********************************************************* SI/USGS Weekly Volcanic Activity Report 25 June-1 July 2008 ********************************************************* Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Llaima, Central Chile | Ulawun, New Britain (SW Pacific) Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Krakatau, Indonesia | Ol Doinyo Lengai, Tanzania | Rabaul, New Britain (SW Pacific) | Sakura-jima, Kyushu (Japan) | San Cristóbal, Nicaragua | 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 LLAIMA Central Chile 38.692°S, 71.729°W; summit elev. 3125 m SERNAGEOMIN reported that sporadic gas-and-ash plumes from Llaima were seen when the weather was clear during 1-20 June. More frequent and continuous gas emissions rose from the nested cone in the main crater. Seismicity increased during 13-16 June. Towards the end of the observation period, steam plumes rose from the W flank. ONEMI reported that during an overflight on 26 June, bluish gas and ash rose from the top of an active pyroclastic cone in the main crater and the NE flank was not covered with snow, in contrast to other portions of the volcano. On 1 July, a lava flow on the W flank was seen from nearby communities prompting authorities to evacuate about 20-30 people and warn others of possible further evacuations. The lava flow descended the W flank to 800-1000 m from the crater, raising concern for lahars in the Calbuca river. The Alert Level was raised to Yellow (the middle level on a 3-level color system). 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. Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/index.php, Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI) http://www.onemi.cl/ ULAWUN New Britain (SW Pacific) 5.05°S, 151.33°E; summit elev. 2334 m RVO reported that increased seismic activity at Ulawun began on 7 June. During 18 June-2 July, mostly moderate-to-strong emissions of white vapor produced plumes that rose from Ulawun and seismometers recorded high-frequency earthquakes. On 22 June, noises heard in villages to the NE accompanied some of the earthquakes. On 28 June, an Intensity II earthquake was felt in areas nearby and accompanied by a booming noise. A team of officers from RVO and West New Britain Provincial Disaster Office informed communities on the activity status of Ulawun. On 30 June, RVO reported that the level of Alert at Ulawun was at "Stage 2", or that there was an increase in seismic activity above background level. During 1-2 July, roaring and jet noises were reported from people to the NE. 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: Herman Patia, Rabaul Volcano Observatory (RVO) Ongoing Activity BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m Based on observations of satellite imagery, the Darwin VAAC reported that on 28 and 30 June, and on 1 July low-level ash plumes from Batu Tara rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted W and WNW. Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m SERNAGEOMIN reported that during 23-26 June, visual observations of Chaitén were inhibited due to inclement weather. Based on web camera views, SIGMET reports, observations of satellite imagery, pilot reports, and information from the Puerto Montt Flight Information Region (FIR), the Buenos Aires VAAC reported continuous ash emissions on 25 June. They further reported ash plumes at altitudes of 0.6-4.6 km (2,000-15,000 ft) a.s.l. during 30 June-1 July. Ash plumes drifted NE and NNW on 30 June, and NNE on 1 July. 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/, 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 at background levels during 20-27 June but may have indicated weak explosions daily. Observations of satellite imagery revealed a thermal anomaly in the crater on 20 and 25 June. The Level of Concern Color Code was lowered to Yellow. 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/index_eng.php KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m Based on visual observations from HVO crews and web camera views, HVO reported that during 25 June-1 July, lava flowed SE through a lava tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex to the Waikupanaha ocean entry. On 24 June, small episodic explosions at Waikupanaha propelled spatter about 50 m into the air; explosions were also noted on other days. The sulfur dioxide emission rate was 1,300 tonnes per day when measured on 24 June; the average background rate was about 2,000 tonnes per day. During 28 June-1 July, a small surface 'a'a lava flow near the E boundary of the Royal Gardens subdivision advanced E. During 30 June-1 July, several surface flows from multiple points along the lava tube system were noted. During the reporting period, Kilauea summit earthquakes were located beneath the summit area, along S-flank faults, and along the E and SW rift zones. Another 20-60 small earthquakes per day also occurred but were too small to be located. The vent in Halema'uma'u crater continued to produce a white plume with minor ash content that drifted mainly SW. Night-time incandescence was seen at the base of the plume. Seismic tremor was elevated. The sulfur dioxide emission rate was 900 tonnes per day when measured on 26 June. The background rate is 150-200 tonnes 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/ KRAKATAU Indonesia 6.102°S, 105.423°E; summit elev. 813 m Based on observations of satellite imagery and pilot reports, the Darwin VAAC reported that a low-level ash plume from Anak Krakatau rose to an altitude less than 3 km (10,000 ft) a.s.l. on 1 July and drifted NW. Geologic Summary. Renowned Krakatau volcano lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, resulted in a 7-km-wide caldera. Remnants of this volcano formed Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. The post-collapse cone of Anak Krakatau (Child of Krakatau), constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan, has been the site of frequent eruptions since 1927. 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 website, visitors whom climbed Ol Doinyo Lengai on 18 June reported that the new active cone covered the former crater floor entirely except for an area N of the summit. The new cone's W, N, and E sides stood about 30 m above the rim of the former crater and enclosed a deep crater. The visitors saw a few small vents on the crater's floor. Frequent emissions of ash-poor plumes originated from the SW part of the crater's floor, producing light ashfall. They heard continuous loud rumbling noises, occasional gas-jetting sounds, and rockfalls. 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. Source: Frederick Belton's Ol Doinyo Lengai website http://frank.mtsu.edu/~fbelton/latestnews.html RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 20-26 June, ash plumes from Rabaul caldera's Tavurvur cone rose to altitudes less than 1.7 km (5,600 ft) a.s.l. and drifted W and NW. Roaring noises were reported. During 26-30 June, steam-and-ash plumes rose to altitudes of 0.9-1.7 km (3,000-5,600 ft) a.s.l. and drifted NW. Nighttime incandescence was noted. During 23-30 June, ashfall was reported in areas downwind, including in Rabaul and surrounding towns. 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 (RVO) SAKURA-JIMA Kyushu (Japan) 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported an explosion from Sakura-jima on 28 June. The altitude and direction of a possible resultant plume were not reported. 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 SAN CRISTOBAL Nicaragua 12.702°N, 87.004°W; summit elev. 1745 m According to news articles, seismic activity from San Cristóbal increased for multiple days, after a moderate explosion and subsequent ash-and-gas emissions from the crater on 22 June. Local authorities alerted nearby populations to be prepared for potential future activity. Geologic Summary. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1,745-m-high youngest cone, San Cristóbal itself (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km to the west of San Cristóbal; it and the eroded Moyotepe volcano, 4 km to the NE of San Cristóbal, are of Pleistocene age. Volcán Casita contains an elongated summit crater and lies immediately E of San Cristóbal; Casita was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristóbal complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes. Source: EFE http://www.unionradio.com.ve/Noticias/Noticia.aspx?noticiaid=246118 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 20-27 June and possibly indicated ash explosions on 21, 22, and 25 June. According to video footage and visual observations, moderate fumarolic activity was noted on 24 and 25 June and an ash plume at an altitude of 4.2 km (13,800 ft) a.s.l. occurred on 25 June. Observations of satellite imagery revealed a thermal anomaly on the lava dome during 19-20 and 23-25 June. 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 no evidence of lava-dome growth at Soufrière Hills during 21-27 June. Seismic activity remained low. Heavy rainfall resulted in minor mudflows down the Belham River. The E talus slope continued to erode, producing minor rockfalls that descended into 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 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 Although clouds occasionally inhibited visual observations, IG reported that during 25-27 June, steam and ash-and-steam plumes from Tungurahua rose to an altitude of 6 km (19,700 ft) a.s.l. and drifted W and N. Incandescence from inside the crater was observed at night. On 29 June, an explosion generated a "cannon shot" noise and roaring, and caused windows to vibrate in Cusúa, about 7 km NW. More explosions were felt later that day. On 30 June and 1 July, slight ashfall was reported in the town of Manzano, about 8 km SW. 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 According to a news articles on 30 June, the Alert level for Ubinas continued at Yellow because small explosions and ash-and-gas emissions continued during the previous two months. Inhabitants of local communities and their livestock have suffered the effects of gas and ash emissions. Local authorities have begun discussion of the potential relocation of about 650 affected families. Based on SIGMET reports, the Buenos Aires VAAC reported that an ash plume rose to altitudes of 5.5-6.1 km (18,000-120,000 ft) a.s.l. on 26 June. The plume drifted NE and was not observed on satellite imagery. 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. Sources: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html, La República http://www.larepublica.com.pe/index.php?option=com_content&task=view&id=229407&Itemid=0, Perú 21 http://www.peru21.com/p21online/Html/2008-06-30/onp2actualidad0914076.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. ==============================================================
