SI/USGS Weekly Volcanic Activity Report 15-21 April 2009

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**********************************************************
SI/USGS Weekly Volcanic Activity Report
15-21 April 2009
**********************************************************

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


New Activity/Unrest: | Ebeko, Paramushir Island | Fernandina,
Galápagos Islands, Ecuador | Kliuchevskoi, Central Kamchatka (Russia)
| NW Rota-1, Mariana Islands | Pagan, Mariana Islands | Paluweh,
Indonesia

Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén,
Southern Chile | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) |
Koryaksky, Eastern Kamchatka | Nevado del Huila, Colombia | Rabaul,
New Britain | Redoubt, Southwestern Alaska | Shiveluch, Central
Kamchatka (Russia) | Suwanose-jima, Ryukyu Islands (Japan) |
Tungurahua, 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 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


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

KVERT reported that during 10-17 April observers from Severo-Kurilsk,
about 7 km E of Ebeko, observed continued activity. Gas-and-steam
plumes with some ash content rose to an altitude of 2.7 km (8,900 ft)
a.s.l. and drifted 15 km SE. The Level of Concern Color Code remained
at Yellow. Based on analysis of satellite imagery and information from
Yelizovo Airport, the Tokyo VAAC reported that on 17 April an ash
plume drifted NE at an altitude of 3 km (10,000 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.

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


FERNANDINA Galápagos Islands, Ecuador 0.37°S, 91.55°W; summit elev. 1,476 m

Based on analysis of satellite imagery and information from IG, the
Washington VVAC reported that during 15-16 April gas-and-steam plumes
from Fernandina drifted up to 555 km W and a thermal anomaly was
detected on the W half of the island. According to news articles, the
eruption caused the deaths of numerous fish and multiple sea lions
that were found floating in the sea.

Geologic Summary. Fernandina, the most active of Galápagos volcanoes
and the one closest to the Galápagos mantle plume, is a basaltic
shield volcano with a deep 5 x 6.5 km summit caldera. The volcano
displays the classic "overturned soup bowl" profile of Galápagos
shield volcanoes. Its caldera is elongated in a NW-SE direction and
formed during several episodes of collapse. Circumferential fissures
surround the caldera and were instrumental in growth of the volcano.
Reporting has been poor in this uninhabited western end of the
archipelago and even a 1981 eruption was not witnessed at the time. In
1968 the caldera floor dropped 350 m following a major explosive
eruption. Subsequent eruptions, mostly from vents located on or near
the caldera boundary faults, have produced lava flows inside the
caldera as well as a lava flow that reached the coast from a SW-flank
vent. Collapse of a nearly 1 cu km section of the east caldera wall
during an eruption in 1988 produced a debris-avalanche deposit that
covered much of the caldera floor and absorbed the caldera lake.

Sources: Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html,
Agence France-Presse
http://www.google.com/hostednews/afp/article/ALeqM5gESLrlrxuZDDvCwlPdNTDjN9PHOA


KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m

KVERT reported that seismic activity from Kliuchevskoi was slightly
above background levels on 11 April and at background levels the other
days during 12-17 April. Satellite imagery revealed gas-and-ash plumes
that drifted 90 km NE on 9 and 10 April, and a weak thermal anomaly
over the volcano on 14 April. Fumarolic activity was seen on 15 and 16
April. The Level of Concern Color remained at Yellow.

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


NW ROTA-1 Mariana Islands 14.601°N, 144.775°E; summit elev. -517 m

According to a news article from 20 April, scientists investigating NW
Rota-1 during the previous two weeks observed the volcano erupting
about 520 m below the ocean’s surface. Measurements indicated that the
volcano had grown about 40 m since 2006. One scientist observed
billowing yellow and white sulfur clouds, carbon dioxide bubbles
streaming out of the vent, and "ash and pebble-sized rocks raining out
of the plume."

Geologic Summary. A submarine volcano detected during a 2003 NOAA
bathymetric survey of the Mariana Island arc was found to be
hydrothermally active and named NW Rota-1. The basaltic to
basaltic-andesite seamount rises to within 517 m of the sea surface SW
of Esmeralda Bank and lies 64 km NW of Rota Island and about 100 km
north of Guam. When Northwest Rota-1 was revisited in 2004, a minor
submarine eruption from a vent named Brimstone Pit on the upper south
flank about 40 m below the summit intermittently ejected a plume
several hundred meters high containing ash, rock particles, and molten
sulfur droplets that adhered to the surface of the remotely operated
submersible vehicle. The active vent was funnel-shaped, about 20 m
wide and 12 m deep. NW Rota-1 is a large submarine volcano with
prominent structural lineaments about a kilometer apart cutting across
the summit of the edifice and down the NE and SW flanks.

Source: GuamPDN
http://www.guampdn.com/article/20090420/NEWS01/904200310&referrer=FRONTPAGECAROUSEL


PAGAN Mariana Islands, central Pacific Ocean 18.13°N, 145.80°E; summit
elev. 570 m

Based on reports from the Washington VAAC, the USGS stated that on 15
April intermittent plumes of steam from Pagan rose to an altitude of
1.8 km (6,000 ft) a.s.l. and drifted 37 km W. Observers on a ship
reported that a white plume “with some black” rose 1.8 km (5,700 ft)
from the volcano. On 16 April a diffuse plume drifted 85 km W. USGS
raised the Aviation Color Code to Yellow and the Volcano Alert Level
to Advisory. The next day fishermen again reported a plume.

Geologic Summary. Pagan Island, the largest and one of the most active
of the Marianas Islands volcanoes, consists of two stratovolcanoes
connected by a narrow isthmus. Both North and South Pagan
stratovolcanoes were constructed within calderas, 7 and 4 km in
diameter, respectively. The 570-m-high Mount Pagan at the NE end of
the island rises above the flat floor of the caldera, which probably
formed during the early Holocene. South Pagan is a 548-m-high
stratovolcano with an elongated summit containing four distinct
craters. Almost all of the historical eruptions of Pagan, which date
back to the 17th century, have originated from North Pagan volcano.
The largest eruption of Pagan during historical time took place in
1981 and prompted the evacuation of the sparsely populated island.

Source: Emergency Management Office of the Commonwealth of the Mariana
Islands, Office of the Governor, United States Geological Survey
Volcano Hazards Program http://volcano.wr.usgs.gov/cnmistatus.php


PALUWEH Lesser Sunda Islands, Indonesia 8.32°S, 121.71°E, summit elev. 875 m

During 1-17 April, seismic activity from Paluweh increased, prompting
CVGHM to raise the Alert Level to 1 (on a scale of 1-4) on 18 April.

Geologic Summary. Paluweh volcano, also known as Rokatenda, forms the
8-km-wide island of Paluweh N of the volcanic arc that cuts across
Flores Island. Although the volcano rises about 3,000 m above the sea
floor, its summit reaches only 875 m above sea level. The broad
irregular summit region contains overlapping craters up to 900 m wide
and several lava domes. Several flank vents occur along a NW-trending
fissure. The largest historical eruption of Paluweh occurred in 1928,
when a strong explosive eruption was accompanied by landslide-induced
tsunamis and lava-dome emplacement.

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


Ongoing Activity


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

Based on analysis of satellite imagery, the Darwin VAAC reported that
during 15-16 April ash plumes from Batu Tara rose to altitudes of
1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted 35-75 km W and NW.

Geologic Summary. The small isolated island of Batu Tara in the Flores
Sea about 50 km north of Lembata (formerly Lomblen) Island contains a
scarp on the eastern side similar to the Sciara del Fuoco of Italy's
Stromboli volcano. Vegetation covers the flanks of Batu Tara to within
50 m of the 748-m-high summit. Batu Tara lies north of the main
volcanic arc and is noted for its potassic leucite-bearing basanitic
and tephritic rocks. The first historical eruption from Batu Tara,
during 1847-52, produced explosions and a lava flow.

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


CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m

SERNAGEOMIN reported that during 12-16 April, seismicity from
Chaitén's Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex continued to
increase. M 4-4.5 hybrid earthquakes occurred every 2-3 hours. Web
camera views showed increased incandescence from the lava domes and
gas-and-ash plumes that were wider at their base than previously seen.
The plumes rose 1.5 km (4,900 ft) above the domes. The Alert Level
remained at Red. Based on web camera views, analysis of satellite
imagery, and a SIGMET notice, the Buenos Aires VAAC reported that
during 16 and 18-19 April, ash plumes rose to altitudes of 1.8-2.4 km
(6,000-8,000 ft) a.s.l. and drifted SE and N.

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.

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


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

KVERT reported that seismic activity at Karymsky was not analyzed
during 9-17 April due to technical reasons. Cloud cover prevented
observations on the other days. 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

During 15-21 April, HVO reported that lava flowed SE from underneath
Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex
through a lava tube system, reaching the Waikupanaha and Kupapa'u
ocean entries. Occasional explosions occurred from the Waikupanaha
ocean entry. Surface flows were present on the coastal plain and at
the base of the pali. The vent in Halema'uma'u crater continued to
produce a white plume occasionally tinged brown that drifted mainly
SW. Incandescence was intermittently seen from the vent, and sounds
resembling rushing gas or rockfalls were sometimes heard in the
vicinity of the crater. Pele's hair, tiny glass spheres, and ash were
frequently retrieved from collection bins placed near the plume. The
sulfur dioxide emission rate at the summit was elevated, reaching 700
tonnes per day on 15 April; 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/


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

During 10-17 April, KVERT reported that seismic activity at Koryaksky
was above background levels. Gas-and-ash plumes were seen on satellite
imagery and drifted 30-680 km in multiple directions. The Level of
Concern Color Code remained Orange. Based on information from the
Yelizovo Airport and analysis of satellite imagery, the Tokyo VAAC
reported that during 18 and 21 April ash plumes rose to altitudes of
3.7-4.6 km (12,000-15,000 ft) a.s.l. and drifted S, SW, W, and NE.

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

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


NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5364 m

During 15-21 April, INGEOMINAS reported that gas plumes from Nevado
del Huila’s lava dome, viewed through the web camera, rose to a
maximum altitude of 6.9 km (22,600 ft) a.s.l. and drifted W. On 19
April, intense degassing observed during an overflight produced
whitish and bluish plumes. Thermal anomalies were detected on the N
and S parts of the dome. The Alert Level was at Yellow.

Geologic Summary. Nevado del Huila, the highest active volcano in
Colombia, is an elongated N-S-trending volcanic chain mantled by a
glacier icecap. The andesitic-dacitic volcano was constructed within a
10-km-wide caldera. Volcanism at Nevado del Huila has produced six
volcanic cones whose ages in general migrated from south to north. Two
glacier-free lava domes lie at the southern end of the Huila volcanic
complex. The first historical eruption from this little known volcano
took place in the 16th century. Two persistent steam columns rise from
the central peak, and hot springs are also present.

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


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

RVO reported that during 10-17 April white and gray plumes from Rabaul
caldera's Tavurvur cone rose 1-2 km above the crater. Plumes drifted
SE and NW. Occasionally, incandescence from the summit crater was seen
at night and roaring noises were reported. Ashfall was reported in
Rabaul town (3-5 km NW) and surrounding areas.

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: Herman Patia, Rabaul Volcano Observatory (RVO)



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

AVO reported that during 15-21 April seismicity from Redoubt remained
above background levels, indicating ongoing growth of the lava dome in
the summit crater. The web camera showed that vigorous steam-and-gas
plumes that may have occasionally contained small amounts of ash rose
from the vent to altitudes below 4.6 km (15,000 ft) a.s.l. Analysis of
satellite imagery revealed thermal anomalies at the summit and
drifting sulfur dioxide plumes. Based on photos and thermal images
obtained on 16 April, the lava dome was estimated to be about 500 x
700 m across and at least 50 m thick. The Volcanic Alert Level
remained at Watch and the Aviation Color Code remained at Orange.

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/


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 10-17 April. Based on interpretations of seismic data,
ash plumes likely rose to altitudes of 4.5-7.5 km (14,800-24,600 ft)
a.s.l. Analysis of satellite imagery revealed a daily thermal anomaly
on the lava dome and ash plumes that drifted about 50 km NW on 13
April. According to observers, fumaroles were active on 15 and 16
April. The Level of Concern Color Code remained at Orange. Based on
information from KEMSD, the Tokyo VAAC reported that eruptions on 19
and 22 April produced plumes that rose to altitudes of 4.6-5.2 km
(15,000-17,000 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.ssd.noaa.gov/VAAC/OTH/JP/messages.html,
Tokyo Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html


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

Based on information from JMA, the Tokyo VAAC reported an explosion
from Suwanose-jima on 21 April. Details of possible resultant ash
plumes were not reported.

Geologic Summary. The 8-km-long, spindle-shaped island of
Suwanose-jima in the northern Ryukyu Islands consists of an andesitic
stratovolcano with two historically active summit craters. Only about
50 persons live on the sparsely populated island. The summit of the
volcano is truncated by a large breached crater extending to the sea
on the east flank that was formed by edifice collapse. Suwanose-jima,
one of Japan's most frequently active volcanoes, was in a state of
intermittent Strombolian activity from On-take, the NE summit crater,
that began in 1949 and lasted nearly a half century. The largest
historical eruption took place in 1813-14, when thick scoria deposits
blanketed residential areas, after which the island was uninhabited
for about 70 years. The SW crater produced lava flows that reached the
western coast in 1813, and lava flows reached the eastern coast of the
island in 1884.

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


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

During 15-21 April, IG reported that clouds mostly prevented
observations of Tungurahua; a steam-and-gas plume rose 100 m above the
crater on 15 April and an ash plume rose 1 km above the crater and
drifted NW on 18 April. Ashfall was reported in areas to the SW and N
during 15-16 and 18-19 April. Roaring noises were occasionally heard.

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/

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