GVP/USGS Weekly Volcanic Activity Report 6-12 February 2008

Kimberly Genareau <kgenarea@xxxxxxx> · Wed, 13 Feb 2008 13:26:47 -0700

****************************************************************
GVP/USGS Weekly Volcanic Activity Report
6-12 February 2008
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
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New Activity/Unrest: | Anatahan, Mariana Islands (Central Pacific) |
Cleveland, Chuginadak Island | Kanlaon, Central Philippines | Llaima,
Central Chile | Shishaldin, Fox Islands | Tungurahua, Ecuador

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

ANATAHAN Mariana Islands (Central Pacific) 16.35°N, 145.67°E; summit elev. 790 m

The USGS reported that seismic tremor levels at Anatahan were
relatively low during 8-13 February, except for short-lived increases
during 8-9 and 12-13 February. On 9 February, a diffuse steam plume
that possibly contained ash was observed on satellite imagery and
drifted W. The Washington VAAC reported that more steam plumes
possibly containing some ash were visible on satellite imagery on 11,
12, and 13 February and drifted NW and SE. On 13 February, vog
(volcanic fog) was also observed N and W of Saipan. Emissions of
sulfur dioxide were detected by the satellite-based Ozone Monitoring
Instrument (OMI). The Volcanic Alert Level remained at Watch and the
Aviation Color Code remained at Orange.

Geologic Summary. The elongate, 9-km-long island of Anatahan in the
central Mariana Islands consists of large stratovolcano with a 2.3 x 5
km, E-W-trending compound summit caldera. The larger western caldera
is 2.3 x 3 km wide, and its western rim forms the island's 790-m high
point. Ponded lava flows overlain by pyroclastic deposits fill the
floor of the western caldera, whose SW side is cut by a fresh-looking
smaller crater. The 2-km-wide eastern caldera contained a steep-walled
inner crater whose floor prior to the 2003 eruption was only 68 m
above sea level. Sparseness of vegetation on the most recent lava
flows on Anatahan had indicated that they were of Holocene age, but
the first historical eruption of Anatahan did not occur until May
2003, when a large explosive eruption took place forming a new crater
inside the eastern caldera.

Sources: Emergency Management Office of the Commonwealth of the
Mariana Islands and the US Geological Survey Hawaiian Volcano
Observatory http://volcano.wr.usgs.gov/cnmistatus.php, Washington
Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html

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

AVO reported that a diffuse ash plume from Cleveland was observed on
satellite imagery drifting 12 km SE at an altitude below 1.5 km (5,000
ft) a.s.l. during a break in cloud cover on 8 February. Later that day
AVO received pilot reports of an ash plume that rose to an altitude of
6.1 km (20,000 ft) a.s.l. and observed the plume on satellite imagery
drifting NW. Due to the increased activity, the Volcanic Alert Level
was raised to Watch and the Aviation Color Code was raised to Orange.
No precursory or current seismic information is available because
Cleveland does not have a real-time seismic network. During 10-11
February, a thermal anomaly was possibly visible on satellite imagery.
The Volcanic Alert Level was lowered back to Advisory and the Aviation
Color Code was lowered to Yellow on 12 February.

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/

KANLAON Central Philippines 10.412°N, 123.132°E; summit elev. 2435 m

PHIVOLCS reported that during 7-10 February the seismic network for
Kanlaon detected a significant rise in earthquakes. On 10 February the
Alert Level was raised from 0 to 1 (out of 5). Cloud cover prohibited
visual observations of the summit. The public was strongly advised not
to enter the 4-km Permanent Danger Zone.

Geologic Summary. Kanlaon volcano (also spelled Canlaon), the most
active of the central Philippines, forms the highest point on the
island of Negros, about 500 km ESE of Manila. The massive
stratovolcano is dotted with fissure-controlled pyroclastic cones and
craters, many of which are filled by lakes. The summit of Kanlaon
contains a broad northern crater with a crater lake and a smaller, but
higher, historically active crater to the south. Historical eruptions,
recorded since 1866, have typically consisted of phreatic explosions
of small-to-moderate size that produce minor ashfalls near the
volcano.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
http://www.phivolcs.dost.gov.ph/

LLAIMA Central Chile 38.692°S, 71.729°W; summit elev. 3125 m

SERNAGEOMIN reported intense Strombolian activity in the main crater
of Llaima and explosions that propelled material 500 m in the air on 6
February. Ash-and-gas plumes from the activity rose to altitudes of
5.1-5.6 km (16,700-18,400 ft) a.s.l. and drifted SE more than 30 km.
Multiple lava flows traveled 0.7-1.5 km W and N and generated steam
plumes due to their interaction with a glacier. Activity declined
later that day. During breaks in cloud cover, ash plumes were observed
at altitudes of 4.1-9.1 km (13,500-29,900 ft) a.s.l. and drifted NW.
During 7-8 February, explosions from two different areas in the main
crater produced brown and gray ash-and-gas plumes that rose to
altitudes of 4.1-6.2 km (13,500-20,300 ft) a.s.l. and drifted 20 km
NW. Incandescent blocks from lava-flow fronts rolled down the flank.

According to a news article on 7 and 12 February, people from two
communities were evacuated, but were allowed to return to their homes
during the daytime.

The Buenos Aires VAAC reported that ash plumes at altitudes of 1.2-3.6
km (4,000-11,800 ft) a.s.l. were visible on satellite imagery during
10-12 February.

Geologic Summary. Llaima, one of Chile's largest and most active
volcanoes, contains two main historically active craters, one at the
summit and the other to the SE. The massive 3,125-m-high,
glacier-covered stratovolcano has a volume of 400 cu km. A Holocene
edifice built primarily of accumulated lava flows was constructed over
an 8-km-wide caldera that formed about 13,200 years ago, following
eruption of the 24 cu km Curacautín Ignimbrite. More than 40 scoria
cones dot the volcano's flanks. Following the end of an explosive
stage about 7,200 years ago, construction of the present edifice
began, characterized by Strombolian, hawaiian, and infrequent
subplinian eruptions. Frequent moderate explosive eruptions with
occasional lava flows have been recorded since the 17th century.

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

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

123.cl http://noticias.123.cl/entel123/html/Tele13/Noticias/Regiones/Temuco/331369.html

El Mostrador.cl
http://www.elmostrador.cl/modulos/noticias/constructor/noticia_new.asp?id_noticia=240194

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

Based on pilot reports, the Anchorage VAAC reported that a small ash
plume from Shishaldin rose to an altitude of 3 km (10,000 ft) a.s.l.
on 12 February. Ash was not observed on satellite imagery.

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: Anchorage Volcanic Ash Advisory Center (VAAC)

http://www.ssd.noaa.gov/VAAC/OTH/AK/messages.html

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

On 6 February, IG reported that pyroclastic flows from Tungurahua
descended multiple NW and W drainages and tephra fall 3 cm in diameter
was reported in areas to the SW. Based on information from the IG and
satellite imagery evaluation, the Washington VAAC reported that ash
plumes rose to estimated altitudes of 7.3-14.3 km (24,000-47,000 ft)
a.s.l. and drifted S and NW. Ashfall was reported in areas downwind
and to the SW and W, including Riobamba (30 km S). Precursory
seismicity saturated local stations and presented similar patterns
seen prior to intense episodes in July and August 2006. According to
news articles, several hundred to 2,000 people were evacuated.

On 7 February, ash plumes rose to altitudes of 7-10 km (23,000-32,800
ft) a.s.l. and drifted mainly NW. Ash and tephra fell in areas to the
SW and W. Strong roaring noises, explosions, and "cannon shots" were
heard and windows vibrated, as far away as the Tungurahua Observatory
(OVT) in Guadalupe, about 13 km NW. Incandescent material was
propelled from the summit and fell on the flanks at about 3.5 km
elevation, below the crater. Pyroclastic flows were detected in the
Chontapamba ravine to the W and in the Juive and Mandur drainages to
the NW. According to news articles, residents were evacuated again,
hours after being allowed to return home.

During 8-11 February, ash plumes rose to altitudes of 6-10 km
(19,700-32,800 ft) a.s.l. and drifted mainly W and E (on 10 February,
only). Ashfall was reported from areas to the NW, W, and SW and was
3-4 mm thick in Choglontus to the SW on 8 February. Incandescence at
the summit was also observed on 8 February. Ground vibrations were
reported all four days. On 11 February, Strombolian activity was seen
at the summit and material that was propelled out rolled 1.2 km down
the flanks.

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

Reuters http://news.yahoo.com/s/nm/20080207/sc_nm/ecuador_volcano_dc_4

Reuters http://www.sciam.com/article.cfm?id=ecuador-farmers-evacuated

Ongoing Activity

ARENAL Costa Rica 10.463°N, 84.703°W; summit elev. 1670 m

In January, activity originating from Arenal's Crater C consisted of
gas emissions, sporadic Strombolian eruptions, and occasional
avalanches from lava-flow fronts that traveled down the S flanks.
Blocks from the lava-flow fronts periodically reached vegetation and
started small fires. Volcanic activity was at relatively low levels
and few eruptions occurred. Acid rain and small amounts of ejected
pyroclastic material affected the NE and SE flanks. Eruptions produced
ash plumes that rose about 2.2 km (7,100 ft) a.s.l. Small avalanches
of volcanic material traveled down several ravines. Crater D showed
only fumarolic activity.

Geologic Summary. Conical Volcan Arenal is the youngest stratovolcano
in Costa Rica and one of its most active. The 1,657-m-high andesitic
volcano towers above the eastern shores of Lake Arenal, which has been
enlarged by a hydroelectric project. The earliest known eruptions of
Arenal took place about 7,000 years ago. Growth of Arenal has been
characterized by periodic major explosive eruptions at
several-hundred-year intervals and periods of lava effusion that armor
the cone. Arenal's most recent eruptive period began with a major
explosive eruption in 1968. Continuous explosive activity accompanied
by slow lava effusion and the occasional emission of pyroclastic flows
has occurred since then from vents at the summit and on the upper
western flank.

Source: Observatorio Vulcanologico y Sismologico de Costa
Rica-Universidad Nacional (OVSICORI-UNA)
http://www.ovsicori.una.ac.cr/

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

Based on field observations, and web camera views when weather
permitted, HVO reported that during 6-12 February activity from
Kilauea's fissure segment D was concentrated at the perched lava
channel, the Thanksgiving Eve Breakout (TEB) shield, and satellitic
shields to the SE. Lava flows issued from the tops and flanks of the
shields. Lava in the original perched lava channel, formed from the 21
July fissure eruption, overflowed the NW and reached a forested area
on 8 February; smoke was seen through the web camera. Incandescence
was observed in Pu'u 'O'o crater for less than 10 minutes at a time
every day during 6-8 February. A few earthquakes were located beneath
the summit, the adjacent flank of Mauna Loa, and along the S-flank
faults.

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/

OL DOINYO LENGAI Tanzania 2.764°S, 35.914°E; summit elev. 2962 m

According to Frederick Belton's Ol Doinyo Lengai website, a local camp
manager reported to  a visitor, that several large explosive eruptions
accompanied by "bangs" on 1 February. The manager noted that ash
plumes were originating from a location in the crater that was further
N than previous locations. The visitor saw ash plumes on 3 February
that rose to altitudes of 3.2-3.3 km (10,500-10,800 ft) a.s.l. The
next day, an ash plume rose to an altitude of 4.3 km (14,100 ft)
a.s.l. Eruptions also occurred on 6 February.

Geologic Summary. The symmetrical Ol Doinyo Lengai stratovolcano is
the only volcano known to have erupted carbonatite tephras and lavas
in historical time. The prominent volcano, known as "The Mountain of
God," rises abruptly above the broad plain S of Lake Natron. The
cone-building stage of the volcano ended about 15,000 years ago and
was followed by periodic ejection of natrocarbonatite and nephelinite
tephra during the Holocene. Historical eruptions have consisted of
smaller tephra eruptions and emission of numerous natrocarbonatitic
lava flows on the floor of the summit crater. Petrologists first
observed the eruption of carbonatitic lava flows in the 1960s.
Subsequent more frequent visits have documented long-term lava
effusion in the summit crater that would not have been seen from the
foot of the volcano.

Source: Frederick Belton's Ol Doinyo Lengai website
http://www.mtsu.edu/~fbelton/lengai.html

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

CENAPRED reported that emissions of steam and gas from Popocatépetl
were visible during 6-12 February. The plumes occasionally contained
slight amounts of ash. On 8 February, ash emissions were occasionally
accompanied by explosions and propelled incandescent fragments that
landed in the vicinity of the crater. Two explosive events on 11
February resulted in ashfall in the town of Huejotzingo, Puebla.

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/es/

RABAUL New Britain (SW Pacific) 4.271°S, 152.203°E; summit elev. 688 m

RVO reported that ash plumes from Rabaul caldera's Tavurvur cone rose
to altitudes of 1.2-1.7 km (3,900-5,600 ft) a.s.l. and drifted NW, W,
SW, S, SE, and E during 6-11 February. Ashfall was reported everyday
in areas downwind, including Matupit, Kokopo, and Rabaul Town, and
surrounding areas. During 6-7 February, incandescence at the summit
was noted and incandescent material was propelled from a vent on the
inner E wall of the crater.

Geologic Summary. The low-lying Rabaul caldera on the tip of the
Gazelle Peninsula at the NE end of New Britain forms a broad sheltered
harbor. The outer flanks of the 688-m-high asymmetrical pyroclastic
shield volcano are formed by thick pyroclastic-flow deposits. The 8 x
14 km caldera is widely breached on the E, where its floor is flooded
by Blanche Bay.Two major Holocene caldera-forming eruptions at Rabaul
took place as recently as 3,500 and 1,400 years ago. Three small
stratovolcanoes lie outside the northern and NE caldera rims.
Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on
the caldera floor near the NE and western caldera walls. Several of
these, including Vulcan cone, which was formed during a large eruption
in 1878, have produced major explosive activity during historical
time. A powerful explosive eruption in 1994 occurred simultaneously
from Vulcan and Tavurvur volcanoes and forced the temporary
abandonment of Rabaul city.

Source: Steve Saunders and Herman Patia, Rabaul Volcano Observatory

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

Based on information from JMA, the Tokyo VAAC reported that explosions
from Sakura-jima on 6 February produced plumes that rose to altitudes
of 1.2-2.1 km (4,000-7,000 ft) a.s.l. and drifted SE. Ash was not
detected on satellite imagery.

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

SHIVELUCH Sredinny Range 56.653°N, 161.360°E; summit elev. 3283 m

KVERT reported that seismic activity at Shiveluch was slightly above
background levels during 1-8 February. Based on seismic
interpretation, ash plumes rose to an altitude of 3.8 km (12,200 ft)
a.s.l. daily. Strong fumarolic activity was noted on 5 and 6 February.
According to observations of satellite imagery, a thermal anomaly was
present in the crater on 1, 3, and 6 February. The Level of Concern
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. During the 1990s,
intermittent explosive eruptions took place 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

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

MVO reported that that during 5-12 February the lava dome at Soufrière
Hills changed very little, based on limited observations (due to
inclement weather) during overflights. Seismic activity was very low
and low-level rockfall activity continued. Fumarolic activity on the N
and E flanks continued. Active fumaroles were also noted in the
Galway's area to the S of the dome. Clouds obscured views to the W in
the Gages Wall area. The Alert Level remained elevated at 4 (on a
scale of 0-5).

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 (MVO) http://www.mvo.ms/

ST. HELENS Washington (USA) 46.20°N, 122.18°W; summit elev. 2549 m

Data from deformation-monitoring instruments indicated that during
6-12 February lava-dome growth at Mount St. Helens continued.
Seismicity persisted at low levels, punctuated by M 1.5-2.5, and
occasionally larger, earthquakes. Clouds and snow cover frequently
inhibited visual observations.

Geologic Summary. Prior to 1980, Mount St. Helens formed a conical,
youthful volcano sometimes known as the Fuji-san of America. During
the 1980 eruption the upper 400 m of the summit was removed by slope
failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially
filled by a lava dome. Mount St. Helens was formed during nine
eruptive periods beginning about 40-50,000 years ago, and has been the
most active volcano in the Cascade Range during the Holocene. The
modern edifice was constructed during the last 2,200 years, when the
volcano produced basaltic as well as andesitic and dacitic products
from summit and flank vents. Historical eruptions in the 19th century
originated from the Goat Rocks area on the N flank, and were witnessed
by early settlers.

Source: Cascades Volcano Observatory (CVO) http://volcano.wr.usgs.gov/

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

Based on information from JMA, the Tokyo VAAC reported that an
eruption plume from Suwanose-jima rose to an altitude of 1.8 km (6,000
ft) a.s.l. on 7 February and drifted E. Explosions were also noted on
8, 9, and 13 February, but altitude and direction of possible plumes
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)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html

+++++++++++++++++++++++++++++++++++++
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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