************************************************************ SI/USGS Weekly Volcanic Activity Report 2-8 July 2008 ************************************************************ Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Kilauea, Hawaii (USA) | Llaima, Central Chile Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Fuego, Guatemala | Krakatau, Indonesia | Rabaul, New Britain (SW Pacific) | Sakura-jima, Kyushu (Japan) | Santa María, Guatemala | Semeru, Eastern Java (Indonesia) | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Tungurahua, Ecuador | Ubinas, Perú | Ulawun, New Britain (SW Pacific) 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 KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m Based on visual observations from HVO crews, video footage, pilot reports, and web camera views, HVO reported that during 2-8 July, lava flowed SE through a lava tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex. The TEB vent is located a little over 2 km NE of Pu'u 'O'o crater. During 2-6 July, lava flows reached the Waikupanaha ocean entry and created a steam plume from contact with the water. Incandescence was also seen from surface lava flows at multiple breakout points along the lava tube system. On 7 July, seismic tremor levels near the TEB vent abruptly doubled, corresponding to a substantial new breakout in the rootless shield area. The steam plume at the Waikupanaha ocean entry was also absent that day and the next. An overflight revealed that a lava fountain from one of the breakouts on rootless shield 3 (about 1 km SE of the TEB vent) was 12-15 m high and fed several lava flows. The lava fountain and a lava pond were active during 7-8 July and incandescence at shield 6 (about 2 km SE of the TEB vent) was noted. At Pu'u 'O'o the sulfur dioxide emission rate fluctuated between 3,100 and 4,800 tonnes per day when measured during 4-6 July; the average background rate is about 2,000 tonnes per day. Incandescence from two distinct sources in the E and W ends of Pu'u 'O'o crater was observed on the web camera during 4-6 July. Diffuse incandescence was noted during 7-8 July. During the reporting period, Kilauea earthquakes were located beneath the summit area, along S-flank faults, along the E and SW rift zones, beneath Halema'uma'u crater, and beneath the area where the Koa'e fault system joins the upper E rift zone. Beneath Halema'uma'u crater, another 20-100 small earthquakes per day also occurred but were too small to be located. The vent in the 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. The sulfur dioxide emission rate was high, between 700 and 1,400 tonnes per day, during 2-7 July. The pre-2008 background rate was 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/ LLAIMA Central Chile 38.692°S, 71.729°W; summit elev. 3125 m SERNAGEOMIN reported that although observations of Llaima were inhibited by cloud cover on 2 July, incandescence from the 1-km-long lava flow on the W flank was observed. An overflight revealed cooled blocks at the end of the lava flow and a second lava flow (on the SW flank) about 150 m S of the first. The lava flows issued from the base of a pyroclastic cone in the main crater. Observers to the W witnessed an explosion from the summit that ejected material 1 km high. The material landed on the SW flank and up to 3.5 km away on the SE flank. Vapor plumes from the main crater were seen on 3 July. An overflight on the same day revealed that the lava flow on the W flank had advanced and generated a small lahar. On 4 July, SERNAGEOMIN characterized the eruptive style as weakly Strombolian. A small explosion from the pyroclastic cone in the main crater produced an ash plume that rose 250-400 m and drifted 50 km SE. During 4-5 July, observers reported sporadic explosions and incandescence at the summit. Fine ashfall was reported in areas nearby. On 6 July, seismicity decreased to low levels. An overflight on 7 July revealed that the lava emission rate had decreased for both flows. The lava flow on the W flank was about 1.6 km long and the flow on the SW flank was about 2 km long. Bluish gas was emitted from the main crater. 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 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 during 2-5 and 8-9 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 NW. 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 27 June-4 July, visual observations of Chaitén were inhibited due to inclement weather. During 27-28 June, lahars descended multiple drainages and were especially notable in the Chaitén and Amarrillo rivers. On 30 June, an ash plume that rose to an altitude of 2.1 km (6,900 ft) a.s.l. was observed by means of a video camera in the city of Chaitén. A photograph of the new lava dome revealed that it completely covered the S side of the old lava dome. Lahar deposits were seen in the W part of the caldera and a drainage in the S caldera was blocked by rockfalls, causing small ponds to form. On 2 July, ash plumes that rose to altitudes of 4.1 km (13,500 ft) a.s.l. originated from a previously active area on the S flank and from a new area farther W. The plumes drifted N and NE. 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 that during 2-3, 5, and 8 July ash plumes rose to altitudes of 2.1-4 km (7,000-13,000 ft) a.s.l. and drifted ENE, E, 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/, Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m INSIVUMEH reported that on 4 July there were rumbling noises from Fuego and the seismic network detected multiple explosions. A lava flow traveled 100 m W towards the Santa Teresa ravine. A lahar carrying blocks descended the Ceniza ravine to the SW. On 7 and 8 July, explosions produced ash plumes that rose to altitudes of 4-4.5 km (13,100-14,800 ft) a.s.l. and drifted S, SE, and SW. Incandescence at the summit was observed and constant avalanches of blocks from lava-flow fronts descended the W flank. Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/ KRAKATAU Indonesia 6.102°S, 105.423°E; summit elev. 813 m CVGHM reported that during 22 June-1 July, the number of seismic events from Anak Krakatau decreased significantly and booming noises were less frequently heard. During 1-3 July, ash emissions also declined. Based on a pilot report, the Darwin VAAC reported that a low-level plume drifted NW on 2 July. On 3 July, CVGHM lowered the Alert Level to 2 (on a scale of 1-4). 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. Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://portal.vsi.esdm.go.id/joomla/, Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 1-7 July, ash-and-steam plumes from Rabaul caldera's Tavurvur cone rose to altitudes up to 1.7 km (5,600 ft) a.s.l. and drifted W and NW. Ashfall was reported downwind in Rabaul town, Namanula Hill, Malaguna, and surrounding areas, and was heavy during 2-3 July. Incandescence at the summit was noted at night during 1-2 July; plumes blocked views of the summit during 3-7 July. During 4-7 July, roaring noises were reported. Based on observations of satellite imagery, the Darwin VAAC reported that on 8 July an ash plume rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted 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: Herman Patia, Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Center (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 an explosion from Sakura-jima on 5 July. A resultant plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted E. 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 SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m On 4 July, INSIVUMEH reported that an explosion from Santa María's Santiaguito lava dome complex produced an ash plume that rose to an altitude of 3.3 km (10,800 ft) a.s.l. and drifted SW. A lahar traveled S down the Nima I river, carrying tree limbs and blocks up to 50 cm in diameter. On 7 and 8 July, sounds resembling avalanches descending the flanks were reported; visual observations were hindered due to cloud cover. Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/ SEMERU Eastern Java (Indonesia) 8.108°S, 112.92°E; summit elev. 3676 m Based on pilot reports and observations of satellite imagery, the Darwin VAAC reported that during 7-9 July ash plumes from Semeru rose to altitudes of 4.9-7.6 km (16,000-25,000 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 possibly indicated ash explosions on 26 June and was slightly above background levels during 26 June-4 July. Moderate fumarolic activity was seen on 29 June, and 1 and 3 July. Observations of satellite imagery revealed a strong thermal anomaly on the lava dome during 27-29 June and 1-3 July. 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 28 June-4 July. Seismic activity remained low. 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 IG reported that during 1-7 July, explosions from Tungurahua were detected by the seismic network. Cloud cover inhibited visual observations during most days. On 1 July, an ash plume rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted W. During 4-6 July, explosions were heard. On 6 July, ashfall was reported in areas to the W and NW and incandescent blocks rolled 500 m down the flanks. On 7 July, explosions rattled windows in areas to the W, NW, and NE; ashfall was reported to the W. 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, the Buenos Aires VAAC reported that ash plumes from Ubinas rose to altitudes of 5.5-5.8 km (18,000-19,000 ft) a.s.l. on 7 July and drifted NE. 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 ULAWUN New Britain (SW Pacific) 5.05°S, 151.33°E; summit elev. 2334 m RVO reported that white vapor plumes from Ulawun were emitted during 2-6 July. Seismicity was low to moderate; seismometers continued to recorded high-frequency earthquakes. The Alert status remained at "Stage 2," indicating that seismic levels remained above background. During 2-3 July occasional roaring noises were reported. 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) +++++++++++++++++++++++++++++++++++++ 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. ==============================================================
