GVP/USGS Weekly Volcanic Activity Report 26 December 2007-1 January 2008

Kimberly Genareau <kgenarea@xxxxxxx> · Wed, 2 Jan 2008 13:51:11 -0700

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GVP/USGS Weekly Volcanic Activity Report
26 December 2007-1 January 2008
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Sally Kuhn Sennert - Weekly Report Editor

URL: http://www.volcano.si.edu/reports/usgs/

New Activity/Unrest: | Llaima, Chile | Sangay, 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
(http://www.volcano.si.edu/reports/usgs/index.cfm) 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
(http://www.volcano.si.edu/reports/usgs/index.cfm?content=disclaimers).
Carefully reviewed, detailed reports on various volcanoes are
published monthly in the Bulletin of the Global Volcanism Network
(http://www.volcano.si.edu/reports/bulletin/).

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

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

Based on pilot reports and observations of satellite imagery, the
Buenos Aires VAAC reported that an ash plume from Llaima rose to an
altitude of 12.5 km (41,000 ft) a.s.l. and drifted E and ESE on 1
January. Lava was visible on the E flank and fumaroles at the summit
were noted. According to a news article, the Alert level was raised to
Yellow affecting four nearby communities resulting in the evacuation
of 150 tourists and National Forest Service employees.

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

Associated Press
http://ap.google.com/article/ALeqM5h6XCGT4X37OvMVvC6CA6UaDMeriAD8TTG8100,

Radio Universidad de Chile

http://www.radio.uchile.cl/notas.aspx?idNota=43037

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

Based on observations of satellite imagery and pilot reports, the
Washington VAAC reported that an ash plume from Sangay rose to an
altitude of 6.1 km (20,000 ft) a.s.l. on 26 December and drifted SW. A
thermal anomaly was seen on satellite imagery during 26-27 December.

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

Ongoing Activity

ANATAHAN United States 16.35°N, 145.67°E; summit elev. 790 m

Low-level tremor at Anatahan continued during 21-29 December. On 31
December, the Washington VAAC reported that a gas-and-steam plume with
low ash content was visible on satellite imagery and drifted NW. The
Volcanic Alert Level remained at Advisory and the Aviation Color Code
remained at Yellow.

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

Sources: Emergency Management Office of the Commonwealth of the
Mariana Islands and the US Geological Survey Hawaiian Volcano
Observatory http://volcano.wr.usgs.gov/cnmistatus.php,

Washington Volcanic Ash Advisory Center (VAAC)

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

BAGANA Papua New Guinea 6.140°S, 155.195°E; summit elev. 1750 m

Based on observations of satellite imagery, the Darwin VAAC reported
that an ash-and-steam plume from Bagana drifted WSW on 26 December. A
plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted W on
27 December. RVO advised that intermittent activity was continuing.

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

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

According to a news article, activity from Colima increased during
29-30 December. An ash plume was visible on 29 December. On 30
December, incandescent material was propelled from the summit and
white and gray plumes rose to altitudes of 4-4.3 km (13,100-14,100 ft)
a.s.l. and drifted SE, W, and NW. Authorities recommended that people
avoid valleys surrounding the volcano.

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: Notimex http://www.milenio.com/index.php/2007/12/31/169817/

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

Based on observations of satellite imagery, the Washington VAAC
reported that a probable ash plume from Fuego drifted N on 26
December.

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

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

INGEOMINAS reported that an ash-and-gas plume from Galeras rose to an
altitude of 4.9 km (16,100 ft) a.s.l. and drifted NW on 31 December.
The emission was associated with an episode of spasmodic tremor.
Another plume rose to an altitude of 4.5 km (14,800 ft) a.s.l. and
drifted S.

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

http://www.ingeominas.gov.co/

KILAUEA United States 19.421°N, 155.287°W; summit elev. 1222 m

Based on overflights and web camera views when weather permitted, HVO
reported that during 25 December -1 January activity from fissure
segment D from Kilauea's 21 July fissure eruption was concentrated at
the Thanksgiving Eve Breakout (TEB) shield and two satellitic shields
to the SE. Short lava flows were noted to the SE and N. During 25-26
December, bursts of high-frequency tremor were noted every 70-90
minutes and interpreted as episodic spattering events near fissure D.
Incandescence was visible from one of the lava seeps E of the perched
lava channel on 1 January. Tremor remained low below Pu'u 'O'o crater.
A few small earthquakes were located beneath the summit and along the
S-flank fault, SW rift zone, and 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. The latest Kilauea
eruption began in January 1983 along the E rift zone. This long-term
ongoing eruption from Pu`u `O`o-Kupaianaha has produced lava flows
that have traveled 11-12 km from the vents to the sea, paving about
104 km2 of land on the S flank of Kilauea and building 207 hectares of
new land.

Source: US Geological Survey Hawaiian Volcano Observatory

http://volcano.wr.usgs.gov/hvostatus.php

MANAM Papua New Guinea 4.080°S, 145.037°E; summit elev. 1807 m

Based on observations of satellite imagery and reports from RVO, the
Darwin VAAC reported that an ash plume from Manam rose to an altitude
of 3 km (10,000 ft) a.s.l. on 27 December and drifted N.

Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the
northern coast of mainland Papua New Guinea, is one of the country's
most active volcanoes. Four large radial valleys extend from the
unvegetated summit of the conical 1807-m-high basaltic-andesitic
stratovolcano to its lower flanks. These "avalanche valleys,"
regularly spaced 90 degrees apart, channel lava flows and pyroclastic
avalanches that have sometimes reached the coast. Two summit craters
are present; both are active, although most historical eruptions have
originated from the southern crater, concentrating eruptive products
during much of the past century into the SE avalanche valley. Frequent
historical eruptions, typically of mild-to-moderate scale, have been
recorded at Manam since 1616. Occasional larger eruptions have
produced pyroclastic flows and lava flows that reached flat-lying
coastal areas and entered the sea, sometimes impacting populated
areas.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

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

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

The Toulouse VAAC reported that an ash plume from Ol Doinyo Lengai was
observed by visiting scientists on 29 December and rose to an
unreported altitude.

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

Source: Toulouse Volcanic Ash Advisory Center (VAAC)

http://www.ssd.noaa.gov/VAAC/OTH/FR/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 30 December-1 January. On 31 December, a
13-minute-long high-frequency tremor event was followed by an emission
of a plume with low ash content. The plume rose to an altitude of 7.4
km (24,300 ft) a.s.l. and drifted E and SE.

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.

Sources: Centro Nacional de Prevencion de Desastres (CENAPRED)

http://www.cenapred.unam.mx/cgi-bin/popo/reportes/ultrep.cgi,

Washington Volcanic Ash Advisory Center (VAAC)

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

SHIVELUCH 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 December. Gas-and-steam plumes rose to an altitude
of 3.5 km (11,500 ft) a.s.l. during 23-24 December. Based on
observations of satellite imagery, a thermal anomaly was present in
the crater every day. The Level of Concern Color Code remained at
Orange.

Based on observations of satellite imagery and information from the
KEMSD, the Tokyo VAAC reported that eruption plumes rose to altitudes
of 4.9-5.8 km (16,000-19,000 ft) a.s.l. during 28-29 December.

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/updates.shtml,

Tokyo Volcanic Ash Advisory Center (VAAC)

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

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

MVO reported that during 24-28 December the lava dome at Soufrière
Hills changed very little, based on visual observations. Seismic
activity was very low and low-level rockfall activity occurred in the
Tar River valley. Fumarolic activity on the N and E flanks of the dome
and W in the Gages Wall area continued. 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

http://www.mvo.ms/

ST. HELENS United States 46.20°N, 122.18°W; summit elev. 2549 m

Data from deformation-monitoring instruments indicated that during 26
December-1 January 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

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 occasionally
limited due to cloud cover, ash-and-steam and ash plumes from
Tungurahua were seen and rose to altitudes of 6-8 km (19,700-26,200
ft) a.s.l. during 25 December-1 January. Plumes drifted predominantly
W and ashfall was reported in areas downwind and to the SW and N.
Roaring noises and "cannon shots" were heard almost daily and windows
and floors vibrated on 26, 27, and 30 December. During 26-27 December,
incandescent blocks rolled down the flanks as far as 500 m. On 29
December, incandescent material observed at the summit was associated
with explosive events. Incandescent blocks rolled 700 m down the NW
flank on 29 December and 1,200 m down the flanks on 30 December.
Incandescence at the summit was noted again on 31 December during the
night.

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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