SI/USGS Weekly Volcanic Activity Report 31 December 2008-6 January 2009

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**************************************************************
SI/USGS Weekly Volcanic Activity Report
31 December 2008-6 January 2009
**************************************************************

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


New Activity/Unrest: | Cleveland, Chuginadak Island | Dempo, Sumatra
(Indonesia) | Koryaksky, Eastern Kamchatka | Shishaldin, Fox Islands |
Soufrière Hills, Montserrat | Tungurahua, Ecuador

Ongoing Activity: | Bagana, Bougainville Island (SW Pacific) | Barren
Island, Andaman Islands (Indian Ocean) | Batu Tara, Komba Island
(Indonesia) | Chaitén, Southern Chile | Colima, México | Dukono,
Halmahera (Indonesia) | Fuego, Guatemala | Karymsky, Eastern Kamchatka
| Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) |
Rabaul, New Britain (SW Pacific) | Sangay, Ecuador | Santa María,
Guatemala | Shiveluch, Central Kamchatka (Russia) | Suwanose-jima,
Ryukyu Islands (Japan) | Ubinas, Perú


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


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

AVO reported that cloud cover prevented satellite observations of
Cleveland during 31 December, and 1, 3, and 5 January. The brief
explosive emission of ash was detected on 2 January. A resultant ash
plume rose to an altitude of 6 km (20,000 ft) a.s.l. and drifted about
240 km ESE. A thermal anomaly over the summit was detected on 4
January. No current seismic information was available because
Cleveland does not have a real-time seismic network. The Volcanic
Alert Level remained at Advisory and the Aviation Color Code remained
at Yellow.

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/


DEMPO Sumatra (Indonesia) 4.03°S, 103.13°E; summit elev. 3173 m

CVGHM reported that on 1 January, a phreatic eruption from Dempo
resulted in a strong sulfur odor and "ash rain" that was noted as far
as about 10 km from the summit. Fog prevented direct observations of
the summit. The Alert Level was raised to 2 (on a scale from 1-4).
Visitors and residents were advised not to go within a 2-km radius of
the summit.

Geologic Summary. Dempo is a prominent 3173-m-high stratovolcano that
rises above the Pasumah Plain of SE Sumatra. Remnants of 7 craters are
found at or near the summit, with volcanism migrating to the WNW with
time. The historically active summit crater of Gunung Dempo contains a
400-m-wide lake, located at the NW end of the crater complex.
Historical eruptions have been restricted to small-to-moderate
explosive activity that produced ashfall near the volcano.

Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM)
http://portal.vsi.esdm.go.id/joomla/


KORYAKSKY Eastern Kamchatka 53.320°N, 158.688°E; summit elev. 3456 m

KVERT reported that during 26 December-7 January seismic activity at
Koryaksky was at background levels. Observers reported that during
30-31 December gas-and-steam plumes possibly containing a small amount
of ash drifted along the surface of the NW flank. During 6-7 January
gas-and-steam plumes drifted SW. The Level of Concern Color Code was
lowered to Yellow.

Geologic Summary. The large symmetrical Koryaksky stratovolcano is the
most prominent landmark of the NW-trending Avachinskaya volcano group,
which towers above Kamchatka's largest city, Petropavlovsk. Erosion
has produced a ribbed surface on the eastern flanks of the 3456-m-high
volcano; the youngest lava flows are found on the upper western flank
and below SE-flank cinder cones. No strong explosive eruptions have
been documented during the Holocene. Extensive Holocene lava fields on
the western flank were primarily fed by summit vents; those on the SW
flank originated from flank vents. Lahars associated with a period of
lava effusion from south- and SW-flank fissure vents about 3900-3500
years ago reached Avacha Bay. Only a few moderate explosive eruptions
have occurred during historical time. Koryaksky's first historical
eruption, in 1895, also produced a lava flow.

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


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

AVO reported that significant thermal anomalies over Shishaldin's
summit were detected in satellite imagery during 5-6 January. Seismic
activity had also increased slightly. AVO raised the Aviation Color
Code to Yellow and the Volcano Alert Level to 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: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/


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

MVO reported that during 26 December-2 January activity from Soufrière
Hills lava dome was characterized by significantly increased lava
extrusion, ash emissions, and pyroclastic flows. Lava extrusion on the
top, N, W, and SW sides of the dome continued, and incandescence on
the dome was visible at night when weather was favorable. Pyroclastic
flows regularly reached the bottom of Tyers Ghaut (NW); surges
associated with the larger flows spilled into the next valley to the
W. Deposits filling Tyers Ghaut caused the flows to travel farther,
into the upper part of the Belham River. Pyroclastic flows were also
noted in valleys to the W. Ash emissions from the top of the lava dome
increased; although most pyroclastic flows originated from rockfalls,
some originated at the vent. Ashfall was reported in areas 6-7 km NW.
Large incandescent blocks, deposited by rockfalls and pyroclastic
flows, were visible on multiple occasions at night in the lower parts
of Tyers Ghaut. Fires triggered by surges were visible in the
neighboring valley. The Hazard Level remained at 4.

Based on analysis of satellite imagery and information from MVO, the
Washington VAAC reported large eruptions on 3 January. Ash plumes
drifted NE at an altitude of 7.6 km (25,000 ft) a.s.l., E at an
altitude of 10.7 km (35,000 ft) a.s.l., S at an altitude of 6.1 km
(20,000 ft) a.s.l., and W at an altitude of 2.4 km (8,000 ft) a.s.l. A
thermal anomaly was detected. According to news articles, about 70
people were evacuated from Area B, about 6-8 km NW. The next day,
steam-and-gas plumes possibly containing ash drifted W and WSW.

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,
Antigua Sun http://www.antiguasun.com/paper/?as=view&sun=281044106701042009&an=175033098901042009&ac=Local


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

The IG reported that during 31 December-6 January ash plumes from
Tungurahua rose to altitudes of 6-7 km (19,700-23,000 ft) a.s.l. and
drifted SW, W, and NW. Ashfall was reported in areas downwind during
31 December-3 January; ashfall was heavy in Choglontus (W) on 2
January. Roaring, explosions, and "cannon shot" noises were reported
almost daily, and large windows vibrated on 1, 3, and 4 January.
During 2-4 January, incandescence at the summit was noted and blocks
rolled up to 800 m down the flanks. Strombolian activity occurred at
the summit on 4 January.

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/


Ongoing Activity


BAGANA Bougainville Island (SW Pacific) 6.140°S, 155.195°E; summit elev. 1750 m

Based on analysis of satellite imagery, the Darwin VAAC reported that
on 31 December an ash plume from Bagana rose to an altitude of 2.4 km
(8,000 ft) a.s.l.

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


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

Based on analysis of satellite imagery, the Darwin VAAC reported that
during 4-6 January ash plumes from Barren Island rose to an altitude
of 2.4 km (8,000 ft) a.s.l. and drifted SW and NW.

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


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
on 6 January an ash plume from Batu Tara rose to an altitude of 2.4 km
(8,000 ft) a.s.l. and drifted ENE.

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 analysis of satellite imagery, pilot observations, and web
camera views, the Buenos Aires VAAC reported that during 31 December-2
January and 4-5 January ash plumes from Chaitén continuously rose to
altitudes 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NW, N, NNE,
and SE. Ash plumes were visible through the web camera on 3 January.

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

On 2 January, incandescent material from Colima was propelled 100 m
above the summit and a gray plume rose to an altitude of 4.1 km
(13,500 ft) a.s.l. During 3-5 January, gray and white plumes rose to
altitudes of 4-4.2 km (13,100-13,800 ft) a.s.l. The plumes drifted N,
NE, E, 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


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

Based on analysis of satellite imagery, the Darwin VAAC reported that
on 6 January an ash plume from Dukono rose to an altitude of 1.8 km
(6,000 ft) a.s.l. and drifted 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)
http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html


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

Based on analysis of satellite imagery, the Washington VAAC reported
that on 1 January two ash plumes from Fuego drifted N. INSIVUMEH
reported that during 4-6 January multiple explosions produced ash
plumes that rose to altitudes of 4.1-5.1 km (13,500-16,700 ft) a.s.l.
and drifted 12 km W and SW. Ashfall was reported in areas downwind.
Some explosions produced rumbling sounds and shock waves that were
detected 10 km away. Constant avalanches of blocks descended the S and
SW flanks.

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.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia,
e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/,
Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html


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

KVERT reported during 26 December-2 January seismic activity from
Karymsky was not evaluated due to technical issues. Clouds prevented
satellite observations of the volcano. 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 31 December-6 January lava flowed SE through
a tube system from underneath Kilauea's Thanksgiving Eve Breakout
(TEB) and rootless shield complex, reaching the Waikupanaha ocean
entry. Surface flows were noted on the coastal plain and incandescence
was seen at the base of the pali. Explosions at the ocean entry were
seen on 31 December and 5 January.

Earthquakes strong enough to be located were variously scattered
beneath 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. Consistent with a
decreasing trend of ash production since 15 December, the vent
produced minimal amounts of fine tephra; essentially no tephra was
collected during 5-6 January. Sounds resembling rockfalls were
sometimes heard in the vicinity of the crater. The sulfur dioxide
emission rate at the summit was 500 tonnes per day on 31 December and
2 January; 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/


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 26 December-2 January. Strombolian activity was
noted on 25 and 27 December, and lava effusion on the NW flank
continued. On 25 December gas-and-steam plumes containing ash rose to
an altitude of 5.5 km (18,000 ft) a.s.l. Analysis of satellite imagery
revealed a large daily thermal anomaly in the crater. Ash plumes
drifted 250 km NE during 25-26 December. On 27 December ashfall was
reported in Kozyrevsk village. The Tokyo VAAC reported that on 2
January ash plumes were continuously observed on satellite imagery.

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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT)
http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html


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

Based on analysis of satellite imagery and pilot observations, the
Darwin VAAC reported that on 31 December, 1 January, and 3-5 January,
ash plumes from Rabaul caldera's Tavurvur cone rose to an altitude 2.4
km (8,000 ft) a.s.l. and drifted W, NW, NNW, and SE.

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


SANGAY Ecuador 2.002°S, 78.341°W; summit elev. 5230 m

Based on a pilot observation, the Washington VAAC reported that on 5
January an ash plume from Sangay rose to an altitude of 7 km (23,000
ft) a.s.l. and drifted S. Ash was not identified on satellite imagery.

Geologic Summary. The isolated Sangay volcano, located E of the Andean
crest, is the southernmost of Ecuador's volcanoes, and its most
active. It has been in frequent eruption for the past several
centuries. The steep-sided, 5,230-m-high glacier-covered volcano grew
within horseshoe-shaped calderas of two previous edifices, which were
destroyed by collapse to the E, producing large debris avalanches that
reached the Amazonian lowlands. The modern edifice dates back to at
least 14,000 years ago. Sangay towers above the tropical jungle on the
E side; on the other sides flat plains of ash from the volcano have
been sculpted by heavy rains into steep-walled canyons up to 600 m
deep. The earliest report of an historical eruption was in 1628. More
or less continuous eruptions were reported from 1728 until 1916, and
again from 1934 to the present. The more or less constant eruptive
activity has caused frequent changes to the morphology of the summit
crater complex.

Source: Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html


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

Based on analysis of satellite imagery, the Washington VAAC reported
that two small ash plumes from Santa María's Santiaguito lava dome
complex drifted ESE on 1 January. During 4-5 January, gas and steam
plumes possibly containing some ash drifted SW and WSW. INSIVUMEH
reported that on 5 and 6 January fumarolic plumes drifted 100 m above
the crater. Five explosions produced ash plumes that rose to altitudes
of 2.8-3 km (9,200-10,000 ft) a.s.l. and drifted W and SE. A few
avalanches originating from a lava flow descended the W flank.

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.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia,
e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/,
Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/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 25 December-2 January. Based on interpretations of
seismic data, ash plumes rose to an altitude of 7 km (23,000 ft)
a.s.l. on 25 and 26 December, and to an altitude of 5.5 km (18,000 ft)
a.s.l. on the other days during the reporting period. An ash plume was
seen on 25 December at an altitude of 5.5 km (18,000 ft) a.s.l. and
gas-and-steam emissions were noted on 25 and 30 December, and on 1
January. Analysis of satellite imagery revealed a daily thermal
anomaly on the lava dome and an ash plume that drifted 40 km NW on 30
December. The Level of Concern Color Code remained at Orange.

Based on information from KEMSD and analysis of satellite imagery, the
Tokyo VAAC reported that during 1, 2, 5, and 6 January eruptions
produced plumes to altitudes of 4.6-5.8 km (15,000-19,000 ft) a.s.l.

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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT)
http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html


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

Based on information from JMA, the Tokyo VAAC reported an eruption
from Suwanose-jima on 3 January. A plume rose to an altitude of 1.2 km
(4,000 ft) a.s.l. and drifted E.

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


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

Based on a SIGMET notice, the Buenos Aires VAAC reported that on 5
January an ash plume from Ubinas rose to an altitude of 5.5 km (18,000
ft) a.s.l. and drifted SE.

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