Accurate analysis of the distribution of epicenters in Western Provence and Eastern Languedoc (Southern France)

The present seismicity in Western Provence and Eastern Languedoc (Southern France) is weak. However, when the historical seismicity is considered, these regions are certainly among the most seismic areas of southern France. The tectonic setting of both regions is one of an active intraplate zone. In comparatively “stable” areas like these, the study of small instrumental earthquakes (M<5M<5) is an indispensable source of information. Unfortunately, in these regions, the instrumental seismicity is, as a rule, rare and diffuse. Therefore, interpreting the spatial pattern of this seismicity through a visual inspection is a difficult and subjective process. This paper presents a quantifiable analysis of the seismicity of the study regions. Earthquakes are associated with fault zones by examining the number of epicenters per unit area. The analysis is performed through the blade method applied on collapsed epicenters. The analysed data are extracted from the Laboratoire de Détection et de Géophysique Catalog. Our analysis highlights several significant epicenter alignments associated with known tectonic features.