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GVP/USGS Weekly Volcanic Activity Report
4-10 October 2006
http://www.volcano.si.edu/reports/usgs/
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New Activity/Unrest: | Fourpeaked, USA | Mayon, Philippines | Rabaul,
Papua New Guinea
Ongoing Activity: | Bulusan, Philippines | Karymsky, Russia | Kilauea,
USA | Ruapehu, New Zealand | Sakura-jima, Japan | Soufrière Hills,
Montserrat | St. Helens, USA | Suwanose-jima, Japan | Taal, Philippines
| 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 volcanic unrest continued at Fourpeaked during 30
September-6 October. A seismometer that was installed on 25 September
indicated ongoing low-level seismicity. Due to the limited number of
seismometers, earthquake epicenters were not located. Emission rates of
sulfur dioxide were high, similar to the previous week.
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-
MAYON southeastern Luzon, Philippines 13.257°N, 123.685°E; summit elev.
2,462 m
PHIVOLCS reported on 1 October that fumarolic activity from Mayon
produced steam plumes that drifted ENE. Intense incandescence was
observed at the summit. Observations were not possible 2-3 October due
to cloud cover. According to news articles, the Alert Level was lowered
to 2 on 3 October.
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.
Sources: Philippine Institute of Volcanology and Seismology
http://www.phivolcs.dost.gov.ph/news/mayon71706.html, Manila Times
http://www.manilatimes.net/national/2006/oct/05/yehey/prov/20061005pro1.html
Mayon Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-03=
RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit
elev. 688 m; All times are local (= UTC + 10 hours)
The RVO reported that a large, sustained Vulcanian eruption of Rabaul
began at about 0845 on 7 October. An ash column rose to over 5 km
(16,400 ft a.s.l.) and had produced thunder and lightning. Sand-sized
particles fell to the E. By 1200, windows rattled and doors slammed in
the nearby town of Rabaul, N of Tavurvur crater, from semi-continuous
air blasts that became rhythmic. Windows in the observatory, 12 km away,
blew out from shockwaves. Moderately heavy ash fell in southern Rabaul
town. Lapilli ~1 mm in diameter and lithics up to 3 cm in diameter fell
in the S and SW parts of the caldera. Residents affected by heavier
ashfall and air blasts self-evacuated. The eruption grew to sub-Plinian
status throughout the day. Thick ash plumes reached 18 km (59,000 ft
a.s.l.) altitude and dispersed N, NW, S, and SW. Ashfall affected the
entire Gazelle Peninsula.
At 1415, the eruption style changed to Strombolian, which lasted until
about 1730. During the night, moderate to bright incandescence was
observed on the N rim of Tavurvur. Explosions and loud roaring noises
were occasionally heard.
On 8 October, thick white and blue vapor clouds were accompanied by ash
explosions and plumes that drifted N and NW. Lava flows on the W and N
flanks were visible from 2 km NW in Rapindik. The lava flow on the W
flank reached the sea, causing secondary explosions.
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.
Sources: Herman Patia and Steve Saunders, Rabaul Volcano Observatory,
Times Online http://www.timesonline.co.uk/article/0,,3-2394856,00.html
Rabaul Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-14=
Ongoing Activity
BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m
On 10 October, an eruption plume from Bulusan that was visible on
satellite imagery reached altitudes of 3 km (10,000 ft) a.s.l. and
drifted SW and SSE.
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: Tokyo Volcanic Ash Advisory Center
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
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
KVERT reported on 6 October that activity at Karymsky continued during
30 September-6 October, with 120-190 shallow earthquakes occurring
daily. Explosions produced ash plumes that possibly reached altitudes of
2.5 km (8,200 ft) a.s.l. A thermal anomaly in the crater was detected on
30 September, and 2 and 4 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.
Source: Kamchatkan Volcanic Eruption Response Team
http://www.kscnet.ru/ivs/kvert/updates.shtml
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 4-5 October. Incandescence was intermittently visible
from the East Pond and January vents, South Wall complex, and Drainhole
vent in Pu'u 'O'o's crater, when weather permitted. 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. Incandescence
from surface flows was intermittently visible on Pulama pali.
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-
RUAPEHU North Island, New Zealand 39.28°S, 175.57°E; summit elev. 2,779 m
A M 2.8 earthquake centered at Ruapehu was recorded on 4 October.
Scientists visited the summit crater lake on 7 October and confirmed
that a small hydrothermal eruption had occurred. The lake water level
had risen 1 m since a previous measurement, and evidence suggested wave
action up to 4-5 m above the surface of the lake. The lake temperature
was 22.5°C, up from 15°C. Ruapehu remained at Volcanic Alert Level 1
(some signs of volcano unrest).
Geologic Summary. Ruapehu, one of New Zealand's most active volcanoes,
is a complex stratovolcano constructed during at least four
cone-building episodes. The 110 cu km volcanic massif is elongated in a
NNE-SSW direction and is surrounded by another 100 cu km ring plain of
volcaniclastic debris. A single historically active vent, Crater Lake,
is located in the broad summit region, but at least five other vents on
the summit and flanks have been active during the Holocene. Frequent
mild-to-moderate explosive eruptions have occurred in historical time
from the Crater Lake vent. Lahars produced by phreatic eruptions from
the summit crater lake are a hazard to a ski area on the upper flanks
and to river valleys below the volcano.
Source: New Zealand GeoNet Project http://data.geonet.org.nz/geonews/sab/
Ruapehu Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0401-10=
SAKURA-JIMA Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m
Based on information from JMA and satellite imagery, the Tokyo VAAC
reported eruptions at Sakura-jima on 7, 8, and 10 October. Plumes rose
to 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted W, S, and SW,
respectively.
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=
SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev.
1,052 m
MVO reported that during 29 September-6 October the lava dome at
Soufrière Hills continued to grow at a moderate rate. Rockfalls were
concentrated on the N and NE sectors. The vents just inside Gage’s wall
and on the summit of the dome periodically produced both ash and gases.
The lava-dome volume was estimated at 90 million cubic meters.
Based on information from the MVO, pilot reports, and the Piarco MWO,
the Washington VAAC reported ongoing emissions during 5-10 October.
Plumes reached altitudes of 2.4 km (8,000 ft) a.s.l. and drifted W.
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
Lava continued to extrude onto the S crater floor of St. Helens during
4-10 October. Low levels of seismicity and periodic tilt of the crater
floor accompanied small rockfalls. A small steam plume was visible on 9
October.
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, the Tokyo VAAC reported an explosion from
Suwanose-jima on 6 October.
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=
TAAL Luzon. Philippines 14.002°N, 120.993°E; summit elev. 1,977
PHIVOLCS reported ongoing seismic unrest at Taal on 26 September. During
25-26 September, 29 volcanic earthquakes occurred with five felt
Modified Mercalli intensities of II to III. Epicenters were dispersed
NE, N, and NW. Approximately five seismic events in a 24-hour period is
typical during quiet periods.
Geologic Summary. Taal volcano is one of the most active volcanoes in
the Philippines and has produced some of its most powerful historical
eruptions. In contrast to Mayon volcano, Taal is not topographically
prominent, but its prehistorical eruptions have greatly changed the
topography of SW Luzon. The 15 x 20 km Taal caldera is largely filled by
Lake Taal, whose 267 sq km surface lies 700 m below the S caldera rim
and only 3 m above sea level. The maximum depth of the lake is 160 m,
and several eruptive centers lie submerged beneath the lake. The
5-km-wide Volcano Island in north-central Lake Taal is the location of
all historical eruptions. The island is a complex volcano composed of
coalescing small stratovolcanoes, tuff rings, and scoria cones that has
grown about 25% in area during historical time. Powerful pyroclastic
flows and surges from historical eruptions of Taal have caused many
fatalities.
Source: Philippine Institute of Volcanology and Seismology
http://www.phivolcs.dost.gov.ph/
Taal Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-07=
TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m
During 4-5 October, fumaroles on the N flank of Tungurahua were active.
Steam emissions with minor ash content rose to 1 km above the summit (or
19,800 ft a.s.l.) and drifted W. Additional steam plumes possibly
originated from the recent lava-flow front. Incandescence was not observed.
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 satellite imagery, the Buenos Aires VAAC issued an aviation ash
advisory for Ubinas on 5 October. The continuous ash emissions reached
altitudes of 5.5 km (18,000 ft) a.s.l. and drifted S.
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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