******************************************************************** GVP/USGS Weekly Volcanic Activity Report 30 August-5 September 2006 ******************************************************************** Reply-To: "Kuhn, Sally" <KUHNS@xxxxxx> GVP/USGS Weekly Volcanic Activity Report 30 August-5 September 2006 http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Soufriere Hills, Montserrat | Tengger Caldera, Indonesia Ongoing Activity: | Bulusan, Philippines | Karymsky, Russia | Kilauea, USA | Manam, Papua New Guinea | Mayon, Philippines | Piton de la Fournaise, Reunion Island | Popocatépetl, México | Sakura-jima, Japan | St. Helens, USA | Tungurahua, Ecuador | Ubinas, Perú | Ulawun, Papua New Guinea New Activity/Unrest SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m; All times are local (= UTC - 4 hours) Based on satellite imagery and reports from the MVO, the Washington VAAC reported that the Soufrière Hills lava dome collapsed at 1740 on 29 August. Ash venting was seen on satellite imagery prior to the collapse at 0615 and 1245. The plumes reached altitudes of 2.4 km (8,000 ft) a.s.l., drifted N, and then shifted to the W and SW. According to the Antigua Aircraft Tower, the dome collapse produced a plume that rose to an altitude of about 9 km (30,000 ft) a.s.l. The upper portion of the cloud drifted E and the lower portion possibly drifted N and W. Pyroclastic flows reached the sea down the Tar River Valley. On 30 August, small pyroclastic flows were visible on the NE and S flanks of the lava dome. On 31 August, two vigorous ash-and-steam vents opened on the W and N flanks accompanied by tremor. A pilot reported an ash plume at an altitude of 4.6 km (15,000 ft) a.s.l. drifting W. The Alert Level was raised to 4 (on a scale of 0-5). The Washington VAAC reported continuous gas and ash emissions during 1-4 September; plumes reached altitudes of 3 km (10,000 ft) a.s.l. and drifted W. 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/messages.html Soufrière Hills Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05= TENGGER CALDERA Java, Indonesia 7.942°S, 112.950°E; summit elev. 2,329 m CVGHM reported that the Alert Level for Tengger Caldera was raised one level to 2 (on a scale of 1-4) on 1 September due to heightened activity and a strong smell of sulfur. Geologic Summary. The 16-km-wide Tengger caldera in eastern Java occupies the northern end of a volcanic massif extending from Semeru volcano. The massive Tengger volcanic complex consists of five overlapping stratovolcanoes, each truncated by a caldera. The most recent is the 9 x 10 km wide Sandsea caldera, which formed incrementally during the late Pleistocene and early Holocene. An overlapping cluster of post-caldera cones was constructed on the floor of the Sandsea caldera within the past several thousand years. The youngest of these is Bromo, one of Java's most frequently visited and most active volcanoes. More than 50 mild-to-moderate explosive eruptions have occurred there since 1804. Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/portal/html/index.php, The Star http://thestar.com.my/news/story.asp?file=/2006/9/6/apworld/20060906101325&sec=apworld Tengger Caldera Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0603-31= Ongoing Activity BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m PHIVOLCS reported that steam plumes from Bulusan reached up to 350 m above the summit (6,300 ft a.s.l.) on 30 August and 1 September. The plumes drifted NW and SE, respectively. 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. Source: Philippine Institute of Volcanology and Seismology http://www.phivolcs.dost.gov.ph/ Bulusan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m Activity at Karymsky continued during 26 August-1 September, with 30-70 shallow earthquakes occurring daily. Based on interpretations of seismic data, ash plumes reached altitudes of 3 km (10,000 ft) a.s.l. A thermal anomaly in the crater was detected on 26 and 28 August. 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= KILAUEA Hawaii, USA 19.43°N, 155.29°W; summit elev. 1,222 m During 23-29 August, lava from Kilauea continued to flow off of a lava delta into the ocean at the East Lae'apuki and East Ka'ili'ili entries. On 1 September, the area of the East Lae'apuki lava bench was an estimated 22 hectares (54 acres) and East Ka'ili'ili was an estimated 2.3 hectares (5.7 acres). Incandescence was visible from the East Pond and January vents, South Wall complex, and Drainhole vent in Pu'u 'O'o's crater during the reporting period. Summit inflation S of Halema'uma'u caldera continued. Tremor at Pu'u 'O'o remained at a very typical moderate level. 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://volcanoes.usgs.gov/update.html Kilauea information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01- MANAM offshore New Guinea, Papua New Guinea 4.10°S, 145.06°E; summit elev. 1,807 m Based on satellite imagery, the Darwin VAAC reported that ash-and-steam plumes from Manam reached altitudes of 4.6 km (15,000 ft) a.s.l. and drifted W on 1 and 2 September. Steam plumes with possible ash were visible on satellite imagery below 3 km (10,000 ft) a.s.l. and drifted NE. Geologic Summary. The 10-km-wide island of Manam is one of Papua New Guinea's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1,807-m-high stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five satellitic centers are located near the island's shoreline. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during the past century into the SE avalanche valley. Frequent historical eruptions have been recorded since 1616. Source: Darwin Volcanic Ash Advisory Centre http://www.bom.gov.au/products/IDD41300.shtml Manam Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0501-02= MAYON southeastern Luzon, Philippines 13.257°N, 123.685°E; summit elev. 2,462 m Occasional explosions at Mayon continued during 30 August-5 September. According to seismic data, four explosions were registered on 31 August. Ashfall was reported in surrounding cities including Tabaco (about 13 km NW) and Guinobatan (about 13 km SW). One small explosion was registered on 3 September. Lava extrusion and collapsing lava-flow fronts on the SE slopes continued to produce blocks and small fragments during the reporting period. Geologic Summary. The 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 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 http://www.phivolcs.dost.gov.ph/news/mayon71706.html, Inquirer http://newsinfo.inq7.net/breakingnews/metroregions/view_article.php?article_id=18078, The Daily Tribune http://www.tribune.net.ph/headlines/20060903hed6.html Mayon Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-03= PITON DE LA FOURNAISE Réunion Island, Indian Ocean 21.23°S, 55.71°E; summit elev. 2,631 m; All times are local (= UTC + 4 hours) A small "seismic crisis" at Piton de la Fournaise began at 1000 on 30 August. A summit eruption started from the SSE edge of Dolomieu Crater at 1135 and scientists witnessed the opening of a fissure on the crater floor. A large portion of the crater floor was covered with lava by the afternoon. A second fissure opened just outside of the crater and produced a lava flow on the E flank. On 31 August, seismicity remained high and a new cone had formed in Dolomieu Crater. Geologic Summary. The massive Piton de la Fournaise shield volcano on the island of Réunion is one of the world's most active volcanoes. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest of three large calderas. This latter caldera is 8 km wide and is breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows within the caldera, have been documented since the 17th century. Source: Thomas Staudacher, Observatoire Volcanologique du Piton de la Fournaise via the Volcano Listserv http://www.volcano.si.edu/reports/volclist/index.htm Piton de la Fournaise Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0303-02= POPOCATÉPETL México 19.02°N, 98.62°W; summit elev. 5,426 m According to the Washington VAAC, emissions of gas, steam, and possibly ash from Popocatépetl were visible from the camera operated by CENEPRED during 4-5 September. The resulting eruption cloud drifted W and did not rise high above the summit. Incandescence was periodically observed at the summit. 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 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= SAKURA-JIMA Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m Based on information from JMA, the Tokyo VAAC reported that eruptions at Sakura-jima on 3 and 4 September generated plumes that rose to ~2.7 km (~9,000 ft) a.s.l. and drifted mainly NW and N, respectively. 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 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= ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m During 30 August-5 September, the lava dome at Mount St. Helens continued to grow. A moderate seismic event and associated rockfall occurred on 3 September. The hazard status remained at Volcano Advisory (Alert Level 2); aviation color code Orange. 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 30 August-5 September, seismicity at Tungurahua remained low. Steam and gas plumes with low to no ash content rose to 300-600 m above the summit (17,500-18,400 ft a.s.l.) and drifted NNW and W. On 1 September, lava flows on the NW flank were confirmed to have ceased. On 2 September, incandescence at the summit was observed. 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/vulcanologia/tungurahua/actividad/informet.htm 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 pilot reports and satellite imagery, the Buenos Aires VAAC reported continuous emissions of ash plumes from Ubinas during 30 August-1 September and on 4 September. The plumes reached altitudes of ~4.9-5.5 km (~16,000-18,000 ft) a.s.l. and drifted NE, E, and SE. 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.bom.gov.au/products/Volc_ash_recent.shtml Ubinas Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02 ULAWUN New Britain Island, Papua New Guinea 5.04°S, 151.34°E; summit elev. 2,334 m Based on satellite imagery, the Darwin VAAC reported that ash-and-steam plumes from Ulawun drifted SW and S on 30 August and 2 September, respectively. 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: Darwin Volcanic Ash Advisory Centre http://www.bom.gov.au/products/IDD41305.shtml Ulawun Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-12= +++++++++++++++++++++++++++++++++++++ Sally S. Kuhn Global Volcanism Program Smithsonian Institution National Museum of Natural History MRC-119 Department of Mineral Sciences Washington, D.C., 20560 http://www.volcano.si.edu/ <http://www.volcano.si.edu/> Phone: 202.633.1805 Fax: 202.357.2476 <http://www.volcano.si.edu/reports/usgs/> ++++++++++++++++++++++++++++++++++++++++++ ----- End forwarded message ----- ============================================================== 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. ==============================================================
