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SI/USGS Weekly Volcanic Activity Report 22-28 July 2009
From: Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx
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SI/USGS Weekly Volcanic Activity Report
22-28 July 2009
22-28 July 2009
New Activity/Unrest: | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia)
Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Kilauea, Hawaii (USA) | Nevado del Huila, Colombia | Sangay, Ecuador | Sarychev Peak, Matua Island | 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
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
Based on information from JMA, the Tokyo VAAC reported that on 22 July explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted E and SE. On 23 July and 27 July pilots observed ash plumes that rose to altitudes of 2.1 and 3 km (7,000 and 10,000 ft) a.s.l. and drifted E and SW, respectively. Explosions were reported during 24-25 and 28 July.
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
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 17-18 and 20-24 July seismic activity from Shiveluch was above background levels. During 17-20 and 22 July, gas-and-steam plumes seen on a video camera rose to an altitude of 3.7 km (12,100 ft) a.s.l. Based on interpretations of seismic data, ash plumes possibly rose to an altitude of 5.2 km (17,000 ft) a.s.l. on 20, 21, and 22 July, and steam-and-gas plumes with some ash content were noted on other days. Analyses of satellite imagery revealed a large daily thermal anomaly over the lava dome, and steam plumes that drifted as far away as 40 km on 18 and 20 July. The Level of Concern Color Code remained at Orange.
Based on analyses of satellite imagery and information from KEMSD, the Tokyo VAAC reported that during 23-24 and 27-28 July eruptions produced plumes that rose to altitudes of 4.6-6.1 km (15,000-20,000 ft) a.s.l. According to news sources, an ash plume rose to an altitude of 7 km (23,000 ft) a.s.l. late on 25 July. Increased seismicity, powerful ash bursts, and avalanches were also reported.
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,
Ria Novosti http://en.rian.ru/russia/20090726/155627424.html
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html,
Ria Novosti http://en.rian.ru/russia/20090726/155627424.html
Ongoing Activity
BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin VAAC reported that on 23 July an ash plume from Batu Tara rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 55 km W. On 27 and 28 July, ash plumes rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted as far away as 150 km NW.
Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow.
Source: Darwin Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m
Based on web camera views from the S, SERNAGEOMIN reported that during 16-22 July gas-and-ash plumes rose 1.5 km from Chaitén's growing Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex. Collapses originating from unstable slopes generated block-and-ash flows, particularly in the W area of the complex. The Alert Level remained at Red. Based on web camera views and analyses of satellite imagery, the Buenos Aires VAAC reported that on 28 July an ash plume rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted NE.
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.
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
Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 22-28 July, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha ocean entry. Thermal anomalies detected in satellite images and visual observations revealed active surface flows at several locations on the pali. Explosions from the Waikupanaha ocean entry were reported on 22 July. The vent in Halema'uma'u crater continued to produce a diffuse white plume that drifted mainly SW. Small amounts of ash-sized "rock dust" were retrieved from collection bins placed near the plume during the reporting period. The sulfur dioxide emission rate at the summit remained elevated; measurements were 800, 500, and 950 tonnes per day on 22, 24, and 27 July, respectively. The 2003-2007 average rate was 140 tonnes per day; between the 30 June rockfall sequence and 19 July rates were 200-400 tonnes per day.
Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/
NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5364 m
INGEOMINAS reported that during 22-28 July four pulses of seismic tremor from Nevado del Huila indicated explosions. Gas plumes were seen on a web camera and during a commercial flight. On 23 July, ashfall was reported in an area to the NW. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").
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.
Source: Instituto Colombiano de Geología y Minería (INGEOMINAS) http://www.ingeominas.gov.co//
SANGAY Ecuador 2.002°S, 78.341°W; summit elev. 5230 m
Based on a pilot observation, the Washington VAAC reported that on 23 July a possible ash plume from Sangay rose to an altitude of 7.9 km (26,000 ft) a.s.l. The plume 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
SARYCHEV PEAK Matua Island 48.092°N, 153.20°E; summit elev. 1496 m
Based on analyses of satellite imagery, SVERT reported that on 22 July a gas-and-steam plume from Sarychev Peak drifted 35 km N. Cloud cover prevented observations during 23-26 July. On 27 July, a steam-and-gas plume possibly containing some ash rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 55 km NW.
Geologic Summary. Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5 km wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows descend all sides of Sarychev Peak and often form capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760's and include both quiet lava effusion and violent explosions. The largest historical eruption of Sarychev Peak in 1946 produced pyroclastic flows that reached the sea.
Sources: Sakhalin Volcanic Eruption Response Team (SVERT) http://www.imgg.ru/rus/labs_vulcan_hazard.php,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
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 23-24 July. Details of possible resultant ash plumes 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.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
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