******************************************************** GVP/USGS Weekly Volcanic Activity Report 17-23 May 2006 ******************************************************** From: Gari Mayberry <mayberry@xxxxxxxxxxxxxx> GVP/USGS Weekly Volcanic Activity Report 17-23 May 2006 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Cleveland, USA | Merapi, Indonesia | Soufriere Hills, Montserrat Ongoing Activity: | Fuego, Guatemala | Galeras, Colombia | Karymsky, Russia | Kelut, Indonesia | Kilauea, USA | Lopevi, Vanuatu | St. Helens, USA | Tungurahua, Ecuador | Ubinas, Perú New Activity/Unrest CLEVELAND Aleutian Islands, USA 52.82°N, 169.95°W; summit elev. 1,730 m; All times are local (= UTC - 8 hours) On 23 May, AVO reported that an astronaut aboard the International Space Station observed an ash plume from Cleveland at 1500. A plume was visible on satellite imagery at 1507 that drifted SW and reached a height of 6.1 km (20,000 ft) a.s.l. At 1700, an image showed the detached ash plume 130 km SW of Cleveland. The Concern Color Code was raised to Yellow <http://www.avo.alaska.edu/color_codes.php>. No precursory or current seismic information is available because Cleveland does not have a real-time seismic network. Geologic Summary. The 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 http://www.avo.alaska.edu/activity/avoreport.php?view=update Cleveland Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1101-24- MERAPI central Java, Indonesia 7.542°S, 110.442°E; summit elev. 2,947 m The Alert Level at Merapi remained at 4, the highest level, during 17-22 May. Incandescence and sulfur-dioxide plumes were observed. Pyroclastic flows to the SW and SE reached 4 km on 19 May and 3 km on 20 May. On 22 May, the lava dome volume was estimated at ~ 2.3 million cubic meters. The Darwin VAAC reported that low-level emissions continued during 18-19 and 23 May. CVGHM recommended that residents who live in valleys on the NNW flanks near Sat, Lamat, Senowo, Trising, and Apu Rivers and on the SE flank near Woro River be allowed to return to their homes. Residents remained evacuated from villages within a 7 km radius from the volcano's summit and within 300 m of the banks of the Krasak/Bebeng, Bedog, and Boyong Rivers to the SW, and the Gendol River to the SE. According to news reports, an eruption producing a cloud of hot gas and ash was witnessed on 17 May. Witnesses said the size of the plume was smaller than ash-and-gas plumes on 15 May. On 18 May, a representative for Merapi from the Center for Volcanological Research and Technology Development (part of CVGHM), reported new ashfall. 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 of the Volcanological Survey of Indonesia. Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/portal/html/index.php, Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/products/IDD41290.shtml, Associated Press http://www.cnn.com/2006/WORLD/asiapcf/05/17/indonesia.volcano/index.html, AFP http://news.yahoo.com/s/afp/20060518/wl_asia_afp/indonesiavolcano_060518151037, Reuters http://news.yahoo.com/s/nm/20060517/sc_nm/indonesia_merapi_dc Merapi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-25= SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m; All times are local (= UTC -4 hours) MVO reported that on the morning of 20 May a major lava-dome collapse at Soufrière Hills occurred over a time period of less than three hours. Approximately 90 million cubic meters of the lava dome material was shed from the summit leaving a broad, deep, eastward-sloping crater. Pyroclastic flows traveled E down the Tar River Valley and were estimated to extend out to 3 km over the sea. Lahars due to excessive rain were produced NW in the Belham River Valley, N in the Trants area, and to the NE. An ash cloud reached 16.8 km (55,000 ft) a.s.l. by 0740, the highest reported ash cloud during the 10 years of the eruption, and traveled NW. Lithics (average size of 3.5 cm across) fell NW of the volcano. On 21 May, ash and mud fell on the northern parts of the island. Prior to the lava-dome collapse, during 12 May and 19 May, lava extrusion had continued. The Washington VAAC reported that the ash plume from the 20 May dome collapse initiated at approximately 0700. On 21 May, the remnant ash cloud from 20 May was at a height of ~11.3 km (37,000 ft) a.s.l. along the northern coast of South America and the Southern Caribbean. An ash cloud at a height of ~7 km (23,000 ft) a.s.l. extended S of Puerto Rico and the Dominican Republic. According to news reports, the ash cloud on 20 May forced the suspension of some international flights in areas of the Caribbean through 21 May. On 22 May, multi-spectral imagery indicated that an ash plume at a height of ~3 km (10,000 ft) a.s.l. extended over the islands of Anguilla, St. Martin, and St. Kitts. On 23 May, a thin ash plume was visible on satellite imagery and moved WNW. 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 east, was formed during an eruption about 4000 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. Sources: Montserrat Volcano Observatory http://www.mvo.ms/, Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/ARCHIVE/FUEG/2006E181541.html, Associated Press http://abcnews.go.com/International/wireStory?id=1988539&CMP=OTC-RSSFeeds0312 Soufrière Hills Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05= Ongoing Activity FUEGO Guatemala 14.47°N, 90.88°W; summit elev. 3,763 m On 17 May, INSIVUMEH reported that fumarolic emissions reached ~600 m above the volcano (14,300 ft a.s.l.). and drifted E and W. Active lava flows reached ~100 m SW toward the Taniluyá River and ~500 m SW toward the Ceniza River. Avalanches occurred from lava-flow fronts. The Washington VAAC reported a short low-level plume on 18 May that drifted N from the volcano. 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, Meterologia, e Hidrologia http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm, Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/ARCHIVE/FUEG/2006E181541.html Fuego Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-09= GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4,276 m INGEOMINAS reported that during 15-22 May, a partially solidified lava dome remained in the main crater of Galeras. Seismicity and the sulfur-dioxide flux continued at very low levels. Galeras remained at Alert Level 2 (likely eruption in days or weeks). Geologic Summary. Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Long-term extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors. Source: Instituto Colombiano de Geología y Minería http://www.ingeominas.gov.co/tmsingeominas/ModuloPublicacionPortal/PublicacionPortal.asp Galeras Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1501-08= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m During 12-19 May, eruptive activity continued at Karymsky. Based on interpretations of seismic and satellite data, ash plumes rose to a height of 8 km (26,200 ft) a.s.l. Ash plumes extended for about 50 km to the S and NE. KVERT warned that activity from the volcano could affect nearby low-flying aircraft. Karymsky remained at Concern Color Code Orange <http://www.avo.alaska.edu/color_codes.php>. 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 http://www.kscnet.ru/ivs/kvert/updates.shtml Karymsky Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-13= KELUT Java, Indonesia 7.93°S, 112.31°E; summit elev. 1,731 m Based on a pilot report, the Darwin VAAC reported that on 18 May an ash plume from Kelut reached a height of 5.5 km (18,000 ft) a.s.l. The report was not verified by ground observations. Geologic Summary. The relatively inconspicuous 1,731-m-high Kelut stratovolcano contains a summit crater lake that has been the source of some of Indonesia's most deadly eruptions. A cluster of summit lava domes cut by numerous craters has given the summit a very irregular profile. More than 30 eruptions have been recorded from Gunung Kelut since 1000 AD. The ejection of water from the crater lake during Kelut's typically short, but violent eruptions has created pyroclastic flows and lahars that have caused widespread fatalities and destruction. After more than 5,000 people were killed during the 1919 eruption, an ambitious engineering project sought to drain the crater lake. This initial effort lowered the lake by more than 50 m, but the 1951 eruption deepened the crater by 70 m, leaving 50 million cubic meters of water after repair of the damaged drainage tunnels. After more than 200 people were killed in the 1966 eruption, a new deeper tunnel was constructed, lowering the lake's volume to only about 1 million cubic meters prior to the 1990 eruption. Source: Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/products/IDD41295.shtml Kelut Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-28= KILAUEA Hawaii, USA 19.43°N, 155.29°W; summit elev. 1,222 m Small lava flows were visible on 19 May and minor incandescence was observed on 21-22 May at Kilauea's East Lae`apuki lava delta. Seismicity levels were low at the summit and moderate at Pu`u `O`o. After 16 May, there was very little change in deformation. 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 by lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. The latest Kilauea eruption began in January 1983 along the E rift zone. This long-term ongoing eruption from Pu`u `O`o-Kupaianaha has produced lava flows that have traveled 11-12 km from the vents to the sea, paving about 104 km2 of land on the S flank of Kilauea and building more than 200 hectares of new land. Source: US Geological Survey Hawaiian Volcano Observatory http://volcanoes.usgs.gov/update.html Kilauea information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01- LOPEVI Central Islands, Vanuatu 16.507°S, 168.346°E; summit elev. 1,413 m According to Vanuatu's National Disaster Management Office, Lopevi volcano remains at Alert Level 2. An official spokesperson reported no new ashfall during 17-22 May. The last report of an ash plume was on 15 May. Geologic Summary. The small 7-km-wide conical island of Lopevi is one of Vanuatu's most active volcanoes. A small summit crater containing a cinder cone is breached to the NW and tops an older cone that is rimmed by the remnant of a larger crater. The basaltic-to-andesitic volcano has been active during historical time at both summit and flank vents, primarily on the NW and SE sides, producing moderate explosive eruptions and lava flows that reached the coast. Historical eruptions at the 1,413-m-high volcano date back to the mid-19th century. The island was evacuated following eruptions in 1939 and 1960. The latter eruption, from a NW-flank fissure vent, produced a pyroclastic flow that swept to the sea and a lava flow that formed a new peninsula on the western coast. Source: Shanghai Daily http://english.eastday.com/eastday/englishedition/world/userobject1ai2053407.html Lopevi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0507-05= ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m During 17-22 May, the lava spine continued to grow inside the crater of Mt. St. Helens producing minor rockfalls and moderately-sized rock avalanches that generated small ash plumes. On 17 May, lava extrusion continued to deform the W part of the lava dome and night-time incandescence from rockfalls was observed. Geologic Summary. Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens was formed during nine eruptive periods beginning about 40-50,000 years ago, and has been the most active volcano in the Cascade Range during the Holocene. The modern edifice was constructed during the last 2,200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century originated from the Goat Rocks area on the N flank, and were witnessed by early settlers. Source: US Geological Survey Cascades Volcano Observatory http://vulcan.wr.usgs.gov/Volcanoes/MSH/CurrentActivity/framework.html St. Helens Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1201-05- TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m During 17-20 May, ash emissions from Tungurahua increased. On 18 May, an ash plume reached a height of 5.2 km (17,000 ft) a.s.l. and extended NW, according to Washington VAAC reports. The Washington VAAC also noted that on 19 May, the Instituto Geofísico observed an ash plume that reached a height of 12 km (40,000 ft) a.s.l. On satellite imagery, ash plumes were visible on 20 and 23 May and extended SW. Hotspots were visible on satellite imagery 19-20 and 23 May. The ash plume and incandescence on 23 May were also observed by Instituto Geofísico staff. The ash plume on 18 May prompted officials to renew a limited state of emergency in nearby towns. According to news reports, many people left their villages. No official evacuations were initiated. 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 been restricted to 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. Sources: Instituto Geofísico-Escuela Poltecnica Nacional http://www.igepn.edu.ec/vulcanologia/tungurahua/actividad/informet.htm, Washington VAAC http://www.ssd.noaa.gov/VAAC/ARCHIVE/TUNG/2006E192311.html, Reuters http://tvnz.co.nz/view/page/411749/716220 Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08= UBINAS Perú 16.355°S, 70.903°W; summit elev. 5,672 m Based on information from significant meteorological advisories (SIGMET) and pilot reports, the Buenos Aires VAAC reported that ash emitted from Ubinas during 20-23 May rose to a maximum height of 7.3 km (24,000 ft) a.s.l. Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives it a truncated appearance. Ubinas is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank of Ubinas extend 10 km from the volcano. Widespread plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions. Source: Buenos Aires Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html Ubinas Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02 Sally S. Kuhn Science Writer Smithsonian Institute Department of Mineral Sciences Global Volcanism Program Washington D.C. 20560-0119 Fax: 202.357.2476 <http://www.volcano.si.edu/>http://www.volcano.si.edu/ ============================================================== 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. ==============================================================
