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Mitigation of Dangers from Natural and Anthropogenic HazardsUncommon but Noteworthy Natural Hazards

Mitigation of Dangers from Natural and Anthropogenic Hazards: Uncommon but Noteworthy Natural... [Lake Nyos is a crater lake in Cameroon. The volcano that underlies it is continually emitting CO2 into the bottom waters. The lake is stratified and the layer of lake water overlying the bottom water traps the CO2 thereby allowing a build up of the gas. In the past, the lake has overturned seasonally releasing the CO2 into the atmosphere relieving the pressure built up during the year. However, in the time preceding 1986, there was no overturn so that the CO2 in the bottom water increased greatly. During the early morning of August 21, there was an event that allowed the eruption of an enormous volume of CO2 into the atmosphere to the degree that more than 15 % of the atmosphere was CO2. An air/CO2 cloud burst forth over the rim of the crater lake and because it was heavier than natural air it flowed down slope into a valley asphyxiating more than 1750 people and thousands of heads of livestock before the cloud dissipated [1]. Where the atmosphere had more than 15 % CO2 there was death. Where there was less than 15 % CO2 in the air because of some dissipation, many survived. What triggered the rupture of the water layer overlying the charged bottom water is unknown but has been attributed by some to a rockfall, by other to a landslide, and by others to a cold rain and the sudden downward current of the heavier cold water through the lighter warmer water. This “eruption” is a rare happening but not unknown. Two years previously at crater Lake Monoun, much smaller than Lake Nyos, 37 people died from CO2 asphyxiation. This was attributed incorrectly by the government to terrorism and someone throwing chemicals into the lake. We know better now. Other crater lakes in Cameroon and elsewhere that fail to overturn seasonally are a natural hazard threat to people and livestock in the nearby vicinity. For example, Lake Kivu is located between Rwanda and Congo, is twice as deep as Lake Nyos, can store more CO2 gas in its bottom water layer from magma leak and bacterial activity, and has two million people living nearby.] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png

Mitigation of Dangers from Natural and Anthropogenic HazardsUncommon but Noteworthy Natural Hazards

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Publisher
Springer International Publishing
Copyright
© Springer International Publishing Switzerland 2016
ISBN
978-3-319-38874-8
Pages
115 –118
DOI
10.1007/978-3-319-38875-5_21
Publisher site
See Chapter on Publisher Site

Abstract

[Lake Nyos is a crater lake in Cameroon. The volcano that underlies it is continually emitting CO2 into the bottom waters. The lake is stratified and the layer of lake water overlying the bottom water traps the CO2 thereby allowing a build up of the gas. In the past, the lake has overturned seasonally releasing the CO2 into the atmosphere relieving the pressure built up during the year. However, in the time preceding 1986, there was no overturn so that the CO2 in the bottom water increased greatly. During the early morning of August 21, there was an event that allowed the eruption of an enormous volume of CO2 into the atmosphere to the degree that more than 15 % of the atmosphere was CO2. An air/CO2 cloud burst forth over the rim of the crater lake and because it was heavier than natural air it flowed down slope into a valley asphyxiating more than 1750 people and thousands of heads of livestock before the cloud dissipated [1]. Where the atmosphere had more than 15 % CO2 there was death. Where there was less than 15 % CO2 in the air because of some dissipation, many survived. What triggered the rupture of the water layer overlying the charged bottom water is unknown but has been attributed by some to a rockfall, by other to a landslide, and by others to a cold rain and the sudden downward current of the heavier cold water through the lighter warmer water. This “eruption” is a rare happening but not unknown. Two years previously at crater Lake Monoun, much smaller than Lake Nyos, 37 people died from CO2 asphyxiation. This was attributed incorrectly by the government to terrorism and someone throwing chemicals into the lake. We know better now. Other crater lakes in Cameroon and elsewhere that fail to overturn seasonally are a natural hazard threat to people and livestock in the nearby vicinity. For example, Lake Kivu is located between Rwanda and Congo, is twice as deep as Lake Nyos, can store more CO2 gas in its bottom water layer from magma leak and bacterial activity, and has two million people living nearby.]

Published: Jun 24, 2016

Keywords: Bottom Water; Crater Lake; Shore Area; Crater Floor; Bottom Water Layer

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