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GVP/USGS Weekly Volcanic Activity Report
13-19 September 2006
http://www.volcano.si.edu/reports/usgs/
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New Activity/Unrest: | Karymsky, Russia | Raoul Island, New Zealand |
Soufrière Hills, Montserrat | Tengger Caldera, Indonesia
Ongoing Activity: | Kilauea, USA | Mayon, Philippines | Sakura-jima,
Japan | Semeru, Indonesia | St. Helens, USA | Suwanose-jima, Japan |
Tungurahua, Ecuador | Ubinas, Perú
New Activity/Unrest
**KARYMSKY* *Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev.
1,536 m
KVERT reported on 15 September that the Concern Color Code level at
Karymsky was raised from Yellow to Orange. Approximately 50-100 shallow
earthquakes occurred daily during 9-15 September. During 8-10 and 12
September, a thermal anomaly was detected in the crater. An ash plume
was visible on satellite imagery extending ~140 km SE on 13 September.
On 17 and 19 September, eruption plumes rose to altitudes of 2.7 km
(9,000 ft) a.s.l. and drifted SE.
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=
**RAOUL ISLAND ** Kermadec Islands, New Zealand 29.27°S, 177.92°W;
summit elev. 516 m
The Alert Level at Raoul Island was lowered to 0 (on a scale of 0-5) on
18 September due to a general decline in activity. Since April 2006, no
significant earthquake activity had occurred within ~30 km of the
island, the water in Green Lake dropped to the pre-eruption level, and
on-going hydrothermal activity returned to normal.
Geologic Summary. Anvil-shaped Raoul Island is the largest and
northernmost of the Kermadec Islands. During the past several thousand
years volcanism has been dominated by dacitic explosive eruptions. Two
Holocene calderas are found at Raoul. The older caldera cuts the center
of Raoul Island is about 2.5 x 3.5 km wide. Denham caldera, formed
during a major dacitic explosive eruption about 2200 years ago,
truncated the western side of the island and is 6.5 x 4 km wide.
Historical eruptions at Raoul during the 19th and 20th centuries have
sometimes occurred simultaneously from both calderas, and have consisted
of small-to-moderate phreatic eruptions, some of which formed ephemeral
islands in Denham caldera. A 240-m-high unnamed submarine cone, one of
several located along a fissure on the lower NNE flank of Raoul volcano,
has also erupted during historical time.
Source: New Zealand GeoNet Project http://data.geonet.org.nz/geonews/sab/
Raoul Island Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0402-03=
**SOUFRIÈRE HILLS* *Montserrat, West Indies 16.72°N, 62.18°W; summit
elev. 1,052 m
MVO reported that during 8-15 September, the lava dome at Soufrière
Hills continued to grow at a high rate. On 9 and 10 September, ash
venting from the Gages wall was vigorous and accompanied by small
explosions producing black jets up to 100 m above the vent. Pyroclastic
flows from fountain collapse occurred on all sides of the dome and
notably reached 1 km W down Gages valley. On 11 September, the collapse
of an over-hanging lava lobe produced pyroclastic flows NE down the Tar
River valley. On 13 September, one pyroclastic flow in the same area
reached the sea. On 14 September, vigorous ash venting resumed.
Based on information from the MVO, pilot reports, and the Piarco MWO,
the Washington VAAC reported that continuous ash and gas emissions
during 13-19 September produced plumes that reached altitudes of 2.4-3.7
km (8,000-12,000 ft) a.s.l. and drifted predominantly NW, W, and SW. A
hotspot was visible on satellite imagery.
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=
*TENGGER CALDERA* Java, Indonesia 7.942°S, 112.950°E; summit elev. 2,329 m
CVGHM reported that the Alert Level for Tengger Caldera was lowered one
level to 2 (on a scale of 1-4) on 18 September due to decreased activity.
Geologic Summary. The 16-km-wide Tengger caldera in eastern Java
occupies the northern end of a volcanic massif extending from Semeru
volcano. The massive Tengger volcanic complex consists of five
overlapping stratovolcanoes, each truncated by a caldera. The most
recent is the 9 x 10 km wide Sandsea caldera, which formed incrementally
during the late Pleistocene and early Holocene. An overlapping cluster
of post-caldera cones was constructed on the floor of the Sandsea
caldera within the past several thousand years. The youngest of these is
Bromo, one of Java's most frequently visited and most active volcanoes.
More than 50 mild-to-moderate explosive eruptions have occurred there
since 1804.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM)
http://www.vsi.esdm.go.id/portal/html/index.php
Tengger Caldera Information from the Global Volcanism Program
http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0603-31=
Ongoing Activity
*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 13-19 September. Incandescence was intermittently visible
from the East Pond and January vents, South Wall complex, and Drainhole
vent in Pu'u 'O'o's crater. 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.
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.
Source: US Geological Survey Hawaiian Volcano Observatory
http://volcanoes.usgs.gov/update.html
Kilauea information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01-
*MAYON* southeastern Luzon, Philippines 13.257°N, 123.685°E; summit
elev. 2,462 m
Seismic activity and lava extrusion from Mayon continued to remain low
during 13-19 September. Steam plumes from the summit crater reached
heights of 300 m above the crater (9,000 ft a.s.l.) and drifted mainly
SW, NE, and SE. The Alert Level remained at 3 with a 6-km-radius
Permanent Danger Zone and 7 km Extended Danger Zone on the SE slopes in
effect.
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/news/mayon71706.html
Mayon Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-03=
*SAKURA-JIMA* Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m
Based on information from JMA, the Tokyo VAAC reported that an eruption
at Sakura-jima on 19 September generated a plume that rose straight up
to ~3 km (~10,000 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
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
Sakura-jima Information from the Global Volcanism Program
http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0802-08=
*SEMERU* Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m
Based on pilot reports, the Darwin VAAC reported that an eruption plume
from Semeru reached 4.3 km (14,000 ft) a.s.l. and drifted W on 15
September.
Geologic Summary. Semeru is the highest volcano on Java and one of its
most active. The symmetrical stratovolcano rises abruptly to 3,676 m
above coastal plains to the S and lies at the southern end of a volcanic
massif extending N to the Tengger caldera. Semeru has been in almost
continuous eruption since 1967. Frequent small-to-moderate Vulcanian
eruptions have accompanied intermittent lava dome extrusion, and
periodic pyroclastic flows and lahars have damaged villages below the
volcano. A major secondary lahar on 14 May 1981 caused more than 250
deaths and damaged 16 villages.
Source: Darwin Volcanic Ash Advisory Centre
http://www.bom.gov.au/info/vaac/advisories.shtml
Semeru Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-30=
*ST. HELENS* Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m
Data from deformation-monitoring instruments showed that the lava dome
at Mount St. Helens continued to grow during 13-19 September, despite
relatively low seismicity levels.
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 on 19 September that ash plumes from Suwanose-jima reached
altitudes of 3.4 km (11,000 ft) a.s.l. and drifted E.
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
During 13-19 September, seismicity at Tungurahua remained relatively
low. Steam-and-gas plumes rose to a maximum height of 1 km above the
summit (19,800 ft a.s.l.) and drifted predominantly W. Incandescence at
the summit was observed at 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 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, the Buenos Aires VAAC reported continuous
emission of ash plumes from Ubinas on 13 September. The plumes rose to
altitudes of 4.9 km (16,000 ft) a.s.l.
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 S. Kuhn
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/ <http://www.volcano.si.edu/>
Phone: 202.633.1805 Fax: 202.357.2476
<http://www.volcano.si.edu/reports/usgs/>
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