New Volcanos Erupting This Week: 2 ~~ Total active 20
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From: Last Post on 23 Nov 2009 23:13 SI / USGS Weekly VolcanicActivityReport NewVolcanosErupting This Week: ~~ Total Active 11 November - 17 November 2009 Sally Kuhn Sennert - Weekly Report Editor http://www.volcano.si.edu/reports/usgs/ NewActivity/Unrest: | Galeras, Colombia | Mayon, Luzon OngoingActivity: | Arenal, Costa Rica | Bagana, Bougainville | Chaitén, Southern Chile | Fuego, Guatemala | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka | Kliuchevskoi, Central Kamchatka (Russia) | Nevado del Huila, Colombia | Popocatépetl, México | Rabaul, New Britain | Reventador, Ecuador | Sakura-jima, Kyushu | Sangay, Ecuador | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Suwanose-jima, Ryukyu Islands (Japan) This page is updated on Wednesdays, please see the GVP Home Page for news of the latest significantactivity. The Weekly VolcanicActivityReport is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey'sVolcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanicactivityposted 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 ofactivityat 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. NewActivity/Unrest: GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4276 m INGEOMINAS reported that an overflight of Galeras on 14 November revealed thermal anomalies in the main crater measuring 110 degrees Celsius and very low rates of gas discharge. 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. Map Source: Instituto Colombiano de Geología y Minería (INGEOMINAS) Galeras Information from the Global Volcanism Program MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m According to news articles, an explosion from Mayon on 11 November prompted authorities to evacuate about 700 families from nearby areas. Incandescence from the crater at night on 14 November was visible from 15 km away. 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. Map Source: The Philippine Star Mayon Information from the Global Volcanism Program Ongoing Activity ARENAL Costa Rica 10.463°N, 84.703°W; summit elev. 1670 m OVSICORI-UNA reported that during October activity originating from Arenal's Crater C consisted of gas emissions, sporadic Strombolian eruptions, and occasional avalanches that traveled down the W and SW flanks. Acid rain and small amounts of ejected pyroclastic material affected the NE and SE flanks. Avalanches from lava-flow fronts traveled down the SW flanks. Crater D produced only fumarolic activity. Geologic Summary. Conical Volcan Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1,657-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. The earliest known eruptions of Arenal took place about 7,000 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred- year intervals and periods of lava effusion that armor the cone. Arenal's most recent eruptive period began with a major explosive eruption in 1968. Continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows has occurred since then from vents at the summit and on the upper western flank. Map Source: Observatorio Vulcanologico y Sismologico de Costa Rica- Universidad Nacional (OVSICORI-UNA) Arenal Information from the Global Volcanism Program BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m Based on analyses of satellite imagery, the Darwin VAAC reported that on 12 November an ash plume from Bagana rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 65 km SW. Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50-m-thick with prominent levees that descend the volcano's flanks on all sides. Map Source: Darwin Volcanic Ash Advisory Centre (VAAC) Bagana Information from the Global Volcanism Program CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m SERNAGEOMIN reported that during 31 October-1 November Chaitén's lava- dome complex produced steam plumes that sometimes contained gas and ash. The plumes were visible on the web camera and rose at most 1 km above the lava domes. 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. Map Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) Chaitén Information from the Global Volcanism Program FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m Based on analyses of satellite imagery, the Washington VAAC reported that on 12 November a gas plume from Fuego, possibly containing ash, drifted SSW. On 13 November, INSIVUMEH reported that explosions produced ash plumes that rose to altitudes of 4.2-4.7 km (13,800-15,400 ft) a.s.l. and drifted 7 km S. Rumbling noises were noted and incandescence was detected. White fumarolic plumes rose 100 m and drifted S and SW. Small plumes of ash on 16 November were seen on satellite imagery. 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. Map Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH), Washington Volcanic Ash Advisory Center (VAAC) Fuego Information from the Global Volcanism Program 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 5-9 November, a possible indication that ash plumes rose to an altitude of 3.7 km (12,100 ft) a.s.l. Analyses of satellite imagery during 5-12 November revealed almost daily thermal anomalies and ash plumes that drifted 190 km E during 8-12 November. The Level of Concern Color Code remained at Orange. Based on information from the Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 14 November an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted E. Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996. Map Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC) Karymsky Information from the Global Volcanism Program KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m During 11-17 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 ocean at multiple locations between Waikupanaha and an area 700 m farther to the W. Thermal anomalies detected by satellite suggested active surface lava flows. Incandescence was seen on the Pu'u 'O'o crater floor and intermittently from an East wall vent. The vent in Halema'uma'u crater continued to produce a diffuse white plume that drifted W and SW. Incandescence originated from a spattering lava pond inside the vent cavity. Measurements indicated that the sulfur dioxide emission rate at the summit remained elevated; 600 tonnes per day was measured on 16 November. 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. Map Source: US Geological Survey Hawaiian Volcano Observatory (HVO) Kilauea Information from the Global Volcanism Program KIZIMEN Eastern Kamchatka 55.130°N, 160.32°E; summit elev. 2376 m KVERT reported that seismicity from Kizimen was slightly above background levels on 6, 8, and 10 November and at background levels the other days during 7-13 November. The Level of Concern Color Code was lowered to Green. Geologic Summary. Kizimen is an isolated, conical stratovolcano that is morphologically similar to Mount St. Helens prior to its 1980 eruption. The summit of Kizimen consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2,376- m-high Kizimen was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2,000-3,500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of longterm lava-dome growth have occurred. The latest eruptive cycle began about 3,000 years ago with a large explosion and was followed by lava-dome growth lasting intermittently about 1,000 years. An explosive eruption about 1,100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. A single explosive eruption, during 1927-28, has been recorded in historical time. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Kizimen Information from the Global Volcanism Program KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m KVERT reported that during 6-13 November seismic activity from Kliuchevskoi was above background levels. Strombolian activity ejected tephra 300 m above the crater on 5, 7, and 10 November. Satellite imagery revealed a large 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. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Kliuchevskoi Information from the Global Volcanism Program NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5364 m INGEOMINAS reported that during 11-17 November gas plumes from Nevado del Huila were seen on the web camera rising 2.5 km and drifting downwind. Ash plumes sometimes accompanied the gas emissions on 12, 13, and 15 November. 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 11-16 November thermal anomalies were seen intermittently through cloud cover. 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. Map Sources: Instituto Colombiano de Geología y Minería (INGEOMINAS), Washington Volcanic Ash Advisory Center (VAAC) Nevado del Huila Information from the Global Volcanism Program POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m CENAPRED reported that on 14 November an ash plume from Popocatépetl rose to an altitude of 7.4 km (24,300 ft) a.s.l. During 14-17 November, steam-and-gas plumes sometimes contained ash. 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. Map Source: Centro Nacional de Prevencion de Desastres (CENAPRED) Popocatépetl Information from the Global Volcanism Program 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 11-14 November ash plumes from Rabaul caldera's Tavurvur cone rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 75-150 km NW 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. Map Source: Darwin Volcanic Ash Advisory Centre (VAAC) Rabaul Information from the Global Volcanism Program REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m Based on analyses of satellite imagery, the Washington VAAC reported that on 14 November ash plumes from Reventador drifted 10-20 km WNW and W. An intermittent thermal anomaly was also detected. 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. Map Source: Washington Volcanic Ash Advisory Center (VAAC) Reventador Information from the Global Volcanism Program 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 11-13 and 15-17 November produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted in multiple directions. 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. Map Source: Tokyo Volcanic Ash Advisory Center (VAAC) Sakura-jima Information from the Global Volcanism Program SANGAY Ecuador 2.002°S, 78.341°W; summit elev. 5230 m Based on analyses of satellite imagery, the Washington VAAC reported that on 16 November small plumes from Sangay, possibly with ash, drifted WNW. A thermal anomaly was also detected. Geologic Summary. The isolated Sangay volcano, located E of the Andean crest, is the southernmost of Ecuador's volcanoes, and its most active. It has been in frequent eruption for the past several centuries. The steep-sided, 5,230-m-high glacier-covered volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the E, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. Sangay towers above the tropical jungle on the E side; on the other sides flat plains of ash from the volcano have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of an historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The more or less constant eruptive activity has caused frequent changes to the morphology of the summit crater complex. Map Source: Washington Volcanic Ash Advisory Center (VAAC) Sangay Information from the Global Volcanism Program SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m On 13 November, INSIVUMEH reported that an explosion from Santa María's Santiaguito lava dome complex produced a plume that drifted SW. Avalanches descended the SW flank of the dome. Based on analyses of satellite imagery, the Washington VAAC reported that on 16 November multiple ash plumes drifted WSW. 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. Map Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH), Washington Volcanic Ash Advisory Center (VAAC) Santa María Information from the Global Volcanism Program SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that during 6-13 November seismic activity from Shiveluch was above background levels, possibly indicating that ash plumes rose to an altitude of 5.5 km (18,000 ft) a.s.l. According to video camera data, ash plumes rose to an altitude of 4.2 km (13,800 ft) a.s.l. on 5 November and hot avalanches were noted during 10-12 November. Analyses of satellite imagery revealed a large daily thermal anomaly on the lava dome and ash plumes that drifted 320 km E on 11 November. The Level of Concern Color Code remained at Orange. Based on information from KEMSD and analyses of satellite imagery, the Tokyo VAAC reported that on 14 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. Map Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC) Shiveluch Information from the Global Volcanism Program SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m MVO reported that during 6-13 November activity from the Soufrière Hills lava dome continued at a high level. Pyroclastic flows mainly occurred towards the W down Gages Valley and SW down Gingoes Ghaut. Good views of the lava dome on 9 and 10 November revealed that recent lava-dome growth was concentrated on the WSW side, immediately NE of Chances Peak; intense incandescence and rockfalls were noted at night. Ash fell across the Montserrat on 11 November, and about 6-8 km NW in Salem, Old Towne, Olveston, and Woodlands on 12 November. The largest pyroclastic flow during the reporting period, on 12 November, traveled WSW, nearly reaching the sea at Kinsale village. 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. Map Source: Montserrat Volcano Observatory (MVO) Soufrière Hills Information from the Global Volcanism Program 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 12 and 16 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. Map Source: Tokyo Volcanic Ash Advisory Center (VAAC) Suwanose-jima Information from the Global Volcanism Program Additional Reports of Volcanic Activity by Country The following websites have frequently updated activity reports on volcanoes in addition to those that meet the criteria for inclusion in the Weekly Volcanic Activity Report. The websites are organized by country and are maintained by various agencies. Ecuador, Indonesia, Japan, New Zealand, United States and Russia Sally Kuhn Sennert - Weekly Report Editor URL: http://www.volcano.si.edu/reports/usgs/ |