SI/USGS Weekly Volcanic Activity Report 3-9 September 2008 Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ Ongoing Activity: | Chaitén, Southern Chile | Karymsky, Eastern Kamchatka | Kasatochi, Andreanof Islands | Kilauea, Hawaii (USA) | Llaima, Central Chile | Nyiragongo, Democratic Republic of Congo | Piton de la Fournaise, Reunion Island | Rabaul, New Britain (SW Pacific) | Sakura-jima, Kyushu (Japan) | Semeru, Eastern Java (Indonesia) | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Suwanose-jima, Ryukyu Islands (Japan) | 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. Ongoing Activity CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m SERNAGEOMIN reported that during 3-5 September two moderately vigorous plumes from Chaitén were visible on the web camera and rose to altitudes of 2.1-3.1 km (6,900-10,200 ft) a.s.l. The plumes drifted NW, N, SE, and S. The plume emitted from the S sector was wider and contained more ash than the plume emitted from the N sector. Clouds prevented observations during 7-8 September. Based on web camera views, analysis of satellite imagery, and information from the Puerto Montt Flight Information Region (FIR), the Buenos Aires VAAC reported that during 3-6 and 8 September, ash plumes rose continuously to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted NW, ESE, and SE. 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/index.php, 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 seismic activity at Karymsky was above background levels during 29 August-5 September. Possible explosions may have generated ash plumes to an altitude of 3.8 km (12,500 ft) a.s.l. Analysis of satellite imagery revealed ash plumes drifting SE on 29 August and a thermal anomaly in the crater during 29-31 August. The Level of Concern Color Code remained at Orange. Based on analysis of satellite imagery, the Tokyo VAAC reported that on 7 September an ash plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted E. 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. Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php, Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html KASATOCHI Andreanof Islands 52.177°N, 175.508°W; summit elev. 314 m AVO reported that during 3-9 September seismic activity from Kasatochi, detected by stations approximately 40 km W on Great Sitkin island, was low. Vigorous steam-and-gas plumes that rose above the crater and drifted up to 32 km downwind were observed on 3 and 4 September by passing mariners. On 4 September the Volcano Alert Level was lowered to Advisory and the Aviation Color Code to Yellow. Clouds mostly prevented satellite image observations; weak thermal anomalies were detected on 5 and 7 September. Geologic Summary. Located at the northern end of a shallow submarine ridge trending perpendicular to the Aleutian arc, Kasatochi is small 2.7 x 3.3 km wide island volcano with a dramatic 750-m-wide summit crater lake. The summit of Kasatochi reaches only 314 m above sea level, and the lake surface lies less than about 60 m above the sea. A lava dome is located on the NW flank at about 150 m elevation. The asymmetrical island is steeper on the northern side than the southern, and the volcano's crater lies north of the center of the island. Reports of activity from the heavily eroded Koniuji volcano to the east probably refer to eruptions from Kasatochi. A lava flow may have been emplaced during the first historical eruption in 1760. Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/ KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m HVO reported that during 3-9 September, lava flowed SE through a lava tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex, reaching the Waikupanaha ocean entry and one further to the E. On 5 September, geologists saw multiple surface flows during an aerial observation: four on the coastal plain, and a large 'a'a flow and a small pahoehoe flow in the abandoned Royal Gardens subdivision. The vent in Halema'uma'u crater continued to produce a predominantly white plume with minor ash content that drifted mainly SW. The plume was occasionally tinged brown in association with small local earthquakes. Weak night-time incandescence was intermittently seen at the base of the plume, and rock impact sounds were heard in the vicinity of the crater. The sample collection bin contained tephra, Pele's hair, Pele's tears, and a variously shaped glass fragments. On 5 September, scientists saw the surface of a sloshing lava lake, 50 m in diameter, about 100 m below the vent rim while hovering over the vent in a helicopter. A second view revealed a roiling pond with multiple bursting bubbles that changed into a central upwelling circulation pattern. The level of the lake dropped slightly before the cycle restarted. 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 that clouds had prevented visual observations of Llaima during 29 August-2 September. On 3 September, fumarolic plumes that originated from three points on the pyroclastic cones in the main crater drifted N. An explosion produced an ash plume that also drifted N; ash deposits on the N flank suggested previous emissions. On 4 September gas plumes from the main crater drifted W. Gas-and-steam plumes were emitted during 5-7 September. The Volcanic 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 NYIRAGONGO Democratic Republic of Congo 1.52°S, 29.25°E; summit elev. 3470 m Based on analysis of satellite imagery, the Toulouse VAAC reported a diffuse sulfur plume from Nyiragongo on 9 September. The plume may have contained some ash. Geologic Summary. One of Africa's most notable volcanoes, Nyiragongo contained an active lava lake in its deep summit crater that drained catastrophically through its outer flanks in 1977. In contrast to the low profile of its neighboring shield volcano, Nyamuragira, Nyiragongo displays the steep slopes of a stratovolcano. Benches in the steep-walled, 1.2-km-wide summit crater mark the levels of former lava lakes, which have been observed since the late 19th century. About 100 parasitic cones are located on the volcano's flanks and along a NE-SW zone extending as far as Lake Kivu. Monitoring is done from a small observatory building located in Goma, ~18 km S of the Nyiragongo crater. Source: Toulouse Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/FR/messages.html PITON DE LA FOURNAISE Reunion Island 21.231°S, 55.713°E; summit elev. 2632 m OVPDLF reported that a seismic crisis at Piton de la Fournaise during 8-9 September was characterized by hundreds of earthquakes. The Alert Level was not changed. Geologic Summary. 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 a 400-m-high lava shield, Dolomieu, that has grown within the youngest of three large calderas. This depression 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. The volcano is monitored by the Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris. Source: Observatoire Volcanologique du Piton de la Fournaise (OVPDLF) http://ovpf.univ-reunion.fr/ RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m RVO reported that ash plumes from Rabaul caldera's Tavurvur cone continued to be emitted during 1-8 September. Ashfall was reported in areas downwind. Ash accumulation in Rabaul Town was significant in mid-to-late July and in August; fresh ashfall and re-suspended ashfall due to winds and cars caused "unpleasant" conditions. During 1-6 September, conditions improved due to decreased ashfall, changes in wind patterns, and light rains that inhibited ash re-suspension. Continuous incandescence at the summit was observed, and roaring and rumbling noises were heard. Explosions also ejected incandescent lava fragments. Based on analysis of satellite imagery and information from RVO, the Darwin VAAC reported that during 4-6 and 8-9 September ash plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted W and NW. 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. Sources: Ima Itikarai, Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html SAKURA-JIMA Kyushu (Japan) 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported that on 7 September an eruption plume from Sakura-jima rose straight up to an altitude greater than 2.1 km (7,000 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 SEMERU Eastern Java (Indonesia) 8.108°S, 112.92°E; summit elev. 3676 m Based on analysis of satellite imagery, the Darwin VAAC reported that on 9 September ash plumes from Semeru rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted SSW. 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 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 during 29 August-5 September. Gas-and-steam plumes with a small amount of ash were generated from avalanches on 29 and 30 August and rose to an altitude of 4 km (13,100 ft) a.s.l. Analysis of satellite imagery revealed a daily thermal anomaly on 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. 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 during 29 August-5 September, data suggested that the W side of the Soufrière Hills lava dome continued to grow. Lahars and rockfalls dominated the activity. Lahars likely descended the Tar River valley on 29 and 31 August. On 1 September, a lahar descended the Belham River valley to the NW; the event lasted approximately 50 minutes. A new vent on the NW part of the lava dome, a little further N of the previous Gages vent, was observed during an overflight on 4 September. The smell of volcanic gases was occasionally noticed when the wind blew N and NE. The Hazard Level remained at 3. 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 reports from JMA, the Tokyo VAAC reported explosions from Suwanose-jima during 5-7 September. Resultant plumes rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. Plumes drifted E on 5 September. 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 TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m The IG reported that clouds mostly prevented visual observations of Tungurahua during 3-9 September. On 3 September, a small lahar carried blocks down river drainages to the NW. Steam plumes rose 200 m above the crater on 6 September. On 8 September, a lahar descended a drainage to the S and carried blocks up to 50 cm in diameter. 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 SIGMET reports and pilot observations, the Buenos Aires VAAC reported that during 5-6 September ash plumes from Ubinas rose to altitudes of 5.5-6.4 km (18,000-21,000 ft) a.s.l. and drifted NE 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 (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. ==============================================================
