GVP/USGS Weekly Volcanic Activity Report June 28- July 4 2006

From: Sally Kuhn

GVP/USGS Weekly Volcanic Activity Report
28 June- 4 July 2006

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

New Activity/Unrest: | Batu Tara, Indonesia | Bulusan, Philippines |
Soufriere
Hills, Montserrat

Ongoing Activity: | Fuego, Guatemala | Karangetang, Indonesia | Karymsky,
Russia
| Kilauea, USA | Merapi, Indonesia | Santa María, Guatemala | Semeru,
Indonesia
| St. Helens, USA | Suwanose-jima, Japan | Tungurahua, Ecuador | Ubinas,
Perú

New Activity/Unrest

BATU TARA Lesser Sunda Islands, Indonesia 7.792°S, 123.579°E; summit elev.
748
m

Based on a pilot report, the Darwin VAAC reported that an ash cloud from
Batu
Tara reached an altitude of 1.5 km (5,000 ft) a.s.l. and drifted NW. Ash was
not
identified on satellite imagery.

Geologic Summary. The small isolated island of Batu Tara in the Flores Sea
about
50 km north of 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 only known historical eruption from Batu Tara,
during
1847-52, produced explosions and a lava flow.

Source: Darwin Volcanic Ash Advisory Center
http://www.bom.gov.au/info/vaac/advisories.shtml

Batu Tara Information from the Global Volcanism Program

http://www.volcano.si.edu/world/volcano.cfm?vnum=0604-26=

BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m

Based on interpretations of seismic data, small explosions occurred at
Bulusan
on 28 and 29 June. No ashfall was reported.

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/news/bulusan_bul_31May2006.html

Bulusan Information from the Global Volcanism Program

http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01=

SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052
m:
All times are local (= UTC - 4 hours)

Due to increased seismic activity at Soufriere Hills during approximately
24-29
June, the Alert Level was raised to 4 (on a scale of 0-5). On 30 June around
1300, the lava dome partially collapsed and produced pyroclastic flows to
the
E.
According to the Washington VAAC, a pilot reported that an ash plume
reached
an
altitude of 3 km (10,000 ft) a.s.l. and drifted NW. The VAAC also reported
that
the Montserrat Volcano Observatory indicated a second dome collapse occurred
at
1830 on 30 June that also generated ash plumes to altitudes of 3 km (10,000
ft)
a.s.l.

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/, Washington
Volcanic
Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html, Associated
Press
http://www.physorg.com/news70901467.html, Antigua Sun
http://www.antiguasun.com/paper/?as=view&sun=131635109906292006&an=2124460989062
92006&ac=Local,
Radio Jamaica
http://www.radiojamaica.com/news/story.php?category=6&story=25911

Soufrière Hills Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05=

Ongoing Activity

FUEGO Guatemala 14.47°N, 90.88°W; summit elev. 3,763 m

On 29 June, INSIVUMEH reported that pyroclastic flows from Fuego traveled
mainly
SW along the Ceniza River and a lesser number moved SW along the Taniluyá
River.
According to a news report, on 29 June an ash plume reached a height of 2.2
km
above the summit (19,500 ft a.s.l.) and drifted W. On 3 July, explosions
propelled incandescent material hundreds of meters above the central crater
(~13,000 ft a.s.l.). Avalanches traveled ~300-500 m SW along the Ceniza
River.

Geologic Summary. Volcán Fuego, one of Central America's most active
volcanoes,
is one of three large stratovolcanoes overlooking Guatemala's former
capital,
Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high
Fuego
and its twin volcano to the N, Acatenango. Construction of Meseta volcano
continued until the late Pleistocene or early Holocene, after which growth
of
the modern Fuego volcano continued the southward migration of volcanism that
began at Acatenango. Frequent vigorous historical eruptions have been
recorded
at Fuego since the onset of the Spanish era in 1524, and have produced major
ashfalls, along with occasional pyroclastic flows and lava flows. The last
major explosive eruption from Fuego took place in 1974, producing
spectacular
pyroclastic flows visible from Antigua.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meterologia, e
Hidrologia http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm,
Associated Press
http://www.forbes.com/entrepreneurs/feeds/ap/2006/06/29/ap2851118.html

Fuego Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-09=

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

According to the Darwin VAAC, a small eruption at Karangetang on 3 July
produced
an ash plume observed on satellite imagery that reached an altitude of 3.7
km
(12,000 ft) a.s.l.

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: Darwin Volcanic Ash Advisory Center
http://www.bom.gov.au/info/vaac/advisories.shtml

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

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

Activity at Karymsky continued during 23-30 June, with 100-350 shallow
earthquakes occurring daily. Based on interpretations of seismic data, ash
plumes reached altitudes of 3.5 km (11,500 ft) a.s.l. According to the Tokyo
VAAC, the Kamchatkan Experimental & Methodical Seismological Department
(KEMSD)
reported that on 1 and 3 July ash plumes reached altitudes of 3.7 km (12,000
ft)
a.s.l. A thermal anomaly in the crater was observed during 24-27 June.
Karymsky
remained at Concern Color Code Orange
php>.

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

During 28 June-4 July, lava from Kilauea continued to flow off of a lava
delta
into the ocean at the East Lae`apuki entry. On 30 June, surface lava flows
originating from the Campout lava tube were visible on the upper part of the
Pulama pali fault scarp, which had not been the case since 8 February.
Incandescence was visible from Drainhole vent in Pu`u `O`o's crater during
most
of the reporting period. Tremor remained at a very typical moderate level at
Pu`u `O`o.

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 about 104 km2 of land on the S flank of
Kilauea and building more than 200 hectares of new land.

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-

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

According to CVGHM, pyroclastic flows and rockfalls at Merapi decreased in
frequency and intensity during 28 June-4 July. Pyroclastic flows were
observed
during 28-30 June and reached a maximum distance of 3 km SE along the Gendol
River. Gas plumes were observed during 28 June-1 July and reached a maximum
height of 1 km above the summit (12,800 ft a.s.l.) on 28 June.

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.

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

Merapi Information from the Global Volcanism Program

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

SANTA MARÍA Guatemala 14.756°N, 91.552°W; summit elev. 3,772 m

According to the Washington VAAC, on 1 July small ash plumes from Santa
María's
Santiaguito lava-dome complex reached altitudes of 5.8 km (19,000 ft) a.s.l.
and
drifted SW. On 3 July, INSIVUMEH reported that an ash plume reached ~800 m
above
the summit (~15,000 ft a.s.l.). White "smoke" from an incandescent
avalanche
deposit was visible from the NE base of Caliente cone.

Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of
a
chain of large stratovolcanoes that rises dramatically above the Pacific
coastal
plain of Guatemala. The stratovolcano has a sharp-topped, conical profile
that
is cut on the SW flank by a large, 1-km-wide crater, which formed during a
catastrophic eruption in 1902 and extends from just below the summit to the
lower flank. The renowned Plinian eruption of 1902 followed a long repose
period
and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome
complex has been growing at the base of the 1902 crater since 1922. Compound
dome growth at Santiaguito has occurred episodically from four
westward-younging
vents, accompanied by almost continuous minor explosions and periodic lava
extrusion, larger explosions, pyroclastic flows, and lahars.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meterologia, e
Hidrologia http://www.insivumeh.gob.gt/geofisica/boletin%20formato.htm,
Washington Volcanic Ash Advisory Center
http://www.ssd.noaa.gov/VAAC/messages.ht
ml

Santa María Information from the Global Volcanism Program

http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-03=

SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m

According to the Darwin VAAC, on 29 June a small plume from Semeru that was
visible on satellite imagery drifted SE at an unknown altitude.

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=

ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m

During 28 June-4 July, the lava dome at Mount St. Helens continued to grow
and
produce small rockfalls. The volcano 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-

SUWANOSE-JIMA Ryukyu Islands, Japan 29.53°N, 129.72°E; summit elev. 799 m

Based on information from JMA, the Tokyo VAAC reported on 30 June that a
small
plume from Suwanose-jima reached an altitude of 1.2 km (4,000 ft) a.s.l. and
drifted NE.

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 28 June- 4 July, small-to-moderate explosions at Tungurahua produced
plumes composed of gas, steam, and small amounts of ash that reached heights
of
1.5 km above the summit (21,400 ft a.s.l.). Light ashfall was reported in
nearby
localities during 29 June-2 July. On 29 June, reports of ground movement
coincided with an explosive eruption that generated blocks of incandescent
material observed to roll 100 m down the W flank. Night-time incandescence
was
observed intermittently during 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, ash clouds identified from Ubinas on 28 June reached
altitudes of 6.7 km (22,000 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