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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

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

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

New Activity/Unrest

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

Based on a pilot report, the Darwin VAAC reported that an ash cloud from
Tara reached an altitude of 1.5 km (5,000 ft) a.s.l. and drifted NW. Ash was
identified on satellite imagery.

Geologic Summary. The small isolated island of Batu Tara in the Flores Sea
50 km north of Lomblen Island contains a scarp on the eastern side similar
the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the
of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north
the main volcanic arc and is noted for its potassic leucite-bearing
and tephritic rocks. The only known historical eruption from Batu Tara,
1847-52, produced explosions and a lava flow.

Source: Darwin Volcanic Ash Advisory Center

Batu Tara Information from the Global Volcanism Program

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

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

Geologic Summary. Luzon's southernmost volcano, Bulusan, was constructed
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;
NE rim is buried by the andesitic Bulusan complex. Bulusan is flanked by
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

Bulusan Information from the Global Volcanism Program

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

Due to increased seismic activity at Soufriere Hills during approximately
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
According to the Washington VAAC, a pilot reported that an ash plume
altitude of 3 km (10,000 ft) a.s.l. and drifted NW. The VAAC also reported
the Montserrat Volcano Observatory indicated a second dome collapse occurred
1830 on 30 June that also generated ash plumes to altitudes of 3 km (10,000

Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano
occupies the southern half of the island of Montserrat. The summit area
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,
a large submarine debris avalanche. Block-and-ash flow and surge deposits
associated with dome growth predominate in flank deposits at Soufrière
Non-eruptive seismic swarms occurred at 30-year intervals in the 20th
but with the exception of a 17th-century eruption that produced the Castle
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
the southern half of the island and ultimately destroyed the capital city of
Plymouth, causing major social and economic disruption.

Source: Montserrat Volcano Observatory, Washington
Ash Advisory Center, Associated
Press, Antigua Sun
Radio Jamaica

Soufrière Hills Information from the Global Volcanism Program

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
SW along the Ceniza River and a lesser number moved SW along the Taniluyá
According to a news report, on 29 June an ash plume reached a height of 2.2
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

Geologic Summary. Volcán Fuego, one of Central America's most active
is one of three large stratovolcanoes overlooking Guatemala's former
Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high
and its twin volcano to the N, Acatenango. Construction of Meseta volcano
continued until the late Pleistocene or early Holocene, after which growth
the modern Fuego volcano continued the southward migration of volcanism that
began at Acatenango. Frequent vigorous historical eruptions have been
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
pyroclastic flows visible from Antigua.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meterologia, e
Associated Press

Fuego Information from the Global Volcanism Program

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

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

Geologic Summary. Karangetang (also known as Api Siau) lies at the northern
of the island of Siau, N of Sulawesi. The 1,784-m-high stratovolcano
five summit craters along a N-S line. One of Indonesia's most active
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

Karangetang Information from the Global Volcanism Program

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
reported that on 1 and 3 July ash plumes reached altitudes of 3.7 km (12,000
a.s.l. A thermal anomaly in the crater was observed during 24-27 June.
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
Karymsky stratovolcano began about 2,000 years later. The latest eruptive
began about 500 years ago, following a 2,300-year quiescence. Much of the
is mantled by lava flows less than 200 years old. Historical eruptions have
Vulcanian or Vulcanian-Strombolian with moderate explosive activity and
occasional lava flows from the summit crater. Most seismicity preceding
eruptions has originated beneath Akademia Nauk caldera, which is located
immediately S of Karymsky volcano and erupted simultaneously with Karymsky

Sources: Kamchatkan Volcanic Eruption Response Team, Tokyo Volcanic Ash Advisory

Karymsky Information from the Global Volcanism Program

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
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
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
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
E and SW rift zones that extend from the caldera to the sea. About 90% of
surface of Kilauea is formed by lava flows less than about 1,100 years old;
of the volcano's surface is younger than 600 years. The latest Kilauea
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
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

Kilauea information from the Global Volcanism Program

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
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
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
volcano. Pyroclastic flows and lahars accompanying growth and collapse of
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)

Merapi Information from the Global Volcanism Program

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
Santiaguito lava-dome complex reached altitudes of 5.8 km (19,000 ft) a.s.l.
drifted SW. On 3 July, INSIVUMEH reported that an ash plume reached ~800 m
the summit (~15,000 ft a.s.l.). White "smoke" from an incandescent
deposit was visible from the NE base of Caliente cone.

Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of
chain of large stratovolcanoes that rises dramatically above the Pacific
plain of Guatemala. The stratovolcano has a sharp-topped, conical profile
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
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
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
Washington Volcanic Ash Advisory Center

Santa María Information from the Global Volcanism Program

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
plains to the S and lies at the southern end of a volcanic massif extending
the Tengger caldera. Semeru has been in almost continuous eruption since
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
than 250 deaths and damaged 16 villages.

Source: Darwin Volcanic Ash Advisory Center

Semeru Information from the Global Volcanism Program

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
produce small rockfalls. The volcano remained at Volcano Advisory (Alert
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
the upper 400 m of the summit was removed by slope failure, leaving a 2 x
horseshoe-shaped crater now partially filled by a lava dome. Mount St.
was formed during nine eruptive periods beginning about 40-50,000 years ago,
has been the most active volcano in the Cascade Range during the Holocene.
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
Rocks area on the N flank, and were witnessed by early settlers.

Source: US Geological Survey Cascades Volcano Observatory

St. Helens Information from the Global Volcanism Program

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
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
northern Ryukyu Islands consists of an andesitic stratovolcano with two
historically active summit craters. Only about 50 persons live on the
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
Suwanose-jima, one of Japan's most frequently active volcanoes, was in a
of intermittent strombolian activity from On-take, the NE summit crater,
began in 1949 and lasted nearly a half century. The largest historical
took place in 1813-14, when thick scoria deposits blanketed residential
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

Suwanose-jima Information from the Global Volcanism Program

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
1.5 km above the summit (21,400 ft a.s.l.). Light ashfall was reported in
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
observed intermittently during the reporting period.

Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than
above its northern base. It sits ~140 km S of Quito, Ecuador's capital city,
is one of Ecuador's most active volcanoes. Historical eruptions have been
restricted to the summit crater. They have been accompanied by strong
and sometimes by pyroclastic flows and lava flows that reached populated
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

Tungurahua Information from the Global Volcanism Program

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
of the stratovolcano, composed primarily of Pleistocene andesitic lava
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
Debris-avalanche deposits from the collapse of the SE flank of Ubinas extend
km from the volcano. Widespread plinian pumice-fall deposits from Ubinas
some of Holocene age. Holocene lava flows are visible on the volcano's
but historical activity, documented since the 16th century, has consisted of
intermittent minor explosive eruptions.

Source: Buenos Aires Volcanic Ash Advisory Center

Ubinas Information from the Global Volcanism Program