VOLCANO MADNESS: [ Volcano ] Smithsonian/USGS Weekly Volcanic Activity Report 2-8 January 2013

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Smithsonian/USGS Weekly Volcanic Activity Report 2-8 January 2013
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Smithsonian/USGS Weekly Volcanic Activity Report

2-8 January 2013

Sally Kuhn Sennert - Weekly Report Editor

kuhns@si.edu

URL: http://www.volcano.si.edu/reports/usgs/

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

ALAID Kuril Islands (Russia) 50.858°N, 155.55°E; summit elev. 2339 m

According to KVERT, observers on both Paramushir (SE) and Shumshu islands reported weak gas-and-steam plumes containing small amounts of ash from Alaid during 5, 11, 16-17, 23, and 27-28 October 2012. Photos taken on 27 October showed ash deposits on the cone and a small cinder cone growing in the crater. The cone was again covered by ash on 8 November. Seismicity increased on 16 November and remained elevated until 6 December, when it decreased until 10 December. Technical problems prevented seismic recordings after that. Satellite imagery showed a weak thermal anomaly on the volcano until 12 December. On 8 January 2013 the Aviation Color Code was lowered to Green.

Geologic Summary. The highest and northernmost volcano of the Kurile Islands, 2,339-m-high Alaid is a symmetrical stratovolcano when viewed from the N, but has a 1.5-km-wide summit crater that is breached widely to the S. Alaid is the northernmost of a chain of volcanoes constructed W of the main Kuril archipelago and rises 3,000 m from the floor of the Sea of Okhotsk. Numerous pyroclastic cones dot the lower flanks of Alaid, particularly on the NW and SE sides, including an offshore cone formed during the 1933-34 eruption. Strong explosive eruptions have occurred from the summit crater beginning in the 18th century. Reports of eruptions in 1770, 1789, 1821, 1829, 1843, 1848, and 1858 were considered incorrect by Gorshkov (1970). Explosive eruptions in 1790 and 1981 were among the largest in the Kurile Islands.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php

COLIMA México 19.514°N, 103.62°W; summit elev. 3850 m

According to news articles, a scientific advisory committee reported that a phreatic eruption from Colima on 6 January ejected tephra and an ash plume that rose 2 km above the crater. Ashfall was reported in Atenquique (20 km E). Visitors were evacuated from the national park.

Geologic Summary. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4,320 m high point of the complex) on the N and the historically active Volcán de Colima on the S. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the S, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.

Source: Televisa http://noticierostelevisa.esmas.com/estados/544760/volcan-fuego-colima-lanza-ceniza/

COPAHUE Central Chile-Argentina border 37.85°S, 71.17°W; summit elev. 2997 m

OVDAS-SERNAGEOMIN reported that seismicity at Copahue during 31 December, and 2 and 4-5 January indicated magma movement focused at 4 km below the crater and moving to shallower depths. On 5 January seismicity increased as well as gray emissions observed with a web camera. The Alert Level was raised to Orange. Incandescence on the crater was noted during 5-6 January, and plumes rose 200 m above the crater and drifted E during 5-7 January.

Based on analysis of satellite imagery, the Buenos Aires VAAC reported that on 2 January a diffuse gas-and-ash plume drifted 93 km NE and E. During 2-3 January web cameras near the volcano recorded steam-and-gas plumes drifting E and dissipating near the summit.

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.

Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/,

Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html

KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m

KVERT reported that on 27 December the eruption at Kizimen had ceased; video data occasionally recorded summit incandescence and satellite imagery detected a thermal anomaly that gradually decreased in intensity. The Aviation Color Code was lowered to Green.

Seismic activity increased on 28 December. Video data showed a new lava flow extruding from the summit onto the NE flank. During 28 December-7 January summit incandescence, strong gas-and-steam activity, and occasional hot avalanches on the W and E flank accompanied the process. Satellite images detected a thermal anomaly over the volcano. The Aviation Color Code was raised to Orange on 31 December.

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

PACAYA Guatemala 14.381°N, 90.601°W; summit elev. 2552 m

INSIVUMEH reported that on 2 January a few hours of increased fumarolic activity at Pacaya generated steam emissions that rose 450 m above MacKenney cone. During 3-4 January plumes only rose 100-150 m. White steam plumes drifted S during 5-8 January.

Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex volcano constructed on the southern rim of the 14 x 16 km Pleistocene Amatitlan caldera. A cluster of dacitic lava domes occupies the caldera floor. The Pacaya massif includes the Cerro Grande lava dome and a younger volcano to the SW. Collapse of Pacaya volcano about 1,100 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (MacKenney cone) grew. During the past several decades, activity at Pacaya has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion on the flanks of MacKenney cone, punctuated by occasional larger explosive eruptions.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/

SEULAWAH AGAM Sumatra (Indonesia) 5.448°N, 95.658°E; summit elev. 1810 m

CVGHM reported that visual observations of Seulawah Agam during 27 December-2 January seismicity increased. Visual observations were prevented due to fog, although on 2 January scientists observed a new solfatara that produced roaring noises and was within 20 m of van Heutsz Crater on the NNE flank. The Alert Level was raised to 2 (on a scale of 1-4) on 3 January.

Geologic Summary. Seulawah Agam at the NW tip of Sumatra is an extensively forested volcano of Pleistocene-Holocene age constructed within the large Pleistocene Lam Teuba caldera. A smaller 8 x 6 km caldera lies within Lam Teuba caldera. The summit contains a forested, 400-m-wide crater. The active van Heutsz crater, located at 650 m on the NNE flank of Suelawah Agam, is one of several areas containing active fumarole fields. Sapper (1927) and the Catalog of Active Volcanoes of the World (CAVW) reported an explosive eruption in the early 16th century, and the CAVW also listed an eruption from the van Heutsz crater in 1839. Rock et al. (1982) found no evidence for historical eruptions. However the Volcanological Survey of Indonesia noted that although no historical eruptions have occurred from the main cone, the reported NNE-flank explosive activity may have been hydrothermal and not have involved new magmatic activity.

Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://proxy.vsi.esdm.go.id/index.php

TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m

On 3 January, IG reported that since 31 December seismicity at Tungurahua had decreased, and during 2-3 and 7-8 January there were no explosions, noises, or reported ashfall. One small explosion was detected on both 4 and 5 January. An explosion on 6 January was accompanied by roaring and sounds of rolling blocks. Minor ashfall was reported in Manzano (8 km SW). Cloud cover had often prevented visual observations during 31 December-8 January.

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/

WHITE ISLAND New Zealand 37.52°S, 177.18°E; summit elev. 321 m

On 7 January GeoNet Data Centre reported that the Aviation Colour Code for White Island was lowered to Yellow (second lowest on a four-color scale) and the Volcanic Alert Level was lowered to 1. A spiny lava dome in the crater formed on 5 August was first clearly observed on 10 December. Observations on 20 December indicated that the dome had not changed. Scientists visited the area on 1 January and again observed no changes. They measured temperatures of 200-240 degrees Celsius from the lava dome and 70-80 degrees from the nearby hot lake, and observed lots of gas coming from the lake. The report also indicated continuing elevated levels of tremor.

Geologic Summary. The uninhabited 2 x 2.4 km White Island, one of New Zealand's most active volcanoes, is the emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The 321-m-high island consists of two overlapping stratovolcanoes; the summit crater appears to be breached to the SE because the shoreline corresponds to the level of several notches in the SE crater wall. Throughout the short historical period beginning in 1826 the volcano has had long periods of continuous hydrothermal activity and steam release, punctuated by small-to-medium eruptions. Its activity also forms a prominent part of Maori legends. The most recent eruptive episode, which began on 7 March 2000, included the largest eruption at White Island in the past 20 years on 27 July.

Source: GeoNet Data Centre http://www.geonet.org.nz/

Ongoing Activity

CHIRPOI Kuril Islands (Russia) 46.525°N, 150.875°E; summit elev. 742 m

SVERT reported that a thermal anomaly was detected over Snow, a volcano of Chirpoi, during 5-6 January; cloud cover prevented observations of the volcano on other days during 1-7 January.

Geologic Summary. Chirpoi, a small island lying between the larger islands of Simushir and Urup, contains a half dozen volcanic edifices constructed within an 8-9 km wide, partially submerged caldera. The southern rim of the caldera is exposed on nearby Brat Chirpoev Island. Two volcanoes on Chirpoi Island have been historically active. The symmetrical Cherny volcano, which forms the 691 m high point of the island, erupted twice during the 18th and 19th centuries. The youngest volcano, Snow, originated between 1770 and 1810. It is composed almost entirely of lava flows, many of which have reached the sea on the southern coast. No historical eruptions are known from 742-m-high Brat Chirpoev, but its youthful morphology suggests recent strombolian activity.

Source: Sakhalin Volcanic Eruption Response Team (SVERT) http://www.imgg.ru/en/home.html

FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m

INSIVUMEH reported that during 3-8 January explosions from Fuego produced ash plumes that rose less than 350 m and drifted W and SW. Lava flows traveled 300-900 m SW down the Taniluya drainage. During 7-8 January explosions produced plumes that drifted 5 km SW. Incandescence emanated 100 m above the crater.

Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/

KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m

KVERT reported that moderate seismic activity at Karymsky was detected during 28 December-4 January. Satellite imagery showed a thermal anomaly on the volcano on 28 and 30 December, as well as on 1 January. The Aviation Color Code remained at Orange.

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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php

KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m

During 2-8 January HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. The gas plume from the vent continued to deposit variable amounts of ash, spatter, and Pele's hair onto nearby areas. A few pieces of the inner ledge of the lake as well as several pieces of veneer on the walls of the conduit occasionally fell into the lake.

At Pu'u 'O'o Crater, glow emanated from spatter cones on the SE part of the crater floor, from a spatter cone at the NW edge of the floor, and from a circulating lava lake on the NE part of the floor. Lava flows were active in a 1-km-wide area that stretched from near the base of the pali to the coast. Web cameras recorded steam plumes from lava sporadically entering the ocean at multiple locations. On 4 January the N and W rims of the lava lake collapsed into the lake.

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

Based on ground reports from CVGHM, the Darwin VAAC reported that ash plumes rose from Lokon-Empung rose to an altitude of 2.4 km (8,000 ft) a.s.l. Ash was not detected in satellite imagery.

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: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/anon/gen/vaac/

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 4 January ash plumes from Paluweh rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 37 km NE. On 7 January an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted less than 20 km NE.

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/

POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m

CENAPRED reported that during 2-8 January views of Popocatépetl were often obscured by cloud cover. Seismicity indicated continuing gas-and-steam emissions that most days contained minor amounts of ash. Variable incandescence from the crater was observed most nights. During 4-8 January, steam-and-gas plumes rose 300 m above the crater and drifted NE or SE. The Alert Level remained at Yellow, Phase Two.

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/

SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m

JMA reported that during 28 December-4 January explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Very small eruptions occurred at Minami-dake Crater on 30 December and 4 January.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 2 and 5-8 January generated plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted NE, E, and SE.

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

SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m

INSIVUMEH reported that during 2-3 January explosions from Santa María's Santiaguito lava-dome complex produced plumes that rose 300 m. During 2-4 January the lava-flow front on the S flank was incandescent because avalanches exposed the hot interior. A weak explosion was detected on 4 January. Explosions during 5-8 January produced ash plumes that drifted W and SW. Lava flows were active on the NE, SE, SW, and NW flanks.

Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/

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 28 December-4 January a viscous lava flow continued to effuse on the NW flank 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 28 December-8 January. Strong seismicity was detected. Gas-and-ash plumes drifted in multiple directions, and a fifth cone continued to grow above the fissure. A very large thermal anomaly on the N part of Tolbachinsky Dol was visible daily in satellite imagery. The Aviation Color Code remained at Orange.

Based on information from KVERT, the Tokyo VAAC reported that on 7 January an ash plume rose to altitudes of 3.7-4.3 km (12,000-14,000 ft) a.s.l. and drifted NE.

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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php

Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.jp/svd/vaac/data/vaac_list.html

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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

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