*************************************************************************************************** SI/USGS Weekly Volcanic Activity Report 28 October-3 November 2009 From: "Sally Kuhn Sennert" <KUHNS@xxxxxx> *************************************************************************************************** SI/USGS Weekly Volcanic Activity Report 28 October-3 November 2009 Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Ebeko, Paramushir Island | Galeras, Colombia | Karangetang [Api Siau], Siau I | Manam, Northeast of New Guinea (SW Pacific) | Nevado del Huila, Colombia | Soufrière Hills, Montserrat Ongoing Activity: | Barren Island, Andaman Is | Chaitén, Southern Chile | Dukono, Halmahera | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Krakatau, Indonesia | Popocatépetl, México | Rabaul, New Britain | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Suwanose-jima, Ryukyu Islands (Japan) 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 EBEKO Paramushir Island 50.68°N, 156.02°E; summit elev. 1156 m KVERT reported that on 26 October a gas-and-steam plume from Ebeko was seen by observers in Severo-Kurilsk, about 7 km E of Ebeko, rising 300 m above the crater and drifting 1-2 km NNE. There was no evidence of ash deposits on the snow cover. Gas-and-steam plumes rose 250 m above the crater and drifted 2 km E on 28 October and NNE on 29 October. The Level of Concern Color Code remained at Green. Geologic Summary. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. The eastern part of the southern crater of Ebeko contains strong solfataras and a large boiling spring. The central crater of Ebeko is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters of Ebeko, on the outer flanks of the cone, and in lateral explosion craters. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4276 m On 30 October, INGEOMINAS reported that the Alert Level for Galeras was raised to II (Orange; "probable eruption in term of days or weeks"). Since 27 October, degassing decreased and seismicity increased, reflecting conditions seen prior to previous eruptions. On 3 November, INGEOMINAS stated that gas emissions had been low during the previous days, and seismicity had decreased that day. Geologic Summary. Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Longterm extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors. Source: Instituto Colombiano de Geología y Minería (INGEOMINAS) http://www.ingeominas.gov.co// KARANGETANG [API SIAU] Siau I 2.78°N, 125.40°E; summit elev. 1784 m Based on a pilot observation and analyses of satellite imagery, the Darwin VAAC reported that on 3 November an ash plume from Karangetang rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 90-185 km W. Geologic Summary. Karangetang (also known as Api Siau) lies at the northern end of the island of Siau, N of Sulawesi, and contains five summit craters strung along a N-S line. One of Indonesia's most active volcanoes, Karangetang has had more than 40 recorded eruptions since 1675. Twentieth-century eruptions have included frequent explosions, sometimes accompanied by pyroclastic flows and lahars. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html MANAM Northeast of New Guinea (SW Pacific) 4.080°S, 145.037°E; summit elev. 1807 m Based on analyses of satellite imagery, the Darwin VAAC reported that during 1-2 November ash plumes from Manam rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 35-55 km NW and N. 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. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5364 m INGEOMINAS reported that on 28 October a pulse of tremor from Nevado del Huila was followed by an ash plume that, according to the Washington VAAC, rose to an altitude of 8.3 km (27,200 ft) a.s.l. On 30 October and 2 November overflights revealed a high rate of lava dome growth compared to the previous observation on 23 October. An ash layer covered the W part of Pico Central. Continuous and intense degassing originated from areas that also exhibited thermal anomalies detected with a thermal imaging camera. Resulting gas plumes drifted NW. The volume estimate for the new lava dome was nearly 9 million cubic meters. Based on analyses of satellite imagery, pilot observations, and web camera views, the Washington VAAC reported that on 31 October an ash plume drifted 65 km S. During 31 October-2 November, thermal anomalies were seen on satellite imagery. On 2 November, a small plume seen on the web camera drifted SE. Gas plumes, occasionally accompanied by ash plumes, drifted 35 km SE. On 3 November, INGEOMINAS reported that a pulse of tremor was followed by an ash plume that, according to the VAAC, rose to an altitude of 11.3 km (37,100 ft) a.s.l. and drifted SW. Ashfall was reported in communities downwind. The VAAC also noted that another ash plume rose to an altitude below 6.7 km (22,000 ft) a.s.l. and drifted E. INGEOMINAS stated that residents of Mosoco (20 km SSW) saw collapses from the W side of the dome generate small pyroclastic flows and incandescence at night. The Alert Level remained at II (Orange; "probable eruption in term of days or weeks"). 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. Sources: Instituto Colombiano de Geología y Minería (INGEOMINAS) http://www.ingeominas.gov.co//, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m MVO reported that during 23-30 October seismic activity from the Soufrière Hills lava dome was at a slightly lower level that the previous week. Numerous pyroclastic flows occurred in most of the major drainage valleys and rockfalls were concentrated in the S. Heavy rainfall caused lahars in the Belham Valley to the W. On 28 October, two pyroclastic flows traveled 2 km W down Gages Valley. On 29 October, a 40-m-high spine was seen protruding from the summit. Changes in lava-dome morphology seen on 30 October, and occurrences of pyroclastic flows traveling NE, indicated that growth was concentrated in the central part of the lava dome. 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/ Ongoing Activity BARREN ISLAND Andaman Is 12.278°N, 93.858°E; summit elev. 354 m Based on analyses of satellite imagery, the Darwin VAAC reported that on 1 November an ash plume from Barren Island rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted about 55-75 km W. 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 CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m Based on analyses of satellite imagery, the Buenos Aires VAAC reported that on 30 October a diffuse ash plume from Chaitén's lava-dome complex rose possibly mixed with steam and gas drifted SSE. On 1 November, a plume drifted 20 km W. 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 DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m Based on analyses of satellite imagery, the Darwin VAAC reported that on 31 October an ash plume from Dukono rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted 35-110 km NE and N. 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 KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that seismic activity at Karymsky was above background levels during 23-27 and 30 October, a possible indication that ash plumes rose to an altitude of 3.7 km (12,100 ft) a.s.l. No seismic data was available on 22 and 28 October. Analyses of satellite imagery revealed an ash plume that drifted 120 km E on 23 October, and a thermal anomaly during 23-26 and 29 October. 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 During 21-27 October, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha ocean entry. Lava began entering the ocean at a second location, 700 m farther to the W, on 31 October. Thermal anomalies detected in satellite images and visual observations revealed active surface lava flows. Breakout lava flows were located inland of the Waikpuanaha entry and also immediately W of the County Public Viewing trail. Intermittent incandescence was seen from the Pu'u 'O'o crater floor and an East wall vent. The vent in Halema'uma'u crater continued to produce a diffuse white plume that drifted SW. Incandescence originated from occasionally spattering holes from a surface inside the vent cavity. On 3 November, a collapse of the surface revealed a circulating and spattering lava pond below. Preliminary measurements indicated that the sulfur dioxide emission rate at the summit remained elevated; 800 tonnes per day was measured on 30 October. 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/ KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m KVERT reported that during 23-30 October seismic activity from Kliuchevskoi was above background levels; tremor increased on 26 October. Strombolian activity ejected tephra 200 m above the crater and fumarolic activity was occasionally noted. Satellite imagery revealed a daily thermal anomaly at the volcano. The Level of Concern Color Code 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. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php KRAKATAU Indonesia 6.102°S, 105.423°E; summit elev. 813 m CVGHM reported that from August to 29 October seismicity from Anak Krakatau, and the occurrence of eruption plumes, decreased. The Alert Level was lowered to 2 (on a scale of 1-4). Geologic Summary. Renowned Krakatau volcano lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, resulted in a 7-km-wide caldera. Remnants of this volcano formed Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. The post-collapse cone of Anak Krakatau (Child of Krakatau), constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan, has been the site of frequent eruptions since 1927. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/ POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m CENAPRED reported that on 29 October a small explosive event from Popocatépetl produced an ash plume that rose to an altitude of 6.4 km (21,000 ft) a.s.l. Geologic Summary. Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America's second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages. Source: Centro Nacional de Prevencion de Desastres (CENAPRED) http://www.cenapred.unam.mx/es/ RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m Based on analyses of satellite imagery, the Darwin VAAC reported that during 28-29 October ash plumes from Rabaul caldera's Tavurvur cone rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 35-45 km N, E, and SE. 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 SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 28 October-3 November produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. Some plumes drifted W, SW, S, SE, and NE. 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 during 23-30 October seismic activity from Shiveluch was above background levels and possibly indicated that ash plumes rose to an altitude of 3.7 km (12,100 ft) a.s.l. and to an altitude of 6.9 km (22,600 ft) a.s.l. on 29 October. Fumarolic activity was occasionally seen. Analyses of satellite imagery revealed a large thermal anomaly over the lava dome during 22-27 October and an ash plume that drifted 24 km NE on 26 October. Based on information from KEMSD and analyses of satellite imagery, the Tokyo VAAC reported that on 30 October an eruption produced a plume that rose to an altitude of 7 km (23,000 ft) a.s.l. A possible eruption plume rose to an altitude of 6.1 km (20,000 ft) a.s.l. later that day. On 1 November, an eruption produced a plume that rose to an altitude of 4.9 km (16,000 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. 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 SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m Based on information from JMA, the Tokyo VAAC reported explosions from Suwanose-jima on 30 October and 2 November. Details of possible resulting emissions were not reported. 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 ============================================================== 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. ==============================================================
