From Freepedia
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Coordinates:
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7°15′0″ S 108°3′0″ E
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Type:
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Stratovolcano (active)
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Age of rock:
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Last eruption:
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1982
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Galunggung (Galoen-gong, Gunung Galunggung) is a
stratovolcano on
Java,
Indonesia.
The last major eruption on Galunggung was in
1982, which had a
Volcanic Explosivity Index of 4 and killed 35 people. This eruption also brought the dangers of
volcanic ash to aviation to worldwide attention, after two 747 passenger jets flying downwind of the eruption suffered temporary total engine failures and damage to exterior surfaces, both planes being forced to make emergency landings at Jakarta.
On the southeast slope of Galunggung Volcano on the densely populated island of
Java, a hummocky deposit called the
Ten Thousand Hills of Tasik Malaja drew the attention of
European geologists in the early part of the
20th century. Dutch geologist
B.G. Escher hypothesized that a breakout of a
crater lake resulted in a watery landslide that formed the deposit. The hummocks were likely material left behind as the more watery parts of the slide flowed away.
Australian geologist
F.X. Schaffer suggested that the hummocks might be manmade; as the local people cleared the land to make
ricefields, they made dumps of the boulders and cobbles that they found. The dumps became hummocks, and were used as sites for homes and fruit trees, as they offered protections from hostile people as well as from the
mosquitoes and
rats of the rice fields. Schaffer noted that the volume of material might seem large for "occidentals but it is not beyond the powers of the numerous and industrious
Malays."
The horseshoe shape of Galunggung's crater and the nature of the hummocks, however, suggest a different cause for the formation of the Ten Thousand Hills. Since
1980, geologists from the
Volcanological Survey of Indonesia and the
U.S. Geological Survey have reinterpreted the deposit as a debris-avalanche deposit. Quarry exposures show pieces of the old volcano -- the block facies -- shattered but intact, that are similar to the deposits at
Mount St. Helens and
Mount Shasta.
Radiocarbon dates of a lava flow within the deposit show that the debris avalanche is less than 23,000 years old.
See also
Source
- Brantley and Glicken, (1986). Volcanic Debris Avalanches: Earthquakes & Volcanoes, v.18, n.6, p.195-206.
External links
