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Smithsonian/USGS Weekly Volcanic Activity Report 29 January-4 February 2014
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Smithsonian/USGS Weekly Volcanic Activity Report
29 January-4 February 2014
Sally Kuhn Sennert - Weekly Report Editor kuhns@si.edu
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Asosan, Kyushu | Kavachi, Solomon Islands | Kelut, Eastern Java (Indonesia) | Shishaldin, Fox Islands | Sinabung, Sumatra (Indonesia) | Tungurahua, Ecuador | Ubinas, Perú
Ongoing Activity: | Dukono, Halmahera | Etna, Sicily (Italy| Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Nyamuragira, Democratic Republic of Congo | Nyiragongo, Democratic Republic of Congo | Sakurajima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Suwanosejima, Ryukyu Islands and Kyushu
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
Based on pilot observations, the Tokyo VAAC reported that on 29 January an ash plume from Asosan rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted NW. Later that day a plume rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted N. JMA reported that a very small explosion from Naka-daka Crater occurred on 31 January. An off-white plume rose 100 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 Aso caldera was formed during four major explosive eruptions from 300,000 to 80,000 years ago. These produced voluminous pyroclastic flows that covered much of Kyushu. A group of 17 central cones was constructed in the middle of the caldera, one of which, Naka-dake, is one of Japan's most active volcanoes. It was the location of Japan's first documented historical eruption in 553 AD. The Naka-dake 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 AD. Historical eruptions have largely consisted of basaltic to basaltic-andesite ash emission with periodic Strombolian and phreatomagmatic activity. The summit crater of Naka-dake is accessible by toll road and cable car, and is one of Kyushu's most popular tourist destinations.
Sources: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/,
Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.jp/svd/vaac/data/vaac_list.html
KAVACHI Solomon Islands 9.02°S, 157.95°E; summit elev. -20 m (submarine)
According to NASA's Earth Observatory, a satellite image acquired on 29 January showed a plume of discolored water E of Kavachi, likely from lava fragments and dissolved gases. A bright area above the submerged peak suggested churning water. There was no sign that the volcano had breached the sea surface.
Geologic Summary. Kavachi, one of the most active submarine volcanoes in the SW Pacific, occupies an isolated position in the Solomon Islands far from major aircraft and shipping lanes. Kavachi, sometimes referred to as Rejo te Kvachi ("Kavachi's oven"), is located S of Vangunu Island only 30 km N of the site of subduction of the Indo-Australian plate beneath the Pacific plate. The shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 150 m long at least eight times since its first recorded eruption during 1939. The roughly conical volcano rises from water depths of 1.1-1.2 km on the N and greater depths to the S.
Source: NASA Earth Observatory http://earthobservatory.nasa.gov/
KELUT Eastern Java (Indonesia) 7.93°S, 112.308°E; summit elev. 1731 m
PVMBG reported that during 1 January-2 February the number of shallow volcanic earthquakes at Kelut increased, with peaks of seismicity occurring during 15-16 January, 28 January, and 2 February. The number of volcanic earthquakes also fluctuated but increased overall. Earthquakes occurred 2-8 km below Kelut. The temperature in the crater lake increased 5.5 degrees Celsius since 10 September 2013. On 2 February the Alert Level was raised to 2 (on a scale of 1-4).
Geologic Summary. The relatively inconcspicuous 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.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) also known CVGHM http://www.vsi.esdm.go.id/
SHISHALDIN Fox Islands 54.756°N, 163.97°W; summit elev. 2857 m
On 30 January, AVO raised the Aviation Color Code for Shishaldin to Yellow and the Volcano Alert Level to Advisory based on increased surface temperatures detected at the summit crater by satellite images over the previous few days, as well as increased steam emissions observed on 29 January in satellite and web-camera images. No steam emissions were observed during 30-31 January. Elevated surface temperatures were again detected on 1 February.
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/
SINABUNG Sumatra (Indonesia) 3.17°N, 98.392°E; summit elev. 2460 m
PVMBG described activity at Sinabung during 24-31 January based on observations from a post in the Ndokum Siroga village, 8.5 km away. On 24 January dense white plumes rose as high as 1 km. During 25-26 and 28-31 January dense grayish-white plumes rose 0.1-1.5 km; on 27 January plumes rose 4 km. Each day pyroclastic flows traveled 0.5-4.5 km SE and S. Incandescent material was observed 0.2-1.5 km SE of the vent. Seismicity remained high, with constant tremor, hybrid earthquakes indicating a growing lava dome, and volcanic earthquakes. The number of low-frequency earthquakes continued to decrease. The Alert Level remained at 4 (on a scale of 1-4). Visitors and tourists were prohibited from approaching the crater within a radius of 5 km.
Badan Nacional Penanggulangan Bencana (BNPB) reported on 31 January that since activity at Sinabung had not increased residents from 16 villages outside of the 5-km radius were allowed to return to their homes. At 1030 on 1 February a large dome collapse generated pyroclastic flows that traveled 4.5 km S, killing 15 and injuring two people that had entered the 5-km exclusion zone without permission. On 4 February the number of displaced people reached 31,739 (9,915 families) in 42 evacuation centers, many from outside of the exclusion zone.
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: 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/
TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m
IG reported that during the morning of 30 January the seismic network recorded an increase in the number of events at Tungurahua including some low-magnitude explosions, long-period events, and seismic tremor. Ashfall was reported in Pungal (40 km SSW), Penipe (15 km SW), and Palictahua in the district of Penipe. Cloud cover prevented ground observations, but IG noted that satellite images indicated the presence of ash plumes and thermal anomalies. The number and size of explosions increased at night during 30-31 January, and then a sharp decline in activity was noted on 31 January, characterized by very low seismicity. At 1701 an explosion generated an ash plume that rose 2 km and drifted SE and SW.
On 1 February, between 0800 and 1700, a swarm of volcano-tectonic earthquakes occurred in the upper conduit. Two moderately-sized explosions, at 1712 and 1732, generated ash plumes that rose 5 km, and pyroclastic flows that traveled 500 m down the NE and NW flanks. A larger explosion at 1739 produced an ash plume that rose 8 km and drifted SE and possibly SSE. Based on reports from IG, satellite images, pilot observations, web-camera images, and the Guayaquil MWO, the Washington VAAC reported that the ash plume rose to an estimated altitude of 13.7 km (45,000 ft) a.s.l., and drifted S at high altitudes and SW at lower altitudes. IG noted that pyroclastic flows traveled 7-8 km, reaching the base of the volcano and traveling over the Achupashal Baños- Penipe highway. Continuous ash-and-gas emissions followed; ash fell in multiple areas and total darkness was reported in Chacauco (NW). Explosions occurred every minute and vibrated structures in local towns. Pyroclastic flows descended the SW, W, NW, and NE flanks, and stopped short of towns and infrastructure. Ash emissions were sustained through the rest of the evening, and Strombolian explosions ejected incandescent blocks 800 m above the crater that fell and rolled 500 m down the flanks.
Activity gradually declined at 1900 until 2100 when explosions became more sporadic. On 2 February explosions at 0659, 0723, and 0801 were followed by ash emissions. During 2-3 February at least 10 explosions occurred and were heard in areas several kilometers away. On 3 February an ash plume rose 4 km and drifted N, reaching Quito as a mist of suspended very fine material that lingered most of the day.
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.
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/,
Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html,
Prensa Latina http://www.plenglish.com/index.php?option=com_content&task=view&id=2338321&Ite mid=1
UBINAS Perú 16.355°S, 70.903°W; summit elev. 5672 m
IGP reported that two earthquake swarms at Ubinas were detected: the first during 8-9 January and the second on 25 January. An emission was observed on 23 January. Seismicity increased again during 30-31 January. The Buenos Aires VAAC reported that, although a pilot reported an ash plume on 2 February, there was no ash detected in satellite images. The next day a pilot observed steam emissions with small amounts of ash; satellite images confirmed the presence of ash.
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.
Sources: Instituto Geofísico del Perú (IGP) http://www.igp.gob.pe/,
Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.smn.gov.ar/vaac/buenosaires/productos.php
Ongoing Activity
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 29 January ash plumes from Dukono rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 75 km SE. During 31 January-4 February ash plumes rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 55-185 km S, SE, and E.
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 on 28 January there was a gradual but steady decrease of activity at Etna's New Southeast Crater (NSEC). Weak and sporadic Strombolian explosions were detected at night, but then the thermal cameras recorded no anomalies associated with Strombolian activity. Lava flows from two vents at the base of the NSEC cone continued to effuse at a very low rate. Weather conditions almost entirely prevented observations of Etna from the morning of 30 January until the evening of 3 February. Late on 3 February observers noted that the lava flow remained active and was several hundred meters long. Almost continuous ash emissions from NSEC began at about 1300 on 4 February and continued into the night; about 5-10 ash puffs were separated by steam emissions. Ash plumes drifted E. After sunset jets of hot material were observed rising 100 m above the crater rim. At 2000 the ash emissions and injection of incandescent material ceased, but the lava flow continued and reached 1 km long.
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/
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 24-31 January. Satellite images detected a daily bright thermal anomaly on the volcano. 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 29 January-4 February 2014 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. A lava pond was active in the NE spatter cone. The 7.8-km-long Kahauale'a 2 lava flow (based on a satellite image from 27 January), fed by the NE spatter cone, was active with scattered break-out flows 4.8 and 6.7 km NE of Pu'u 'O'o that burned the forest. On 31 January a few brief lava overflows occurred from two of the cones.
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/
NYAMURAGIRA Democratic Republic of Congo 1.408°S, 29.20°E; summit elev. 3058 m
According to NASA's Earth Observatory, a satellite image acquired on 29 January showed a gas-and-steam plume rising from Nyamuragira.
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: NASA Earth Observatory http://earthobservatory.nasa.gov/
NYIRAGONGO Democratic Republic of Congo 1.52°S, 29.25°E; summit elev. 3470 m
According to NASA's Earth Observatory, a satellite image acquired on 29 January showed a gas-and-steam plume rising from Nyiragongo.
Geologic Summary. One of Africa's most notable volcanoes, Nyiragongo contained an active lava lake in its deep summit crater that drained catastrophically through its outer flanks in 1977. In contrast to the low profile of its neighboring shield volcano, Nyamuragira, Nyiragongo displays the steep slopes of a stratovolcano. Benches in the steep-walled, 1.2-km-wide summit crater mark the levels of former lava lakes, which have been observed since the late 19th century. About 100 parasitic cones are located on the volcano's flanks and along a NE-SW zone extending as far as Lake Kivu. Monitoring is done from a small observatory building located in Goma, ~18 km S of the Nyiragongo crater.
Source: NASA Earth Observatory http://earthobservatory.nasa.gov/
SAKURAJIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
JMA reported that during 27-31 January five explosions from Sakurajima's Showa Crater ejected tephra as far as 1,300 m. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 29 January and during 31 January-2 February and on 4 February ash plumes rose to altitudes of 1.5-4.9 km (5,000-12,000 ft) a.s.l. and drifted N, NE, and E.
Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.
Sources: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/index.html,
Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.jp/svd/vaac/data/vaac_list.html
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 24-31 January a newer lava dome continued to extrude onto the NW part of Shiveluch's older lava dome. Lava-dome extrusion was accompanied by hot avalanches, incandescence, and fumarolic activity. A thermal anomaly was detected daily in satellite images, and ash plumes rose to altitudes of 7-8 km (23,000-26,200 ft) a.s.l. on 23 January and drifted N. 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
SUWANOSEJIMA Kyushu 29.635°N, 129.716°E; summit elev. 799 m
Based on JMA notices and pilot observations, the Tokyo VAAC reported that on 2 February ash plumes from Suwanosejima rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE and SSE.
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 (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 On-take 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.
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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