SI/USGS Weekly Volcanic Activity Report 3-9 December 2008

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SI/USGS Weekly Volcanic Activity Report
3-9 December 2008
**********************************************************

Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/


New Activity/Unrest: | Barren Island, Andaman Islands (Indian Ocean) |
Kliuchevskoi, Central Kamchatka (Russia) | Nevado del Huila, Colombia
| Soufrière Hills, Montserrat

Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén,
Southern Chile | Colima, México | Karymsky, Eastern Kamchatka |
Kilauea, Hawaii (USA) | Rabaul, New Britain (SW Pacific) | Shiveluch,
Central Kamchatka (Russia) | Tongariro, New Zealand | 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


BARREN ISLAND Andaman Islands (Indian Ocean) 12.278°N, 93.858°E;
summit elev. 354 m

The Darwin VAAC reported that during 7-8 December pilots observed lava
flows on Barren Island; ash plumes were not present. Thermal anomalies
were detected on satellite imagery.

Geologic Summary. Barren Island, a possession of India in the Andaman
Sea about 135 km NE of Port Blair in the Andaman Islands, is the only
historically active volcano along the N-S-trending volcanic arc
extending between Sumatra and Burma (Myanmar). The 354-m-high island
is the emergent summit of volcano that rises from a depth of about
2,250 m. The small, uninhabited 3-km-wide island contains a roughly
2-km-wide caldera with walls 250-350 m high. The caldera, which is
open to the sea on the W, was created during a major explosive
eruption in the late Pleistocene that produced pyroclastic-flow and
-surge deposits. The morphology of a fresh pyroclastic cone that was
constructed in the center of the caldera has varied during the course
of historical eruptions. Lava flows fill much of the caldera floor and
have reached the sea along the western coast during historical
eruptions.

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


KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m

KVERT reported that seismic activity at Kliuchevskoi was above
background levels during 28 November-10 December; Strombolian activity
ejected bombs 500 m above the crater and lava effusion on the NW flank
continued. Analysis of satellite imagery revealed a large daily
thermal anomaly in the crater. During 27-29 November, and 2 and 4
December, gas-and-steam plumes with little ash content rose to
altitudes of 6-6.2 km (19,700-20,300 ft) a.s.l. and drifted 40-115 km
NE, E, SE, and SW. During 4-5 December, the ash content in plumes
increased. On 8 December, phreatic bursts occurred where the lava flow
front contacted the Erman Glacier. On 9 December, a 50-km-wide ash
plume drifted about 550 km ENE. The Level of Concern Color Code was
raised to Red. KVERT warned that the activity was dangerous for
international and low-flying aircraft. On 10 December, the Level of
Concern Color Code was lowered back to Orange because explosive
activity decreased. A gas-and-steam plume with a small amount of ash
drifted NE.

Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active
volcano. Since its origin about 7,000 years ago, the beautifully
symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent
moderate-volume explosive and effusive eruptions without major periods
of inactivity. More than 100 flank eruptions, mostly on the NE and SE
flanks of the conical volcano between 500 m and 3,600 m elevation,
have occurred during the past 3,000 years. The morphology of its
700-m-wide summit crater has been frequently modified by historical
eruptions, which have been recorded since the late-17th century.
Historical eruptions have originated primarily from the summit crater,
but have also included major explosive and effusive events from flank
craters.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
http://www.kscnet.ru/ivs/kvert/updates.shtml


NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5365 m

INGEOMINAS reported that seismicity from Nevado del Huila continued to
be elevated during 2-9 December. On 4 and 6 December overflights were
conducted to view the new lava dome at the S flank of Pico Central.
The dome elongated towards the SW of Pico Central, following the
topography, and measured 400 m in the north-south direction, 150 m in
the east-west direction, and was 120 m high. The approximate volume of
the dome was 4,500,000 cubic meters. Gas plumes rose 1 km above the
dome. New cracks in the glacier were also noted.

Geologic Summary. Nevado del Huila, the highest active volcano in
Colombia, is an elongated N-S-trending volcanic chain mantled by a
glacier icecap. The andesitic-dacitic volcano was constructed within a
10-km-wide caldera. Volcanism at Nevado del Huila has produced six
volcanic cones whose ages in general migrated from south to north. Two
glacier-free lava domes lie at the southern end of the Huila volcanic
complex. The first historical eruption from this little known volcano
took place in the 16th century. Two persistent steam columns rise from
the central peak, and hot springs are also present.

Source: Instituto Colombiano de Geología y Minería (INGEOMINAS)
http://www.ingeominas.gov.co//


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

MVO reported a total of four explosive events from the Soufrière Hills
lava dome during 2-5 December. The first event was triggered by a
small dome collapse on 2 December, occurred without precursory
seismicity, and was followed by a pyroclastic flow on the W flank.
Resultant ash plumes, accompanied by lightning strikes, rose to an
altitude of 12.2 km (40,000 ft) a.s.l. and drifted W. Explosions
ejected incandescent blocks up to 1.6 km away from the dome that
landed on Gages Mountain (about 1 km WNW), leaving impact craters. The
pyroclastic flow also generated multiple pyroclastic surges that
traveled S and N, setting fire to trees and bushes.

On 3 December another explosion scattered incandescent blocks all over
the NW side of Gages Mountain. The third eruptive event, forceful
emissions of ash on 4 December, resulted in ash plumes that rose to an
altitude of 4.6 km (15,000 ft) a.s.l. The fourth explosive event
occurred on 5 December and ejected incandescent blocks that were
deposited on the NW side of Gages Mountain. A pyroclastic flow
traveled to the W down Gages valley into Plymouth (about 5 km W) and
an ash plume drifted NW.

On 3, 4, and 5 December small, relatively slow moving pyroclastic
flows traveled no more than 3.2 km down the Gages valley. In periods
between the events, near-continuous emissions of ash-laden steam were
noted. The Hazard Level remained at 3.

According to the Washington VAAC, MVO reported eruptions on 6
December. Ash was seen on satellite imagery expanding in multiple
directions, then to the E, SE, and W.

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.

Sources: Montserrat Volcano Observatory (MVO) http://www.mvo.ms/,
Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html


Ongoing Activity


BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m

Based on analysis of satellite imagery, the Darwin VAAC reported that
during 6-7 December ash plumes from Batu Tara rose to an altitude of
1.5 km (5,000 ft) a.s.l. and drifted about 55 km NW and SW.

Geologic Summary. The small isolated island of Batu Tara in the Flores
Sea about 50 km north of Lembata (formerly Lomblen) Island contains a
scarp on the eastern side similar to the Sciara del Fuoco of Italy's
Stromboli volcano. Vegetation covers the flanks of Batu Tara to within
50 m of the 748-m-high summit. Batu Tara lies north of the main
volcanic arc and is noted for its potassic leucite-bearing basanitic
and tephritic rocks. The first historical eruption from Batu Tara,
during 1847-52, produced explosions and a lava flow.

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


CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m

Based on observations of satellite imagery, pilot reports, SIGMET
notices, and web camera views, the Buenos Aires VAAC reported that
during 3-8 December, ash plumes from Chaitén rose to altitudes 1.8-4.6
km (6,000-15,000 ft) a.s.l. and drifted NE, NW, and SW. A thermal
anomaly was detected on satellite imagery during 4 and 6-8 December.

Geologic Summary. Chaitén is a small, glacier-free caldera with a
Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf
of Corcovado. A pyroclastic-surge and pumice deposit considered to
originate from the eruption that formed the elliptical 2.5 x 4 km wide
summit caldera was dated at about 9400 years ago. A rhyolitic,
962-m-high obsidian lava dome occupies much of the caldera floor.
Obsidian cobbles from this dome found in the Blanco River are the
source of prehistorical artifacts from archaeological sites along the
Pacific coast as far as 400 km away from the volcano to the north and
south. The caldera is breached on the SW side by a river that drains
to the bay of Chaitén, and the high point on its southern rim reaches
1122 m.

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


COLIMA México 19.514°N, 103.62°W; summit elev. 3850 m

During 3-8 December, gray plumes from Colima rose to altitudes of
4.2-4.6 km (13,800-15,100 ft) a.s.l. and drifted N and W; a gray plume
rose to an altitude of 6.4 km (21,000 ft) a.s.l. on 4 December. White
plumes were also observed and, during 4-8 December, rose to a maximum
altitude of 4.2 km (13,800 ft) a.s.l. The white plumes drifted SW and
SE.

Geologic Summary. The Colima volcanic complex is the most prominent
volcanic center of the western Mexican Volcanic Belt. It consists of
two southward-younging volcanoes, Nevado de Colima (the 4,320 m high
point of the complex) on the N and the historically active Volcán de
Colima on the S. Volcán de Colima (also known as Volcán Fuego) is a
youthful stratovolcano constructed within a 5-km-wide caldera,
breached to the S, that has been the source of large debris
avalanches. Major slope failures have occurred repeatedly from both
the Nevado and Colima cones, and have produced a thick apron of
debris-avalanche deposits on three sides of the complex. Frequent
historical eruptions date back to the 16th century. Occasional major
explosive eruptions (most recently in 1913) have destroyed the summit
and left a deep, steep-sided crater that was slowly refilled and then
overtopped by lava dome growth.

Source: Gobierno del Estado de Colima
http://www.colima-estado.gob.mx/2006/seguridad/indvolcan.php


KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m

KVERT reported that seismic activity at Karymsky was at background
levels during 27-30 November; possible explosions may have generated
ash-and-gas plumes to an altitude of 3.7 km (12,100 ft) a.s.l.
Analysis of satellite imagery revealed a thermal anomaly in the crater
during 27-29 November and 1 December. The Level of Concern 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

HVO reported that during 3-9 December lava flowed SE through a tube
system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and
rootless shield complex, reaching the Waikupanaha ocean entry.
Incandescence was occasionally seen at the TEB vent, and surface flows
were noted on and at the base of the pali. On 6 December, a few
explosions originated from the ocean entry. Observers reported that a
small bench collapse that occurred sometime between 6 and 7 December
sent boulders up to 0.5 m in diameter inland about 50-75 m.

Earthquakes were variously located beneath and to the S of the
caldera, along the SW rift zone, and along the S-flank fault. The vent
in Halema'uma'u crater continued to produce a predominantly white
plume that drifted mainly SW and deposited small amounts of tephra.
Night-time incandescence was rarely seen at the base of the plume, and
sounds resembling rockfalls were heard in the vicinity of the crater.
During 2-4 December, the plume drifted NW and high concentrations of
sulfur dioxide were measured at various locations. On 4 December,
hybrid earthquakes were followed by several minutes of dense brown
emissions. A vent rim collapse was seen on 5 December after rockfall
and booming sounds were heard, and brown ash was emitted. The sulfur
dioxide emission rate at the summit was 1,000 and 500 tonnes per day
on 4 and 5 December, respectively; the 2003-2007 average rate was 140
tonnes per day.

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/


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

Based on analysis of satellite imagery and information from RVO, the
Darwin VAAC reported that during 3-5, 7, and 9 December ash plumes
from Rabaul caldera's Tavurvur cone rose to altitudes of 2.1-3 km
(7,000-10,000 ft) a.s.l. and drifted E, NE, NNW, WNW, and W.

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


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

KVERT reported that seismic activity at Shiveluch was above background
levels during 28 November-5 December. Based on interpretations of
seismic data, ash plumes rose to an altitude of 5.8 km (19,000 ft)
a.s.l. According to visual observations, gas-and-steam plumes rose to
an altitude of 3.5 km (11,500 ft) a.s.l. during 27 and 29-30 November,
and 2 December. Analysis of satellite imagery revealed a daily thermal
anomaly on the lava dome. 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/updates.shtml


TONGARIRO New Zealand 39.13°S, 175.642°E; summit elev. 1978 m

The Alert Level for Tongariro was lowered to 0 (typical background
activity) on 2 December. The number of volcanic earthquakes declined
to background levels since mid-2008. In addition, regular measurements
of volcanic gas levels and the temperature of the summit gas vent
showed no changes over the previous two and a half years.

Geologic Summary. Tongariro is a large andesitic volcanic massif,
located immediately NE of Ruapehu volcano, that is composed of more
than a dozen composite cones constructed over a period of 275,000
years. Vents along a NE-trending zone extending from Saddle Cone
(below Ruapehu volcano) to Te Mari crater (including vents at the
present-day location of Ngauruhoe) were active during a several
hundred year long period around 10,000 years ago, producing the
largest known eruptions at the Tongariro complex during the Holocene.
The youngest cone of the complex, Ngauruhoe, has grown to become the
highest peak of the massif since its birth about 2500 years ago. The
symmetrical, steep-sided Ngauruhoe, along with its neighbor Ruapehu to
the south, have been New Zealand's most active volcanoes during
historical time.

Source: GeoNet Data Centre http://www.geonet.org.nz/index.html


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

The IG reported that on 4 December an ash plume from Tungurahua rose
to an altitude of 7 km (23,000 ft) a.s.l. and drifted E. Light ashfall
was reported in Runtún (6 km NNE) and Pondoa (about 8 km N). Cloud
cover prevented visual observations during 5-9 December.
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/


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