Smithsonian/USGS Weekly Volcanic Activity Report 25-31 January 2012
From: "Faulk, Elisabeth" <FaulkE@xxxxxx>
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Smithsonian/USGS Weekly Volcanic Activity Report
25-31 January 2012
Elisabeth Faulk - Weekly Report Editor faulke@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Cleveland, Chuginadak Island | Gamalama, Halmahera | Krakatau, Indonesia | Lewotolo, Lomblen Island (Indonesia) | Nyamuragira, Democratic Republic of Congo | Paluweh, Lesser Sunda Islands (Indonesia)
Ongoing Activity: | Dukono, Halmahera | Etna, Sicily (Italy) | Hierro, Canary Islands (Spain) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Pagan, Mariana Islands | Popocatépetl, México | Puyehue-Cordón Caulle, Central Chile | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat
This page is updated on Wednesdays. Please see the GVP Home Page for news of the latest significant activity.
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 on 31 January the Volcano Alert Level for Cleveland was raised to Watch and the Aviation Color Code was raised to Orange due to the formation of a new 40-m-wide lava dome in the summit crater that was observed in satellite imagery on 30 January. The lava dome that formed during the past fall and winter was removed by explosive activity on 25 and 29 December 2011. 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/
GAMALAMA Halmahera 0.80°N, 127.33°E; summit elev. 1715 m
CVGHM lowered the Alert Level for Gamalama from 3 to 2 (on a scale of 1-4) on 24 January based on visual observations of white plumes rising as high as 100 m above the crater and a decrease in seismicity since the last eruption on 23 December 2011.
Geologic Summary. Gamalama (Peak of Ternate) is a near-conical stratovolcano that comprises the entire island of Ternate off the western coast of Halmahera and is one of Indonesia's most active volcanoes. The island of Ternate was a major regional center in the Portuguese and Dutch spice trade for several centuries, which contributed to the thorough documentation of Gamalama's historical activity. Three cones, progressively younger to the N, form the summit of Gamalama, which reaches 1,715 m. Several maars and vents define a rift zone, parallel to the Halmahera island arc, that cuts the volcano. Eruptions, recorded frequently since the 16th century, typically originated from the summit craters, although flank eruptions have occurred in 1763, 1770, 1775, and 1962-63.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
KRAKATAU Indonesia 6.102°S, 105.423°E; summit elev. 813 m
CVGHM lowered the Alert Level for Anak Krakatau from 3 to 2 (on a scale of 1-4) on 26 January. No details or reasons for the change were given in the report.
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: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
LEWOTOLO Lomblen Island (Indonesia) 8.272°S, 123.505°E; summit elev. 1423 m
On 25 January CVGHM lowered the Alert Level for Lewotolo from 3 to 2 (on a scale of 1-4) based on decreased seismicity and visual observations during 5-15 January. During 5-15 January fumarolic plumes rose 200-500 m above the summit and incandescence was observed.
Geologic Summary. Anchoring the eastern end of an elongated peninsula that is connected to Lomblen Island by a narrow isthmus and extends northward into the Flores Sea, Lewotolo rises to 1,423 m. Lewotolo is a symmetrical stratovolcano as viewed from the N and E. A small cone with a 130-m-wide crater constructed at the SE side of a larger crater forms the volcano's high point. Many lava flows have reached the coastline. Historical eruptions, recorded since 1660, have consisted of explosive activity from the summit crater.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
NYAMURAGIRA Democratic Republic of Congo 1.408°S, 29.20°E; summit elev. 3058 m
The VolcanoDiscovery Team observed the fissure eruption at Nyamuragira that began on 6 November 2011 during 22-25 January 2012 from the newly formed cinder cones located about 10 km E of the summit crater. They reported three coalescent cones with the largest cone containing a small lava lake. The lake ejected spatter every few seconds as high as 200 m above the summit; individual bombs reached the base of the cone. Lava flows from the vent extended several kilometers N. Numerous small breakouts formed secondary flows, and a large breakout about 2 km N of the cone fed a large lava flow about 20 m wide. Burning forests were reported to the NNE.
Geologic Summary. Africa's most active volcano, Nyamuragira (Also spelled Nyamulagira) is a massive basaltic shield volcano N of Lake Kivu and NW of Nyiragongo volcano. Lava flows from Nyamuragira cover 1,500 sq km of the East African Rift. The 3058-m-high summit is truncated by a small 2 x 2.3 km summit caldera that has walls up to about 100 m high. About 40 historical eruptions have occurred since the mid-19th century within the summit caldera and from numerous fissures and cinder cones on the volcano's flanks. A lava lake in the summit crater, active since at least 1921, drained in 1938. Twentieth-century flank lava flows extend more than 30 km from the summit, reaching as far as Lake Kivu.
Source: VolcanoDiscovery http://www.volcanodiscovery.com/view_news/4622/Nyamuragira-volcano-DR-Congo-update-eruption-continues-with-active-lava-lake-and-lava-flow-from-new-.html
PALUWEH Lesser Sunda Islands (Indonesia) 8.32°S, 121.708°E; summit elev. 875 m
Seismic activity from Paluweh (also known as Rokatenda) increased during 12-18 January, prompting CVGHM to raise the Alert Level from 1 to 2 (on a scale of 1-4) on 19 January. Fog prevented visual observations of the volcano.
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: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
Ongoing Activity
DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 30-31 January ash plumes from Dukono rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted 220 km SW.
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
ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m
Sezione di Catania - Osservatorio Etneo reported that an explosion at the New Southeast Crater (New SEC) of Etna generated an ash plume at that rose 400 m above the crater at 1906 on 27 January. An explosive ash emission at 1124 from the vent on the W portion of the crater floor was followed by others that were less intense. At 2140 an explosion ejected incandescent material in a narrow vertical jet that rose a few tens of meters above the crater. A small Strombolian explosion occurred at 2231. On 28 January sporadic ash emissions continued from New SEC.
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/index.php
HIERRO Canary Islands (Spain) 27.73°N, 18.03°W; summit elev. 1500 m
Instituto Geográfico Nacional (IGN) reported that during 25-31 January the submarine eruption continued S of El Hierro Island. Mean tremor amplitude maintained very low values during this report period. Frequent and persistent emissions of large steaming lava fragments were observed on the sea surface, some of them about 3 m wide.
Seventy-eight seismic events were registered during this period, most of them located in the central part of the island, with offshore events extending primary to the S. Depths of the hypocenters varied between 10 and 23 km, and magnitudes between 0.4 and 2.8. Analyses of GPS deformation showed stability both in vertical and horizontal components.
Geologic Summary. The triangular island of Hierro is the SW-most and least studied of the Canary Islands. The massive Hierro shield volcano is truncated by a large NW-facing escarpment formed as a result of gravitational collapse of El Golfo volcano about 130,000 years ago. The steep-sided 1500-m-high scarp towers above a low lava platform bordering 12-km-wide El Golfo Bay, and three other large submarine landslide deposits occur to the SW and SE. Three prominent rifts oriented NW, NE, and south at 120 degree angles form prominent topographic ridges. The subaerial portion of the volcano consists of flat-lying Quaternary basaltic and trachybasaltic lava flows and tuffs capped by numerous young cinder cones and lava flows. Holocene cones and flows are found both on the outer flanks and in the El Golfo depression. Hierro contains the greatest concentration of young vents in the Canary Islands. Uncertainty surrounds the report of an historical eruption in 1793.
Source: Instituto Geográfico Nacional (IGN) http://www.02.ign.es/ign/resources/volcanologia/html/informesHIERRO.html
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that seismic activity continued at a moderate level at Karymsky during 19-27 January and indicated that ash plumes possibly rose to an altitude of 3 km (9,840 ft) a.s.l. during 19-21 and on 25 January. Satellite imagery showed a thermal anomaly at the volcano during 21-24 January and gas-and-steam plumes containing ash that were drifting as far as 70 km NW on 23 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/updates.php
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 25-31 January, HVO reported that the lava lake circulated and periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash and fresh spatter nearby. During 25-27 January lava ejections on the SE edge built a small spatter rampart and produced small lava flows on the inner ledge.
Incandescence was visible on the NE, SE, and W edges of the Pu'u 'O'o crater floor during 25-31 January. On 25 January lava started to fill a Pu'u 'O'o crater floor depression and continued episodically all week. Geologists on a 26 January overflight reported lava flows 4 km SE of Pu'u 'O'o. On 27 January the SE and NE vents started to effuse lava. During 24-31 January, thermal anomalies were seen in satellite imagery 3-4 km SE of Pu'u 'O'o cone.
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 moderate seismic activity at Kizimen during 20-27 January and a large thermal anomaly that was detected daily in satellite images. Video and satellite observations indicated both continued effusion of a large lava flow on the E flank and accompanying hot avalanches. Video data showed strong gas-and-steam activity 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/updates.php
PAGAN Mariana Islands 18.13°N, 145.80°E; summit elev. 570 m
Low-level gas-and-steam plumes from Pagan were observed in satellite imagery during 20-27 January. Based on information from the Honolulu MWO, satellite imagery, and a pilot observation, the Washington VAAC reported gas emissions and a possible light-brown ash plume drifting E on 30 January. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.
Geologic Summary. Pagan Island, the largest and one of the most active of the Mariana Islands volcanoes, consists of two stratovolcanoes connected by a narrow isthmus. Both North and South Pagan stratovolcanoes were constructed within calderas, 7 and 4 km in diameter, respectively. The 570-m-high Mount Pagan at the NE end of the island rises above the flat floor of the caldera, which probably formed during the early Holocene. South Pagan is a 548-m-high stratovolcano with an elongated summit containing four distinct craters. Almost all of the historical eruptions of Pagan, which date back to the 17th century, have originated from North Pagan volcano. The largest eruption of Pagan during historical time took place in 1981 and prompted the evacuation of the sparsely populated island.
Sources: Emergency Management Office of the Commonwealth of the Mariana Islands, Office of the Governor, United States Geological Survey Volcano Hazards Program http://volcanoes.usgs.gov/nmi/activity/index.php, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED reported that during 25-31 January steam-and-gas emissions rose from Popocatépetl; some of the emissions contained moderate amounts of ash on 25 and 29 January. On 25 January an ash plume rose 3 km above the crater and drifted NE. Crater incandescence was observed at night on 29 and 31 January.
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/cgi-bin/popo/reportes/consulta.cgi
PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m
Based on seismicity detected during 25-31 January OVDAS-SERNAGEOMIN reported that the eruption from the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex, continued at a low level. During 25-28 January plumes observed with a web camera rose 2-4 km above the crater and satellite images showed ash plumes drifting 90-320 km S and SE. During 29-31 January clouds prevented views. 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
Based on information from JMA, the Tokyo VAAC reported that during 25-27 and 29-30 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted E and SE. On 29 January a pilot observed an ash plume that rose to an altitude of 2.1 km (7,000 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
SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m
INSIVUMEH reported that active lava flows on the S and SE flanks of Santa María's Santiaguito lava-dome complex generated block avalanches on 27 and 30 January. Moderate explosions generated ash plumes that rose 700 m above the complex and drifted SW and S. Strong winds caused re-suspended ash to rise 1 km high and drift several kilometers W and S. Ashfall was reported in Monte Claro (S) and Palajunoj (SW) on 27 January.
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/geofisica/vulcanologia/boletin%20formato.htm
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that mostly low levels of seismic activity were detected at Shiveluch during 20-27 January, though seismicity was higher during 22-23 January. Satellite imagery showed a daily thermal anomaly over the lava dome. Ground-based observers noted that a viscous lava flow continued to effuse in the crater that was formed during a 2010 eruption. Moderate fumarolic activity at the lava dome and occasional hot avalanches were observed during 25-26 January; clouds prevented observations on the other days of the week. Ash plumes rose to altitudes of 5-6 km (16,400-19,700 ft) a.s.l. and drifted 174 km NE on 23 January. 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/updates.php
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 20-27 January activity at the Soufrière Hills lava dome was at a low level. Small areas of incandescence emanated from the lava dome at night, similar to observations noted in recent months. On 27 January a small lahar descended from the W side of the lava dome. The Hazard Level remained at 2.
Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.
Source: Montserrat Volcano Observatory http://www.mvo.ms/
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