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Smithsonian/USGS Weekly Volcanic Activity Report 19-25 January 2011
From: "Kuhn, Sally" <KUHNS@si.edu>
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Smithsonian/USGS Weekly Volcanic Activity Report
19-25 January 2011
Sally Kuhn Sennert - Weekly Report Editor
kuhns@si.edu
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Fuego, Guatemala | Kirishima, Kyushu | Mayon, Luzon | Tengger Caldera, Eastern Java (Indonesia)
Ongoing Activity: | Bulusan, Luzon | Chaitén, Southern Chile | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Merapi, Central Java (Indonesia) | Pacaya, Guatemala | Sakura-jima, Kyushu | Sangay, Ecuador | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Suwanose-jima, Ryukyu Islands (Japan) | Taal, Luzon
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
FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m
INSIVUMEH reported that during 19-20 and 23-24 January explosions from Fuego produced ash plumes that rose 500-800 m above the crater and drifted W, NW, and S. Incandescent material was ejected as high as 100 m above the crater. Rumbling and degassing sounds were noted, and avalanches descended a few drainages.
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.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
KIRISHIMA Kyushu 31.931°N, 130.864°E; summit elev. 1700 m
According to JMA, an eruption from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, on 19 January produced a shock wave that was detected 12 km NE and an ash plume that drifted SE. Ashfall up to 5 mm thick was reported in Miyakonojo (30 km SE); ashfall was also reported as far as Nichinan City (60 km SE). An eruption on 22 January ejected material 200 m above the vent. Based on reports from JMA and pilot observations, the Tokyo VAAC reported that ash plumes rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SE.
Geologic Summary. Kirishima is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene volcano group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1,700-m-high Karakuni-dake being the highest. Onami-ike and Mi-ike, the two largest maars, are located SW of Karakuni-dake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Mi-ike to Ohachi, and at Shinmoe-dake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.
Sources: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/indexe.html,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m
PHIVOLCS reported that a deformation survey of Mayon conducted in November and December 2010 showed inflation since a survey in 2008. During 18-25 January, up to two daily volcanic earthquakes were detected by the seismic network. Although cloud cover often prevented observations of the summit area, white steam emissions from the crater and nighttime crater incandescence were occasionally observed. The Alert Level remained at 1 and the public was reminded not to enter the 6-km-radius Permanent Danger Zone (PDZ).
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/index.php
TENGGER CALDERA Eastern Java (Indonesia) 7.942°S, 112.95°E; summit elev. 2329 m
CVGHM reported that during 22-23 January gray-to-brown plumes from Tengger Caldera's Bromo cone rose 400-800 m above the crater and drifted E. Incandescent material was ejected 200 m above the crater and landed as far as 500 m away on 22 January. The Alert Level remained at 3 (on a scale of 1-4). Residents and tourists were not permitted within a 2-km-radius of the active crater. Based on analysis of satellite imagery and information from CVGHM, the Darwin VAAC reported that on 24 January an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted more than 220 km E. A high concentration of sulfur dioxide in the area was also detected.
Geologic Summary. The 16-km-wide Tengger caldera in eastern Java is located at the northern end of a volcanic massif extending from Semeru volcano. The massive Tengger volcanic complex consists of five overlapping stratovolcanoes, each truncated by a caldera. The most recent is the 9 x 10 km wide Sandsea caldera, which formed incrementally during the late Pleistocene and early Holocene. An overlapping cluster of post-caldera cones was constructed on the floor of the Sandsea caldera within the past several thousand years. The youngest of these is Bromo, one of Java's most frequently visited and most active volcanoes. More than 50 mild-to-moderate explosive eruptions have occurred since 1804.
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
Ongoing Activity
BULUSAN Luzon 12.770°N, 124.05°E; summit elev. 1565 m
During 18-19 January, PHIVOLCS reported that 11 volcanic earthquakes at Bulusan were detected by the seismic network. From 20 to 25 January up to five volcanic earthquakes per day were detected. Cloud cover mostly prevented observations of the summit area. Diffuse steam plumes rose from vents on 20 and 22 January. The Alert Level remained at 1 (on a scale of 0-5).
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/index.php
CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m
SERNAGEOMIN reported that during 1-14 January cameras installed around Chaitén's caldera rim, as well as cameras in Pumalin Park and Chaitén town, showed degassing from the lava-dome complex. Gas plumes composed primarily of water vapor rose at most 800 m above the complex. Incandescence on the surface of the dome was observed at night. The Alert Level remained at 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.
Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that moderate seismic activity was detected at Karymsky during 14-21 January. Seismic data showed that possible ash plumes rose to an altitude of 4.6 km (15,100 ft) a.s.l. A thermal anomaly was observed in satellite imagery during 15 and 18-20 January, and an ash plume drifted 24 km SW on 20 January. Based on analyses of satellite imagery, the Tokyo VAAC reported that eruptions during 24-25 January produced plumes that rose to altitudes of 3.4-4.6 km (11,000-15,000 ft) a.s.l. and drifted SE. The Aviation 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.
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
HVO reported that the largest of about 36 rockfalls that occurred in the deep pit within Kilauea's Halema'uma'u crater on 17 January was followed by an explosive event, of a magnitude not seen since 2008, and felt locally. Ballistics up to 10 cm in diameter and hot tephra ejected from the pit were deposited on the rim of Halema'uma'u crater. Spatter up to 8 cm long was ejected onto the crater rim after collapses on 21 January.
During 19-25 January, activity 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 circulated and remained mostly stable at approximately 120 m below the crater floor, periodically rising or falling. Nighttime incandescence was visible from the Jaggar Museum on the NW caldera rim. A plume from the vent that drifted mostly SW and W deposited ash and fresh spatter nearby.
At the east rift zone, lava that broke out of the Quarry tube, at a saddle between two rootless shields around 610 m elevation, continued to advance both E and W. At the lowest elevation of the E branch, lava advanced along Highway 130 near Kalapana, periodically burning vegetation. Steam sporadically rising near the ocean suggested that the lava entered the ocean, although not continuously. One part of the W branch stopped entering the ocean on 18 January, but remained active. Incandescence emanated from a spatter cone on the N portion of the Pu'u 'O'o crater floor and from the fuming vent in the E wall of the crater.
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
KVERT reported that during 14-21 January seismicity from Kizimen was high but variable, and many shallow volcanic earthquakes as well as volcanic tremor continued to be detected. Seismic data analyses suggested that ash plumes possibly rose to an altitude no higher than 6 km (19,700 ft) a.s.l. Satellite images showed a daily bright thermal anomaly over the volcano, and ash plumes that drifted more than 200 km W during 15-16 and 20 January. The Aviation Color Code remained at Orange.
Based on analyses of satellite imagery and reports from KVERT, the Tokyo VAAC reported that during 23-25 January eruptions produced plumes that rose to altitudes of 4.9-10.1 km (16,000-33,000 ft) a.s.l.
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
MERAPI Central Java (Indonesia) 7.542°S, 110.442°E; summit elev. 2968 m
CVGHM reported that the Alert Level for Merapi was lowered to 2 (on a scale of 1-4) on 9 January. During 10-16 January seismicity had decreased compared to the previous week. Gas plumes rose from the crater; on 11 January gas plumes rose to a maximum height of 80 m above the crater. On 12 January avalanches descended the Krasak drainage, traveling 1.5 km SW. Lahars and high water during 15-23 January damaged infrastructure and caused temporary road closures. On 22 January plumes rose 175 m above the crater and drifted E.
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).
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
PACAYA Guatemala 14.381°N, 90.601°W; summit elev. 2552 m
INSIVUMEH reported on 20 January that a blue plume rose from the base of the NW flank of Pacaya's MacKenney cone. The Pacaya National Park authority was advised to not allow tourists near the area with the new plume. During 21-24 January fumarolic activity in the crater had variable intensity.
Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex volcano constructed on the southern rim of the 14 x 16 km Pleistocene Amatitlan caldera. A cluster of dacitic lava domes occupies the caldera floor. The Pacaya massif includes the Cerro Grande lava dome and a younger volcano to the SW. Collapse of Pacaya volcano about 1,100 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (MacKenney cone) grew. During the past several decades, activity at Pacaya has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion on the flanks of MacKenney cone, punctuated by occasional larger explosive eruptions.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
Based on information from JMA, the Tokyo VAAC reported that during 19 and 21-23 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted SE and E. On 22 January, a pilot reported that an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted E.
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
SANGAY Ecuador 2.002°S, 78.341°W; summit elev. 5230 m
Based on a pilot observation, the Washington VAAC reported that on 20 January an ash plume from Sangay rose to an altitude of 7.6 km (25,000 ft) a.s.l. Ash was not detected in satellite imagery.
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.
Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m
Based on a METAR weather notice, the Washington VAAC reported ash above Santa María's Santiaguito lava dome on 20 January. Satellite imagery showed a small plume drifting NNE at a possible altitude of 5.2 km (17,000 ft) a.s.l. During 20-21 January, INSIVUMEH reported that steam plumes rose 150 m above the crater and drifted SW. Avalanches originated from the lava dome SW of Caliente lava dome. On 21 January, the VAAC reported that an ash plume detected in satellite imagery drifted SW at an estimated altitude of 4.3 km (14,000 ft) a.s.l. They also noted that INSIVUMEH reported mostly steam plumes and rockfall-generated small ash plumes that drifted within 5 km of the crater. During 23-24 January fumarolic plumes rose 300 m above the crater and drifted N.
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 moderate seismic activity from Shiveluch was recorded during 14-21 January. Moderate gas-and-steam activity was visually observed during 17-20 January, and on 18 January an ash plume was observed rising to an altitude of 6.5 km (21,300 ft) a.s.l. A bright thermal anomaly over the volcano was detected in satellite imagery during 13-15 and 18-20 January. The Aviation 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
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 during 22-23 and 25 January. A plume rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted S on 23 January.
Geologic Summary. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent Strombolian activity from On-take, the NE summit crater, that began in 1949 and lasted nearly a half century. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, after which the island was uninhabited for about 70 years. The SW crater produced lava flows that reached the western coast in 1813, and lava flows reached the eastern coast of the island in 1884.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
TAAL Luzon 14.002°N, 120.993°E; summit elev. 311 m
PHIVOLCS reported that field observations of Taal on 18 January revealed steam rising from the thermal area inside the Main Crater. Temperature and acidity of the lake were at normal levels, and the color had not changed. During 18-25 January, up to seven daily volcanic earthquakes were detected by the seismic network. The Alert Level remained at 1 (on a scale of 0-5).
Geologic Summary. Taal volcano is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. In contrast to Mayon volcano, Taal is not topographically prominent, but its prehistorical eruptions have greatly changed the topography of SW Luzon. The 15 x 20 km Taal caldera is largely filled by Lake Taal, whose 267 sq km surface lies 700 m below the S caldera rim and only 3 m above sea level. The maximum depth of the lake is 160 m, and several eruptive centers lie submerged beneath the lake. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all historical eruptions. The island is a complex volcano composed of coalescing small stratovolcanoes, tuff rings, and scoria cones that has grown about 25% in area during historical time. Powerful pyroclastic flows and surges from historical eruptions of Taal have caused many fatalities.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/index.php
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