Danau Nyos: Perbedaan antara revisi
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==Formation and geological history== |
==Formation and geological history== |
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[[Berkas:Lake_nyos_map.jpg|left|thumb|150px|Map showing the location of Lake Nyos]] |
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Lake Nyos fills a roughly circular [[maar]] in the [[Oku Volcanic Field]], an explosion crater caused when a [[lava flow]] interacts violently with [[groundwater]]. The maar is believed to have formed in an eruption about 400 years ago, and is 1,800 m (5,900 feet) across and 208 m (682 feet) deep. The area has been volcanically active for millions of years - after [[South America]] and [[Africa]] were split apart by [[plate tectonics]] about 110 million years ago, West Africa also experienced rifting, although to a lesser degree. The rift is known as the [[Mbéré Rift Valley]], and crustal extension has allowed [[magma]] to reach the surface along a line extending through Cameroon. [[Mount Cameroon]] also lies on this fault line. Lake Nyos is surrounded by old lava flows and [[pyroclastic flow|pyroclastic]] deposits. |
Lake Nyos fills a roughly circular [[maar]] in the [[Oku Volcanic Field]], an explosion crater caused when a [[lava flow]] interacts violently with [[groundwater]]. The maar is believed to have formed in an eruption about 400 years ago, and is 1,800 m (5,900 feet) across and 208 m (682 feet) deep. The area has been volcanically active for millions of years - after [[South America]] and [[Africa]] were split apart by [[plate tectonics]] about 110 million years ago, West Africa also experienced rifting, although to a lesser degree. The rift is known as the [[Mbéré Rift Valley]], and crustal extension has allowed [[magma]] to reach the surface along a line extending through Cameroon. [[Mount Cameroon]] also lies on this fault line. Lake Nyos is surrounded by old lava flows and [[pyroclastic flow|pyroclastic]] deposits. |
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==The 1986 disaster== |
==The 1986 disaster== |
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[[Berkas:Cow killed by Lake Nyos gasses.jpg|thumb|right|150px|A cow suffocated by gasses from Lake Nyos]] |
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Although a sudden outgassing of CO<sub>2</sub> had occurred at Lake Monoun in [[1984]], killing 37 local residents, a similar threat from Lake Nyos was not anticipated. On [[August 21]], [[1986]], an event occurred at Lake Nyos which triggered the sudden release of about 1.6 million [[tonne]]s of CO<sub>2</sub>. The gas rushed up two nearby valleys, displacing all the air and suffocating up to 1800 people within 20 km of the lake. |
Although a sudden outgassing of CO<sub>2</sub> had occurred at Lake Monoun in [[1984]], killing 37 local residents, a similar threat from Lake Nyos was not anticipated. On [[August 21]], [[1986]], an event occurred at Lake Nyos which triggered the sudden release of about 1.6 million [[tonne]]s of CO<sub>2</sub>. The gas rushed up two nearby valleys, displacing all the air and suffocating up to 1800 people within 20 km of the lake. |
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Revisi per 13 November 2008 09.51
Danau Nyos adalah sebuah danau kawah gunung api di Kamerun, Afrika Barat, terletak di 6°22′N 10°09′E / 6.36°N 10.15°E. Pada 1986 danau ini melepaskan awan raksasa karbon dioksida, yang mengakibatkan sufokasi (kekurangan oksigen) sampai 1800 orang di desa sekitarnya.
Lihat pula
Referensi
- Cotel A (1999), A trigger mechanism for the Lake Nyos disaster, American Physical Society, Division of Fluid Dynamics Meeting, November 21-23, 1999
- Decker, R. and Decker, B. (1997) Volcanoes, 3rd edition, WH Freeman, New York.
- Sano Y., Kusakabe M., Hirabayashi J. et al (1990), Helium and carbon fluxes in Lake Nyos, Cameroon: constraint on next gas burst, Earth and Planetary Science Letters, v. 99, p. 303-314
- Sano Y., Wakita H., Ohsumi T., Kusakabe M. (1987), Helium isotope evidence for magmatic gases in Lake Nyos, Cameroon, Geophysical Research Letters, v. 14, p. 1039-1041