Smithsonian/USGS Weekly Volcanic Activity Report 3-9 August 2011
From: "Kuhn, Sally" <KUHNS@xxxxxx>
**************************************************************************************************************************
Smithsonian/USGS Weekly Volcanic Activity Report
3-9 August 2011
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Cleveland, Chuginadak Island | Etna, Sicily (Italy) | Karangetang [Api Siau], Siau I | Kilauea, Hawaii (USA) | Lokon-Empung, Sulawesi | Rabaul, New Britain | Reventador, Ecuador | Stromboli, Aeolian Islands (Italy)
Ongoing Activity: | Arenal, Costa Rica | Karymsky, Eastern Kamchatka (Russia) | Kirishima, Kyushu | Kizimen, Eastern Kamchatka (Russia) | Krakatau, Indonesia | Puyehue-Cordón Caulle, Central Chile | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia)
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
CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m
AVO reported that observations from 2 August of the lava dome growing in Cleveland's summit crater revealed growth from about 40 m to 50 m in diameter since 29 July. Weak thermal anomalies were observed in satellite imagery during 2-3, 5, and 7-9 August when cloud cover was limited or absent. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange. No current seismic information was available because Cleveland does not have a real-time seismic network.
Geologic Summary. Symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.
Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/
ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m
Sezione di Catania - Osservatorio Etneo reported that the ninth paroxysmal eruptive episode from Etna in 2011 took place at the New SE Crater (located on the E flank of the old SE Crater cone and previously called the "pit crater") during the night of 5-6 August. Weak Strombolian explosions occurred in the crater during the afternoon on 5 August and gradually increased over the next few hours. At 2215 lava flowed over the E rim of the crater and towards the W slope of the Valle del Bove. Strombolian activity rapidly increased and formed a lava fountain that rose 100 m above the crater rim. Activity again intensified and jets of lava rose several hundred meters high. An eruption plume laden with ash and lapilli rose a few kilometers above the crater and drifted SE. At the climax of the eruption lava fountains exceeded 500 m in height. Just after midnight the incandescent jets diminished in height, continued to pulsate for about an hour, then further diminished. By 0215 on 6 August the eruption was substantially over. Ash-and-lapilli fall were observed in the SE sector of the volcano, between Zafferana (10 km SE) and Viagrande (16 km SSE) and between Acitrezza (23 km SE) and Pozzillo (19 km SE) along the Ionian coast.
Geologic Summary. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BC. Historical lava flows cover much of the surface of this massive basaltic stratovolcano, the highest and most voluminous in Italy. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater. Flank eruptions, typically with higher effusion rates, occur less frequently and originate from fissures that open progressively downward from near the summit. A period of more intense intermittent explosive eruptions from Etna's summit craters began in 1995. The active volcano is monitored by the Instituto Nazionale di Geofisica e Volcanologia (INGV) in Catania.
Source: Sezione di Catania - Osservatorio Etneo http://www.ct.ingv.it/
KARANGETANG [API SIAU] Siau I 2.78°N, 125.40°E; summit elev. 1784 m
CVGHM reported that during July and August cloud cover often prevented observations of Karangetang, although white smoke was sometimes observed rising as high as 500 m above the crater. At night incandescence up to 10 m was often observed.
On 8 July a phreatic eruption occurred from the N part of the Main Crater, ejecting material 150 m high. On 24 July and 1 August incandescent material traveled 1,500 m from the Main Crater. Sounds indicating an eruption were heard on 7 August, although fog prevented observations of the crater. Based on recent visual observations and increased seismicity, the Alert Level was raised to 3 (on a scale of 1-4) on 8 August. According to a news article, about 600 people living on the flanks evacuated.
Geologic Summary. Karangetang (also known as Api Siau) lies at the northern end of the island of Siau, N of Sulawesi, and contains five summit craters strung along a N-S line. One of Indonesia's most active volcanoes, Karangetang has had more than 40 recorded eruptions since 1675. Twentieth-century eruptions have included frequent explosions, sometimes accompanied by pyroclastic flows and lahars.
Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/,
Herald Sun http://www.heraldsun.com.au/news/breaking-news/indonesian-volcano-unleashes-fresh-burst/story-e6frf7jx-1226110781797
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
HVO reported that on 3 August at 1402 the floor of Kilauea's Pu'u 'O'o crater, which had risen significantly over the past month, began to subside. At 1420 lava erupted from a vent low on the W flank of the Pu'u 'O'o cone, about halfway between Pu'u 'O'o Crater and the E end of the Kamoamoa fissure, and formed two branches. The weaker flow traveled N into a forested kipuka. The higher-volume S branch quickly advanced down Kilauea's S flank along the edge of flows erupted during 2002-2004. By 1515, the crater floor and perched lava lake began to collapse; the circulation in the lava lake was maintained as the crater floor dropped. Within a few hours the lava lake was no longer visible and the crater floor, which had dropped 75-85 m, was covered with rubble. Between 1530 and 1615, the preliminary sulfur dioxide emission rate from all east rift zone sources was as high as 7,000 tonnes/day. The rate decreased to 4,000 tonnes/day at about 1700. Also by that time the lava flow had advanced 3.6 km.
During 4-9 August lava continued to flow from multiple W-flank vents topped with spatter cones, ponding in a low area due to a decreasing effusion rate. The Pu'u 'O'o crater rim was extremely unstable; continued collapses along the crater walls sendt blocks of rock onto the crater floor. Lava also slowly flowed back onto the collapsed crater floor.
During 3-9 August the level of the summit lava lake fluctuated deep in the 150-m-diameter vent inset within the E wall of Halema'uma'u Crater and circulated with various patterns. Overall, the lake level receded and on 6 August was about 75 m below the crater floor. Periodic measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash and occasionally fresh spatter nearby.
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/
LOKON-EMPUNG Sulawesi 1.358°N, 124.792°E; summit elev. 1580 m
CVGHM reported that during 24 July-8 August seismicity decreased at Tompaluan crater, in the saddle between the Lokon-Empung peaks, with a drastic reduction on 26 July. During 27 July-8 August white plumes rose 100-400 m above the crater. The Alert Level remained at 3 (on a scale of 1-4). Residents and tourists were not permitted within a 3-km radius of the crater.
Geologic Summary. The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2.2 km apart) has a flat, craterless top. The morphologically younger Empung volcano has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m wide double crater situated in the saddle between the two peaks. Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m
RVO reported that white vapor plumes rose from Rabaul caldera's Tavurvur cone during 1-3 August. An explosion on 3 August produced a gray ash plume that rose 1 km above the crater and drifted NNW. Sustained emissions of pale-gray ash continued for about an hour afterwards. In addition, ash deposited at the former airport was re-suspended and blown NW into the E part of Rabaul town (3-5 km NW) and towards Namanula hill (3 km W). Seismicity was very low, although two periods of harmonic tremor on 2 August and the explosion and ash emissions on 3 August were detected.
During 4-5 August gray ash emissions periodically continued, punctuated by a few large and notable explosions. Ash plumes from the explosions rose 1 km above the crater and drifted N and NW producing fine ashfall in the E part of Rabaul town, Namanula Hill, and further downwind towards Tavui Point. Moderate seismicity consisting of low-frequency earthquakes, explosions, and volcanic tremors with variable durations was detected. During 5-9 August activity increased, characterized by an increased frequency and duration of ash emissions and more explosions. About 34 explosions were recorded between 5 and 8 August. Ash-rich clouds that rose 1.5 km above the crater drifted NW causing ashfall in most parts of Rabaul town and in areas between Toliap and Nonga (10 km NW). GPS measurements on Matupit Island continued to show long-term inflation; about 10-11 cm of uplift had been recorded since August 2010.
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: Rabaul Volcano Observatory (RVO)
REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m
The IG reported that scientists conducting an overflight of Reventador on 14 July noted that the lava dome at the top of the 2008 cone continued to grow, filling the crater. The dome had reached the same height as the highest part of the crater rim, formed during 2002. Intense fumarolic activity produced continuous plumes. The dome was thought to have formed during 2011, growing at a rapid rate and producing high temperatures. IG also noted that seismicity had increased starting in May but was more pronounced during the previous few weeks. During 3-9 August cloud cover prevented observations of the lava dome, but the seismic network detected long-period and explosion-type earthquakes.
Geologic Summary. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/
STROMBOLI Aeolian Islands (Italy) 38.789°N, 15.213°E; summit elev. 924 m
Sezione di Catania - Osservatorio Etneo reported that during the morning of 9 August a new episode of weak spattering occurred on Stromboli's crater terrace, generating a small intra-crater lava flow. The source vent was located in the central portion of the crater terrace. Regular explosive activity also continued from the vents located in the N and S parts of the crater terrace. Spattering continued into the afternoon, then ceased.
Geologic Summary. Spectacular incandescent nighttime explosions at Stromboli volcano have long attracted visitors to the "Lighthouse of the Mediterranean."Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout historical time. The small, 926-m-high island of Stromboli is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The active summit vents are located at the head of the Sciara del Fuoco, a horseshoe-shaped scarp formed as a result of slope failure that extends to below sea level and funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded at Stromboli since Roman times.
Source: Sezione di Catania - Osservatorio Etneo http://www.ct.ingv.it/
Ongoing Activity
ARENAL Costa Rica 10.463°N, 84.703°W; summit elev. 1670 m
OVSICORI-UNA reported that occasionally during early mornings in July web-camera images showed a plume rising from Arenal that drifted SE and S. Scientists that conducted fieldwork during 29-30 July observed plumes rising from the last cone that formed in the NE part of Crater C.
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.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that during 29 July-5 August moderate seismic activity continued at Karymsky and possible ash plumes rose to an altitude of 5.5 km (18,000 ft) a.s.l. A thermal anomaly on the volcano was detected by satellite during 30 July-3 August; cloud cover prevented observations on the other days. The Aviation Color Code remained at Orange.
Based on information from Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 8 August an ash plume rose to an altitude of 4.3 km (14,000 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
KIRISHIMA Kyushu 31.931°N, 130.864°E; summit elev. 1700 m
Based on notifications from JMA, the Tokyo VAAC reported an eruption from Kirishima on 6 August.
Geologic Summary. Kirishima is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene volcano group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1,700-m-high Karakuni-dake being the highest. Onami-ike and Mi-ike, the two largest maars, are located SW of Karakuni-dake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Mi-ike to Ohachi, and at Shinmoe-dake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m
KVERT reported that during 29 July-5 August seismicity from Kizimen was above background levels and weak volcanic tremor continued to be detected. Video images showed fumarolic activity and an occasional steam plume that rose to an altitude of 4.5 km (14,800 ft) a.s.l. A lava flow on the E flank was active. Satellite images showed a bright thermal anomaly on the volcano all week. The Aviation Color Code remained at Orange.
Geologic Summary. Kizimen is an isolated, conical stratovolcano that is morphologically similar to Mount St. Helens prior to its 1980 eruption. The summit of Kizimen consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2,376-m-high Kizimen was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2,000-3,500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of longterm lava-dome growth have occurred. The latest eruptive cycle began about 3,000 years ago with a large explosion and was followed by lava-dome growth lasting intermittently about 1,000 years. An explosive eruption about 1,100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. A single explosive eruption, during 1927-28, has been recorded in historical time.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
KRAKATAU Indonesia 6.102°S, 105.423°E; summit elev. 813 m
A satellite image acquired on 31 July showed a diffuse ash plume rising from Anak Krakatau and drifting W.
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: NASA Earth Observatory http://earthobservatory.nasa.gov/
PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m
During 3-8 August, OVDAS-SERNAGEOMIN reported that the eruption continued from the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex. During 3-4 August a video camera recorded plumes rising 2 km above the crater. Satellite imagery showed plumes drifting 1,000 km NE on 3 August and 700 km SE on 4 August. Cloud cover prevented video camera and satellite observations on 5 August. The next day cloud cover again prevented camera observations, though satellite imagery detected a plume that drifted 250 km E then SE. Plumes that were mostly white rose no higher than 2.5 km above the crater during 7-8 August. Satellite imagery on 7 August detected plumes that drifted 100-200 km SE. The Alert Level remained at Red.
Geologic Summary. The Puyehue-Cordón Caulle volcanic complex (PCCVC) is a large NW-SE-trending late-Pleistocene to Holocene basaltic-to-rhyolitic transverse volcanic chain SE of Lago Ranco. The 1799-m-high Pleistocene Cordillera Nevada caldera lies at the NW end, separated from Puyehue stratovolcano at the SE end by the Cordón Caulle fissure complex. The Pleistocene Mencheca volcano with Holocene flank cones lies NE of Puyehue. The basaltic-to-rhyolitic Puyehue volcano is the most geochemically diverse of the PCCVC. The flat-topped, 2236-m-high Puyehue volcano was constructed above a 5-km-wide caldera and is capped by a 2.4-km-wide summit caldera of Holocene age. Lava flows and domes of mostly rhyolitic composition are found on the eastern flank of Puyehue. Historical eruptions originally attributed to Puyehue, including major eruptions in 1921-22 and 1960, are now known to be from the Cordón Caulle rift zone. The Cordón Caulle geothermal area, occupying a 6 x 13 km wide volcano-tectonic depression, is the largest active geothermal area of the southern Andes volcanic zone.
Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
The Tokyo VAAC reported that on 3 August an ash plume from Sakura-jima observed by a pilot rose to an altitude of 1.5 km (5,000 ft) a.s.l. Based on information from JMA, plumes rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted W, NW, and NE during 3 and 5-9 August.
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
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that seismic activity at Shiveluch was moderate during 29 July-5 August. Satellite imagery showed a thermal anomaly on the lava dome during 30 July and 1-3 August. Ground-based observers indicated that ash plumes rose to an altitude of 7 km (23,000 ft) a.s.l. on 1 August and 4 km (13,100 ft) a.s.l. on 2 August. Satellite images from 1 August showed an ash plume drifting 24 km S. A strong dust storm at the volcano was observed on 3 August; a dust plume detected in satellite imagery drifted 160 km SE. The Aviation Color Code remained at Orange.
Based on information from KEMSD, the Tokyo VAAC reported that on 6 August an eruption produced a plume that rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted E. Ash was seen in subsequent satellite images that same day. An eruption on 9 August produced a plume that rose to an altitude of 6.7 km (22,000 ft) a.s.l.
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.
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
+++++++++++++++++++++++++++++++++++++
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@xxxxxxx.
To contribute to the volcano list, send your message to: volcano@xxxxxxx. Please do not send attachments.
==============================================================
