Lake Nyos

Lake Nyos is a crater lake in Cameroon, which is known as one of the two Cameroonian “Killer Lakes”. A large amount of carbon dioxide (CO₂) gas erupted from the lake in 1984, killing more than 1700 people. Several research projects were launched after this catastrophic incident, which showed that the lake was slowly recharged with CO₂, and that consequently further eruptions would have to be expected in the future. To avoid this scenario, a degassing system was developed for the lake which is in operation since 2001.
We developed a one-dimensional model of the lake to predict the future development of the CO₂ content and the stratification in Lake Nyos for different degassing scenarios. The calculations showed that the presently installed system is sufficient to degas the lake and then keep the CO₂ content at a low level, provided that its long-term maintenance is ensured.
As a side effect of our research on Lake Nyos, we were able to observe a unique time series of double-diffusive convection, a rare phenomenon in lakes, which can occur when a permanently salinity stratified lake is heated from below. It was the first time that the formation, expansion and disappearance of a double-diffusive layer system was observed in a natural system.

Publications

• Schmid et al (2003). Development and sensitivity analysis of a model for assessing stratification and safety of Lake Nyos during artificial degassing. [pdf, 605KB]
  
  
• Halbwachs, M., Sabroux, J.-C., Grangeon, J., Kayser, G., Tochon-Danguy, J.-C., Felix, A., Béard, J.-C., Villevieille, A., Vitter,G., Richon, P., Wüest, A., and Hell, J. (2004). Degassing the “Killer Lakes” Nyos and Monoun, Cameroon. EOS,Transactions, American Geophysical Union, 85 (30), 281–288, 2004. [pdf, 1.92MB]
  
  
• Schmid et al (2004). Double-diffusive convection in Lake Nyos, Cameroon. [pdf, 732KB]
  
  
• Schmid, M., M. Halbwachs, and A. Wüest. (2006). Simulation of CO2 concentrations, temperature, and stratification in Lake Nyos for different degassing scenarios. Geochemistry, Geophysics, and Geosystems 7: Q06019, doi:06010.01029/02005GC001164. [pdf, 1.67MB]