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Galunggung

Galunggung

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Mount Galunggung is an active stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

 in West Java
West Java
West Java , with a population of over 43 million, is the most populous and most densely populated province of Indonesia. Located on the island of Java, it is slightly smaller in area than densely populated Taiwan, but with nearly double the population...

, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

, around 80 km southeast of the West Java provincial capital, Bandung
Bandung
Bandung is the capital of West Java province in Indonesia, and the country's third largest city, and 2nd largest metropolitan area in Indonesia, with a population of 7.4 million in 2007. Located 768 metres above sea level, approximately 140 km southeast of Jakarta, Bandung has cooler...

 (or around 25 km to the east of the West Java town of Garut
Garut
Garut is a town in the West Java province of Indonesia and is the capital of the Garut Regency. It is located about 75 km to the southeast of the major city of Bandung.-History:...

). Mount Galunggung is part of the Sunda Arc
Sunda Arc
The Sunda Arc is a volcanic arc that has produced the islands of Sumatra and Java, the Sunda Strait and the Lesser Sunda Islands. A chain of volcanoes forms the topographic spine of these islands...

 extending through Sumatra, Java and Bali, which has resulted from the subduction of the Indian oceanic plate and the Australian plate beneath the Eurasian plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...

.

Hazardous eruption of 1982


The last major eruption
Types of volcanic eruptions
During a volcanic eruption, lava, tephra , and various gases are expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed...

 on Galunggung was in 1982, which had a Volcanic Explosivity Index
Volcanic Explosivity Index
The Volcanic Explosivity Index was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions....

 of 4 and killed 72 people. This eruption also brought the dangers of volcanic ash
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...

 to aviation to worldwide attention, after two Boeing 747
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...

 passenger jets flying downwind of the eruption suffered temporary engine failures and damage to exterior surfaces, both planes being forced to make emergency landings at Jakarta
Jakarta
Jakarta is the capital and largest city of Indonesia. Officially known as the Special Capital Territory of Jakarta, it is located on the northwest coast of Java, has an area of , and a population of 9,580,000. Jakarta is the country's economic, cultural and political centre...

 airport.

One, a British Airways aircraft
British Airways Flight 9
British Airways Flight 9, sometimes referred to by its callsign Speedbird 9 or Jakarta incident, was a scheduled British Airways flight from London Heathrow to Auckland, with stops in Bombay, Madras, Kuala Lumpur, Perth, and Melbourne....

 carrying 240 passengers, accidentally entered the ash cloud during night time in June 1982 150 km downwind of the volcano. All four engines failed due to the buildup of volcanic ash, and the aircraft descended for 16 minutes, losing 7,500 metres of its 11,500-meter altitude, until the crew managed to restart the engines.

The following month a Singapore Airlines
Singapore Airlines
Singapore Airlines Limited is the flag carrier airline of Singapore. Singapore Airlines operates a hub at Changi Airport and has a strong presence in the Southeast Asia, East Asia, South Asia, and "Kangaroo Route" markets...

 aeroplane with 230approx passengers aboard also inadvertently entered the cloud at night time, and three of its four engines stopped. The crew succeeded in restarting one of the engines after descending 2,400 metres. Both aircraft suffered serious damage to their engines and exterior surfaces

Historical avalanche deposits


A hummocky deposit known as the Ten Thousand Hills of Tasikmalaya
Tasikmalaya
Tasikmalaya is a city in southeastern West Java, Indonesia, between Bandung and Purwokerto on the southerly of the two major road routes across Java...

 attracted the attention of early 20th century geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...

s. Houses were built on the hummocks since they provided good defence against hostile people, and being above the paddy fields were free of mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...

es and rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

s.

Originally, it was thought that either it had been formed by a lahar
Lahar
A lahar is a type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water. The material flows down from a volcano, typically along a river valley. The term is a shortened version of "berlahar" which originated in the Javanese language of...

 caused by the release of the waters of the crater lake
Crater lake
A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...

, or that it was man-made;
composed of rocks and boulders dumped there after being cleared from paddy fields.

However, in the light of the Mount St. Helens
Mount St. Helens
Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is south of Seattle, Washington and northeast of Portland, Oregon. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a...

 eruption of 1980 and from examination of the Mount Shasta
Mount Shasta
Mount Shasta is located at the southern end of the Cascade Range in Siskiyou County, California and at is the second highest peak in the Cascades and the fifth highest in California...

 deposits it has become clear that the hummocks are a debris-avalanche deposit. Like these mountains, Galunggung has a horseshoe
Horseshoe
A horseshoe, is a fabricated product, normally made of metal, although sometimes made partially or wholly of modern synthetic materials, designed to protect a horse's hoof from wear and tear. Shoes are attached on the palmar surface of the hooves, usually nailed through the insensitive hoof wall...

-shaped crater indicating a massive landslide, and examination of shattered lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

 blocks revealed them to be similar to deposits on the other two volcanoes. According to radiocarbon dating of samples taken from a lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

 flow the landslide happened within the last 23,000 years.

See also


External links