ubinas extend 10 km from the volcano. Widespread Plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions. Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html +++++++++++++++++++++++++++++++++++++ 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. ==============================================================
