Smithsonian/USGS Weekly Volcanic Activity Report 8-14 May 2013
************************************************************************************************
Smithsonian/USGS Weekly Volcanic Activity Report
8-14 May 2013
Sally Kuhn Sennert - Weekly Report Editor
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Cleveland, Chuginadak Island | Copahue, Central Chile-Argentina border | Dieng Volcanic Complex, Central Java (Indonesia) | Guntur, Western Java (Indonesia) | Mayon, Luzon | Pavlof, Alaska Peninsula | Popocatépetl, México | Tungurahua, Ecuador
Ongoing Activity: | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Paluweh, Lesser Sunda Islands (Indonesia) | Reventador, Ecuador | Sabancaya, Perú | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Tolbachik, 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 during 8-9 May no further explosions had been detected at Cleveland based on regional infrasonic data. Cloud cover prevented satellite observations of the crater. Clear satellite views revealed vigorous steam plumes during 10-11 May and thermal anomalies during 10-14 May. On 14 May AVO noted that analysis of recent satellite imagery revealed a 100-m-wide lava flow, breaching the SE rim of the summit crater, and extending about 1.5 km down the SE flank. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange.
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/
COPAHUE Central Chile-Argentina border 37.85°S, 71.17°W; summit elev. 2997 m
OVDAS-SERNAGEOMIN reported that an explosion from Copahue at 1015 on 7 May recorded by a webcam produced a gas, steam, and ash plume that rose 350 m and drifted SE. Incandescence from the crater was visible at night. The Alert Level was raised to Yellow.
Geologic Summary. Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded at Copahue since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.
Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/
DIENG VOLCANIC COMPLEX Central Java (Indonesia) 7.20°S, 109.92°E; summit elev. 2565 m
CVGHM reported that on 28 March gas emissions continued to be elevated at Timbang, a cone that is part of the Dieng Volcanic Complex. Plumes containing carbon dioxide drifted 2 km towards the S valley of Kali Sat, prompting a road closure until the early evening when the gas concentration decreased. On 30 March carbon dioxide gas emissions were not detected; however, "smoke" rose at most 100 m above the crater. Hydrogen sulfide odors were very potent in areas 1 km W and weak in areas 1.5 km S. On 19 April sulfur dioxide odors were reported.
On 24 March Sileri Crater lake water changed from dark gray to brown. On 7 April white plumes rose 50 m and the water color returned to normal. Diffuse white plumes rose 15 m on 20 April. Other craters had not exhibited any changes by 28 April.
Based on gas concentrations, seismicity, and visual observations, CVGHM raised the Alert Level to 3 (on a scale of 1-4) on 8 May and warned the public not to approach Timbang Crater within a 500-m radius.
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/
GUNTUR Western Java (Indonesia) 7.143°S, 107.840°E; summit elev. 2249 m
CVGHM reported that in early March a slight increase of deep and shallow volcanic-tectonic earthquakes at Guntur was recorded; volcanic tremor became continuous on 2 April, prompting CVGHM to raise the Alert Level to 2 (on a scale of 1-4).
Temperature measurements of hot springs in five different areas fluctuated until mid-April and then were relatively stable through early May. Seismicity also decreased in early May. On 7 May the Alert Level was lowered to 1.
Geologic Summary. Guntur is a complex of several overlapping stratovolcanoes about 10 km NW of the city of Garut in western Java. Young lava flows, the most recent of which was erupted in 1840, are visible on the flanks of the erosionally unmodified Gunung Guntur, which rises about 1,550 m above the plain of Garut. Guntur is one of a group of younger cones constructed to the SW of an older eroded group of volcanoes at the NE end of the complex. Guntur, whose name means "thunder," is the only historically active center, with eruptions having been recorded since the late-17th century. Although Guntur produced frequent explosive eruptions in the 19th century, making it one of the most active volcanoes of western Java, it has not erupted since.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m
At 0800 on 8 May, PHIVOLCS reported that two rockfalls at Mayon had been detected within the previous 24 hours. Seismicity remained within background levels and indicated no increase in overall volcanic activity. The Alert Level remained at 0 and the public was reminded not to enter the 6-km-radius Permanent Danger Zone (PDZ).
Geologic Summary. Beautifully symmetrical Mayon volcano, which rises to 2,462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes that average 35-40° and is capped by a small summit crater. The historical eruptions of this basaltic-andesitic volcano date back to 1616 and range from Strombolian to basaltic Plinian. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1,200 people and devastated several towns. Eruptions that began in February 2000 led PHIVOLCS to recommend on 23 February 2000 the evacuation of people within a radius of 7 km from the summit in the SE and within a 6 km radius for the rest of the volcano.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/
PAVLOF Alaska Peninsula 55.42°N, 161.887°W; summit elev. 2519 m
AVO reported that on 13 May seismicity at Pavlof increased at 0800 commensurate with the presence of an intense thermal anomaly at the summit observed in satellite imagery. Several spikes in seismicity occurred between 0900 and 1000. AVO noted that similar patterns of seismicity and elevated surface temperatures have previously signaled the onset of eruptive activity at Pavlof. Although not yet visually confirmed at the time of the report, a low-level eruption of lava had likely begun from a summit vent. No ash clouds were detected. The Volcanic Alert Level was increased Watch and the Aviation Color Code was increased Orange. On 14 May pilot reports and satellite images confirmed activity; a spatter-fed lava flow advanced about 0.5 km down the N flank. Minor steam-and-ash emissions from the summit were visible from Cold Bay (60 km SW).
Geologic Summary. The most active volcano of the Aleutian arc, Pavlof is a 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavolf, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing strombolian to vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest historical eruption of Pavlof took place in 1911, at the end of a 5-year-long eruptive episode; a fissure opened on the northern flank of the volcano, ejecting large blocks and issuing lava flows.
Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/
POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED reported that an episode of high-amplitude spasmodic tremor detected at Popocatépetl began between 1928 on 7 May and 0159 on 8 May. The seismic increase was accompanied by an ash plume that rose 3 km above the crater and drifted SE, producing ashfall in San Pedro Benito Juarez (10-12 km SE), San Juan Tianguismanalco (22 km SE), Atlixco (23 km SE), and in some areas of Puebla (~50 km to the E). Incandescent tephra ejected from the crater landed 500 m away on the NE flank. On 8 May an explosion produced an ash plume that drifted SE. Incandescence from the crater was observed at night. The next day gas-and-steam plumes drifted SE.
On 10 May steam, gas, and ash plumes were detected; one of two explosions produced an ash plume that drifted E. A series of ash emissions and periods of harmonic tremor occurred between 1142 and 1443; cloud cover prevented clear views of the ash plumes. On 11 May steam, gas, and ash plumes were again detected. An explosion produced an ash plume that rose 1 km and drifted NE, and ejected incandescent tephra 500 m down the NE flank. Ash possibly fell in villages downwind. Gas-and-ash plumes rose 0.1-2 km and drifted ENE and NE. During 11-12 May periods of spasmodic and harmonic tremor were detected, and activity increased overall.
On 12 May CENAPRED noted that there had been an increase in activity during the previous two weeks, and another intensification that day prompting the Alert Level to be raised to Yellow, Phase Three. Access to the crater within a 12-km radius was prohibited. Stream-and-gas plumes with small amounts of ash rose from the carter. Sporadic ejections of incandescent tephra fell back into the crater and onto the NNE flank, 300 m from the crater rim. On 13 May steam-and-gas plumes were observed rising from the crater during periods of good visibility. On 14 May an explosive event generated an ash plume that rose 3 km and ejected incandescent tephra that landed 600 m away on the NE flank. Cloud cover again obscured summit views. Seismicity remained elevated.
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.gob.mx/es/
TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m
IG reported that although cloud cover often prevented observations of Tungurahua during 8-14 May, ash plumes were observed almost daily. Seismicity remained at a moderate level. Explosions occasionally vibrated structures nearby and at the Tungurahua Observatory (OVT) in Guadalupe (14 km N). Strombolian activity was observed on most nights ejecting blocks sometimes 500 m above the crater; blocks that fell onto the flanks rolled as far as 1 km. During 9-10 May lava fountains rose 700 m above the crater. During 8-11 May ash plumes rose 1-2.5 km and drifted SW, W, and NW, producing ashfall in El Manzano (8 km SW), Choglontus (SW), Quero (20 km NW), Mocha (25 km WNW), Pillate (8 km W), Tisaleo (29 km NW), and Penipe on 8 and 10 May, and in Santa Fe de Galán, Mocha, Sabañag (15 km WNW), Tisaleo, and Quero (20 km NW) on 11 May. Ashfall was reported in Quero on 12 May. The next day explosions generated ash plumes that rose 2-3 km and drifted NW and W, producing ashfall in El Manzano. Roaring and sounds resembling rolling blocks were reported. On 14 May ash fell in Choglontus, El Manzano, and Mocha.
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/
Ongoing Activity
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 8-14 May HVO reported that the circulating lava lake occasionally rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. The plume from the vent continued to deposit variable amounts of ash, spatter, and Pele's hair onto nearby areas.
At Pu'u 'O'o Crater, glow emanated from three spatter cones and a small lava pond on the E part of the crater floor. Lava from the E lava pond traveled down the N, NE, E, and S flanks, extending beyond the base of Pu'u 'O'o cone. During 10-11 May the SW spatter cone erupted lava, and during 11-12 May the SE spatter cone also produced flows.
Peace Day activity, fed by lava tubes extending from Pu'u 'O'o, consisted of lava flows active on the pali and on the coastal plain. Lava also entered the ocean in at least two locations spanning the National Park boundary.
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 3-10 May moderate seismic activity continued at Kizimen. Video and satellite data showed that lava continued to extrude from the summit, producing incandescence, strong gas-and-steam activity, and hot avalanches on the W and E flanks. A thermal anomaly was detected daily in satellite images. 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
PALUWEH Lesser Sunda Islands (Indonesia) 8.32°S, 121.708°E; summit elev. 875 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 13 May ash plumes from Paluweh rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted over 90 km WNW and NW.
Geologic Summary. Paluweh volcano, also known as Rokatenda, forms the 8-km-wide island of Paluweh N of the volcanic arc that cuts across Flores Island. Although the volcano rises about 3,000 m above the sea floor, its summit reaches only 875 m above sea level. The broad irregular summit region contains overlapping craters up to 900 m wide and several lava domes. Several flank vents occur along a NW-trending fissure. The largest historical eruption of Paluweh occurred in 1928, when a strong explosive eruption was accompanied by landslide-induced tsunamis and lava-dome emplacement.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/anon/gen/vaac/
REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m
IG reported that during the morning of 8 May incandescence from Reventador's crater was observed in addition to steam-and-ash plumes that rose 1 km above the crater and drifted NW. Cloud cover prevented observations the rest of the day and most of the time during 9-14 May. At 1700 on 10 May a steam plume with low ash content rose 1 km above the crater, and on 11 May a vapor plume rose 500 m and drifted SW.
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/
SABANCAYA Perú 15.78°S, 71.85°W; summit elev. 5967 m
On 10 May Instituto Geofísico de Perú (IGP) reported that results of an interferogram of Sabancaya provided by a collaborator at Cornell University showed that an area of deformation (subsidence of 7 cm centered at 6 km NE of the crater) was coincident with the main area of seismicity. Volcano-tectonic (VT) earthquakes continued to dominate the seismic signals, although long-period (LP) events continued to be detected. There was also an increase of hybrid events. On 10 May a M 4 VT event occurred 15 km W and fumarolic activity increased, with plumes rising 1.2 km high.
Geologic Summary. Sabancaya, located on the saddle between 6288-m-high Ampato and 6025-m-high Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three volcanoes, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. Both Nevado Ampato and Nevado Sabancaya are only slightly affected by glacial erosion and consist of a series of lava domes aligned along a NW-SW trend. The name of 5967-m-high Sabancaya (meaning "tongue of fire" in the Quechua Indian language) first appeared in records in 1595 AD, suggesting activity prior to that date. Holocene activity has consisted of plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions of Sabancaya date back to 1750.
Source: Instituto Geofísico de Perú (IGP) http://www.igp.gob.pe/index.html
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
JMA reported that during 7-10 May eight explosions from Sakura-jima's Showa Crater ejected tephra that fell at most 1.8 km from the crater. Crater incandescence was occasionally detected at night. Based on information from JMA, the Tokyo VAAC reported that on most days during 8-14 May explosions produced plumes that rose to altitudes of 2.1-4.3 km (7,000-14,000 ft) a.s.l. and drifted in multiple directions. During 9 and 13-14 May pilots observed ash plumes rising to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and drifting N, NW, and W.
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.
Sources: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/index.html,
Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.jp/svd/vaac/data/vaac_list.html
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
Based on visual observations and analyses of satellite data, KVERT reported that during 3-10 May a viscous lava flow effused on the NW and NE flanks of Shiveluch's lava dome, accompanied by hot avalanches, incandescence, and fumarolic activity. Satellite imagery showed a daily thermal anomaly on the lava dome. The Aviation 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. 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.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
TOLBACHIK Central Kamchatka (Russia) 55.830°N, 160.330°E; summit elev. 3682 m
KVERT reported that the S fissure along the W side of Tolbachinsky Dol, a lava plateau on the SW side of Tolbachik, continued to produce very fluid lava flows during 3-10 May that traveled to the W, S, and E sides of the plateau. Cinder cones continued to grow along the S fissure and gas-and-ash plumes were observed. A large thermal anomaly on the N part of Tolbachinsky Dol was visible daily in satellite imagery. The Aviation Color Code remained at Orange.
Geologic Summary. The massive Tolbachik basaltic volcano is located at the southern end of the dominantly andesitic Kliuchevskaya volcano group. The Tolbachik massif is composed of two overlapping, but morphologically dissimilar volcanoes. The flat-topped Plosky Tolbachik shield volcano with its nested Holocene Hawaiian-type calderas up to 3 km in diameter is located east of the older and higher sharp-topped Ostry Tolbachik stratovolcano. The summit caldera at Plosky Tolbachik was formed in association with major lava effusion about 6500 years ago and simultaneously with a major southward-directed sector collapse of Ostry Tolbachik volcano. Lengthy rift zones extending NE and SSW of the volcano have erupted voluminous basaltic lava flows during the Holocene, with activity during the past two thousand years being confined to the narrow axial zone of the rifts. The 1975-76 eruption originating from the SSW-flank fissure system and the summit was the largest historical basaltic eruption in Kamchatka.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
+++++++++++++++++++++++++++++++++++++
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: 202.633.1805Fax: 202.357.2476
Volcano Listserv is a collaborative venture among Arizona State University (ASU), Portland State University (PSU), the Global Volcanism Program (GVP) of the Smithsonian Institution's National Museum of Natural History, and the International Association for Volcanology and Chemistry of the Earth's Interior (IAVCEI).
ASU - http://www.asu.edu/ PSU - http://pdx.edu/ GVP - http://www.volcano.si.edu/ IAVCEI - http://www.iavcei.org/
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.
==============================================================
