VOLCANO MADNESS: [ Volcano ] Smithsonian/USGS Weekly Volcanic Activity Report 12-18 February 2014

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Smithsonian/USGS Weekly Volcanic Activity Report 12-18 February 2014
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Smithsonian/USGS Weekly Volcanic Activity Report

12-18 February 2014

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

ASOSAN Kyushu 32.881°N, 131.106°E; summit elev. 1592 m

JMA reported that a very small explosion from Asosan's Nakadake Crater occurred on 16 February. An off-white plume rose 300 m above the crater rim and drifted S. The Alert Level remained at 2 (on a scale of 1-5).

Geologic Summary. The 24-km-wide Asosan caldera was formed during four major explosive eruptions from 300,000 to 90,000 years ago. These produced voluminous pyroclastic flows that covered much of Kyushu. The last of these, the Aso-4 eruption, produced more than 600 cu km of airfall tephra and pyroclastic-flow deposits. A group of 17 central cones was constructed in the middle of the caldera, one of which, Nakadake, is one of Japan's most active volcanoes. It was the location of Japan's first documented historical eruption in 553 AD. The Nakadake complex has remained active throughout the Holocene. Several other cones have been active during the Holocene, including the Kometsuka scoria cone as recently as about 210 CE. Historical eruptions have largely consisted of basaltic to basaltic-andesite ash emission with periodic strombolian and phreatomagmatic activity. The summit crater of Nakadake is accessible by toll road and cable car, and is one of Kyushu's most popular tourist destinations.

Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/

KELUT Eastern Java (Indonesia) 7.93°S, 112.308°E; summit elev. 1731 m

PVMBG reported that at 2115 on 13 February the Alert Level for Kelut was raised to 4 (on a scale of 1-4). Visitors and residents were prohibited from approaching the crater within a 10-km radius. BNPB reported that a major eruption occurred less than two hours later at 2250, followed by another large explosion at 2330. Ash plumes rose to an altitude of 17 km (55,800 ft) a.s.l. and caused ashfall in areas NE, NW, and W, as far as Pacitan (133 km WSW), Kulon Progo (236 km W), Temanggung (240 km WNW), and Banyuwangi (228 km E). Forty flights from the Juanda (81 km NE), Adi Sucipto Yogya (208 km W), and Adi Sumarmo Solo (175 km WNW) airports were cancelled. News articles reported that flights in and out of seven airports were cancelled or rerouted. Ashfall and tephra 5-8 cm in diameter caused structures to collapse, including schools, homes, and businesses.

On 14 February BNPB reported that the eruption had killed four people: one died due to a collapsing wall, one from ash inhalation, and two from "shortness of breath". All four victims lived within 7 km of Kelut in the regency of Malang, an area that received ashfall up to 20 cm thick. By 0600 the number of displaced people reached 100,248, but the report also noted that activity had declined. A report issued later that day noted that 76,388 people remained evacuated. Seismicity continued to decline and was at moderate levels during 15-17 February. An 18 February report noted that a total of seven people in Malang had died, and that the ashfall had affected cattle health and dairy production, farms, and the water supply. Damage to infrastructure in Malang included 3,782 houses, 20 government buildings, 251 schools, nine hospitals, and 36 churches.

Geologic Summary. The relatively inconspicuous 1,731-m-high Kelut stratovolcano contains a summit crater lake that has been the source of some of Indonesia's most deadly eruptions. A cluster of summit lava domes cut by numerous craters has given the summit a very irregular profile. More than 30 eruptions have been recorded from Gunung Kelut since 1000 AD. The ejection of water from the crater lake during Kelut's typically short, but violent eruptions has created pyroclastic flows and lahars that have caused widespread fatalities and destruction. After more than 5,000 people were killed during the 1919 eruption, an ambitious engineering project sought to drain the crater lake. This initial effort lowered the lake by more than 50 m, but the 1951 eruption deepened the crater by 70 m, leaving 50 million cubic meters of water after repair of the damaged drainage tunnels. After more than 200 people were killed in the 1966 eruption, a new deeper tunnel was constructed, lowering the lake's volume to only about 1 million cubic meters prior to the 1990 eruption.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) also known CVGHM http://www.vsi.esdm.go.id/,

Badan Nacional Penanggulangan Bencana (BNPB) http://www.bnpb.go.id/,

Jakarta Globe http://www.thejakartaglobe.com/news/death-toll-rises-as-tens-of-thousands-flee-mount-kelud -eruption/

SHISHALDIN Fox Islands 54.756°N, 163.97°W; summit elev. 2857 m

AVO reported that no activity from Shishaldin was observed in party-to-mostly-cloudy satellite images during 12-18 February. The nearest working seismic station detected low seismicity. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Geologic Summary. The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2,857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. Constructed atop an older glacially dissected volcano, Shishaldin is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the W and NE sides at 1,500-1,800 m elevation. Shishaldin contains over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of Strombolian ash eruptions from the small summit crater, sometimes producing lava flows, have been recorded since the 18th century.

Source: US Geological Survey Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/

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

IG reported that on 11 February explosions from Tungurahua generated ash plumes that rose 3 km above the crater and drifted WNW. Roaring noises and sounds resembling blocks rolling down the flanks were noted. A small pyroclastic flow traveled down the flanks at 1720, and ashfall was reported in El Manzano (8 km SW). Incandescence on the N flank was observed at night during 12-13 February. Ash plumes again rose 3 km on 13 February causing ashfall in Choglontus (SW) and Capil. During 13-14 February Strombolian activity ejected blocks that rolled 500 m down the N flank. Ash plumes rose 3 km and drifted W, and minor amounts of ash fell in Tisaleo (29 km NW). Cloud cover prevented views on 15 February; ashfall was reported in Penipe (15 km SW). During periods of clear weather on 16 February observers noted that ash plumes rose 3 km. Ash fell in Runtún (6 km NNE), Penipe, and El Manzano. At night during 16-17 February incandescence from the crater was observed along with blocks that rolled 500 m down the flanks. Gas-and-ash plumes rose 5 km and drifted N, NW, W and SW, and ashfall was reported in Penipe, Chacauco (NW), and Pillate (8 km W). An ash plume rose 4 km on 18 February and drifted W. Minor amounts of ash fell in Choglontus.

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/

UBINAS Perú 16.355°S, 70.903°W; summit elev. 5672 m

IGP reported that a phreatic explosion from Ubinas occurred at 1445 on 14 February and generated a water vapor, gas, and ash plume that rose 1 km above the crater. Seismic activity had been increasing before the explosion, since 8 February.

Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives it a truncated appearance. Ubinas is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank of Ubinas extend 10 km from the volcano. Widespread Plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions.

Source: Instituto Geofísico del Perú (IGP) http://www.igp.gob.pe/

Ongoing Activity

AIRA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m

The Tokyo VAAC reported that explosions during 12-18 February from Aira Caldera's Sakurajima volcano generated ash plumes on most days that rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. and drifted E, NE, and N. On 12 February a pilot observed an ash plume drifting E at an altitude of 3 km (10,000 ft) a.s.l. JMA reported that during 14-17 February two explosions from Showa Crater ejected tephra as far as 800 m. The Alert Level remained at 3 (on a scale of 1-5).

Geologic Summary. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. 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

BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 12 February an ash plume from Bagana rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 110 km E.

Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50-m-thick with prominent levees that descend the volcano's flanks on all sides.

Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html

CHIRINKOTAN Kuril Islands 48.980°N, 153.480°E; summit elev. 724 m

SVERT reported that a thermal anomaly over Chirinkotan was observed in satellite images on 12 and 15 February, and steam-and-gas emissions were observed on 16 February. Cloud cover obscured views on other days during 11-17 February. The Aviation Color Code remained at Yellow.

Geologic Summary. The small, mostly unvegetated 3-km-wide island of Chirinkotan occupies the far end of an E-W-trending volcanic chain that extends nearly 50 km west of the central part of the main Kuril Islands arc. Chirinkotan is the emergent summit of a volcano that rises 3000 m from the floor of the Kuril Basin. A small 1-km-wide caldera about 300-400 m deep is open to the SE. Lava flows from a cone within the breached crater reached the north shore of the island. Historical eruptions have been recorded at Chirinkotan since the 18th century. Fresh lava flows also descended the SE flank of Chirinkotan during an eruption in the 1880s that was observed by the English fur trader Captain Snow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT) http://www.imgg.ru/?id_d=659

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

SVERT reported that a thermal anomaly over Snow, a volcano of Chirpoi, was detected in satellite images during 11-12 February. Cloud cover obscured views during 13-17 February. The Aviation Color Code remained at Yellow.

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

DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 17 February an ash plume from Dukono rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 55 km SSW.

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) ftp://ftp.bom.gov.au/anon/gen/vaac/

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

INGV reported that Strombolian activity continued at Etna's New Southeast Crater (NSEC) and slightly intensified on 12 February. An unstable part of the lower E flank of the cone that collapsed on 11 February continued to produce small collapses and reddish ash clouds. Lava continued to flow from the cone towards the Valle del Bove, and by nightfall had reached the base of the steep W wall of the valley, then advanced on the flat land to the N of Mount Centenarians. Strombolian activity continued during 14-15 February. Lava emissions declined, but produced lava flows a few hundred meters long. At 1208 on 15 February an explosion generated a vapor-and-ash plume, and was then followed by more explosions from the same area. During the afternoon a small lava flow emerged from a new vent at the N base of the NSEC cone. The flow traveled 100 m towards the W wall of the Valle del Bove, and remained active the next day. During 16-17 February Strombolian activity continued to produce small quantities of ash. Lava continued to flow from the vent at the base of the cone.

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 (INGV) http://www.ct.ingv.it/

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

INSIVUMEH reported that during 13-14 February explosions at Fuego produced ash plumes that rose 500-1,000 m above the crater and drifted 8-10 km N and NE. Incandescent material was ejected 200 m high, and avalanches descended the Ceniza (SSW), Trinidad, Las Lajas (SE), and Honda drainages. On 16 February explosions produced ash plumes that rose 500-700 m above the crater and drifted 10 km SW, S, and SE. Shock waves were detected 20-25 km away in Escuintla (20 km SSE), Santa Lucia Cotzulmaguapa (20 km SW), Yepocapa (8 km WNW), Alotengando (8 km W), and Antigua Guatemala (18 km NE). Explosions continued during 16-17 February; ash plumes rose 300-1,100 m above the crater and drifted 15-17 km. Incandescent material was ejected 100-200 m high, and avalanches descended the Taniluyá (SW), Ceniza, Trinidad, and Santa Teresa (S) drainages, reaching vegetated areas.

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 Vulcanian and Strombolian activity at Karymsky continued during 7-14 February. Satellite images detected a thermal anomaly on the volcano on 12 February; cloud cover obscured views of the volcano on the other days. 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 12-18 February 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 spatter cones on the N and S portions of the crater floor, and a lava pond was active in the NE spatter cone. The 7.8-km-long Kahauale'a 2 lava flow, fed by the NE spatter cone, was active with scattered break-out flows behind the flow front that burned the forest.

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/

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

In a special bulletin on 11 February, INSIVUMEH noted that activity at Santa María's Santiaguito lava-dome complex had increased in recent days. Explosions from Caliente dome were accompanied by block avalanches and pyroclastic flows that traveled NE. Ash plumes rose 3.5 km and drifted over 15 km S and SW. Some explosions were audible in areas as far as15 km S. During 13-14 February explosions generated ash plumes that rose no more than 200 m above the crater. During 16-17 February the E part of the lava dome was incandescent and lava flows descended the E and W flanks. Gas plumes from Caliente dome rose 300 m.

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

KVERT reported that during 7-14 February lava-dome extrusion at Shiveluch was accompanied by ash explosions, incandescence, and fumarolic activity. A thermal anomaly was detected in satellite images on 9 and 12 February; cloud cover prevented views on the other days. Pyroclastic flow deposits on the SW flank from the 6 February were observed to be 12 km long. On 17 February at 1108 video data showed an ash plume rising to an altitude of 4 km (13,100 ft) a.s.l. 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

SINABUNG Sumatra (Indonesia) 3.17°N, 98.392°E; summit elev. 2460 m

Based on webcam images, Indonesian Met office notices, wind data, and ground reports, the Darwin VAAC reported that during 12-13 and 15-18 February ash plumes from Sinabung rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 25-95 km N, NE, and E. On 16 February BNPB reported that villagers outside of the 5-km evacuation zone around Sinabung continued to return to their homes.

Geologic Summary. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical, 2460-m-high andesitic-to-dacitic volcano is at the southern end of the four overlapping summit craters. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks of Sinabung in 1912, although no confirmed historical eruptions were recorded prior to 2010.

Sources: Badan Nacional Penanggulangan Bencana (BNPB) http://www.bnpb.go.id/,

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

SUWANOSEJIMA Kyushu 29.635°N, 129.716°E; summit elev. 799 m

The Tokyo VAAC reported explosions from Suwanosejima during 12-14 February. On 12 February a plume rose to an altitude of 1.2 km (4,000 ft) a.s.l. and drifted SE, and on 14 February a plume rose to an altitude of 1.8 km (6,000 ft) a.s.l.

Geologic Summary. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. 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. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 persons live on the island.

Source: 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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