Activité du gaz radon dans l'air du sol et sismicité locale : exemple du bassin de l'Arax (Arménie)

A survey of soil gas radon concentrations has been carried out at three sites, in the seismic area of Armenia, from 1996 to 1999. The seismicity generates opposed behaviours at the different sites. This heterogeneity is related to the sites locations in the tectonic frame. An increase of radon concentration occurs inside the tectonic micro-blocks during local seismic activity. On the contrary, an abrupt co-seismic decrease is recorded close to the fault area. These variations can be due to ‘pore-collapse’ phenomena which expulse the pore-gas and increases Rn concentration in soil at intra-blocs sites, but also to pore-elastic deformations and microfracturing modifications in the fault area. To cite this article: K. Kharatian et al., C. R. Geoscience 334 (2002) 179–185.