Modelling Air Dispersion of CO2 from Limnic Eruptions

Abstract

Limnic eruptions, like the August 1986 Lake Nyos event, can release huge amounts of dense CO2 that, under the control of local topography and wind, can travel up to distal areas suffocating wildlife, livestock and humans. We present a computational approach, based on shallow layer equations, used to simulate the dispersion of dense CO2 clouds and assess the associated gas hazard. Examples of application of such an approach to hazard assessment of gas accumulations generated by persistent CO2 emissions in Italy, and simulation results of the CO2 air dispersion from the limnic eruption of the 21 August 1986 at Nyos are also discussed. The method presented can be a useful tool to evaluate gas hazard both for persistent gas emissions and for the most hazardous gas-driven limnic eruptions.