GVP/USGS Weekly Volcanic Activity Report 30 January-5 February 2008

Kimberly Genareau <kgenarea@xxxxxxx> · Wed, 6 Feb 2008 12:00:36 -0700

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GVP/USGS Weekly Volcanic Activity Report
30 January-5 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) |
Guagua Pichincha, Ecuador | Llaima, Central Chile

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 elevated seismic tremor levels at Anatahan were
detected during the last week in January through 5 February.
Observations of satellite imagery showed that the lake in the E crater
had disappeared, and steam and sulfur dioxide plumes drifted generally
W and SW. On 3 February, an ash plume rose to an estimated altitude of
below 2.3 km (7,500 ft) a.s.l. and drifted W. On 5 February, the USGS
announced that the Volcanic Alert Level was raised to Watch and the
Aviation Color Code was raised to Orange as a result of the observed
ash emissions.

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.

Source: 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

GUAGUA PICHINCHA Ecuador 0.171°S, 78.598°W; summit elev. 4784 m

IG reported seven moderate phreatic explosions from Guagua Pichincha
on 1 February, following a few weeks of slightly increased internal
activity and a few days of almost constant precipitation. IG
recommended that visitors stay away from inside the caldera.

Geologic Summary. Guagua Pichincha rises immediately west of Quito,
Ecuador's capital city. The broad volcanic massif is cut by a large
horseshoe-shaped summit caldera, ~6 km in diameter and 600 m deep,
that was breached to the W during a slope failure ~50,000 years ago.
Subsequent late-Pleistocene and Holocene eruptions from the central
vent consisted of explosive activity with pyroclastic flows
accompanied by periodic lava dome growth and destruction. A major
eruption in 1660 deposited 30 cm of ash in Quito, but most of the many
eruptions since the Spanish colonial era have been minor. The latest
eruptive period began with phreatic explosions in 1998. Magmatic
eruptions first occurred in October 1999, and intermittent eruptions
of varying scale since have blanketed Quito and surrounding towns with
ash.

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

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

SERNAGEOMIN reported that eruptive activity at Llaima continued from
the main crater and from multiple areas on the E flank during 30
January-4 February. An overflight on 28 January revealed Strombolian
eruptions from a central pyroclastic cone in the main crater
accompanied by emissions of ash and ballistic fragments. The craters
surrounding the cone were incandescent and emitted bluish sulfur
dioxide. Ash-and-gas plumes drifted WSW. A pyroclastic flow deposit
was seen on the E flank. During 29 January-1 February, Strombolian
eruptions were seen when weather permitted and emissions of ash and
gases formed plumes that rose to altitudes of 3.6-6.1 km
(11,800-20,000 ft) a.s.l. and drifted SW, SE, NE, and NW. Sporadic
activity from the N and S lateral fissures on the E flank was also
noted. During 1-2 February, ballistics propelled from the main crater
landed both inside and outside of the crater. Strombolian activity
declined on 2 February and steam and ash plumes rose to altitudes of
4.6-9.1 km (15,100-29,900 ft) a.s.l. and drifted NW. Emissions from
multiple points along fissures on the E flank were noted.

On 3 February, material from intense Strombolian activity was
propelled 500 m above the crater floor and fell inside and outside of
the crater. Multiple lava flows from the W edge of the main crater
descended about 150 m. Incandescent blocks from lava-flow fronts
rolled down the flank. Plumes rose to an approximate altitude of 4.6
km (15,100 ft) a.s.l. and drifted WNW. Lava flows originating from a
lava lake were observed during an overflight. These flows extended
about 1.5-2 km in length and caused strong steam plumes due to their
interaction with a glacier. According to a news article, about 20
people were evacuated from an area of La Selva, in the community of
Vilcún (43 km W).

Activity was similar on 4 February. A phreatic explosion on the E
flank was accompanied by steam plumes and a small pyroclastic flow.
Orange ash emissions were noted from the S lateral fissure. Ash plumes
from the main crater rose to an altitude of 6 km (19,700 ft) a.s.l.
and drifted E.

Based on pilot observations, the Buenos Aires VAAC reported that ash
plumes rose to altitudes of 4.6-6.7 km (15,000-22,000 ft) a.s.l. and
drifted SE, NE, and W during 5-6 February.

Geologic Summary. Llaima, one of Chile's largest and most active
volcanoes, contains two 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/,

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

Relief Web http://www.reliefweb.int/rw/RWB.NSF/db900SID/LRON-7BHE54?OpenDocument

Ongoing Activity

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

On 4 February, CVGHM reported that since 9 October 2007, white plumes
from Batu Tara were a daily occurrence. On 8 January, gray plumes rose
to an altitude of 1.5 km (4,900 ft) a.s.l. and drifted E. On 26 and 30
January, white plumes rose to altitudes of 1.5-1.7 km (4,900-5,600 ft)
a.s.l. and also drifted E. The Darwin VAAC reported that eruption
plumes were observed from a ship on 31 January, but ash was not
identified on satellite imagery. The Alert level remained at 1 (on a
scale of 1-4).

Geologic Summary. The small isolated island of Batu Tara in the Flores
Sea about 50 km north of 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.

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

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

Based on observations of satellite imagery, the Washington VAAC
reported that ash plumes from Fuego rose to an altitude of 5 km
(16,500 ft) a.s.l. and drifted W on 4 February.

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.

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

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

Based on observations during overflights, and web camera views when
weather permitted, HVO reported that during 30 January-5 February
activity from Kilauea's fissure segment D was concentrated at 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 N end. On 30 January, the channelized 'a'a
lava flow from a rootless shield that collapsed on 26 January
advanced, burning small kipukas and another small area of the Royal
Gardens subdivision. The lava flow was inactive the next day. During
30-31 February, the rootless shields at the SE end of the field
(within 2 km of fissure D) issued abundant lava flows overnight. The
lava pond within the Shield-4 collapse overflowed several times; lava
flows advanced S.

Incandescence was observed in Pu'u 'O'o crater for less than 10
minutes at a time every day during the reporting period. A few small
earthquakes were located beneath Halema'uma'u crater and along the
S-flank faults, SW rift zone, and upper E rift zone.

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/

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 30 January-5 February. The plumes occasionally
contained slight amounts of ash. On 4 February, ash emissions were
accompanied by an explosion that propelled incandescent fragments 300
m from the crater.

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 gray and brown ash plumes and steam plumes from
Rabaul caldera's Tavurvur cone rose to altitudes of 0.9-2.7 km
(3,000-8,900 ft) a.s.l. and drifted E and SE during 31 January-5
February. Incandescence from the center of the crater was visible
almost every night. On 1 February, ashfall was reported in Kokopo,
about 20 km SE. Roaring noises were heard from near-by areas during
1-3 February. On 4 February, a strong smell of hydrogen sulfide gas
was reported from Rabaul Town (3-5 km NW).

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 3 February produced plumes that rose to altitudes
of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted SE. Ash was not
detected on satellite imagery. On 5 February, a pilot reported an ash
plume at an altitude of 2.1 km (7,000 ft) a.s.l.

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

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

Based on observations of satellite imagery, the Washington VAAC
reported that gas plumes with possible ash content from Santa María's
Santiaguito lava dome complex drifted SW on 30 January. Ash plumes
drifted WNW on 3 February.

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.

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

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

KVERT reported that seismic activity at Shiveluch was slightly above
background levels during 25 January-1 February. Based on seismic
interpretation, ash plumes rose to an altitude of 3.9 km (12,800 ft)
a.s.l. daily. Fumarolic activity was noted on 24, 29, and 30 January.
According to observations of satellite imagery, a thermal anomaly was
present in the crater every day during the reporting period. 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

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

MVO reported that that during 30 January-5 February the lava dome at
Soufrière Hills changed very little, based on visual observations
during an over flight on 30 January and from multiple locations.
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
and 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 30
January-5 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 occasionally 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://vulcan.wr.usgs.gov/Volcanoes/MSH/CurrentActivity/framework.html

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

IG reported that although visual observations were limited due to
cloud cover, ash plumes were spotted and rose to altitudes of 6-9 km
(19,700-29,500 ft) a.s.l. during 30 January-5 February. Ash plumes
drifted mainly W, NW, and E, and ashfall was also reported in areas to
the SW, N, and NE. Roaring noises and "cannon shots" were heard almost
everyday and the seismic network detected between 65-208 explosions
daily.

On 30 January, incandescence at the summit was observed at night and
incandescent blocks that were propelled from the summit by explosions
rolled 600 m down the W flank. Explosions rattled windows as far away
as the Tungurahua Observatory (OVT) in Guadalupe, about 13 km NW. A
lahar descended the Mandur drainage, to the NW. On 1 and 4 February,
incandescence at the summit was again noted and incandescent blocks
traveled down the flanks. On 4 February, heavy ashfall to the SW was
reported and explosions rattled windows in near-by areas. On 5
February, ashfall was reported in areas to the NW.

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
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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