SI/USGS Weekly Volcanic Activity Report 11-17 February 2009

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SI/USGS Weekly Volcanic Activity Report
11-17 February 2009
*********************************************************

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


New Activity/Unrest: | Asama, Honshu | Ebeko, Paramushir Island |
Galeras, Colombia | Redoubt, Southwestern Alaska

Ongoing Activity: | Arenal, Costa Rica | Dukono, Halmahera | Karymsky,
Eastern Kamchatka | Kilauea, Hawaii (USA) | Popocatépetl, México |
Rabaul, New Britain | Sakura-jima, Kyushu | Santa María, Guatemala |
Shishaldin, Fox Islands | Shiveluch, Central Kamchatka (Russia) |
Soufrière Hills, Montserrat | 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


ASAMA Honshu 36.403°N, 138.526°E; summit elev. 2568 m

Based on information from JMA, the Tokyo VAAC reported that during
11-12 February eruptions from Asama produced plumes that rose to
altitudes of 3-3.7 km (10,000-12,000 ft) a.s.l. and drifted NE, E, and
SE. JMA reported that on 16 and 17 February eruptions produced colored
plumes containing ash that rose to an altitude of 3 km (10,000 ft)
a.s.l. and drifted E. Incandescence in the crater was seen on web
cameras.

Geologic Summary. Asama, Honshu's most active volcano, is located at
the junction of the Izu-Marianas and NE Japan arcs and has an
historical record dating back at least to the 11th century. The modern
cone of Maekake-yama is situated E of the horseshoe-shaped remnant of
an older andesitic volcano, Kurofu-yama, which was destroyed by a
late-Pleistocene landslide about 20,000 years before present (BP).
Growth of a dacitic and rhyolitic lava cone was accompanied by
pumiceous pyroclastic flows, the largest of which occurred about
14,000-11,000 years BP, and by growth of the Ko-Asama-yama lava dome
on the E flank. Maekake-yama is probably only a few thousand years
old, but has had several major Plinian eruptions, the last two of
which occurred in 1108 and 1783 AD.

Sources: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/indexe.html,
Tokyo Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html


EBEKO Paramushir Island 50.68°N, 156.02°E; summit elev. 1156 m

Based on analysis of satellite imagery and information from Yelizovo
Airport, the Tokyo VAAC reported that on 11 February an ash plume
drifted NE from Ebeko at an altitude of 0.6 km (2,000 ft) a.s.l. On 17
February, an ash plume drifted SW at an altitude of 1.2 km (4,000 ft)
a.s.l.

Geologic Summary. The flat-topped summit of the central cone of Ebeko
volcano, one of the most active in the Kuril Islands, occupies the
northern end of Paramushir Island. Three summit craters located along
a SSW-NNE line form Ebeko volcano proper, at the northern end of a
complex of five volcanic cones. The eastern part of the southern
crater of Ebeko contains strong solfataras and a large boiling spring.
The central crater of Ebeko is filled by a lake about 20 m deep whose
shores are lined with steaming solfataras; the northern crater lies
across a narrow, low barrier from the central crater and contains a
small, cold crescentic lake. Historical activity, recorded since the
late-18th century, has been restricted to small-to-moderate explosive
eruptions from the summit craters. Intense fumarolic activity occurs
in the summit craters of Ebeko, on the outer flanks of the cone, and
in lateral explosion craters.

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


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

INGEOMINAS reported an explosive eruption from Galeras that began at
1910 on 14 February; the Alert Level was raised from III (Yellow;
"changes in the behavior of volcanic activity") to I (Red; "imminent
eruption or in progress"), on a scale of 4-1. An accompanying shock
wave was detected in multiple areas, including in parts of Pasto
(about 10 km E). The altitude of the resultant ash plume was not known
nor observed on satellite images due to cloud cover. From about 1930
until 2030 ashfall, rain, and an odor of sulfur gas were reported on
the slopes of the volcano as well as in Pasto. Ash deposits were
mainly in areas to the E and as far away as 25 km. Seismicity returned
at 1950 to similar levels recorded prior to the eruption and remained
low. On 16 February, the Alert Level was lowered to II (Orange;
"probable eruption in term of days or weeks"). During 16-17 February,
small steam plumes rose to altitudes of 4.6-6.7 km (15,100-22,000 ft)
a.s.l. and drifted SE, E, and NE.

According to news articles, authorities ordered the evacuation of
about 8,000 people living on the slopes, but few went to evacuation
shelters.

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.

Sources: Instituto Colombiano de Geología y Minería (INGEOMINAS)
http://www.ingeominas.gov.co//,
Agence France-Presse
http://www.google.com/hostednews/afp/article/ALeqM5heHGCmJjg6GrYeMK3MSrZn-3JYRw,
Caracol Radio http://www.caracol.com.co/nota.aspx?id=763627


REDOUBT Southwestern Alaska 60.485°N, 152.742°W; summit elev. 3108 m

AVO reported that during 10-17 February seismic activity at Redoubt
was variable but remained elevated above background levels. Web camera
views were often obscured by snow, clouds, or ice on the camera
housing. On 10 February, scientists noted that the outflow stream on
the W side of Drift Glacier was frozen.

Geologic Summary. Redoubt is a 3108-m-high glacier-covered
stratovolcano with a breached summit crater in Lake Clark National
Park about 170 km SW of Anchorage. Next to Mount Spurr, Redoubt has
been the most active Holocene volcano in the upper Cook Inlet.
Collapse of the summit of Redoubt 10,500-13,000 years ago produced a
major debris avalanche that reached Cook Inlet. Holocene activity has
included the emplacement of a large debris avalanche and clay-rich
lahars that dammed Lake Crescent on the south side and reached Cook
Inlet about 3500 years ago. Eruptions during the past few centuries
have affected only the Drift River drainage on the north. Historical
eruptions have originated from a vent at the north end of the
1.8-km-wide breached summit crater. The 1989-90 eruption of Redoubt
had severe economic impact on the Cook Inlet region and affected air
traffic far beyond the volcano.

Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/


Ongoing Activity


ARENAL Costa Rica 10.463°N, 84.703°W; summit elev. 1670 m

OVSICORI-UNA reported that during January, activity originating from
Arenal's Crater C consisted of gas emissions, sporadic Strombolian
eruptions, and occasional avalanches from lava-flow fronts that
traveled down the SW flanks. Volcanic activity was at relatively low
levels and few eruptions occurred. Acid rain and small amounts of
ejected pyroclastic material affected the NE and SE flanks. Eruptions
produced ash plumes that rose about 2.2 km (7,100 ft) a.s.l. Small
avalanches of volcanic material traveled down several ravines. Crater
D showed only fumarolic activity.

Geologic Summary. Conical Volcan Arenal is the youngest stratovolcano
in Costa Rica and one of its most active. The 1,657-m-high andesitic
volcano towers above the eastern shores of Lake Arenal, which has been
enlarged by a hydroelectric project. The earliest known eruptions of
Arenal took place about 7,000 years ago. Growth of Arenal has been
characterized by periodic major explosive eruptions at
several-hundred-year intervals and periods of lava effusion that armor
the cone. Arenal's most recent eruptive period began with a major
explosive eruption in 1968. Continuous explosive activity accompanied
by slow lava effusion and the occasional emission of pyroclastic flows
has occurred since then from vents at the summit and on the upper
western flank.

Source: Observatorio Vulcanologico y Sismologico de Costa
Rica-Universidad Nacional (OVSICORI-UNA)
http://www.ovsicori.una.ac.cr/


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

Based on analysis of satellite imagery, the Darwin VAAC reported that
an ash plume from Dukono drifted SE at an altitude of 3 km (10,000 ft)
a.s.l. on 11 February.

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


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

KVERT reported that seismic activity at Karymsky was above background
levels during 6-9 February and at background levels during 10-13
February. Ash explosions produced plumes that rose to an altitude of
2.5 km (8,200 ft) a.s.l. Clouds prevented satellite observations. 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 11-17 February lava flowed SE from underneath
Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex
through a lava tube system, reaching the Waikupanaha and Waha'ula
ocean entries. On most days, multiple explosions and spatter at the
ocean entry were seen. On 11 February, geologists found a new littoral
cone, on the edge of the bench, with a large crack running through it.
Spatter on the cone and the bench behind it resulted from lava bubble
bursts and steam jetting reported during the previous two days. A
second crack between the cone and the sea cliff was also noted. The
cracks suggested that the bench was slowly failing and did not
collapse as reported a few days prior. Occasional incandescence
originated from the Prince lobe, the flow that feeds the Waha'ula
ocean entry. Thermal anomalies suggesting surface flows were noted on
the coastal plain and on the pali.

The vent in Halema'uma'u crater continued to produce a predominantly
white plume that drifted mainly SW; incandescence was intermittently
seen from the vent. Small amounts of tephra, including Pele's hair and
some spatter, were routinely collected. Infrared images taken during
an overflight on 11 February revealed the development of a small
spattering cone over the conduit that hosted a lava pond the previous
week. Images taken on 14 February indicated that the conduit had
mostly crusted over; a small, puffing vent was visible. The sulfur
dioxide emission rate at the summit was 800 tonnes per day on 12
February, and 500 tonnes on 13 February; 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/


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 11-17 February; the plumes occasionally contained
slight amounts of ash. On 13 February, a plume with low ash content
rose to an altitude of 7.2 km (23,600 ft) a.s.l. and drifted NE at
2230; 95 minutes of increased seismicity followed.

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


RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m

Based on analysis of satellite imagery, the Darwin VAAC reported that
during 13-14 February ash plumes from Rabaul caldera's Tavurvur cone
rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE and W.
On 17 February, a low-level ash plume drifted 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


SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m

Based on analysis of satellite imagery and pilot observations, the
Tokyo VAAC reported that during 11-12 February ash plumes from
Sakura-jima rose to altitudes of 1.2-1.5 km (4,000-5,000 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 analysis of satellite imagery, the Washington VAAC reported
that on 12 February ash puffs from Santa María's Santiaguito lava dome
complex drifted WSW and W. On 16 and 17 February, INSIVUMEH reported
that explosions produced ash plumes that rose to altitudes of 2.7-3.3
km (8,900-10,800 ft) a.s.l. and drifted SW. Small pyroclastic flows on
16 February descended the SE flank and reached the Nima I river. On 17
February, incandescent avalanches were noted and fumarolic plumes
drifted SW.

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


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

AVO reported that seismic activity from Shishaldin had returned to
background levels in December 2008 and remained low. On 3 February, a
weak thermal anomaly was detected on satellite imagery. The Aviation
Color Code was lowered to Green and the Volcano Alert Level was
lowered to Normal on 11 February.

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/


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 6-13 February. Based on interpretations of seismic data,
ash plumes likely rose to altitudes of 5.5 km (18,000 ft) a.s.l. Lava
flows continued to be active on the S and N flanks. Analysis of
satellite imagery revealed a thermal anomaly on the lava dome during 6
and 8-10 February; clouds prevented observations on the other days
during the reporting period. The Level of Concern Color Code remained
at Orange.

Based on information from KEMSD, the Tokyo VAAC reported that an
eruption on 12 February produced a plume that rose to an altitude of
4.6 km (15,000 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


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

MVO reported that during 6-13 February activity from the Soufrière
Hills lava dome was at a low level. Two rockfalls were detected and
seismicity was low. On 13 February, one small pyroclastic flow that
originated in a gully on the N side of the lava dome traveled less
than 1 km. The Hazard Level remained at 4.

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/


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

The IG reported that although visual observations of Tungurahua were
occasionally limited due to cloud cover; gas-and-ash plumes were seen
and rose to altitudes of 5.5-7.5 km (18,000-24,600 ft) a.s.l. during
11-17 February. Plumes drifted W, NE, E, and SE. On 11 February, small
lahars descended multiple gorges to the NW and S. Incandescence in the
crater was seen at night on 11 and 12 February, and roaring was heard
on 12 and 16 February. Ashfall was reported in areas to the SW on 12
February and to the N on 14 February. An explosion on 16 February that
vibrated windows was followed by ash emissions that generated a plume
to an altitude of 8 km (26,200 ft) a.s.l. The plume drifted W.

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

INGEMMET reported that although cloud cover occasionally prevented
visual observations of Ubinas, steam and steam-and-ash plumes were
seen during 11-16 February and rose to altitudes of 5.7-6.5 km
(18,700-21,300 ft) a.s.l. The plumes drifted NE, N, W, and 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: Instituto Geológical Minero y Metalúrgico (INGEMMET)
http://www.ingemmet.gob.pe/


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