************************************************************************************************************************** SI/USGS Weekly Volcanic Activity Report 16-22 December 2009 From: Sally Kuhn Sennert <kuhns@xxxxxx> ************************************************************************************************************************** SI/USGS Weekly Volcanic Activity Report 16-22 December 2009 Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Bezymianny, Central Kamchatka (Russia) | Cleveland, Chuginadak Island | Gaua, Banks Islands (SW Pacific) | Mayon, Luzon | San Cristóbal, Nicaragua Ongoing Activity: | Chaitén, Southern Chile | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Sakura-jima, Kyushu | Sangay, Ecuador | Shiveluch, Central Kamchatka (Russia) | 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 BEZYMIANNY Central Kamchatka (Russia) 55.978°N, 160.587°E; summit elev. 2882 m KVERT reported that seismic activity from Bezymianny increased on 8 December. After a significant thermal anomaly was detected in satellite imagery on 17 December, the Level of Concern Color Code was raised to Red. A few hours later a large explosive eruption produced ash plumes that were seen drifting as far as 350 km W and NW in satellite imagery. Ash plumes likely rose to altitudes greater than 10 km (32,800 ft) a.s.l.; clouds in the area prevented visual observations. Ashfall up to 3 mm thick was noted in Kozyrevsk, 45 km W, and other surrounding villages. The Level of Concern Color Code was lowered to Orange after seismic activity significantly decreased. On 18 December another large thermal anomaly was seen over the volcano and on the SE flank. Gas-and-steam activity was also noted. During 19-20 December, a thermal anomaly continued to be detected in satellite imagery. KVERT lowered the Level of Concern Color Code to Yellow on 21 December. Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. That eruption, similar to the 1980 event at Mount St. Helens, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m On 18 December, AVO reported that a diffuse ash plume emitted from Cleveland on 12 December was retrospectively detected in satellite imagery. No other activity was noted. Geologic Summary. Symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks. Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/ GAUA Banks Islands (SW Pacific) 14.27°S, 167.50°E; summit elev. 797 m On 14 December, Vanuatu Geohazards Observatory reported that activity from Gaua during the previous month was characterized by continuous ash emissions accompanied by periodic steam emissions. Ashfall was reported in the W part of the island. Satellite imagery revealed that periods of significant gas emissions were more frequent than during November. Ash emissions during 14-18 December were thicker and darker, and possibly represented a new eruptive phase. Ash plumes continued to drift W and produce ashfall. The Vanuatu Volcanic Alert Level remained at 2 (on a scale of 0-4). Geologic Summary. The roughly 20-km-diameter Gaua Island, also known as Santa Maria, consists of a basaltic-to-andesitic stratovolcano with an 6 x 9 km wide summit caldera. Small parasitic vents near the caldera rim fed Pleistocene lava flows that reached the coast on several sides of the island; several littoral cones were formed where these lava flows reached the sea. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash eruptions. Construction of the historically active cone of Mount Garat (Gharat) and other small cinder cones in the SW part of the caldera has left a crescent-shaped caldera lake. The symmetrical, flat-topped Mount Garat cone is topped by three pit craters. The onset of eruptive activity from a vent high on the SE flank of Mount Garat in 1962 ended a long period of dormancy. Source: Vanuatu Geohazards Observatory http://www.geohazards.gov.vu/ MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m PHIVOLCS reported that during 14-19 December sulfur dioxide emissions from Mayon fluctuated between 750 and 2,034 tonnes per day. During 15-16 December, detached fragments from lava accumulating in the summit crater traveled as far as 4 km down the SE-flank Bonga-Buyuan gully, and lava flows traveled 700-800 m. Occasionally detached lava fragments produced small pyroclastic surges down the SW flank that generated light ashfall 13 km S and W in Camalig and Guinobatan, respectively. Steam plumes rose 200 m above the crater rim and drifted SW and WSW. During 17-20 December the seismic network detected 66 explosion-type signals; only 23 events were seen during periods of good visibility. These explosions produced dark gray to dark brown ash plumes that rose 500-2,000 m above the crater rim and drifted SW. Harmonic tremor was detected by the seismic network. Brownish-colored steam and intensified incandescence at night were noted. On 20 December lava flows had advanced 4.5 km from the crater. PHIVOLCS raised the Alert Level to 4 (on a scale of 0-5) and recommended that the Extended Danger Zone (EDZ) encompass an area 8 km S from the summit and 7 km N from the summit. During 20-22 December the rate and intensity of seismic signals dramatically increased. The sulfur dioxide emission rate also increased; 6,089-6,529 tonnes per day was measured. Booming and rumbling sounds, and intensified crater incandescence, were noted. Lava fountains rose 200 m above the crater and lava flowed as far as 5 km down the Bonga-Buyuan, Miisi, and Lidong gullies. According to news articles, more than 47,000 people from 30 villages were in evacuation centers across Albay province. About 3,000-6,000 residents had not evacuated. 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. Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/, Inquirer Southern Luzon and Associated Press http://newsinfo.inquirer.net/inquirerheadlines/nation/view/20091222-243359/Mayon-hit-by-2000-tremors, Associated Press http://www.google.com/hostednews/ap/article/ALeqM5hAsh86J3QWdxWNEaLHMmNk7dMbiQD9CNLMDO0 SAN CRISTOBAL Nicaragua 12.702°N, 87.004°W; summit elev. 1745 m Based on METAR weather reports, the Washington VAAC reported that on 22 December a gas-and-steam plume that rose from San Cristóbal possibly contained ash. Geologic Summary. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1,745-m-high youngest cone, San Cristóbal itself (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km to the west of San Cristóbal; it and the eroded Moyotepe volcano, 4 km to the NE of San Cristóbal, are of Pleistocene age. Volcán Casita contains an elongated summit crater and lies immediately E of San Cristóbal; Casita was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristóbal complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes. Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html Ongoing Activity CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m SERNAGEOMIN reported that during 1-15 December Chaitén's lava-dome complex produced steam, gas, and ash plumes that rose 2 km above the lava domes. On 7 December emissions originated from the N and S areas of the complex. Block-and-ash flows were noted the next day. The Alert Level remained at Red. Based on web camera views and SIGMET notices, the Buenos Aires VAAC reported that on 18 December an ash plume drifted SSE at altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. 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 KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that during 11-13 and 17 December a thermal anomaly over Karymsky was detected in satellite imagery. Seismic activity was above background levels on 12 and 13 December; data were not available during 11-21 December due to technical problems. The Level of Concern 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. 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 16-22 December, HVO reported that lava flowed SE from beneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the ocean at Waikupanaha. Incandescence was seen almost daily coming from Pu'u 'O'o crater. The vent in Halema'uma'u crater continued to produce an off-white plume that drifted E and SW, dropping small amounts of ash downwind. Incandescence originated from a few holes in the deep floor of the vent cavity. Occasionally, lava ponded on the floor of the cavity. Spatter originated from a small spatter cone on the E side of the vent cavity floor. Spatter from the opening frequently fed small lava flows that traveled down the flank of the cone. The sulfur dioxide emission rate at the summit remained elevated; 600 tonnes per day were measured on 18 December. The 2003-2007 average rate was 140 tonnes per day. Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island. 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 11-21 December seismic activity from Kliuchevskoi was above background levels. Satellite imagery revealed a large daily thermal anomaly at the volcano. The Level of Concern Color Code remained at Orange. Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included major explosive and effusive events from flank craters. 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 Based on information from JMA, the Tokyo VAAC reported that during 16-17 and 20-22 December 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 E, SE, and S. On 19 and 22 December, pilots reported that ash plumes rose to altitudes of 2.1-2.4 km (7,000-8,000 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 SANGAY Ecuador 2.002°S, 78.341°W; summit elev. 5230 m Based on pilot observations, the Washington VAAC reported that on 18 and 21 December ash plumes from Sangay rose to an altitude of 7.9 km (26,000 ft) a.s.l. and drifted W. Ash was not identified in satellite imagery, although weather clouds were present in the area. Thermal anomalies were occasionally detected in the 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 11-21 December seismic activity from Shiveluch was above background levels, possibly indicating ash plumes rising to an altitude of 5.5 km (18,000 ft) a.s.l. Analyses of satellite imagery revealed a large daily thermal anomaly from the lava dome. The Level of Concern 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 SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m MVO reported that during 11-19 December activity from the Soufrière Hills lava dome continued at a high level. Night-time incandescence and observations with a high resolution thermal camera showed that activity was concentrated on the NW flank. Pyroclastic flows and semi-continuous rockfalls traveled down the NE, N, and NW flanks, channelling NE directly into Whites Ghaut and continuing into Whites Bottom Ghaut. Pyroclastic flows also traveled as far as 2 km NW down Tyers Ghaut multiple times a day, occasionally as far as 2 km W down Gages valley, and rarely E down Tar River valley. Fresh deposits from small pyroclastic flows moving S were seen at the head of the White River and Gingoes Ghaut. On 19 December heavy ashfall occurred in several areas in NW Montserrat. 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/ SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m Based on information from JMA, the Tokyo VAAC reported eruptions from Suwanose-jima during 17-20 and 22 December. A plume rose to an altitude of 1.5 km (5,000 ft) a.s.l. on 22 December. 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 ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
