The following constitutes the new activity and unrest report from the
Weekly Volcanic Activity Report, a cooperative project between the Smithsonian's
Global Volcanism Program and the US Geological Survey's
Volcano Hazards Program.
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| Batu Tara, Komba Island, Indonesia. |
BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin
VAAC reported that during 25-26 April
ash plumes from Batu Tara rose to an altitude of 2.4 km (8,000 ft)
a.s.l.
and drifted 37 km W and SW. During 30 April-1 May ash plumes again rose
to an altitude of 2.4 km (8,000 ft) a.s.l. then drifted 37-55 km NW.
Geologic Summary.
The small isolated island of Batu Tara in the Flores Sea about 50 km
north of Lembata (formerly 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 first
historical eruption from Batu Tara, during 1847-52, produced explosions and a
lava flow.
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CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m
AVO
reported that elevated surface temperatures were detected over
Cleveland in satellite imagery during 25-29 April and possibly on 30
April. Observations showed that a small
lava dome, 25 m across, had recently been emplaced.
Geologic Summary. Symmetrical Mount Cleveland
stratovolcano
is situated at the western end of the uninhabited dumbbell-shaped
Chuginadak Island in the east-central Aleutians. The 1,730-m-high
stratovolcano is the highest of the Islands of Four Mountains group and
is one of the most active in the Aleutians. Numerous large
lava
flows descend its flanks. It is possible that some 18th to 19th century
eruptions attributed to Carlisle (a volcano located across the Carlisle
Pass Strait to the NW) should be ascribed to Cleveland. In 1944
Cleveland produced the only known fatality from an Aleutian eruption.
Recent eruptions from Mt. Cleveland have been characterized by
short-lived explosive
ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.
Map
IOTO [IWO-JIMA] Volcano Islands (Japan) 24.754°N, 141.290°E; summit elev. 161 m
According to a
JMA report on 2 May, an eruption at Ioto (Iwo-jima) caused water discoloration to the NE. A new fumarole was also confirmed.
Geologic Summary.
Ioto (also known as Iwo-jima) in the central Volcano Islands portion of
the Izu-Marianas arc lies within a 9-km-wide submarine caldera. Ioto,
Iwo-jima, and Io-jima are among many transliterations of the name, which
means "Sulfur Island;" the volcano is also known as Ogasawara Io-jima
to distinguish it from several other "Sulfur Island" volcanoes in Japan.
The triangular, low-elevation, 8-km-long island narrows toward its SW
tip and has produced trachyandesitic and trachytic rocks that are more
alkalic than those of other Izu-Marianas arc volcanoes. The island has
undergone dramatic uplift for at least the past 700 years accompanying
resurgent doming of the caldera. A shoreline landed upon by Captain
Cook's surveying crew in 1779 is now 40 m above sea level. The Moto-yama
plateau on the NE half of the island consists of submarine tuffs
overlain by coral deposits and forms the island's high point. Many
fumaroles are oriented along a NE-SW zone cutting through Moto-yama. Numerous
historical phreatic eruptions, many from vents on the west and NW sides of the island, have accompanied the remarkable uplift.
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LOKON-EMPUNG Sulawesi 1.358°N, 124.792°E; summit elev. 1580 m
According to the Darwin
VAAC,
ash plumes from Lokon-Empung, that rose to an altitude of 3.7 km (12,000 ft)
a.s.l. and drifted 75 km N, were detected in satellite imagery and reported by ground-based observers.
Geologic Summary.
The twin volcanoes Lokon and Empung, rising about 800 m above the plain
of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the
higher of the two peaks (whose summits are only 2.2 km apart) has a
flat, craterless top. The morphologically younger Empung volcano has a
400-m-wide, 150-m-deep crater that erupted last in the 18th century, but
all subsequent eruptions have originated from Tompaluan, a 150 x 250 m
wide double crater situated in the saddle between the two peaks.
Historical eruptions have primarily produced small-to-moderate
ash plumes that have occasionally damaged croplands and houses, but
lava-dome growth and
pyroclastic flows have also occurred.
Map
POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED
reported that gas-and-steam plumes, occasionally containing ash, rose
from Popocatépetl during 25-29 April. Gas-and-ash plumes rose 1.5 km
above the crater on 25 and 27 April. On 28 April incandescent fragments
ejected from the crater landed on E flank as far as 1 km. The next day
steam-and-gas plume rose from the crater. On 1 May gas-and-steam plumes,
that occasionally contained low amounts of ash, and rose 1 km above the
crater. The Alert Level remained at Yellow Phase Three.
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.
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For the complete list of ongoing volcanic activity and additional geological summary, click
HERE or select the specific volcano name below for additional details:
ONGOING ACTIVITY: Bulusan, Luzon
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Etna, Sicily (Italy)
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Karymsky, Eastern Kamchatka (Russia)
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Kilauea, Hawaii (USA)
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Nevado del Ruiz, Colombia
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Sakura-jima, Kyushu
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Santa MarÃa, Guatemala
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Shiveluch, Central Kamchatka (Russia)
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Soufrière Hills, Montserrat
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Tungurahua, Ecuador