SI/USGS Weekly Volcanic Activity Report 26 November-2 December 2008

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***********************************************************
SI/USGS Weekly Volcanic Activity Report
26 November-2 December 2008
***********************************************************

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


New Activity/Unrest: | Akan, Hokkaido (Japan) | Karangetang [Api
Siau], Sangihe Islands (Indonesia) | Kliuchevskoi, Central Kamchatka
(Russia) | Piton de la Fournaise, Reunion Island | Soufrière Hills,
Montserrat

Ongoing Activity: | Bagana, Bougainville Island (SW Pacific) |
Chaitén, Southern Chile | Galeras, Colombia | Karymsky, Eastern
Kamchatka | Kilauea, Hawaii (USA) | Masaya, Nicaragua | Popocatépetl,
México | Rabaul, New Britain (SW Pacific) | Shiveluch, Central
Kamchatka (Russia) | Tungurahua, Ecuador | 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


AKAN Hokkaido (Japan) 43.384°N, 144.013°E; summit elev. 1499 m

JMA reported an eruption from Me-Akan (also known as Meakan-dake,
which means Meakan Peak) of the Akan volcanic complex on 28 November.
Ash plumes rose to an altitude of 2 km (6,600 ft) a.s.l. and drifted
N, E, and SE. Ash was deposited on the E flank up to 4 km away from
the crater. The Alert Level remained at "near-crater warning" (levels
2 and 3 on a 5-level scale).

Geologic Summary. Akan is a 13 x 24 km, elongated caldera that formed
more than 31,500 years ago immediately SW of Kutcharo caldera. Growth
of four post-caldera stratovolcanoes, three at the SW end of the
caldera and the other at the NE side, has restricted the size of the
caldera lake. The 1-km-wide Nakamachineshiri crater was formed during
a major pumice-and-scoria eruption about 13,500 years ago. Of the
Holocene volcanoes of the Akan volcanic complex, only the Me-Akan
group, E of Lake Akan, has been historically active, producing mild
phreatic eruptions since the beginning of the 19th century. Me-Akan is
composed of 9 overlapping cones. The main cone of Me-Akan proper has a
triple crater at its summit. Historical eruptions at Me-Akan have
consisted of minor phreatic explosions, but four major magmatic
eruptions including pyroclastic flows have occurred during the
Holocene.

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


KARANGETANG [API SIAU] Sangihe Islands (Indonesia) 2.78°N, 125.40°E;
summit elev. 1784 m

CVGHM reported that on 28 November seismicity from Karangetang
increased and indicated rockfalls. White plumes rose from summit
craters I and II to approximate altitudes of 1.8-2.2 km (5,900-7,200
ft) a.s.l. On 29 November white and brownish plumes rose to an
altitude of 1.8 km (5,900 ft) a.s.l. Incandescent rockslides from the
main crater traveled 250 m S towards the Bahembang River, 250 m W
towards the Beha Timur River, and 500-1,000 m S towards the Keting
River. Thunderous noises were reported. On 30 November, fog prevented
visual observations; the seismic network recorded 160 rockfalls. On 1
December, incandescent rockslides traveled 250 m S towards the
Bahembang River, 750 m W towards the Beha Timur River, and 500-1,500 m
S towards the Keting River. On 2 December, the Alert Level was raised
to 3 (on a scale of 1-4) due to the continuation of elevated
seismicity, run-out distances of incandescent rockslides, and height
of incandescent material ejected from the summit.

Based on analysis of satellite imagery and information from CVGHM, the
Darwin VAAC reported that on 2 December an ash plume from Karangetang
rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted W.

Geologic Summary. Karangetang (also known as Api Siau) lies at the
northern end of the island of Siau, N of Sulawesi, and contains five
summit craters strung along a N-S line. One of Indonesia's most active
volcanoes, Karangetang has had more than 40 recorded eruptions since
1675. Twentieth-century eruptions have included frequent explosions,
sometimes accompanied by pyroclastic flows and lahars.

Sources: Center of Volcanology and Geological Hazard Mitigation
(CVGHM) http://portal.vsi.esdm.go.id/joomla/,
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 21-28 November; Strombolian activity and lava
effusion continued. On 21 November, a lava flow traveled 1.5-1.8 km
down the NW flank. Gas-and-steam plumes drifted 80 km NW on 24
November and 20-40 km SE during 25-26 November. Gas-and-steam plumes
containing slight amounts of ash rose to altitudes of 5.3-5.5 km
(17,400-18,000 ft) a.s.l. during 26-27 November. Analysis of satellite
imagery revealed a large daily thermal anomaly in the crater during
21-28 November. The Level of Concern Color Code remained Orange.

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/index_eng.php


PITON DE LA FOURNAISE Reunion Island 21.231°S, 55.713°E; summit elev. 2632 m

OVPDLF reported that on 28 November after a period of increased
seismicity Piton de la Fournaise erupted from the same vent that
produced lava flows on 21 September. Lava flows issued from a fissure
about halfway up the W wall of Dolomieu crater and ponded at the
bottom, covering about 50 percent of the 21 September lava flow. A
small quantity of Pele's hair was deposited inside Bory crater.

Geologic Summary. Massive Piton de la Fournaise shield volcano on the
island of Réunion is one of the world's most active volcanoes. Most
historical eruptions have originated from the summit and flanks of a
400-m-high lava shield, Dolomieu, that has grown within the youngest
of three large calderas. This depression is 8 km wide and is breached
to below sea level on the eastern side. More than 150 eruptions, most
of which have produced fluid basaltic lava flows within the caldera,
have been documented since the 17th century. The volcano is monitored
by the Piton de la Fournaise Volcano Observatory, one of several
operated by the Institut de Physique du Globe de Paris.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPDLF)
http://ovpf.univ-reunion.fr/


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

MVO reported that during 21-28 November the activity level at the
Soufrière Hills lava dome remained low, and there was no evidence of
lava extrusion. Rockfalls were detected by the seismic network. The
lava dome continued to emit steam vigorously from multiple places,
including new fumarolic areas on the W and S sides. Long-exposure
photographs revealed several hot spots on the dome. The vertical cliff
face on the W side of the dome was cracked in several places and
erosion was evident at the base.

At approximately 2135 on 2 December, an explosion occurred on the W
side of the lava dome without any precursory seismicity. Large blocks
were ejected up to 1 km from the dome and incandescent blocks were
scattered over the NW side of Gages Mountain (about 1 km WNW). A
pyroclastic flow traveled to the W down Gages valley into Plymouth
(about 5 km W), and further to the sea. Buildings in Plymouth caught
fire and could be seen burning from Salem (about 4 km N of Plymouth)
for several hours afterwards. Ash plumes were accompanied by lightning
strikes and drifted W. The Hazard Level remained at 3.

Based on analysis of satellite imagery, the Washington VAAC reported
that on 28 November a puff of ash and steam drifted SW and S.

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


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 2 December an ash plume from Bagana rose to an altitude of 3 km
(10,000 ft) a.s.l. and drifted NW.

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


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 on
23, 25, 27, and 29 November, and 2 December, ash plumes from Chaitén
rose to altitudes 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE and
NNW. A thermal anomaly was detected on satellite imagery on 25 and 29
November.

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


GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4276 m

INGEOMINAS reported that on 30 November ash emissions from Galeras
were associated with seismic tremor that lasted about 30 minutes.
Resultant ash plumes drifted 6-12.5 km S and SSW.

Geologic Summary. Galeras, a stratovolcano with a large breached
caldera located immediately W of the city of Pasto, is one of
Colombia's most frequently active volcanoes. The dominantly andesitic
Galeras volcanic complex has been active for more than 1 million
years, and two major caldera collapse eruptions took place during the
late Pleistocene. Longterm extensive hydrothermal alteration has
affected the volcano. This has contributed to large-scale edifice
collapse that has occurred on at least three occasions, producing
debris avalanches that swept to the W and left a large
horseshoe-shaped caldera inside which the modern cone has been
constructed. Major explosive eruptions since the mid Holocene have
produced widespread tephra deposits and pyroclastic flows that swept
all but the southern flanks. A central cone slightly lower than the
caldera rim has been the site of numerous small-to-moderate historical
eruptions since the time of the Spanish conquistadors.

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


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 21-23 and 26-28 November. Seismicity increased above
background levels on 24 and 25 November; possible explosions may have
generated ash plumes to an altitude of 3 km (10,000 ft) a.s.l. during
23-25 November. During an overflight, scientists observed
gas-and-steam plumes that rose to altitudes of 2-2.4 km (6,600-7,900
ft) a.s.l. Analysis of satellite imagery revealed a thermal anomaly in
the crater during 20, 22, and 24-26 November. 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 26 November-2 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 seen at the TEB vent. Breakout lava flows low
on the pali fed channelized flows that traveled S towards the Hawai'i
Volcanoes National Park boundary. GPS stations spanning Pu'u 'O'o
Crater recorded almost 4 cm of contraction during the previous 3
months. Earthquakes were variously located beneath and to the S of the
caldera, and along the SW rift zone, the S-flank fault, and the Koa'e
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 occasionally seen at
the base of the plume. The sulfur dioxide emission rate at the summit
was 500 tonnes per day on 26 November; 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/


MASAYA Nicaragua 11.984°N, 86.161°W; summit elev. 635 m

Based on analysis of satellite imagery, the Washington VAAC reported
that on 2 December a plume possibly containing some ash drifted less
than 20 km SW.

Geologic Summary. Masaya is one of Nicaragua's most unusual and most
active volcanoes. It is a broad, 6 x 11 km basaltic caldera with
steep-sided walls up to 300 m high that is filled on its NW end by
more than a dozen vents erupted along a circular, 4-km-wide fracture
system. The twin volcanoes of Nindiri and Masaya, the source of
historical eruptions, were constructed at the southern end of the
fracture system and contain multiple summit craters. A major basaltic
Plinian tephra was erupted from Masaya about 6,500 years ago.
Historical lava flows cover much of the caldera floor and have
confined a lake to the far eastern end of the caldera. A lava flow
from the 1670 eruption overtopped the N caldera rim. Masaya has been
frequently active since the time of the Spanish Conquistadors, when an
active lava lake prompted several attempts to extract the volcano's
molten "gold."

Source: Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.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 26-2 December. The plumes occasionally contained
slight amounts of ash.

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 during 21-27 November light gray ash plumes and
white steam plumes from Rabaul caldera's Tavurvur cone rose to an
altitude of 1.7 km (5,600 ft) a.s.l. and drifted SE, S, SW, and W.
Ashfall was reported in areas downwind. Incandescence from the vent
was observed, and rumbling and roaring noises were reported on some
days. Explosions or forceful emissions sometimes ejected incandescent
lava fragments.

Based on analysis of satellite imagery, the Darwin VAAC reported that
during 30 November-1 December ash plumes rose to an altitude of 3 km
(10,000 ft) a.s.l. and drifted W and WSW.

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.

Sources: Ima Itikarai, Rabaul Volcano Observatory (RVO),
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 21-28 November. Based on interpretations of seismic
data, ash plumes rose to an altitude of 5.6 km (18,400 ft) a.s.l.
Ashfall was reported in the town of Klyuchi, about 30 km SW, on 22
November. Visual observations confirmed that ash plumes rose to an
altitude of 5.5 km (18,000 ft) a.s.l. on 25 November. Fumarolic
activity was visible on the web camera during 26-28 November. Analysis
of satellite imagery revealed a daily thermal anomaly on the lava dome
and a gas-and-steam plume that drifted about 30 km SE on 26 November.
The Level of Concern Color Code remained at Orange.

Based on information from KEMSD and analysis of satellite imagery, the
Tokyo VAAC reported that on 1 December eruptions produced plumes to an
altitude of 4.9 km (16,000 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


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

The IG reported that multiple lahars descended the S, NW, N, and NNE
flanks of Tungurahua on 25 November. A landslide into the Puela River
(to the S) reduced the flow volume by narrowing the river's channel.
Lahars in the Vazcún River (to the N) dragged blocks up to 3 m in
diameter. During 28-29 November, fumarolic activity originated from
the NE and NW areas of the crater.

Geologic Summary. The steep-sided Tungurahua stratovolcano towers more
than 3 km above its northern base. It sits ~140 km S of Quito,
Ecuador's capital city, and is one of Ecuador's most active volcanoes.
Historical eruptions have all originated from the summit crater. They
have been accompanied by strong explosions and sometimes by
pyroclastic flows and lava flows that reached populated areas at the
volcano's base. The last major eruption took place from 1916 to 1918,
although minor activity continued until 1925. The latest eruption
began in October 1999 and prompted temporary evacuation of the town of
Baños on the N side of the volcano.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)
http://www.igepn.edu.ec/


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

Based on a SIGMET notice, the Buenos Aires VAAC reported that on 30
November an ash plume from Ubinas rose to altitudes of 5.5-6.1 km
(18,000-20,000 ft) a.s.l. and drifted SW.

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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