Geologic Background:
The massive Gunung Awu stratovolcano occupies
the northern end of Great Sangihe Island, the largest of
the Sangihe arc. Deep valleys that form passageways for
lahars dissect the flanks of the volcano, which was
constructed within a 4.5-km-wide caldera. Awu contains a
summit crater lake that was 1 km wide and 172 m deep in
1922, but was largely ejected during the 1966 eruption.
Historic Activity:
- At least 16 eruptions since 1640. Eruptions in 1640,
1646, 1711, 1812,1856, 1875, 1883, 1885, 1892, 1893,
1913, 1921, 1922, 1931, and 1966.
- Awu is one of Indonesia's deadliest volcanoes;
powerful explosive eruptions in 1711, 1812, 1856, 1892,
and 1966 produced devastating pyroclastic flows and
lahars that caused more than 8,000 fatalities.
- Awu's last eruption began on August 12, 1966, when
powerful explosions ejected the lava dome and crater
lake. Pyroclastic flows advanced about 5 km down the
flanks killing 39 people and injuring about 1000.
Recent Activity:
- About 80% of the crater lake drained on February 1,
1992.
- During a visit in May 1992, fumaroles along the inter
north wall were steaming and had temperatures of 70-92
degrees C. Active solfataras with temperatures of 70 to
97 degrees C. had left substantial sulfur along the south
and east walls. In the SE section of the crater, a deep
vent 20 m in diameter produced a thick 50-m-high steam
cloud that smelled of sulfur and was accompanied by an
audible boiling sound. The presence of lithic ejecta
around the vent suggested that it had been formed by a
phreatic explosion.
Data Sources:
- Global Volcanism Network (V. 17, No.2 and V. 17, No.
4).
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