Degassing Lakes Nyos and Monoun: Defusing certain disaster

Proceedings of the National Academy of Sciences of the United States of America
By: , and 

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Abstract

Since the catastrophic releases of CO2 in the 1980s, Lakes Nyos and Monoun in Cameroon experienced CO2 recharge at alarming rates of up to 80 mol/m2 per yr. Total gas pressures reached 8.3 and 15.6 bar in Monoun (2003) and Nyos (2001), respectively, resulting in gas saturation levels up to 97%. These natural hazards are distinguished by the potential for mitigation to prevent future disasters. Controlled degassing was initiated at Nyos (2001) and Monoun (2003) amid speculation it could inadvertently destabilize the lakes and trigger another gas burst. Our measurements indicate that water column structure has not been compromised by the degassing and local stability is increasing in the zones of degassing. Furthermore, gas content has been reduced in the lakes ≈12-14%. However, as gas is removed, the pressure at pipe inlets is reduced, and the removal rate will decrease over time. Based on 12 years of limnological measurements we developed a model of future removal rates and gas inventory, which predicts that in Monoun the current pipe will remove ≈30% of the gas remaining before the natural gas recharge balances the removal rate. In Nyos the single pipe will remove ≈25% of the gas remaining by 2015; this slow removal extends the present risk to local populations. More pipes and continued vigilance are required to reduce the risk of repeat disasters. Our model indicates that 75-99% of the gas remaining would be removed by 2010 with two pipes in Monoun and five pipes in Nyos, substantially reducing the risks.

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Publication type Article
Publication Subtype Journal Article
Title Degassing Lakes Nyos and Monoun: Defusing certain disaster
Series title Proceedings of the National Academy of Sciences of the United States of America
DOI 10.1073/pnas.0502274102
Volume 102
Issue 40
Year Published 2005
Language English
Publisher PNAS
Contributing office(s) Volcano Hazards Program
Description 6 p.
First page 14185
Last page 14190
Country Cameroon
Other Geospatial Lakes Nyos and Monoun
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