Sunday, February 26, 2012

[ Volcano ] Smithsonian/USGS Weekly Volcanic Activity Report 1-7 February 2012

Smithsonian/USGS Weekly Volcanic Activity Report 1-7 February 2012
From: "Faulk, Elisabeth" <>

Smithsonian/USGS Weekly Volcanic Activity Report

1-7 February 2012

Elisabeth Faulk - Weekly Report Editor


New Activity/Unrest: | Cameroon, Cameroon | Cleveland, Chuginadak Island | Karkar, Northeast of New Guinea (SW Pacific) | Papandayan, Western Java (Indonesia) | Semeru, Eastern Java (Indonesia) | Tungurahua, Ecuador

Ongoing Activity: | Dukono, Halmahera | Etna, Sicily (Italy) | Fuego, Guatemala | Hierro, Canary Islands (Spain) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Popocatépetl, México | Puyehue-Cordón Caulle, Central Chile | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Suwanose-jima, Ryukyu Islands (Japan)

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

CAMEROON Cameroon 4.203°N, 9.170°E; summit elev. 4095 m

A news article stated that explosions from Mount Cameroon were observed by tourists who were in the area on 3 February. The tourists reported hearing strong explosions followed by observations of "flames" and ash.

Geologic Summary. Mount Cameroon, one of Africa's largest volcanoes, rises to 4095 m above the coast of west Cameroon. The massive steep-sided volcano of dominantly basaltic-to-trachybasaltic composition forms a volcanic horst constructed above a basement of Precambrian metamorphic rocks covered with Cretaceous to Quaternary sediments. More than 100 small cinder cones, often fissure-controlled parallel to the long axis of the massive 1400 cu km volcano, occur on the flanks and surrounding lowlands. A large satellitic peak, Etinde (also known as Little Cameroon), is located on the southern flank near the coast. Historical activity, the most frequent of west African volcanoes, was first observed in the 5th century BC by the Carthaginian navigator Hannon. During historical time, moderate explosive and effusive eruptions have occurred from both summit and flank vents. A 1922 SW-flank eruption produced a lava flow that reached the Atlantic coast, and a lava flow from a 1999 south-
 flank eruption stopped only 200 m from the sea.

Source: The Associated Press rief-volcanic-explosion-cameroon-radio-says/2012/02/06/gIQAZNRBuQ_story.html

CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m

AVO reported that during 2-7 February cloud cover over Cleveland prevented views of the lava dome in the summit crater. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange. No current seismic information was available because Cleveland does not have a real-time seismic network.

Geologic Summary. Symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.

Source: Alaska Volcano Observatory (AVO)

KARKAR Northeast of New Guinea (SW Pacific) 4.649°S, 145.964°E; summit elev. 1839 m

Based on analyses of satellite imagery, the Darwin VAAC reported that a possible ash plume from Karkar rose to altitudes of 7.6-10.7 km (25,000-35,000 ft) a.s.l. and drifted NE and E on 1 February.

Geologic Summary. Karkar is a 19 x 25 km wide, forest-covered island that is truncated by two nested summit calderas. The 5.5-km-wide outer caldera was formed during one or more eruptions, the last of which occurred 9000 years ago. The eccentric 3.2-km-wide inner caldera was formed sometime between 1500 and 800 years ago. Parasitic cones are present on the northern and southern flanks of basaltic-to-andesitic Karkar volcano; a linear array of small cones extends from the northern rim of the outer caldera nearly to the coast. Most historical eruptions, which date back to 1643, have originated from Bagiai cone, a pyroclastic cone constructed within the steep-walled, 300-m-deep inner caldera. The floor of the caldera is covered by young, mostly unvegetated andesitic lava flows.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

PAPANDAYAN Western Java (Indonesia) 7.32°S, 107.73°E; summit elev. 2665 m

CVGHM lowered the Alert Level for Papandayan from 3 to 2 (on a scale of 1-4) on 31 January. No eruption details or reasons for the change were given in the report.

Geologic Summary. Papandayan is a complex stratovolcano with four large summit craters, the youngest of which was breached to the NE by collapse during a brief eruption in 1772 and contains active fumarole fields. The broad 1.1-km-wide, flat-floored Alun-Alun crater truncates the summit of Papandayan, and Gunung Puntang to the N gives the volcano a twin-peaked appearance. Several episodes of collapse have given the volcano an irregular profile and produced debris avalanches that have impacted lowland areas beyond the volcano. Since its first historical eruption in 1772, in which a catastrophic debris avalanche destroyed 40 villages, only two small phreatic eruptions have occurred from vents in the NE-flank fumarole field, Kawah Mas.

Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM)

SEMERU Eastern Java (Indonesia) 8.108°S, 112.92°E; summit elev. 3676 m

On 3 February, CVGHM reported that from 29 December 2011 to 2 February 2012 seismicity increased at Semeru, and dense white and gray plumes rose as high as 600 m above the Jonggring Seloko crater. During the month of January crater incandescence was observed and avalanches carried incandescent material 200-400 m away from the crater. On 2 February a large explosion was reported and incandescent material was ejected 2.5 km from the crater. Based on the seismic activity and visual observations, CVGHM raised the Alert Level from 2 to 3 (on a scale of 1-4) on 2 February.

Geologic Summary. Semeru is the highest volcano on Java and one of its most active. The symmetrical stratovolcano rises abruptly to 3,676 m above coastal plains to the S and lies at the southern end of a volcanic massif extending N to the Tengger caldera. Semeru has been in almost continuous eruption since 1967. Frequent small-to-moderate Vulcanian eruptions have accompanied intermittent lava dome extrusion, and periodic pyroclastic flows and lahars have damaged villages below the volcano. A major secondary lahar on 14 May 1981 caused more than 250 deaths and damaged 16 villages.

Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM)

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

IG reported a new episode of activity from Tungurahua on 4 February with an explosion that produced roaring heard 14 km NW in Palitahua and Guadalupe. On 4 February an ash plume rose to altitudes of 7-8 km above the crater and drifted NE; lapilli fall was reported in Baños (9 km N), Pillate (7 km W), and Juive (7 km NNW). IG staff aboard a commercial flight on 4 February observed an ash plume that rose to an altitude of 1 km above the crater and drifted W. Ashfall and roaring noises were reported in Baños, Pillate, Juive, Pondoa (8 km N), Pelileo ( about 7 km NW), Guadalupe, Cevallos (23 km NW), and Patate (NW). A pyroclastic flow descended into the Achupashal drainage (NW). At night incandescent blocks ejected by an explosion traveled 1 km down the flanks. On 5 February clouds prevented views of the volcano, though loud "cannon shots" were heard in Baños and Juive, and ashfall was reported in Manzano (8 km SW). Clouds prevented views of the volcano during 6-7 February.

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)

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 1-4 February ash plumes from Dukono rose to an altitude of 2.7 km (9,000 ft) a.s.l. The plumes drifted 220 km SW on 1 February and 45 km SW and S during 2-4 February.

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)

ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m

Sezione di Catania - Osservatorio Etneo reported on 6 February that mild Strombolian activity and small ash emissions continued from Etna's New Southeast Crater (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

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

INSIVUMEH reported that during 1-3 and on 6 February explosions from Fuego generated ash plumes that rose 400-900 m above the crater; the plumes drifted about 12 km S and SW on 1 February and to the SSW during 2-3 February. On 1 February rumbling noises were heard, incandescence material rose as high as 100 m above the crater, and block avalanches descended the S flank. A new 200-m-long lava flow descended the SW flank into the Taniluya drainage and block avalanches reached vegetation during 2-3 February. On 6 February the lava flow descended towards the Ceniza drainage and block avalanches again reached vegetation. Strong winds caused re-suspended ash to rise 1 km high and drift several kilometers W and S during 1-3 February.

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)

HIERRO Canary Islands (Spain) 27.73°N, 18.03°W; summit elev. 1500 m

Instituto Geográfico Nacional (IGN) reported that during 1-7 February the submarine eruption continued S of El Hierro Island. The amplitude of the tremor signal started to increase on 1 February around 0700, maintaining significant values until 6 February, when it dropped again to almost no signal. On 7 February the amplitude values increased for a few hours. Scarce emissions of lava fragments were observed over the vent area.

Fifty seismic events were registered during this period, most of them located in the central part of the island, with offshore events extending mainly to the S. Three of them were felt by residents, with a maximum intensity value of III (EMS-98). Depths of the hypocenters varied between 6 and 23 km, and magnitudes between 0.6 and 3.2.

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)

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 27 January-3 February and indicated that ash plumes possibly rose to an altitude of 2.6 km (8,530 ft) a.s.l. during 28 and 30-31 January. Satellite imagery showed a thermal anomaly at the volcano all week and gas-and-steam plumes containing ash that were drifting as far as 80 km E during 30-31 January and on 1 February. 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)

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

During 1-7 February, HVO reported that the lava lake circulated and periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater, remaining below the inner ledge (75 m below the crater floor). On 1 February lava ejections on the S edge rebuilt a low spatter cone. On 3 February two large rockfalls into the lake originated from the Halema'uma'u Crater floor. The first collapse from the N rim induced secondary collapses of the inner ledge and ejected spatter onto nearby portions of the Halema'uma'u Crater floor. The second collapse deposited large amounts of debris into the NE side of the lava lake.

At Pu'u 'O'o short lava flows issued from the SE vent during 1-2 February. Incandescence was visible on the NE and SE edges of the Pu'u 'O'o crater floor during 3-7 February and from a small cone on the NE edge during 5-7 February. The web camera showed incandescence reflected in the clouds above the pali on 2 and 4 February. During 1-7 February, thermal anomalies were seen in satellite imagery 4-5 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)

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

KVERT reported moderate seismic activity at Kizimen during 27 January-3 February 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, ha
 s been recorded in historical time.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

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

CENAPRED reported that during 1-7 February steam-and-gas emissions rose from Popocatépetl; some of the emissions contained small amounts of ash during 1-4 February. Gas-and-steam plumes rose 200-800 m above the crater during 1-5 February. Crater incandescence was observed at night on 1 and 5 February. Clouds prevented views on 7 February.

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)

PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m

Based on seismicity detected during 1-7 February 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 1-7 February plumes observed with a web camera rose 1-4 km above the crater and satellite images showed ash plumes drifting 90-180 km NE, ENE, E, and SE. On 2 February a plume drifted 32 km NE and then dispersed 100 km N. 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 volc
 ano-tectonic depression, is the largest active geothermal area of the southern Andes volcanic zone.

Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)

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

Based on information from JMA, the Tokyo VAAC reported that during 1-7 February explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3.7 km (4,000-12,000 ft) a.s.l. and drifted E and SE. On 5 and 6 February pilots observed ash plumes that rose to an altitude of 2.1 km (7,000 ft) a.s.l. and 3.7 km (12,000 ft) a.s.l. respectively.

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)

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 during 1-3 February. Explosions sent ash plumes 500-600 m above the complex that drifted S, SW, and WSW. Ashfall was reported in Monte Claro (S) and Palajunoj (SW) on 1 February, and in La Florida (5 km S), San Marcos (46 km NW), and Palajunoj during 2-3 February. Strong winds caused re-suspended ash to rise 1 km high and drift several kilometers W and S. Rumbling noises were heard 15 km away on the S and W flanks during 1-3 February. Gas plumes rose 500 m above the Caliente Cone and drifted S and SW during 2-3 February.

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)

SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m

KVERT reported that low levels of seismic activity were detected at Shiveluch during 26 January-3 February. 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 all week. Weak ash explosions from the lava dome were reported from the SE flank on 26 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)

SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m

MVO reported that during 27 January-3 February activity at the Soufrière Hills lava dome was at a low level. On 28 January a pyroclastic flow from the W side of the lava dome traveled 300 m. 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 ca
 pital city of Plymouth, causing major social and economic disruption.

Source: Montserrat Volcano Observatory (MVO)

SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m

Based on information from JMA, the Tokyo VAAC reported an explosion from Suwanose-jima on 6 February. Details of a possible resulting plume were not reported.

Geologic Summary. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent Strombolian activity from On-take, the NE summit crater, that began in 1949 and lasted nearly a half century. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, after which the island was uninhabited for about 70 years. The SW crater produced lava flows that reached the western coast in 1813, and lava flows reached the eastern coast of the island in 1884.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


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