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SI/USGS Weekly Volcanic Activity Report 17-23 February 2010
From: Sally Kuhn Sennert kuhns@xxxxxx
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SI/USGS Weekly Volcanic Activity Report
17-23 February 2010
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Ol Doinyo Lengai, Tanzania | Reventador, Ecuador | Soufrière Hills, Montserrat | Ulawun, New Britain
Ongoing Activity: | Bagana, Bougainville | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Sakura-jima, Kyushu | Sangay, Ecuador | Shiveluch, Central Kamchatka (Russia) | Suwanose-jima, Ryukyu Islands (Japan) | Talang, Sumatra (Indonesia) | Tungurahua, Ecuador
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
OL DOINYO LENGAI Tanzania 2.764°S, 35.914°E; summit elev. 2962 m
According to Frederick Belton's website, geologists that had climbed Ol Doinyo Lengai on 11 February saw periodic eruptions from a small fissure, and steam emissions from an area of the crater rim next to a part that had collapsed. Another group of geologists that visited during 14-15 February noted three new hornitos on the W part of the crater floor that were black and very fresh. They also noted a cone-shaped gray hornito on the middle of the floor and a new black lava flow to the S.
Geologic Summary. The symmetrical Ol Doinyo Lengai stratovolcano is the only volcano known to have erupted carbonatite tephras and lavas in historical time. The prominent volcano, known as "The Mountain of God," rises abruptly above the broad plain S of Lake Natron. The cone-building stage of the volcano ended about 15,000 years ago and was followed by periodic ejection of natrocarbonatite and nephelinite tephra during the Holocene. Historical eruptions have consisted of smaller tephra eruptions and emission of numerous natrocarbonatitic lava flows on the floor of the summit crater. Petrologists first observed the eruption of carbonatitic lava flows in the 1960s. Subsequent more frequent visits have documented long-term lava effusion in the summit crater that would not have been seen from the foot of the volcano.
Source: Frederick Belton's Ol Doinyo Lengai website http://frank.mtsu.edu/~fbelton/latestnews.html
REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m
The MODIS satellite detected a thermal anomaly over Reventador on 14 February. Based on information from the Guayaquil MWO, the Washington VAAC reported an ash emission on 18 February. Ash was not identified in satellite imagery. IG reported that seismic signals indicated an emission that day, but weather conditions prevented visual observations.
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/,
Hawai'i Institute of Geophysics and Planetology (HIGP) Moderate Resolution imaging Spectroradiometer (MODIS) Thermal Alert System http://modis.higp.hawaii.edu/,
Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 12-19 February activity from the Soufrière Hills lava dome was at a low level. Rockfalls originated from the inner walls of the 300-m-wide collapse scar on the N flank, formed from the 11 February event, and from the dome summit. Gas measurements on 17 February and seismicity were consistent with lava-dome growth, but growth was unconfirmed.
Inspection of the deposits from the 11 February collapse event revealed that the NE coastline had extended into the sea an additional 650 m. Pyroclastic flows razed many buildings in both Harris (3 km N) and Streatham (2 km NNW), and destroyed trees in the Gun Hill area (2 km NNW). Pyroclastic-flow deposits were approximately 15 m thick in the Trants region of the coast (near the old Bramble airport, about 5 km NE). A deep crater, similar in diameter to the collapse scar, was seen in the summit of the lava dome. The Hazard Level remained at 4.
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/
ULAWUN New Britain 5.05°S, 151.33°E; summit elev. 2334 m
RVO reported that during 12-20 February Ulawun emitted white vapor that was occasionally forceful. A plume seen on satellite imagery on 14 February drifted NNE.
Geologic Summary. The symmetrical basaltic to andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.
Source: Rabaul Volcano Observatory (RVO)
Ongoing Activity
BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m
RVO reported that white vapor from Bagana was emitted during 1-21 February. Ash plumes were seen on 5 February and night-time incandescence was seen on 2, 12, 13, and 19 February. Sulfur dioxide plumes drifted ENE during 11-20 February and NNW on 20 and 21 February.
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.
Source: Rabaul Volcano Observatory (RVO)
KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that seismic activity from Karymsky was above background levels during 11-14 February, possibly indicating weak ash explosions. Analyses of satellite imagery revealed a thermal anomaly over the volcano during that time and also on 15 February. Seismic activity was at background levels during 15-19 February. 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 17-23 February, HVO reported an active lava surface about 200 m below a vent in the floor of Kilauea's Halema'uma'u crater. The lava surface circulated and occasionally spattered, and both rose and drained through holes in the cavity floor. Bursting bubbles and low lava fountains were also noted. A plume from the vent drifted mainly SW, dropping small amounts of ash downwind. Measurements on 18 February indicated that the sulfur dioxide emission rate at the summit remained elevated at 600 tonnes per day. The 2003-2007 average rate was 140 tonnes per day.
Lava from beneath the Thanksgiving Eve Breakout (TEB) and rootless shield complex flowed over 3 km SE through a lava tube system before breaking out onto the surface. Thermal anomalies detected by satellite and visual observations revealed active lava flows on the W side of the TEB flow field, on the pali, and on the coastal plain. Incandescence was sometimes seen from a vent low on the S wall of Pu'u 'O'o 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/
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 12-19 February seismic activity from Kliuchevskoi was above background levels and lava continued to flow down the NW flank. Strombolian activity periodically ejected material 200 m above the crater, and phreatic explosions occurred from the front of the lava flow. Satellite imagery revealed a large daily thermal anomaly at the volcano and gas-and-steam plumes that drifted over 240 km NE. The Aviation Color Code level 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
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
The Tokyo VAAC reported that during 17-23 February plumes from Sakura-jima identified on satellite imagery, and ash plumes seen by pilots, rose to altitudes of 1.5-4 km (5,000-13,000 ft) a.s.l. and drifted NE, E, SE, and S.
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 pilot observations, the Washington VAAC reported that on 22 February an ash plume from Sangay rose to an altitude of 7.6 km (25,000 ft) a.s.l. Ash was not identified 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
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 12-19 February seismic activity from Shiveluch was above background levels, possibly indicating ash plumes rising to an altitude of 5.1 km (16,700 ft) a.s.l. Fumarolic activity was occasionally observed. Analyses of satellite imagery revealed a large daily thermal anomaly from the lava dome and ash plumes that drifted over 70 km in northern directions on 11, 13, and 17 February. The Aviation Color Code level remained at Orange. Based on information from KVERT, the Tokyo VAAC reported that on 23 February an eruption produced a plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted N.
Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m
Based on information from JMA, the Tokyo VAAC reported explosions from Suwanose-jima during 17-19 and 21-22 February. Plumes occasionally rose to altitudes of 1.2-1.8 km (4,000-6,000 ft) a.s.l. and drifted E and SE.
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
TALANG Sumatra (Indonesia) 0.978°S, 100.679°E; summit elev. 2597 m
On 17 February, CVGHM lowered the Alert Level for Talang from 3 to 2 (on a scale of 1-4) because seismicity had declined in general since February 2009. Visitors and tourists were advised not approach the crater.
Geologic Summary. Talang, which forms a twin volcano with the extinct Pasar Arbaa volcano, has two crater lakes on its flanks. The largest of these is 1 x 2 km wide Danau Talang. No historical eruptions have occurred from the summit of the volcano, which lacks a crater. All historical eruptions from Gunung Talang volcano have involved small-to-moderate 19th-century explosive activity originating from a series of small craters in a valley on the upper NE flank.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/
TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m
The IG reported that explosions from Tungurahua were detected by the seismic network during 16-23 February. Although inclement weather often prevented observations of the volcano, ash plumes were seen rising to altitudes of 6-8 km (19,700-26,200 ft) a.s.l. and drifting S, SW, W, and ENE. Ashfall was noted almost daily, in areas to the SW and S. Blocks rolled down the flanks on 18 February. Lahars descended NW and W drainages on 20 February and a SW drainage on 22 February. On 21 February small block avalanches on the N flank generated pyroclastic flows.
Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/
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