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GVP/USGS Weekly Volcanic Activity Report 11-17 October 2006
http://www.volcano.si.edu/reports/usgs/
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New Activity/Unrest: | Fourpeaked, USA | Rabaul, Papua New Guinea | San
Miguel, El Salvador
Ongoing Activity: | Bulusan, Philippines | Karymsky, Russia | Kilauea,
USA | Langila, Papua New Guinea | Mayon, Philippines | Piton de la
Fournaise, Reunion Island | Sangay, Ecuador | Soufrière Hills,
Montserrat | St. Helens, USA | Suwanose-jima, Japan | Tungurahua,
Ecuador | Ubinas, Perú
New Activity/Unrest
FOURPEAKED Alaska Peninsula, USA 58.770°N, 153.672°W; summit elev. 2,105 m
The AVO reported that earthquake activity and gas emissions continued at
Fourpeaked during 7-13 October. Observations through most of the week
were hindered due to cloud cover, but on 12 October AVO staff reported
that two prominent vents were emitting steam and gas.
Geologic Summary. Poorly known Fourpeaked volcano in NE Katmai National
Park consists of isolated outcrops surrounded by the Fourpeaked Glacier,
which descends eastward almost to the Shelikof Strait. The orientation
of lava flows and extensive hydrothermal alteration of rocks near the
present summit suggest that it probably marks the vent of Fourpeaked
volcano.
Source: Alaska Volcano Observatory (AVO)
http://www.avo.alaska.edu/activity/avoreport.php?view=update
Fourpeaked Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1102-26-
RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit
elev. 688 m
Based on information from the RVO, the Washington VAAC reported that a
brief eruption of Rabaul on 11 October produced a plume that reached an
altitude of 7.6 km (25,000 ft) a.s.l. and dissipated NW. Continuous
low-level emissions and Vulcanian eruptions produced plumes to 1 km
(3,300 ft) a.s.l. during 12-17 October.
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: Washington Volcanic Ash Advisory Center
http://www.ssd.noaa.gov/VAAC/messages.html
Rabaul Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-14=
SAN MIGUEL El Salvador 13.431°N, 88.272°W; summit elev. 2,130 m
Servicio Nacional de Estudios Territoriales (SNET) reported on 10
October that an Alert Level for San Miguel was established as Green
within 4 km from the center of the crater due to a slight increase in
seismic activity. On 15 October, the Alert Level was increased to Yellow
due to further increases in seismic activity, but then decreased to
Green again the next day.
Geologic Summary. The symmetrical cone of San Miguel volcano, one of the
most active in El Salvador, rises from near sea level to form one of the
country's most prominent landmarks. A broad, deep crater that has been
frequently modified by historical eruptions (recorded since the early
16th century) caps the truncated summit of the towering volcano, which
is also known locally as Chaparrastique. Radial fissures on the flanks
of the basaltic volcano have fed a series of fresh lava flows, including
several erupted during the 17th-19th centuries that reached beyond the
base of the volcano on the N, W, and SE sides. The SE-flank lava flows
are the largest and form broad sparsely vegetated lava fields.
Source: Servicio Nacional de Estudios Territoriales (SNET)
http://www.snet.gob.sv
San Miguel Reports from the monthly Bulletin of the Global Volcanism
Network
http://www.volcano.si.edu/gvp/world/region14/elsalv/sanmigue/var.htm
Ongoing Activity
BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m
PHIVOLCS reported that an explosion from Bulusan on 10 October produced
an ash-and-steam plume that rose to 4.5 km (15,000 ft) a.s.l. and
drifted mainly SE and SSW. Light ashfall (1.5-5.0 mm thick) was reported
in neighboring towns downwind. Based on seismic data, the activity
lasted for 9 minutes. On 11 and 12 October, steam plumes drifted SW and SSW.
Geologic Summary. Luzon's southernmost volcano, Bulusan, was constructed
within the 11-km-diameter dacitic Irosin caldera, which was formed more
than 36,000 years ago. A broad, flat moat is located below the prominent
SW caldera rim; the NE rim is buried by the andesitic Bulusan complex.
Bulusan is flanked by several other large intracaldera lava domes and
cones, including the prominent Mount Jormajan lava dome on the SW flank
and Sharp Peak to the NE. The summit of Bulusan volcano is unvegetated
and contains a 300-m wide, 50-m-deep crater. Three small craters are
located on the SE flank. Many moderate explosive eruptions have been
recorded at Bulusan since the mid-19th century.
Source: Philippine Institute of Volcanology and Seismology
http://www.phivolcs.dost.gov.ph/
Bulusan Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01=
KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m
Activity at Karymsky continued during 11-17 October, with 100-190
shallow earthquakes occurring daily. Based on interpretations of seismic
data and satellite observations, ash plumes may have reached altitudes
of 2.5 km (8,200 ft) a.s.l. A thermal anomaly in the crater was detected
on 7 and 12 October. According to the Tokyo VAAC, an ash plume rose to
3.7 km (12,000 ft) a.s.l. on 17 October. Karymsky remained at Concern
Color Code 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.
Sources: Kamchatkan Volcanic Eruption Response Team
http://www.kscnet.ru/ivs/kvert/updates.shtml,
Tokyo Volcanic Ash Advisory Center
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
Karymsky Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-13=
KILAUEA Hawaii, USA 19.43°N, 155.29°W; summit elev. 1,222 m
The summit of Kilauea continued to slowly inflate S of Halema'uma'u
caldera during 11-17 October. Incandescence from surface flows was
intermittently visible on the pali and at the base of the pali on 14
October. Lava from the Campout and PKK systems continued to flow off of
a lava delta into the ocean at the East Lae'apuki and East Ka'ili'ili
entries. Two large earthquakes (largest, M 6.7) occurred on 15 October
on the northwest side of Hawai`i Island. On 16 October, HVO reported
that the earthquakes did not affect the Kilauea eruption.
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 by
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 broad areas on the S flank of Kilauea and
adding new land beyond the former coastline.
Sources: US Geological Survey Hawaiian Volcano Observatory
http://volcanoes.usgs.gov/update.html,
Associated Press
http://www.mercurynews.com/mld/mercurynews/living/health/15773540.htm
Kilauea information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01-
LANGILA New Britain Island, Papua New Guinea 5.53°S, 148.42°E; summit
elev. 1,330 m; All times are local (= UTC + 10 hours)
According to the Darwin VAAC, the RVO reported that Langila erupted at
1130 on 17 October. Satellite imagery from 1133 showed no activity over
Langila, but a “low level plume” was visible farther W over Ritter Island.
Geologic Summary. Langila, one of the most active volcanoes of New
Britain, consists of a group of four small overlapping composite cones
on the lower eastern flank of the extinct Talawe volcano. Talawe is the
highest volcano in the Cape Gloucester area of NW New Britain. A
rectangular, 2.5-km-long crater is breached widely to the SE; Langila
volcano was constructed NE of the breached crater of Talawe. An
extensive lava field reaches the coast on the N and NE sides of Langila.
Frequent mild-to-moderate explosive eruptions, sometimes accompanied by
lava flows, have been recorded since the 19th century from three active
craters at the summit of Langila. The youngest and smallest crater (no.
3 crater) was formed in 1960 and has a diameter of 150 m.
Source: Darwin Volcanic Ash Advisory Centre
http://www.bom.gov.au/info/vaac/advisories.shtml
Langila Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-01=
MAYON southeastern Luzon, Philippines 13.257°N, 123.685°E; summit elev.
2,462 m
PHIVOLCS reported that on 11 and 12 October steaming from Mayon was
moderate and one volcanic earthquake was recorded.
Geologic Summary. The beautifully symmetrical Mayon volcano, which rises
to 2,462 m above the Albay Gulf, is the Philippines' most active
volcano. The structurally simple volcano has steep upper slopes that
average 35-40° and is capped by a small summit crater. The historical
eruptions of this basaltic-andesitic volcano date back to 1616 and range
from Strombolian to basaltic Plinian. Eruptions occur predominately from
the central conduit and have also produced lava flows that travel far
down the flanks. Pyroclastic flows and mudflows have commonly swept down
many of the approximately 40 ravines that radiate from the summit and
have often devastated populated lowland areas. Mayon’s most violent
eruption, in 1814, killed more than 1,200 people and devastated several
towns. Eruptions that began in February 2000 led PHIVOLCS to recommend
on 23 February the evacuation of people within a radius of 7 km from the
summit in the SE and within a 6 km radius for the rest of the volcano.
Source: Philippine Institute of Volcanology and Seismology
http://www.phivolcs.dost.gov.ph/
Mayon Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-03=
PITON DE LA FOURNAISE Réunion Island, Indian Ocean 21.23°S, 55.71°E;
summit elev. 2,631 m
The eruption of Piton de la Fournaise that began on 30 August continued
within the Dolomieu Crater. A new cone about 20-25 m high was formed in
the SE part of Dolomieu and lava flows up to 10 m thick filled up 75% of
the crater floor. The E part of the crater was filled up to the rim
where lava flowed over and down the flank for hundreds of meters. On 9
October, a new crater formed about 100 m SW of the first one.
Geologic Summary. The massive Piton de la Fournaise shield volcano on
the island of Réunion is one of the world's most active volcanoes. Most
historical eruptions have originated from the summit and flanks of
Dolomieu, a 400-m-high lava shield that has grown within the youngest of
three large calderas. This latter caldera is 8 km wide and is breached
to below sea level on the eastern side. More than 150 eruptions, most of
which have produced fluid basaltic lava flows within the caldera, have
been documented since the 17th century.
Source: Thomas Staudacher, Observatoire Volcanologique du Piton de la
Fournaise via the Volcano Listserv
http://www.volcano.si.edu/reports/volclist/index.htm
Piton de la Fournaise Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0303-02=
SANGAY Ecuador 2.03°S, 78.34°W; summit elev. 5,188 m
Based on information from Guayaquil MWO and a pilot report, the
Washington VAAC reported on 11 October that emission plumes from Sangay
reached altitudes of 2.7 km (9,000 ft) a.s.l. and drifted W.
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
http://www.ssd.noaa.gov/VAAC/messages.html
Sangay Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-09=
SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev.
1,052 m
During 6-13 October, lava-dome growth at Soufrière Hills continued and
was concentrated on the NE part of the edifice. The vents just inside
Gage’s wall and on the summit of the dome periodically produced both ash
and gas. Heavy rainfall on 9 and 11-12 October resulted in mudflow
activity in all drainage systems. Ash fell in the N part of the island.
Based on information from the MVO, pilot reports, and the Piarco MWO,
the Washington VAAC reported that continuous ash and gas emissions
during 10-17 October produced plumes that drifted NW, N, and NE. Plumes
reached altitudes of 2.1-4.6 km (7,000-15,000 ft) a.s.l. A minor
pyroclastic flow on 16 October produced an ash plume that drifted NNE. A
hotspot was detected on satellite imagery from 12 to 17 October.
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 east, was formed during an eruption about 4000 years ago
in which the summit collapsed, producing a large submarine debris
avalanche. Block-and-ash flow and surge deposits associated with dome
growth predominate in flank deposits at Soufrière Hills. Non-eruptive
seismic swarms occurred at 30-year intervals in the 20th century, but
with the exception of a 17th-century eruption that produced the Castle
Peak lava dome, no historical eruptions were recorded on Montserrat
until 1995. Long-term small-to-moderate ash eruptions beginning in that
year were later accompanied by lava-dome growth and pyroclastic flows
that forced evacuation of the southern half of the island and ultimately
destroyed the capital city of Plymouth, causing major social and
economic disruption.
Sources: Montserrat Volcano Observatory http://www.mvo.ms/,
Washington Volcanic Ash Advisory Center
http://www.ssd.noaa.gov/VAAC/messages.html
Soufrière Hills Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05=
ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m
Data from deformation-monitoring instruments showed that during 11-17
October the lava dome at Mount St. Helens continued to grow and produce
small rockfalls.
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: US Geological Survey Cascades Volcano Observatory
http://vulcan.wr.usgs.gov/Volcanoes/MSH/CurrentActivity/framework.html
St. Helens Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1201-05-
SUWANOSE-JIMA Ryukyu Islands, Japan 29.53°N, 129.72°E; summit elev. 799 m
Based on information from JMA and a pilot report, the Tokyo VAAC
reported that on 14, 16, and 17 October, ash plumes from Suwanose-jima
reached altitudes of 3 km (10,000 ft) a.s.l.
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 E 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 around 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
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
Suwanose-jima Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0802-03=
TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m
IG reported an increase in emissions and seismicity at Tungurahua on 11
and 12 October. Steam plumes with slight to moderate amounts of ash
reached heights of 9-12 km (29,500-39,500 ft) a.s.l. and resulted in
light ashfall in areas NW and W. During 13-17 October, seismicity
decreased and emissions produced plumes that reached heights of 7-8 km
(23,000-26,000 ft) a.s.l. On 16 October, a small lava flow produced
incandescent blocks and gas plumes. Lahars traveled NNW and NNE down the
gorges of Vazcún and Ulba, respectively. Incandescence from the crater
could be seen during most of the reporting period.
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 been restricted to 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 Poltécnica Nacional
http://www.igepn.edu.ec/vulcanologia/tungurahua/actividad/informet.htm
Tungurahua Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08=
UBINAS Perú 16.355°S, 70.903°W; summit elev. 5,672 m
Based on pilot reports and satellite imagery, the Buenos Aires VAAC
reported continuous emission of ash plumes from Ubinas during 12-17
October. The plumes rose to 4.9-6.7 km (16,000-22,000 ft) a.s.l. and
drifted S, SE, E, and N.
Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of
Ubinas, Peru's most active volcano, gives it a truncated appearance.
Ubinas is the northernmost of three young volcanoes located along a
regional structural lineament about 50 km behind the main volcanic front
of Peru. The upper slopes of the stratovolcano, composed primarily of
Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The
steep-walled, 150-m-deep summit caldera contains an ash cone with a
500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche
deposits from the collapse of the SE flank of Ubinas extend 10 km from
the volcano. Widespread plinian pumice-fall deposits from Ubinas include
some of Holocene age. Holocene lava flows are visible on the volcano's
flanks, but historical activity, documented since the 16th century, has
consisted of intermittent minor explosive eruptions.
Source: Buenos Aires Volcanic Ash Advisory Center
http://www.bom.gov.au/products/Volc_ash_recent.shtml
Ubinas Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02
**+++++++++++++++++++++++++++++++++++++**
**Sally Kuhn Sennert**
**Global Volcanism Program**
Smithsonian Institution
National Museum of Natural History MRC-119
Department of Mineral Sciences
Washington, D.C., 20560
http://www.volcano.si.edu/reports/usgs/index.cfm
Phone: 202.633.1805
Fax: 202.357.2476
<http://www.volcano.si.edu/reports/usgs/>++++++++++++++++++++++++++++++++++++++++++
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