GVP/USGS Weekly Volcanic Activity Report 2-8 August 2006

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From: Sally Kuhn

GVP/USGS Weekly Volcanic Activity Report

2-8 August 2006

http://www.volcano.si.edu/reports/usgs/

New Activity/Unrest: | Karangetang, Indonesia | Mayon, Philippines |
Merapi, Indonesia | Tungurahua, Ecuador

Ongoing Activity: | Karymsky, Russia | Kilauea, USA | Manam, Papua New
Guinea | Popocatépetl, México | Sakura-jima, Japan | Semeru, Indonesia |
Soufriere Hills, Montserrat | St. Helens, USA | Ubinas, Perú

New Activity/Unrest

KARANGETANG [Api Siau] Siau Island, Indonesia 2.47°N, 125.29°E; summit
elev. 1,784 m

On 2 August, the Alert Level at Karangetang was raised to 4, the highest
level. During 1-5 August, white plumes reached heights of 50-300 m
(164-984 ft) above the summit (6,000-6,800 ft a.s.l.). Lava flows
advanced hundreds of meters to over a kilometer E toward the Batu Awang
river and S towards the Keting river during the reporting period.
Incandescent rockfalls originating from the summit and ends of the lava
flows traveled hundreds of meters E toward the Kahetang and Batu Awang
rivers and S towards the Keting and Batang rivers. On 5 August, the
Alert level was lowered to 3.

Geologic Summary. Karangetang (also known as Api Siau) lies at the
northern end of the island of Siau, N of Sulawesi. The 1,784-m-high
stratovolcano contains five summit craters along a N-S line. One of
Indonesia's most active volcanoes, Karangetang has had more than 40
recorded eruptions since 1675. Twentieth-century eruptions have included
frequent explosions, sometimes accompanied by pyroclastic flows and lahars.

Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM)

Karangetang Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0607-02=

MAYON southeastern Luzon, Philippines 13.257°N, 123.685°E; summit elev.
2,462 m; All times are local (= UTC + 8 hours)

PHIVOLCS reported that during 2-8 August, lava from Mayon continued to
flow mainly SSE along the Mabinit channel and subsequently over a broad
sector of the upper and middle SE slopes. During 17 July-3 August, the
volume of lava discharged amounted to 17 million cubic meters.

Voluminous steaming accompanied lava extrusion. On 4 August, lava flows
extended 30 m beyond the 6-km-radius region designated as the Permanent
Danger Zone. Areas SE and E experienced light ash fall on 4 August
generated by the collapse of deposits. On 6 August, lava flows spilled
into the Bonga Valley, E of the Mabinit Chanel.

The Tokyo VAAC reported an eruption cloud at 2331 that reached an
altitude of 3.4 km (11,000 ft) a.s.l. and drifted E. On 7 August, the
Alert Level was raised to 4 (scale is 0-5, 0 referring to No Alert
status) and the Extended Danger Zone (8 km from the summit) was defined.
Three explosions (out of nine in a 24-hour period) at 2236, 2246, and
2249 produced incandescent ejections of lava fragments, ash, gas, and
steam. According to news reports, ~40,000 people were evacuated from
inside the Extended Danger Zone to 20 evacuation centers on 7 and 8 August.

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,

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

Associated Press
http://www.cnn.com/2006/WORLD/asiapcf/08/09/philippines.volcano.ap/index.html

Mayon Information from the Global Volcanism Program

http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-03=

MERAPI central Java, Indonesia 7.542°S, 110.442°E; summit elev. 2,947 m

Based on pilot reports, the Darwin VAAC reported that eruption plumes
from Merapi on 2 and 3 August reached altitudes of ~6.1 km (~20,000 ft)
a.s.l. and drifted W. According to CVGHM, during 2-4 August rockfalls
traveled 1 km SE toward the Gendol river and gas plumes reached a
maximum of 400 m above the summit (10,900 ft a.s.l.). On 3 August, the
Alert Level was lowered to 2 (on a scale of 1-4).

Geologic Summary. Merapi, one of Indonesia's most active volcanoes, lies
in one of the world's most densely populated areas and dominates the
landscape immediately N of the major city of Yogyakarta. The steep-sided
modern Merapi edifice, its upper part unvegetated due to frequent
eruptive activity, was constructed to the SW of an arcuate scarp cutting
the eroded older Batulawang volcano. Pyroclastic flows and lahars
accompanying growth and collapse of the steep-sided active summit lava
dome have devastated cultivated and inhabited lands on the volcano's
western-to-southern flanks and caused many fatalities during historical
time. The volcano is the object of extensive monitoring efforts by the
Merapi Volcano Observatory.

Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM)
http://www.vsi.esdm.go.id/portal/html/index.php,

Darwin Volcanic Ash Advisory Center
http://www.bom.gov.au/products/IDD41300.shtml

Merapi Information from the Global Volcanism Program

http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-25=

TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m

According to the Instituto Geofísico, on 1 August a pyroclastic flow
from Tungurahua that traveled an unstated distance W left deposits an
estimated 50 m thick consisting largely of blocks and ash. On 2 August,
a small lahar that traveled NW caused the closing of a highway.
Strombolian activity was observed at night on 3 August. Small explosions
were registered during 3-7 August. On 6 August, light ash fall was
reported ~8 km SW in the town of Manzano.

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=

Ongoing Activity

KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m

Activity at Karymsky continued during 29 July-4 August, with 100-300
shallow earthquakes occurring daily. Based on interpretations of seismic
data, ash plumes reached altitudes of 3.1 km (10,200 ft) a.s.l.
According to the Tokyo VAAC, the Kamchatkan Experimental and Methodical
Seismological Department (KEMSD) reported that on 4 August ash plumes
reached altitudes of 3.7 km (12,000 ft) a.s.l. A thermal anomaly in the
crater was observed. 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

A 4-hectare (10-acre) area of the lava delta at Kilauea's East Lae`apuki
collapsed into the ocean on 30 July. The collapse represented less than
15% of the delta's total area.

During 2-8 August, lava from the PKK lava tube flowed into the ocean at
two entries on the SE flank, East Lae`apuki and about 3.5 km E at East
Ka`ili`ili. Tilt at the Pu`u `O`o cone displayed a saw tooth pattern and
tremor remained at a moderate level.

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,

The Honolulu Advertiser
http://www.honoluluadvertiser.com/apps/pbcs.dll/article?AID=/20060804/NEWS0101/608040351/1001/NEWS

Kilauea information from the Global Volcanism Program

http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01-

MANAM offshore New Guinea, Papua New Guinea 4.10°S, 145.06°E; summit
elev. 1,807 m

On 4 and 5 August, an ash plume from Manam was visible on satellite
imagery at an unknown altitude and extended 30 km NW.

Geologic Summary. The 10-km-wide island of Manam is one of Papua New
Guinea's most active volcanoes. Four large radial valleys extend from
the unvegetated summit of the conical 1,807-m-high stratovolcano to its
lower flanks. These "avalanche valleys," regularly spaced 90 degrees
apart, channel lava flows and pyroclastic avalanches that have sometimes
reached the coast. Five satellitic centers are located near the island's
shoreline. Two summit craters are present; both are active, although
most historical eruptions have originated from the southern crater,
concentrating eruptive products during the past century into the SE
avalanche valley. Frequent historical eruptions have been recorded since
1616.

Source: Darwin Volcanic Ash Advisory Center
http://www.bom.gov.au/products/IDD41300.shtml

Manam Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0501-02=

POPOCATÉPETL México 19.02°N, 98.62°W; summit elev. 5,426 m

According to the Washington VAAC, the Meteorological Watch Office
reported emissions from Popocatépetl on 3 August. Ash was not visible on
satellite imagery. A bright glow was visible with the camera operated by
CENEPRED.

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.

Source: Washington Volcanic Ash Advisory Center
http://www.ssd.noaa.gov/VAAC/messages.html

Popocatépetl Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1401-09=

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 explosion
at Sakura-jima on 2 August generated a plume that rose to ~2.4 km (8,000
ft) a.s.l. and drifted SW.

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

Eruption plumes from Semeru were visible on satellite imagery on 2
August. They reached a maximum altitude of 5.2 km (17,000 ft) a.s.l.

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 Center
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=

SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev.
1,052 m

During 29 July-4 August, the Soufrière Hills lava dome continued to
grow, mainly to the E. The loss of prominent spines made the dome appear
more symmetrical. On 2 August, a small pyroclastic flow occurred and was
associated with light ash fall to the N of the island. The Alert Level
remained at 3 (on a scale of 0-5).

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.

Source: Montserrat Volcano Observatory http://www.mvo.ms/

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

During 2-8 August, the lava dome at Mount St. Helens continued to grow
and produce small rockfalls. On 5 August, two earthquakes (the largest,
M 3.6) triggered rockfalls. Resulting dust plumes rose well above the
crater rim. The hazard status remained at Volcano Advisory (Alert Level
2); aviation color code Orange.

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-

UBINAS Perú 16.355°S, 70.903°W; summit elev. 5,672 m

According to the Buenos Aires VAAC, during 1-8 August pilots reported
that ash plumes emitted from Ubinas reached altitudes of between 4.6 km
to 6.7 km (15,000 ft-22,000 ft) a.s.l. and drifted generally NE and SW.
Ash was visible on satellite imagery on 4 and 6 August.

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/



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