*********************************************************************************** SI/USGS Weekly Volcanic Activity Report 4-10 November 2009 From: "Sally Kuhn Sennert" <KUHNS@xxxxxx> *********************************************************************************** SI/USGS Weekly Volcanic Activity Report 4-10 November 2009 Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Batur, Bali (Indonesia) | Galeras, Colombia | Karangetang [Api Siau], Siau I | Mayon, Luzon | Nevado del Huila, Colombia | Piton de la Fournaise, Reunion Island | Reventador, Ecuador | San Vicente, El Salvador Ongoing Activity: | Chaitén, Southern Chile | Dukono, Halmahera | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Koryaksky, Eastern Kamchatka | Rabaul, New Britain | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | 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 BATUR Bali (Indonesia) 8.242°S, 115.375°E; summit elev. 1717 m CVGHM reported increased seismicity from Batur from September to 7 November and a significant increase in the number of volcanic earthquakes on 8 November. The Alert Level was raised to 2 (on a scale of 1-4). Geologic Summary. The historically active Batur volcano is located at the center of two concentric calderas NW of Agung volcano in eastern Bali. The SE side of the larger 10 x 13 km caldera contains a caldera lake. The inner 7.5-km-wide caldera, which was formed during emplacement of the Bali (or Ubud) ignimbrite, has been dated at either 23,670 or 28,500 years ago. The SE wall of the inner caldera lies beneath Lake Batur; Batur cone has been constructed within the inner caldera to a height above the outer caldera rim. The Batur stratovolcano has produced vents over much of the inner caldera, but a NE-SW fissure system has localized the Batur I, II, and III craters along the summit ridge. Historical eruptions have been characterized by mild-to-moderate explosive activity sometimes accompanied by lava flows from summit and flank vents that have reached the caldera floor and the shores of Lake Batur. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/ GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4276 m INGEOMINAS reported that during 7-10 November seismic activity from Galeras decreased, although some seismic signals resembled patterns seen prior to previous eruptions. Sulfur dioxide emissions were not detected. The Alert Level remained at II (Orange; "probable eruption in term of days or weeks"). 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 According to news articles, a pyroclastic flow and a lahar descended the flanks of Karangetang on 4 November. Residents saw active lava flows the next day. On 11 November, incandescent material was ejected 5 m into the air. 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. Sources: Manado Post http://mdopost.com/news2009/index.php?option=com_content&view=article&id=9273:akvitas-karangetang-mereda-&catid=47:sangihe-sitaro-talaud&Itemid=63, Berita http://berita.liputan6.com/daerah/200911/250136/Gunung.Karangetang.Semburkan.Lava.Pijar MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m PHIVOLCS reported that on 11 November an explosion from Mayon's summit crater ejected incandescent rock fragments that were seen from nearby areas. Cloud cover prevented observations of an ash plume, however field investigations after the event revealed ashfall to the SW. The Alert Level remained at 2 (on a scale of 0-5). The 7-km Extended Danger Zone (EDZ) on the SE flank and the 6-km Permanent Danger Zone (PDZ) in all other areas remained in effect. Geologic Summary. Beautifully symmetrical Mayon volcano, which rises to 2,462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes that average 35-40° and is capped by a small summit crater. The historical eruptions of this basaltic-andesitic volcano date back to 1616 and range from Strombolian to basaltic Plinian. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1,200 people and devastated several towns. Eruptions that began in February 2000 led PHIVOLCS to recommend on 23 February 2000 the evacuation of people within a radius of 7 km from the summit in the SE and within a 6 km radius for the rest of the volcano. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/ NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5364 m INGEOMINAS reported that overflights of Nevado del Huila on 4, 6, and 10 November revealed a continued high rate of lava dome growth; the volume estimate for the new lava dome was nearly 25 million cubic meters. Small collapses occurred on the W part of the dome. Gas emissions were sometimes accompanied by pulsating ash emissions. Sulfur dioxide plumes rose 2.5 km above the lava dome and were seen in satellite imagery and the web camera drifting with the prevailing winds. The Alert Level remained at II (Orange; "probable eruption in term of days or weeks"). Based on analyses of satellite imagery, the Washington VAAC reported that during 4-6 and 10 November thermal anomalies on the volcano were seen intermittently through cloud cover. On 7 November, Bogota MWO reported an ash plume at an altitude of 9.4 km (31,000 ft) a.s.l., and a plume was seen drifting ESE on satellite imagery. Later that day, an ash plume was seen on satellite imagery and on the web cameras drifting SE at an altitude below 7.3 km (24,000 ft) a.s.l. 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 PITON DE LA FOURNAISE Reunion Island 21.231°S, 55.713°E; summit elev. 2632 m OVPDLF reported that on 5 November a vent inside the S part of Piton de la Fournaise’s Dolomieu crater opened, following an intense seismic crisis. Within thirty minutes, a fissure on the upper SE flank propagated E and a second fissure opened on the E flank. Lava fountains 20 m high and ‘a’a lava flows were emitted from both fissures. The Alert Level was raised to 2. Lava flows ceased by the morning of 6 November; the Alert level was lowered to 1 later that day. Geologic Summary. Massive Piton de la Fournaise shield volcano on the island of Réunion is one of the world's most active volcanoes. Most historical eruptions have originated from the summit and flanks of a 400-m-high lava shield, Dolomieu, that has grown within the youngest of three large calderas. This depression is 8 km wide and is breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows within the caldera, have been documented since the 17th century. The volcano is monitored by the Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris. Source: Observatoire Volcanologique du Piton de la Fournaise (OVPDLF) http://www.ipgp.fr/pages/03030810.php REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m Based on a pilot observation, the Washington VAAC reported that on 5 November an ash plume from Reventador rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted NE. Ash was not seen in satellite imagery, although meteorological clouds were present. IG reported that an ash plume rose 500 m above the crater on 7 November. Geologic Summary. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html SAN VICENTE El Salvador 13.595°N, 88.837°W; summit elev. 2182 m According to news articles, heavy rains caused landslides and flooding in the town of Verapaz, about 6 km NW of the summit of San Vicente, during 7-8 November. Mud and boulders swept down the flanks San Vicente, and in conjunction with flooded rivers, buried homes and cars; at least 144 people were killed and about 60 were missing. Geologic Summary. The twin peaks of San Vicente volcano, also known as Chichontepec, rise dramatically to the SE of Lake Ilopango. The modern stratovolcano was constructed within the Pleistocene La Carbonera caldera, whose rim is visible only on its SW side. San Vicente volcano, the second highest in El Salvador, grew within the caldera to form a paired volcano with summit craters along a WSW-ENE line. The northern and southern flanks are covered by lava flows from the central vent, but lava flows on the eastern side originated from a vent on the upper flank. Volcanism has continued into the Holocene, but the latest lava flows are covered by deposits from the major ca. 260 AD eruption from neighboring Ilopango volcano. Reports of historical eruptions in 1643 and 1835 are false, but numerous hot springs and fumaroles are found on the northern and western flanks of the volcano. Sources: Associated Press http://www.news-gazette.com/news/local/2009/11/09/rescuers_seek_salvador_mudslide_survivors_124_dead, Associated Press http://www.google.com/hostednews/ap/article/ALeqM5j0XCCb1n12DyhoBoDzGj_hTyEtrAD9BSRP1G1 Ongoing Activity CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m SERNAGEOMIN reported that Chaitén's lava-dome complex continued to grow during 16-30 October. The Alert Level remained at Red. 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: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/ DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m Based on analyses of satellite imagery, the Darwin VAAC reported that on 8 November an ash plume from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 35 km NW. 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 29-31 October; data was not collected during 1-4 November due to technical reasons. Seismic signals possibly indicated that ash plumes rose to an altitude of 3.7 km (12,100 ft) a.s.l. on 31 October and 5 November. Analyses of satellite imagery during 29 October-5 November revealed almost daily thermal anomalies and intermittent ash plumes that drifted 180 km E. The Level of Concern Color Code remained at Orange. Based on information from KEMSD, the Tokyo VAAC reported that eruptions on 8 and 10 November produced plumes that rose to altitudes of 3-3.4 km (10,000-11,000 ft) a.s.l. Ash was not identified on satellite imagery. 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 KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m During 4-10 November, 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 and a second location, 700 m farther to the W. 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 W of the County Public Viewing trail. The last remaining structure on the flow field burned on 3 November. Incandescence was seen from the Pu'u 'O'o crater floor and an East wall vent during 6-7 November. The vent in Halema'uma'u crater continued to produce a diffuse white plume that drifted SW and likely produced some ashfall. Incandescence originated from a spattering lava pond inside the vent cavity. Preliminary measurements indicated that the sulfur dioxide emission rate at the summit remained elevated; 700 and 400 tonnes per day were measured on 6 and 9 November, 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/ KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m KVERT reported that during 30 October-6 November seismic activity from Kliuchevskoi was above background levels. Strombolian activity ejected tephra 300 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 KORYAKSKY Eastern Kamchatka 53.320°N, 158.688°E; summit elev. 3456 m KVERT reported that during 30 October-6 November seismic activity from Koryaksky did not exceed background levels. Fumarolic activity was noted on 29 October and during 4-5 November. The Level of Concern Color Code was lowered to Green. Geologic Summary. The large symmetrical Koryaksky stratovolcano is the most prominent landmark of the NW-trending Avachinskaya volcano group, which towers above Kamchatka's largest city, Petropavlovsk. Erosion has produced a ribbed surface on the eastern flanks of the 3456-m-high volcano; the youngest lava flows are found on the upper western flank and below SE-flank cinder cones. No strong explosive eruptions have been documented during the Holocene. Extensive Holocene lava fields on the western flank were primarily fed by summit vents; those on the SW flank originated from flank vents. Lahars associated with a period of lava effusion from south- and SW-flank fissure vents about 3900-3500 years ago reached Avacha Bay. Only a few moderate explosive eruptions have occurred during historical time. Koryaksky's first historical eruption, in 1895, also produced a lava flow. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m Based on analyses of satellite imagery, the Darwin VAAC reported that on 9 November an ash plume from Rabaul caldera's Tavurvur cone rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted 110 km NW. 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 4-10 November produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted in multiple directions. Pilots reported ash plumes that rose to an altitude of 2.4 km (8,000 ft) a.s.l. on 5 November and to an altitude of 1.2 km (4,000 ft) a.s.l. on 9 November. Plumes drifted E and N, respectively. According to a news article, Sakura-jima exploded for the 400 th time in 2009 on 5 November. 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. Sources: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html, Japan Times http://search.japantimes.co.jp/rss/nn20091107a5.html SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m On 6 November, INSIVUMEH reported that an explosion from Santa María's Santiaguito lava dome complex produced a plume that rose 900 m and drifted SW. Based on analyses of satellite imagery, the Washington VAAC reported that on 8 November a small gas plume possibly containing ash drifted less than 10 km SSW. Another small plume was seen later that day. Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars. 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 SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that during 30 October-6 November seismic activity from Shiveluch was above background levels and possibly indicated that ash plumes rose to an altitude of 4.7 km (15,400 ft) a.s.l. Fumarolic activity was noted and analyses of satellite imagery revealed a large thermal anomaly over the lava dome. According to video camera data, ash plumes rose to an altitude of 8 km (26,400 ft) a.s.l. on 30 October. Ash plumes seen on satellite imagery drifted 130-255 km E on 30 October, and 1 and 5 November. 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. 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 during 30 October-6 November activity from the Soufrière Hills lava dome was at a high level; hybrid earthquakes were recorded for the first time since the renewal of activity in early October. Numerous pyroclastic flows occurred in most of the major drainage valleys. On 4 November, pyroclastic flows were seen from a helicopter traveling SW down Gingoes Ghaut to within 200 m of the sea. The frequency of pyroclastic flows increased on 5 November and particularly vigorous flows occurred in Tuitt's Ghaut to the NE. Ash fell in inhabited areas on a few occasions. Lahars descended the Belham Valley to the W several times. 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/ SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m Based on information from JMA, the Tokyo VAAC reported that explosions from Suwanose-jima during 4-5 November produced plumes that rose to altitudes of 1.2-1.8 km (4,000-6,000 ft) a.s.l. and drifted SW and W. An explosion was also reported on 6 November. 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. ==============================================================
