************************************************************* SI/USGS Weekly Volcanic Activity Report 17-23 June 2009 ************************************************************* Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Rinjani, Lombok Island (Indonesia) | Sarychev Peak, Matua Island Ongoing Activity: | Arenal, Costa Rica | Bezymianny, Central Kamchatka (Russia) | Chaitén, Southern Chile | Ebeko, Paramushir Island | Galeras, Colombia | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Koryaksky, Eastern Kamchatka | Krakatau, Indonesia | Llaima, Central Chile | Rabaul, New Britain | Redoubt, Southwestern Alaska | Shiveluch, Central Kamchatka (Russia) | Tungurahua, Ecuador 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 RINJANI Lombok Island (Indonesia) 8.42°S, 116.47°E; summit elev. 3726 m Based on analysis of satellite imagery, the Darwin VAAC reported that during 21 June ash plumes from Rinjani rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 55 km N. Geologic Summary. Rinjani volcano on the island of Lombok rises to 3,726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the E, but the W side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak caldera. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the E end of the caldera. Historical eruptions at Rinjani dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake. Map Source: Darwin Volcanic Ash Advisory Center (VAAC) Rinjani Information from the Global Volcanism Program SARYCHEV PEAK Matua Island 48.092°N, 153.20°E; summit elev. 1496 m The eruption from Sarychev Peak that began on 11 June continued through the 19th. SVERT reported another explosive eruption at 1730 UTC on 15 June, followed by the satellite observation of a plume early on 16 June that extended 360 km NW. The Tokyo VAAC estimated that the 16 June plume rose to an altitude of 9.7 km (32,000 feet) a.s.l., while higher ash clouds from earlier explosions reached 13.7 km (45,000 feet) altitude. Ash emissions continued during 17-18 June, causing ashfall in Yuzhno-Sakhalinsk, and gas-and-steam plumes spread NE and SW. Thermal anomalies were detected in satellite data on 18 and 19 June, but cloudy conditions prevented clear observations. One MODIS image on 18 June showed an ash plume spreading SW above the weather clouds. Although the Aviation Color Code was lowered from Red to Orange on 19 June, satellite observations showed that a diffuse ash cloud had spread approximately 20 km S and 40 km W of the volcano. Geologic Summary. Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5 km wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows descend all sides of Sarychev Peak and often form capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760's and include both quiet lava effusion and violent explosions. The largest historical eruption of Sarychev Peak in 1946 produced pyroclastic flows that reached the sea. Map Source: Sakhalin Volcanic Eruption Response Team (SVERT) Sarychev Peak Information from the Global Volcanism Program Ongoing Activity ARENAL Costa Rica 10.463°N, 84.703°W; summit elev. 1670 m Three strong eruptions on 16 June resulted in pyroclastic flows. The National Park was evacuated as a precaution, but reopened the next day. Increased degassing the previous week had prompted an elevation of the hazard status to Level 3 (on a scale of 1-4). Geologic Summary. Conical Volcan Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1,657-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. The earliest known eruptions of Arenal took place about 7,000 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. Arenal's most recent eruptive period began with a major explosive eruption in 1968. Continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows has occurred since then from vents at the summit and on the upper western flank. Map Sources: Inside Costa Rica, Tico Times Arenal Information from the Global Volcanism Program BEZYMIANNY Central Kamchatka (Russia) 55.978°N, 160.587°E; summit elev. 2882 m Reports from KVERT since August 2008 have indicated continuing dome growth and weak fumarolic activity at Bezymianny, with thermal anomalies visible in satellite data when the volcano was visible. Over the previous month such anomalies were seen on 21 and 30 May, and 2-4, 7, and 11-14 June. Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. That eruption, similar to the 1980 event at Mount St. Helens, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Bezymianny Information from the Global Volcanism Program CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m As noted in an OVDAS-SERNAGEOMIN report, eruptive activity continued during 8-16 June with sustained growth of the lava dome complex, from which block-and-ash flows were generated. Steam-and-ash plumes generally rose 1.5 km above the dome. Seismicity remained at typical levels. The Alert Level remained at Red. 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. Map Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) Chaitén Information from the Global Volcanism Program EBEKO Paramushir Island 50.68°N, 156.02°E; summit elev. 1156 m KVERT reported that gas-and-steam plumes rose to an altitude of 1.7 km (5,600 ft) a.s.l. during 13-18 June. The Level of Concern Color Code remained at Yellow. Geologic Summary. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. The eastern part of the southern crater of Ebeko contains strong solfataras and a large boiling spring. The central crater of Ebeko is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters of Ebeko, on the outer flanks of the cone, and in lateral explosion craters. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Ebeko Information from the Global Volcanism Program GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4276 m Increased sulfur-dioxide degassing and seismicity related to fluid movement, resulting in the overall lowering of pressure in the system, prompted INGEOMINAS to further lower the alert level to Yellow (Level III) on 19 June. By 23 June some rock-fracture seismicity had been detected, though events related to fluid movement had declined significantly. That same day clear weather allowed observation of a small gas column with minor ash content, while scientists on a monitoring flight saw gas emissions near the crater rim and recorded a thermal anomaly within the main crater. Geologic Summary. Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Longterm extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors. Map Source: Instituto Colombiano de Geología y Minería (INGEOMINAS) Galeras Information from the Global Volcanism Program KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m Satellite data reported by KVERT indicated a weak thermal anomaly over the volcano on 4-6 and 13-14 June. Gas-and-steam plumes extended 30 km SE on 4 June. The Level of Concern Color Code remained at 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. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Karymsky Information from the Global Volcanism Program KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m Daily reports from HVO about Kilauea during 17-23 June indicated continuing visible glow from the Halema'uma'u vent. Molten lava remained in the neck of a funnel-shaped cavity in the floor of Halema'uma'u Crater. Webcam views showed the lava level rising several meters for brief periods before returning to depths of about 290 m below the crater rim and 205 m below the crater floor, as determined by laser-ranging measurements. Throughout the week lava from east rift zone vents flowed through tubes to the coast and entered the ocean at two locations west of Kalapana; active surface flows also continued on the pali within the abandoned Royal Gardens subdivision. Sulfur dioxide emission rates from the Halema`uma`u and Pu`u `O`o vents remained elevated. The plume continued to carry glassy bits of spatter and small amounts of ash. A deflation-inflation event began on 22 June and was continuing the next 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. Map Source: US Geological Survey Hawaiian Volcano Observatory (HVO) Kilauea Information from the Global Volcanism Program KORYAKSKY Eastern Kamchatka 53.320°N, 158.688°E; summit elev. 3456 m Moderate to strong fumarolic activity at Koryaksky has been reported by KVERT in recent weeks. Satellite data showed a weak thermal anomaly over the volcano 11 and 13 June. The Level of Concern Color Code remained at Yellow. Geologic Summary. The large symmetrical Koryaksky stratovolcano is the most prominent landmark of the NW-trending Avachinskaya volcano group, which towers above Kamchatka's largest city, Petropavlovsk. Erosion has produced a ribbed surface on the eastern flanks of the 3456-m-high volcano; the youngest lava flows are found on the upper western flank and below SE-flank cinder cones. No strong explosive eruptions have been documented during the Holocene. Extensive Holocene lava fields on the western flank were primarily fed by summit vents; those on the SW flank originated from flank vents. Lahars associated with a period of lava effusion from south- and SW-flank fissure vents about 3900-3500 years ago reached Avacha Bay. Only a few moderate explosive eruptions have occurred during historical time. Koryaksky's first historical eruption, in 1895, also produced a lava flow. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Koryaksky Information from the Global Volcanism Program KRAKATAU Indonesia 6.102°S, 105.423°E; summit elev. 813 m A news report on 18 June noted that activity at Krakatau had increased significantly. According to the head of the volcano monitoring post in Pasauran village there were 828 small eruptions in the previous six days, reaching the rate of a new explosion every three minutes. Observers on beaches in Java could clearly see rising white gas-and-steam plumes along with incandescent ejecta at night. Residents also reported loud explosion noises. The level of activity decreased again on 19 June, and the Alert Level remained at 3 (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. Map Source: Antara News Krakatau Information from the Global Volcanism Program LLAIMA Central Chile 38.692°S, 71.729°W; summit elev. 3125 m The camera in Melipueco used by OVDAS-SERNAGEOMIN to monitor Llaima again showed glow on the NW inner margin of the main crater during 9-16 June. Occasional steam emissions with minor amounts of ash were also seen from the E flank. Seismic tremor has also increased since 5 June. 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. Map Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) Llaima Information from the Global Volcanism Program RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m An RVO report for 12-18 June noted that the Tavurvur cone at Rabaul produced pale gray ash plumes during 16-17 June. Activity after that consisted primarily of dense white steam plumes, with occasional ash emissions. Continuous glow was seen at night. 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. Map Source: Ima Itikarai, Rabaul Volcano Observatory (RVO) Rabaul Information from the Global Volcanism Program REDOUBT Southwestern Alaska 60.485°N, 152.742°W; summit elev. 3108 m Seismicity at Redoubt, as reported by AVO, was low during 17-23 June, but remained above background level. Seismicity was primarily comprised of small, discrete events associated with continued growth and instability of the lava dome. Webcam images on 19 and 23 June showed continued steam and gas emissions from the dome. Poor weather conditions throughout the week limited fieldwork opportunities, but one crew was able to observe the dome on 15 June. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange. Geologic Summary. Redoubt is a 3108-m-high glacier-covered stratovolcano with a breached summit crater in Lake Clark National Park about 170 km SW of Anchorage. Next to Mount Spurr, Redoubt has been the most active Holocene volcano in the upper Cook Inlet. Collapse of the summit of Redoubt 10,500-13,000 years ago produced a major debris avalanche that reached Cook Inlet. Holocene activity has included the emplacement of a large debris avalanche and clay-rich lahars that dammed Lake Crescent on the south side and reached Cook Inlet about 3500 years ago. Eruptions during the past few centuries have affected only the Drift River drainage on the north. Historical eruptions have originated from a vent at the north end of the 1.8-km-wide breached summit crater. The 1989-90 eruption of Redoubt had severe economic impact on the Cook Inlet region and affected air traffic far beyond the volcano. Map Source: Alaska Volcano Observatory (AVO) Redoubt Information from the Global Volcanism Program SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m A new viscous lava flow from the lava dome was reported by KVERT during 11-18 June. Satellite thermal data indicated a large anomaly over the lava dome the entire week. Above-background levels of seismicity persisted throughout that time. Video recordings revealed ash plumes up to an altitude of 6.1 km (20,000 ft) a.s.l on 12-15 and 18 June. Ash plumes extended up to 50 km (31 miles) to the south 11 and 13-14 June. Another ash cloud on 12 June was 40 x 20 km in size at a distance of 140 km (87 miles) SW. Moderate to strong gas-and-steam plumes were observed during other times. 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. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964. Map Source: Kamchatkan Volcanic Eruption Response Team (KVERT) Shiveluch Information from the Global Volcanism Program TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m Continued moderate seismic and eruptive activity was reported by the IG during 17-23 June. Explosions with resulting ashfall were reported on most days. Lava fountains were observed on the night of 21 June rising to a height of 500 m above the crater. Incandescent blocks seen over the next two days rolled as far as 2 km downslope. 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. Map Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) Tungurahua Information from the Global Volcanism Program +++++++++++++++++++++++++++++++++++++ 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. ==============================================================
