**************************************************************** GVP/USGS Weekly Volcanic Activity Report 27 February-4 March 2008 Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ **************************************************************** *NEW* RSS and CAP news feeds of the Weekly Volcanic Activity Report are now available!!! New Activity/Unrest: | Bagana, Bougainville Island (SW Pacific) | Ol Doinyo Lengai, Tanzania | Veniaminof, Alaska Peninsula Ongoing Activity: | Anatahan, Mariana Islands (Central Pacific) | Cleveland, Chuginadak Island | Kilauea, Hawaii (USA) | Llaima, Central Chile | Lokon-Empung, Sulawesi (Indonesia) | Nevado del Huila, Colombia | Rabaul, New Britain (SW Pacific) | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Tungurahua, Ecuador | Ubinas, Perú 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 BAGANA Bougainville Island (SW Pacific) 6.140°S, 155.195°E; summit elev. 1750 m Based on observations of satellite imagery and information from RVO, the Darwin VAAC reported that a diffuse plume from Bagana rose to an altitude of less than 3 km (10,000 ft) a.s.l. and drifted SW on 3 March. Later that day an ash-and-steam plume drifted SW. Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50-m-thick with prominent levees that descend the volcano's flanks on all sides. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html OL DOINYO LENGAI Tanzania 2.764°S, 35.914°E; summit elev. 2962 m According to Frederick Belton's Ol Doinyo Lengai website, a visitor reported a large plume accompanied by a "bang" during 26-27 February. The Toulouse VAAC reported that a pilot observed an ash plume that rose to an altitude of 10.7 km (35,000 ft) a.s.l. on 27 February. Another possible ash plume rose to the same altitude on 28 February and drifted SW. Based on a SIGMET, pilot reports, and observations of satellite imagery, the VAAC reported that eruption plumes possibly containing ash rose to altitudes of 10.7-13.7 km (35,000-45,000 ft) a.s.l. during 29 February and 3-4 March. Geologic Summary. The symmetrical Ol Doinyo Lengai stratovolcano is the only volcano known to have erupted carbonatite tephras and lavas in historical time. The prominent volcano, known as "The Mountain of God," rises abruptly above the broad plain S of Lake Natron. The cone-building stage of the volcano ended about 15,000 years ago and was followed by periodic ejection of natrocarbonatite and nephelinite tephra during the Holocene. Historical eruptions have consisted of smaller tephra eruptions and emission of numerous natrocarbonatitic lava flows on the floor of the summit crater. Petrologists first observed the eruption of carbonatitic lava flows in the 1960s. Subsequent more frequent visits have documented long-term lava effusion in the summit crater that would not have been seen from the foot of the volcano. Sources: Frederick Belton's Ol Doinyo Lengai website http://www.mtsu.edu/%7Efbelton/latestnews.html Toulouse Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/FR/messages.html VENIAMINOF Alaska Peninsula 56.17°N, 159.38°W; summit elev. 2507 m AVO reported elevated seismic activity from Veniaminof during 27 February-4 March. Web camera views showed steaming from the cone and occasional small ash bursts that rose to 200 m above the crater on 27 February. During 28 February-3 March views were obscured by cloud cover; low-level steaming was seen on 29 February during a break in the weather. Geologic Summary. Massive Veniaminof volcano, one of the highest and largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 years ago. The caldera rim is up to 520 m high on the N, is deeply notched on the W by Cone Glacier, and is covered by an ice sheet on the S. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which reaches an elevation of 2,156 m and rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface. Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/ Ongoing Activity ANATAHAN Mariana Islands (Central Pacific) 16.35°N, 145.67°E; summit elev. 790 m The USGS reported that levels of seismicity at Anatahan were elevated during 27 February-4 March. During 27-29 February emissions of sulfur dioxide were detected by the satellite-based Ozone Monitoring Instrument (OMI). Based on observations of satellite imagery, the Washington VAAC reported that an ash plume drifted SSW on 28 February. The USGS reported that a second plume rose to an altitude of less than 3 km (10,000 ft) a.s.l. and drifted 240 km NW during 3-4 March. Geologic Summary. The elongate, 9-km-long island of Anatahan in the central Mariana Islands consists of large stratovolcano with a 2.3 x 5 km, E-W-trending compound summit caldera. The larger western caldera is 2.3 x 3 km wide, and its western rim forms the island's 790-m high point. Ponded lava flows overlain by pyroclastic deposits fill the floor of the western caldera, whose SW side is cut by a fresh-looking smaller crater. The 2-km-wide eastern caldera contained a steep-walled inner crater whose floor prior to the 2003 eruption was only 68 m above sea level. Sparseness of vegetation on the most recent lava flows on Anatahan had indicated that they were of Holocene age, but the first historical eruption of Anatahan did not occur until May 2003, when a large explosive eruption took place forming a new crater inside the eastern caldera. Sources: Emergency Management Office of the Commonwealth of the Mariana Islands and the US Geological Survey Hawaiian Volcano Observatory http://volcano.wr.usgs.gov/cnmistatus.php Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m AVO reported that a weak thermal anomaly and an ash plume from Cleveland were visible on satellite imagery on 29 February. The ash plume rose to an altitude of below 3 km (10,000 ft) a.s.l. The Volcanic Alert Level remained at Advisory and the Aviation Color Code remained at Yellow. 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/ KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m Based on observations during overflights, and web camera views when weather permitted, HVO reported that during 27 February-4 March activity from Kilauea's fissure segment D was concentrated at the Thanksgiving Eve Breakout (TEB) shield and satellitic shields to the E and SE. A pahoehoe flow ponded between the rootless shields and Kalalua Cone. Two lava flow lobes advanced through Royal Gardens subdivision and destroyed three abandoned homes by 28 February. One lobe reached the base of the Royal Gardens kipuka and Campout flow from early 2007.On 1 March the lobes merged and cut off the road access to the homes of the last two known residents. Incandescence from the TEB vent was noted during 29 February and 2-3 March. Diffuse incandescence was observed in Pu'u 'O'o crater through the fume during 27 February and 1-3 March. Earthquakes were located beneath Halema'uma'u crater, along the S-flank faults, beneath the summit, N of Makaopuhi crater, and along the upper E and SW rift zones. Sulfur dioxide emission rates from the summit area were elevated at 2-4 times background values where levels have been since early January. The emission rate was about 970 tonnes per day on 3 March, compared to a background rate of 150-200 tons 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/ LLAIMA Central Chile 38.692°S, 71.729°W; summit elev. 3125 m SERNAGEOMIN reported weak sulfur dioxide plumes from two cones in Llaima's main crater during 26-28 February. An overflight on 28 February revealed that the internal structure of the crater had not changed since observations on 21 February. Weak fumarolic emissions from the main crater were noted during 2-3 March. The Alert Level remained at Yellow. Geologic Summary. Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other to the SE. The massive 3,125-m-high, glacier-covered stratovolcano has a volume of 400 cu km. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following eruption of the 24 cu km Curacautín Ignimbrite. More than 40 scoria cones dot the volcano's flanks. Following the end of an explosive stage about 7,200 years ago, construction of the present edifice began, characterized by Strombolian, hawaiian, and infrequent subplinian eruptions. Frequent moderate explosive eruptions with occasional lava flows have been recorded since the 17th century. Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/index.php LOKON-EMPUNG Sulawesi (Indonesia) 1.358°N, 124.792°E; summit elev. 1580 m CVGHM reported that on 28 February the Alert level for Lokon-Empung was lowered from 3 to 2 (on a scale of 1-4) due to a decrease in seismicity during 3-26 February, analysis of visual observations, and a lack of deformation. During 14-26 February, white plumes rose to an altitude of 1.7 km (5,600 ft) a.s.l. Visitors and tourists were prohibited from going within a 1-km radius of the crater. Geologic Summary. The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2.2 km apart) has a flat, craterless top. The morphologically younger Empung volcano has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m wide double crater situated in the saddle between the two peaks. Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred. Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/ NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5365 m INGEOMINAS reported that seismic tremor from Nevado del Huila on 2 March was possibly associated with ash emission. Based on a Bogota SIGMET, the Washington VAAC reported that an ash plume rose to an altitude of 7.6 km (25,000 ft) a.s.l. the same day. 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. Sources: Instituto Colombiano de Geología y Minería (INGEOMINAS) http://www.ingeominas.gov.co// Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m RVO reported that ash and steam plumes from Rabaul caldera's Tavurvur cone rose to altitudes of 0.9-2.2 km (3,000-7,200 ft) a.s.l. and drifted W during 27 February-4 March. Ashfall was reported in areas downwind, including Matupit, during 27 February-1 March. A smell of hydrogen-sulfide gas was reported in Rabaul Town and roaring noises were heard during 1-3 March. On 3 March, incandescence at the summit was observed. 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 and Steve Saunders, Rabaul Volcano Observatory (RVO) SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that seismic activity at Shiveluch was slightly above background levels and small hot avalanches descended the lava dome during 22-29 February. According to video footage, fumarolic activity was observed during 21-22 and 24-25 February. Based on seismic interpretation, ash plumes possibly rose to an altitude of 5.6 km (18,400 ft) a.s.l. during 24-26 February. Observations of satellite imagery revealed that a thermal anomaly was present in the crater during the reporting period. 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. 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/index_eng.php SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m MVO reported that that during 27 February-4 March the lava dome at Soufrière Hills changed very little, based on limited visual observations during an overflight on 29 February and from ground locations. The E talus slope continued to erode, with both fresh and older material accumulating in the Tar River Valley. Active fumaroles around the lava dome were observed during breaks in cloud cover. 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 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/ TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m IG reported that although visual observations were very limited due to cloud cover, steam and ash-and-steam plumes from Tungurahua were spotted and rose to altitudes of 5.8-8 km (19,000-26,200 ft) a.s.l. during 27 February-1 March. Ash plumes drifted NW, W, SW, and SE, ashfall was reported in areas to the SW on 27 February. Lahars or mudflows descended the Mapayacu and Choglontus drainages in the SW, and drainages in the Pampas sector to the S on 27 and 28 February. 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 all originated from 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 Politécnica Nacional (IG) http://www.igepn.edu.ec/ UBINAS Perú 16.355°S, 70.903°W; summit elev. 5672 m Based on pilot reports, the Buenos Aires VAAC reported that an ash plume from Ubinas rose to altitudes of 5.5-6.1 km (18,000-20,000 ft) a.s.l. and drifted SE on 2 March. 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 (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html +++++++++++++++++++++++++++++++++++++ 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. ==============================================================
