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Smithsonian/USGS Weekly Volcanic Activity Report 1-7 June 2011
From: "Kuhn, Sally" <KUHNS@xxxxxx>
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Smithsonian/USGS Weekly Volcanic Activity Report
1-7 June 2011
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Aso, Kyushu | Dieng Volcanic Complex, Central Java (Indonesia) | Kliuchevskoi, Central Kamchatka (Russia) | Popocatépetl, México | Puyehue-Cordón Caulle, Central Chile | Yasur, Vanuatu (SW Pacific)
Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Dukono, Halmahera | Karangetang [Api Siau], Siau I | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Rabaul, New Britain | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Villarrica, Central Chile
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
ASO Kyushu 32.881°N, 131.106°E; summit elev. 1592 m
Based on notices from JMA, the Tokyo VAAC reported that during 1-7 June plumes from Aso rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted NW, N, NE, E, and S.
Geologic Summary. The 24-km-wide Aso caldera was formed during four major explosive eruptions from 300,000 to 80,000 years ago. These produced voluminous pyroclastic flows that covered much of Kyushu. A group of 17 central cones was constructed in the middle of the caldera, one of which, Naka-dake, is one of Japan's most active volcanoes. It was the location of Japan's first documented historical eruption in 553 AD. The Naka-dake complex has remained active throughout the Holocene. Several other cones have been active during the Holocene, including the Kometsuka scoria cone as recently as about 210 AD. Historical eruptions have largely consisted of basaltic to basaltic-andesite ash emission with periodic Strombolian and phreatomagmatic activity. The summit crater of Naka-dake is accessible by toll road and cable car, and is one of Kyushu's most popular tourist destinations.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
DIENG VOLCANIC COMPLEX Central Java (Indonesia) 7.20°S, 109.92°E; summit elev. 2565 m
CVGHM reported that during 29 May-5 June carbon dioxide gas emissions from Timbang, a cone that is part of the Dieng Volcanic Complex, remained elevated. Seismicity for Dieng also remained high. During 4-5 June white plumes from Sileri crater rose 20-60 m high and white plumes from Timbang rose only 2 m and drifted 300 m S. The Alert Level remained at 3 (on a scale of 1-4).
Geologic Summary. The Dieng plateau in the highlands of central Java is renowned both for the variety of its volcanic scenery and as a sacred area housing Java's oldest Hindu temples, dating back to the 9th century AD. The Dieng volcanic complex consists of two or more stratovolcanoes and more than 20 small craters and cones of Pleistocene-to-Holocene age over a 6 x 14 km area. Prahu stratovolcano was truncated by a large Pleistocene caldera, which was subsequently filled by a series of dissected to youthful cones, lava domes, and craters, many containing lakes. Lava flows cover much of the plateau, but have not occurred in historical time, when activity has been restricted to minor phreatic eruptions. Toxic volcanic gas emission has caused fatalities and is a hazard at several craters. The abundant thermal features that dot the plateau and high heat flow make Dieng a major geothermal prospect.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 27 May-3 June seismic activity at Kliuchevskoi was detected. Moderate steam-and-gas activity was observed on 30 May and 1 June; cloud cover prevented observations on the other days of the week. The Aviation Color Code was lowered to Green.
The Tokyo VAAC reported that on 6 June a possible eruption detected in satellite imagery produced a plume that rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted NE. The VAAC stated that the ash could have also originated at Bezymianny.
Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included major explosive and effusive events from flank craters.
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
POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED reported that during 31 May-1 June steam-and-gas emissions from Popocatépetl occasionally contained small amounts of ash. At 0637 on 3 June an ash plume rose 3 km above the crater following seismic tremor. The lower-altitude portion of the plume drifted W (towards the state of Morelos) and the higher-altitude portion of the plume drifted ENE (over Puebla, 40 km E). Within a few hours ashfall was reported in the Morelos state, municipalities of Tetela del Volcán (20 km SW), Zacualpan (31 km SW), Jonacatepec (43 km SW), and Axochiapan (60 km SSW). At 2112 high-frequency, low-amplitude tremor was detected that was followed by an ash plume at 2116 that rose 1 km above the crater and drifted W. By 2130 activity had returned to normal levels. On 4 June an ash plume rose 1 km above the crater and drifted SSW at lower altitudes and NE at higher altitudes.
Geologic Summary. Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America's second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED) http://www.cenapred.unam.mx/es/
PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m
OVDAS-SERNAGEOMIN reported that between 2000 on 2 June and 1959 on 3 June about 1,450 earthquakes at Puyehue-Cordón Caulle were detected, or an average of about 60 earthquakes per hour. The earthquakes were mostly hybrid and long-period, and located in the SE sector of the Cordón Caulle rift zone at depths of 2-5 km. SERNAGEOMIN scientists along with regional authorities flew over the volcano, noting no significant changes. The Alert Level remained at 4, Yellow. Area residents reported feeling earthquakes during the evening of 3 June through the morning of 4 June.
For a six-hour period on 4 June, seismicity increased to an average of 230 earthquakes per hour, at depths of 1-4 km. About 12 events were magnitudes greater than 4, and 50 events were magnitudes greater than 3. The Alert Level was raised to 5, Red. ONEMI reported that the border crossing into Argentina was closed and about 700 local people were to start evacuating. Later, an explosion from Cordón Caulle produced a 5-km-wide ash-and-gas plume that rose to an altitude of 12.2 km (40,000 ft) a.s.l. as noted by OVDAS scientists. The plume drifted S at 5 km altitude, and W and E at 10 km altitude. The Alert Level was raised to 6, Red. ONEMI reported the continuation of evacuations and increased the potential number of evacuees to 3,000. ONEMI also reported that the National Director of SERNAGEOMIN noted that lava was not detected, but pyroclastic flow deposits were observed. Residents reported a strong sulfur odor and significant ash and pumice fall. During 4-5 June ashfall several centimeters thick was reported in San Carlos de Bariloche, 100 km SE in Argentina, and surrounding areas.
Based on analyses of satellite imagery, SIGMET notices, and information from the Puerto Montt Flight Information Region (FIR), the Buenos Aires VAAC reported that on 4 June ash plumes rose to altitudes of 10.7-13.7 km (35,000-45,000 ft) a.s.l. and drifted 870 km ESE. Diffuse gas-and-steam plumes drifted W. The next day an ash plume continued to rise to altitudes of 10.7-12.2 km (35,000-40,000 ft) a.s.l. and had drifted as far as 1,778 km ESE, over the coast of Argentina, and out into the Atlantic Ocean. A portion of the plume drifted WSW. News outlets reported that flights in southern Argentina were canceled during 4-5 June. On 6 June the continuous ash plume changed direction and was blown ENE as far as 178 km while the previous portion of the plume continued to drift ESE over the ocean. On 7 June the VAAC reported continuous emissions. Ash plumes rose to altitudes of 5.5-9.8 km (18,000-32,000 ft) a.s.l. and were 65-95 km wide. A large area of ash continued to drift E over the Atlantic Ocean. News articles noted that some flights in Paraguay and Chile were cancelled and about 4,000 people had evacuated. News photos showed ashfall and people collecting pumice in San Martin de los Andes, Argentina, 80 km NE.
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.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/,
Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI) http://www.onemi.cl/,
Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html,
Earth Observatory http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=50882&src="">,
National http://www.latercera.com/noticia/nacional/2011/06/680-370765-9-onemi-de-los-rios-confirma-que-comenzo-proceso-eruptivo-de-complejo-volcanico.shtml
YASUR Vanuatu (SW Pacific) 19.53°S, 169.442°E; summit elev. 361 m
On 1 June, the Vanuatu Geohazards Observatory raised the Alert Level for Yasur to 3 (on a scale of 0-4) following increasing explosive activity during May. Access to the volcano was closed and a 500-m zone around the volcano was restricted. The Geohazards team noted strong explosions from all three active vents along with ash emissions and bomb ejections during 31 May-3 June. Bombs fell around the crater rim and explosions were heard and observed from nearby villages.
Geologic Summary. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous Strombolian and vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Yasur is a mostly unvegetated pyroclastic cone with a nearly circular, 400-m-wide summit crater. Yasur is largely contained within the small Yenkahe caldera in SE Tanna Island. It is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. Active tectonism along the Yenkahe horst accompanying eruptions of Yasur has raised Port Resolution harbor more than 20 m during the past century.
Source: Vanuatu Geohazards Observatory http://www.geohazards.gov.vu/
Ongoing Activity
BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 1-7 June ash plumes from Batu Tara rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted 40-130 km NW, W, and SW.
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
DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m
Based on analyses of satellite imagery, the Darwin VAAC reported that on 1 June an ash plume from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 110 km NE.
Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
KARANGETANG [API SIAU] Siau I 2.78°N, 125.40°E; summit elev. 1784 m
CVGHM reported that during 25 March-5 June seismic activity at Karangetang decreased along with the potential threat of avalanches and pyroclastic flows. During 1 May-5 June no pyroclastic flows were observed. Lava flowed 200 m down the flanks and produced incandescent material from the flow fronts that traveled an additional 1.5-1.8 km. Bluish-white emissions rose as high as 500 m from the main crater and incandescence from the crater was observed at night. Lava flow and avalanche activity decreased on 19 May. The Alert Level was lowered to 2 (on a scale of 1-4) on 6 June.
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.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported moderate seismic activity at Karymsky during 27 May-3 June. Seismic data indicated that possible ash plumes rose to an altitude of 3.1 km (10,200 ft) a.s.l. Satellite imagery detected a thermal anomaly during 28-30 May and 1-2 June, and an ash plume that drifted 10 km SW on 30 May. The Aviation Color Code remained at Orange.
Based on information from KVERT, the Tokyo VAAC reported that on 4 June an ash plume rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted SE.
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
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
HVO reported that two lava lakes at Kilauea were active during 1-7 June. The level of the summit lava lake remained mostly stable deep in the vent inset within the E wall of Halema'uma'u Crater. Occasional increases in the lake level covered a vent on the south side wall; on other days lava from the vent cascaded down into the lake. A gas plume from the vent drifted SW. The (preliminary) sulfur dioxide emission rate from all east rift zone sources was 1,100 tonnes/day on 3 June.
Lava from a vent near the W edge of the perched lava lake in the center of Pu'u 'O'o crater floor continued to fill the lake. The lake level fluctuated and occasionally overflowed the edges or flowed through rim breaches, sending lava onto the Pu'u 'O'o crater floor. The rim of the perched lava lake was elevated 2-3 m higher than the surrounding crater floor, which was 39 m below the E crater rim on 1 June.
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/
KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m
KVERT reported that during 27 May-3 June seismicity from Kizimen was above background levels and strong tremor continued to be detected. Seismic data indicated that possible ash plumes rose to an altitude of 6 km (19,700 ft) a.s.l. Satellite images showed a large bright thermal anomaly daily on the volcano. The Aviation Color Code remained at Orange.
Based on information from KVERT, the Tokyo VAAC reported that on 4 June an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted SE.
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.
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
RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m
RVO reported that variable amounts of white vapor plumes rose from Rabaul caldera's Tavurvur cone during 1-31 May and were occasionally tinted brown. During 19-21 May thick white plumes rose 2-3 km above the crater.
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)
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
Based on information from JMA, the Tokyo VAAC reported that during 2-6 June explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. Plumes drifted S on 2 June. On 2 and 4 June, pilots observed ash plumes that rose to altitudes of 2.4-3.7 km (8,000-12,000 ft) a.s.l.
Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 27 May-3 June seismic activity at Shiveluch indicated that possible ash plumes rose to altitudes of 4.7-9 km (15,400-29,500 ft) a.s.l. During 29-30 May satellite imagery showed a thermal anomaly over the lava dome. Those same two days, ground-based observers noted that ash plumes rose to an altitude of 10 km (32,800 ft) a.s.l. and drifted S. Clouds prevented observations on the other days. During 30-31 May long ash clouds drifted 1,000 km SW and approached Petropavlovsk-Kamchatsky. The Aviation Color Code remained at Orange.
Based on information from KVERT and analyses of satellite imagery, the Tokyo VAAC reported that on 4 June an eruption produced a plume that rose to an altitude of 5.2 km (17,000 ft) a.s.l. According to KEMSD, eruptions during 5-6 June produced plumes that rose to altitudes of 6.1-9.1 km (20,000-30,000 ft) a.s.l. Plumes drifted E on 5 June.
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
VILLARRICA Central Chile 39.42°S, 71.93°W; summit elev. 2847 m
On 31 May brief emissions of gas and steam with possible light ash from Villarrica was observed through the OVDAS web camera.
Geologic Summary. Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km wide caldera formed during the late Pleistocene, more than 0.9 million years ago. A 2-km-wide postglacial caldera is located at the base of the presently active, dominantly basaltic-to-andesitic cone at the NW margin of the Pleistocene caldera. About 25 scoria cones dot Villarrica's flanks. Plinian eruptions and pyroclastic flows have been produced during the Holocene from this dominantly basaltic volcano, but historical eruptions have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Lahars from the glacier-covered volcano have damaged towns on its flanks.
Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html
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