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SI/USGS Weekly Volcanic Activity Report 10-16 November 2010
From: "Kuhn, Sally" <KUHNS@si.edu>
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SI/USGS Weekly Volcanic Activity Report
10-16 November 2010
Sally Kuhn Sennert - Weekly Report Editor
kuhns@si.edu
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Bulusan, Luzon | Etna, Sicily (Italy) | Merapi, Central Java (Indonesia) | Shiveluch, Central Kamchatka (Russia)
Ongoing Activity: | Chaitén, Southern Chile | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Kliuchevskoi, Central Kamchatka (Russia) | Manam, Northeast of New Guinea (SW Pacific) | Nevado del Huila, Colombia | Planchón-Peteroa, Central Chile-Argentina border | Popocatépetl, México | Sakura-jima, Kyushu | 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
BULUSAN Luzon 12.770°N, 124.05°E; summit elev. 1565 m
During 10-11 November, PHIVOLCS reported that 18 volcano tectonic earthquakes from Bulusan were detected by the seismic network. On 11 November white steam plumes rose 150 m above the crater and drifted ENE. During an aerial survey, scientists saw that recent explosions resulted in the joining of two of the 2006-2007 craters into one. They also noted that deposits from an explosion on 9 November did not contain juvenile material. On 12 November an ash explosion produced an ash-and-steam plume that rose 700 m above the crater and drifted SW. Multiple neighborhoods to the W and SW reported light ashfall. Four volcano-tectonic earthquakes were detected during the previous 24 hours. Steam plumes rose to a maximum height of 100 m above the crater. Some steaming was seen during 13-14 November. White steam rose from the NW vent, but no steaming was observed from the crater and SE vent on 14 and 15 November. An explosion late at night on 15 November was followed by ashfall in nearby neighborhoods. Cloud cover prevented observations of the summit area the next morning. The Alert Level remained at 1 (out of 5).
Geologic Summary. Luzon's southernmost volcano, Bulusan, was constructed within the 11-km-diameter dacitic Irosin caldera, which was formed more than 36,000 years ago. A broad, flat moat is located below the prominent SW caldera rim; the NE rim is buried by the andesitic Bulusan complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit of Bulusan volcano is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded at Bulusan since the mid-19th century.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/
ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m
Following several days of ash emissions from Etna's Northeast Crater, INGV-CT reported that on 14 November there was a significant increase in both the frequency and volume of ash emissions. The emissions were intermittent, alternating with periods of gas-and-steam. Ash plumes rose a few hundred meters high and drifted first SW on 14 November, then NE during 14-15 November, and finally E on 15 November.
INGV-CT staff visited the summit craters on 15 November and saw a few millimeters of brown ash on the ground mainly to the S of Northeast Crater. Ash deposits were 1 cm thick on the rim of the crater. Ash emissions were accompanied by nearly continuous deep rumblings. The vent on the crater floor was at least 75 m in diameter compared to about 25 m in October.
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/index.php
MERAPI Central Java (Indonesia) 7.542°S, 110.442°E; summit elev. 2968 m
CVGHM reported that during 10-11 November seismicity from Merapi along with the number of avalanches and pyroclastic flows decreased compared to the previous two days. Lahar deposits were seen in multiple drainages around Merapi at a maximum distance of 16.5 km from the summit.
On 10 November, plumes generally rose 800 m above the crater, but at about 2200 a brownish plume rose to a height of 1.5 km. Heavy ashfall was reported in areas to the WSW and WNW. A 3.5-km-long pyroclastic flow and a 200-m-long avalanche both traveled S in the Gendol drainage. Incandescence from the crater was observed through a closed-circuit television (CCTV) system installed at the Merapi museum. On 11 November, roaring was followed by light ashfall at the Ketep observation post. Plumes, brownish-black at times, rose 800 m above the crater and drifted W and NW. Avalanches again traveled S in the Gendol drainage. One pyroclastic flow was observed through the CCTV traveling 3 km S. A brownish plume rose 1.5 km above the crater. The Alert Level remained at 4 (on a scale of 1-4).
Based on analysis of satellite imagery, the Darwin VAAC reported that during 12-14 November ash plumes drifted 185-280 km SW at an altitude of 7.6 km (25,000 ft) a.s.l. High-altitude sulfur dioxide clouds detected over the Indian Ocean possibly contained ash. In the latter part of 14 November and during 15-16 November, ash plumes rose to altitude of 6.1-7.6 km (20,000-25,000 ft) a.s.l. and drifted 110-130 km S, SW, and W. The sulfur dioxide concentration in the high-level clouds had decreased; the clouds were not thought to contain ash.
During 14-15 November, news articles stated that the death toll from the eruption was over 250, and the Yogyakarta airport had remained closed. About 390,000 residents also began to return home after the "danger zones" were reduced in some areas due to decreased activity during the previous few days.
Geologic Summary. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately N of the major city of Yogyakarta. The steep-sided modern Merapi edifice, its upper part unvegetated due to frequent eruptive activity, was constructed to the SW of an arcuate scarp cutting the eroded older Batulawang volcano. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated and inhabited lands on the volcano's western-to-southern flanks and caused many fatalities during historical time. The volcano is the object of extensive monitoring efforts by the Merapi Volcano Observatory (MVO).
Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/,
Darwin Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html,
Associated Press http://www.msnbc.msn.com/id/40174863/ns/technology_and_science-science/,
RTT News http://news.ino.com/headlines/?newsid=111520101005,
Jakarta Post http://www.thejakartapost.com/news/2010/11/15/thousands-return-slopes-indonesian-volcano.h tml
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that moderate seismic activity from Shiveluch was detected during 5-12 November and a large thermal anomaly over the volcano was observed in satellite imagery. Seismic data suggested that possible ash plumes rose to altitudes of 6.5 and 7 km (21,300 and 23,000 ft) a.s.l. on 6 and 8 November, respectively. Ash plumes were detected in satellite imagery during 7-9 November drifting 150 km SE. An ash plume observed on 10 November rose to an altitude of 5 km (16,400 ft) a.s.l. KVERT noted that growth of the lava dome continued. The Aviation Color Code level remained at Orange.
During 13-14 November, the Tokyo VAAC reported that ash plumes from eruptions were observed in satellite imagery drifting E at altitudes of 4.6-5.2 km (15,000-17,000 ft) a.s.l. A possible eruption on 16 November produced a plume that rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted NE.
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
Ongoing Activity
CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m
On 11 November, SERNAGEOMIN reported that, although seismic events at Chaitén's lava-dome complex continued to increase in the previous weeks, the magnitudes of the earthquakes remained relatively low. Gas-and-steam plumes rose 300-400 m above the caldera rim. Based on analyses of satellite imagery and web camera footage, the Buenos Aires VAAC reported that on 13 November a gas-and-ash plume rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted 40 km SE. On 15 November ash plumes observed through the web camera rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted E. The Alert Level remained Yellow Level 3 on a three-color scale.
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 layer that was 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. Two small lakes occupy the caldera floor on the west and north sides of the lava dome. The first historical eruption of Chaitén volcano in 2008 produced major rhyolitic explosive activity and growth of a lava dome that filled much of the caldera.
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
FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m
On 12 November, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose 800 m above the crater and drifted S and SW. At night, incandescent material was ejected to low heights above the crater. Avalanches occurred around the crater rim. Based on analyses of satellite imagery, the Washington VAAC reported that during 12-13 November ash plumes drifted as far as 37 km SW.
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 (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that seismic activity from Karymsky was above background levels during 9-10 November, suggesting that possible ash plumes rose to altitudes of 3.5-4.9 km (11,500-16,100 ft) a.s.l. Seismic activity was at background levels on the other days during 5-12 November. Satellite imagery showed a daily thermal anomaly over the volcano. The Aviation Color Code level 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 10-16 November, HVO reported that activity at Kilauea continued from the summit caldera and the east rift zone. At the summit caldera, the level of the lava-pool surface in the deep pit within Halema'uma'u crater remained mostly stable at 155 m below the crater floor. Periodically the lava rose about 20 m above that level. Nighttime incandescence was seen from the Jaggar Museum on the NW caldera rim. A plume from the vent drifted SW and deposited ash nearby. At the east rift zone, lava continued to flow through the TEB lava-tube system and fed some small lava flows on the coastal plain and the Puhi-o-Kalaikini ocean entry. Incandescence was frequently visible from areaS on the N part of the Pu'u 'O'o crater floor.
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/
KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m
According to staff at a tourist center 10 km from Kizimen, KVERT reported strong gas-and-steam activity on 11 November resulted in a plume, possible containing some ash, that rose to an altitude of 4 km (13,100 ft) a.s.l. Seismic activity continued to be detected during 5-12 November. The Level of Aviation Color Code remained at 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.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 8-10 November seismic activity at Kliuchevskoi was at background levels. During 9-10 November strong fumarolic activity was seen and a weak thermal anomaly over the crater was observed in satellite imagery. Based on analyses of satellite imagery and information from KVERT, the Tokyo VAAC reported that on 13 November an eruption produced a plume that drifted NE. Later that day, images showed that the ash had dissipated. The Aviation Color Code level remained at Yellow.
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.
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
MANAM Northeast of New Guinea (SW Pacific) 4.080°S, 145.037°E; summit elev. 1807 m
Based on analysis of satellite imagery, the Darwin VAAC reported that during 14-16 November ash plumes from Manam rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted about 95 km NW.
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
According to the Washington VAAC, INGEOMINAS reported a seismic event from Nevado del Huila on 11 November consistent with a potential ash emission. A possible ash plume detected in satellite imagery drifted 25 km WSW. A subsequent notice stated that seismicity returned to background levels and the plume was no longer visible. INGEOMINAS reported that during 10-16 November whitish-colored gas plumes seen through the Tafxnú and Maravillas (12 km SE) web cameras rose 2 km above the crater. The Alert Level had been lowered to III (Yellow; "changes in the behavior of volcanic activity") on 12 October, and remained at that level during the reporting period.
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
PLANCHON-PETEROA Central Chile-Argentina border 35.240°S, 70.570°W; summit elev. 4107 m
On 11 November, SERNAGEOMIN reported that seismicity from Planchón-Peteroa remained low. Observations from multiple sources, including a web camera and satellite images, showed that the height of the gas plume was lower than the previously reported height of 200 m, observed during 15-25 October. The Alert Level was lowered to 2, Green.
Geologic Summary. Planchón-Peteroa is an elongated complex volcano along the Chile-Argentina border with several overlapping calderas. Activity began in the Pleistocene with construction of the basaltic-andesite to dacitic Volcán Azufre, followed by formation of basaltic and basaltic-andesite Volcán Planchón, 6 km to the N. About 11,500 years ago, much of Azufre and part of Planchón collapsed, forming the massive Río Teno debris avalanche, which reached Chile's Central Valley. Subsequently, Volcán Planchón II was formed. The youngest volcano, andesitic and basaltic-andesite Volcá Peteroa, consists of scattered vents between Azufre and Planchón. Peteroa has been active into historical time and contains a small steaming crater lake. Historical eruptions from the Planchón-Peteroa complex have been dominantly explosive, although lava flows were erupted in 1837 and 1937.
Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/
POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m
Based on information from the Mexico City MWO, the Washington VAAC reported a small and brief emission from Popocatépetl on 12 November. CENAPRED reported four steam-and-gas emissions during 12-13 November.
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.
Sources: Centro Nacional de Prevencion de Desastres (CENAPRED) http://www.cenapred.unam.mx/es/,
Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/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 during 10-16 November explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted E, SE, and S. During 15-16 November, pilots reported that ash plumes rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l.
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
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 5-12 November activity from the Soufrière Hills lava dome was at a low level. Photographs from 11 November showed areas of nighttime incandescence from the lava dome, indicating that although extrusion stopped nine months earlier, the lava dome remained hot. Small pyroclastic flows occurred in the Tar River valley to the E on 6 November and from the N side of the dome on 9 November. Light ashfall associated with the 9 November event occurred in inhabited areas of N Montserrat. Helicopter observations revealed that the overhanging part of the dome on the W side, immediately E of Chances Peak, was more pronounced by further undercutting of rockfalls and pyroclastic flows. 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 explosions from Suwanose-jima on 10 and 12 November. On 11 November a pilot reported an ash plume. A subsequent satellite image showed that the ash had dissipated. The next day, a pilot reported that an ash plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted S.
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
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