********************************************************* GVP/USGS Weekly Volcanic Activity Report 1-7 August 2007 http://www.volcano.si.edu/reports/usgs/ ********************************************************* New Activity/Unrest: | Bulusan, Philippines | Cleveland, USA | Fuego, Guatemala | Kilauea, USA | Papandayan, Indonesia Ongoing Activity: | Karymsky, Russia | Popocatépetl, México | Rabaul, Papua New Guinea | Sakura-jima, Japan | Sangay, Ecuador | Semeru, Indonesia | Shiveluch, Russia | Soufrière Hills, Montserrat | St. Helens, USA | Tungurahua, Ecuador New Activity/Unrest BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m An explosion from Bulusan on 31 July produced an ash plume that rose to an altitude of 6.6 km (21,700 ft) a.s.l. The plume drifted WSW and WNW, causing light ashfall. According to a news article, white steam plumes rose from active craters and fissures on 2 August. The Alert Level remained at 1 (out of 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. Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/, Agence France-Presse http://news.yahoo.com/s/afp/20070802/sc_afp/philippinesvolcanobulusan_070802043227 Bulusan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01= CLEVELAND Aleutian Islands, USA 52.82°N, 169.95°W; summit elev. 1,730 m A thermal anomaly in the crater of Cleveland was intermittently visible on satellite imagery during 2-6 August, though bad weather often limited observations. Photographs from 27 July and a pilot report from 2 August indicated fresh volcanic ejecta on the slopes and summit. The E portion of Chuginadak Island was dusted with ash on 3 August. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch <http://www.avo.alaska.edu/color_codes.php>. 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/ Cleveland Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1101-24- FUEGO Guatemala 14.47°N, 90.88°W; summit elev. 3,763 m INSIVUMEH reported that explosions from Fuego expelled incandescent material 50-75 m above the crater on 1 August. Incandescent avalanches traveled 500-700 m down the S and W flanks. Rumbling noises and shock waves were noted at nearby locations. On 2 August, a moderate eruption produced pyroclastic flows that traveled approximately 2 km SSW down the Ceniza River valley. A resultant ash plume rose to an altitude of 5.3 km (17,400 ft) a.s.l. and produced ashfall in areas to the S, SW, and W for several minutes. 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/geofisica/boletin%20formato.htm Fuego Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-09= KILAUEA Hawaii, USA 19.43°N, 155.29°W; summit elev. 1,222 m HVO reported that two of the four fissures from Kilauea's 21 July fissure eruption remained active during 1-7 August. The four fissures, A, B, C, and D, consecutively segment an approximately 2 km-long line that trends NE; fissure A is to the SE and fissure D is to the NE. During the reporting period, fissure C minimally fed a perched lava pond. Fissure D fed a NE-advancing 'a'a lava flow that was an estimated 3.5 km long on 1 August. The 'a'a flow entered the forest on 6 August as evident by smoke near the flow front. Fuming was seen on Pu'u 'O'o's crater web camera images on 4, 5, and 7 August. A few small earthquakes were located beneath Halema'uma'u crater, the S flank, and an area offshore between Kilauea and Lo'ihi during 1-7 August. 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 broad areas on the S flank of Kilauea and adding new land beyond the former coastline. Source: US Geological Survey Hawaiian Volcano Observatory http://volcano.wr.usgs.gov/hvostatus.php Kilauea information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01- PAPANDAYAN Java, Indonesia 7.32°S, 107.73°E; summit elev. 2,665 m On 2 August, CVGHM raised the Alert Level at Papandayan from 1 to 2 (on a scale of 1-4) due to increased activity at the volcano. During 15 July-1 August, the number of volcanic earthquakes increased. By 31 July, the temperatures of fumaroles had increased 10 degrees C above normal levels in Mas crater. Temperatures were 3.5 degrees C above normal levels in Balagadama crater since 26 June. On 1 August, a diffuse white plume rose to an altitude of 2.7 km (8,900 ft) a.s.l. Associated with the increase in Alert Level, villagers and tourists were not permitted within a 1 km radius of the active craters. Geologic Summary. Papandayan is a complex stratovolcano with four large summit craters, the youngest of which was breached to the NE by collapse during a brief eruption in 1772 and contains active fumarole fields. The broad 1.1-km-wide, flat-floored Alun-Alun crater truncates the summit of Papandayan, and Gunung Puntang to the N gives the volcano a twin-peaked appearance. Several episodes of collapse have given the volcano an irregular profile and produced debris avalanches that have impacted lowland areas beyond the volcano. During its first historical eruption in 1772, a catastrophic debris avalanche destroyed 40 villages. In the next two centruries only two small phreatic eruptions have occurred from vents in the NE-flank fumarole field, Kawah Mas. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/ Papandayan Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0603-10= Ongoing Activity KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Seismic activity at Karymsky was above background levels during 27 July-3 August, with 150-600 shallow earthquakes occurring daily. Based on seismic interpretation, ash plumes may have risen to an altitude of 3 km (9,800 ft) a.s.l. Observations of satellite imagery revealed that a thermal anomaly was present in the crater on 31 July and 2 August and gas-and-steam plumes drifted SW on 2 August. The Level of Concern Color Code remained at 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 (KVERT) 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= POPOCATÉPETL México 19.02°N, 98.62°W; summit elev. 5,426 m According to the Washington VAAC, CENAPRED reported that on 28 July an eruption plume from Popocatépetl with minor ash content was visible on a web camera. The plume rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted WSW. A pilot reported an ash plume on 3 August. Ash was not identified on satellite imagery on either day. Geologic Summary. Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America's second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages. Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html Popocatépetl Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1401-09= RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 22 July-1 August, white and blue vapor plumes from Rabaul caldera's Tavurvur cone rose to an approximate altitude of 0.9 km (3,000 ft) a.s.l. and drifted NNW. Roaring noises were occasionally heard and incandescence was intermittently visible at the crater rim. On 30 July, a white plume with little ash content rose to an altitude of 2.7 km (8,900 ft) a.s.l. and drifted SW. During 1-7 August, ash plumes rose to altitudes of 0.9-1.7 km (3,000-5,600 ft) a.s.l. and drifted N, NW, and W. Slight ashfall was reported at Rabaul town and surrounding areas. Geologic Summary. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the E, where its floor is flooded by Blanche Bay. Two major Holocene caldera-forming eruptions at Rabaul took place as recently as 3,500 and 1,400 years ago. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city. Source: Herman Patia, Rabaul Volcano Observatory Rabaul Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-14= SAKURA-JIMA Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m Based on information from JMA, the Tokyo VAAC reported an explosion from Sakura-jima on 4 August. Ash was not detected on satellite imagery. 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 Sakura-jima Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0802-08= SANGAY Ecuador 2.03°S, 78.34°W; summit elev. 5,188 m Based on pilot observations, the Washington VAAC reported that an ash plume from Sangay rose to an altitude of 5.5 km (18,000 ft) a.s.l. and drifted W on 2 August. Ash was not detected on 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 Sangay Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-09= SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m Based on a pilot observation, the Darwin VAAC reported that an ash plume, possibly from Semeru, rose to an altitude of 6.1 km (20,000 ft) a.s.l. on 6 August. Ash was not detected on satellite imagery. Geologic Summary. Semeru is the highest volcano on Java and one of its most active. The symmetrical stratovolcano rises abruptly to 3,676 m above coastal plains to the S and lies at the southern end of a volcanic massif extending N to the Tengger caldera. Semeru has been in almost continuous eruption since 1967. Frequent small-to-moderate Vulcanian eruptions have accompanied intermittent lava dome extrusion, and periodic pyroclastic flows and lahars have damaged villages below the volcano. A major secondary lahar on 14 May 1981 caused more than 250 deaths and damaged 16 villages. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html Semeru Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-30= SHIVELUCH Kamchatka Peninsula, Russia 56.653°N, 161.360°E; summit elev. 3,283 m KVERT reported that seismic activity at Shiveluch was slightly above background levels during 27 July-3 August. Observations of satellite imagery revealed that a thermal anomaly was present in the crater. Based on seismic interpretation, ash plumes and avalanches occurred during the reporting period. Gas-and-steam plumes were visible drifting S on 31 July; clouds inhibited visual observations on other days. The Level of Concern Color Code remained at Orange <http://www.avo.alaska.edu/color_codes.php>. 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 horseshoe-shaped 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. During the 1990s, intermittent explosive eruptions took place 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/updates.shtml Shiveluch Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=1000-27= SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m MVO reported that during 27 July-3 August, the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity affected all sides of the dome. On 30 July, three pyroclastic flows traveled about 1.5 km down the N side of the Tar River Valley. The Alert Level remained elevated at 4 (on a scale of 0-5). 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. Source: Montserrat Volcano Observatory http://www.mvo.ms/ Soufrière Hills Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05= ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m Data from deformation-monitoring instruments indicated that during 1-7 August lava-dome growth at Mount St. Helens continued. Seismicity persisted at low levels, punctuated by M 1.5-2.5, and occasionally larger, earthquakes. In some instances, clouds inhibited visual observations. 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 IG reported that on 1 August, ash-and-gas plumes from Tungurahua rose to altitudes of 5.5 km (18,000 ft) a.s.l. and drifted NW. Ashfall was reported from areas downwind. Noises indicating rolling blocks were heard. On 2 August, steam emissions and roaring noises were reported. On 5 August, roaring noises were reported and a steam-and-gas plume rose to an altitude of 5.1 km (16,700 ft) a.s.l. and drifted W. On 6 August, explosions were accompanied by roaring noises that were reported from the NW and SW sectors. A steam plume rose to an altitude of 5.2 km (17,100 ft) a.s.l. and drifted W on 7 August. Clouds occasionally inhibited visual observations. 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. Source: Instituto Geofísico-Escuela Poltécnica Nacional http://www.igepn.edu.ec/ Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08= +++++++++++++++++++++++++++++++++++++ Sally Kuhn Sennert SI/USGS Weekly Volcanic Activity Report Editor Global Volcanism Program http://www.volcano.si.edu/reports/usgs/ Smithsonian Institution, National Museum of Natural History Department of Mineral Sciences, MRC-119 Washington, D.C., 20560 Phone: 202.633.1805 Fax: 202.357.2476 ============================================================== 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. ==============================================================
