South East France Potentially Active Faults: A database for seismic hazard assessment

Abstract. The South-East of France has been structured by numerous tectonic episodes resulting in a complex compound of crustal deformations. This fallouts in a large network of faults which have evolved throughout subsequent tectonic events. Nevertheless, the present-day tectonic deformation is slow and of debated origin, giving place to a low to moderate seismicity. This seismotectonic context is a challenge for seismic hazard analysis, specifically for the identification and characterisation of potentially active faults. In this study we present a fault-related data compilation, named South-East France Potentially Active Faults (SEFPAF, Mowbray et al., 2025, https://doi.org/10.5281/zenodo.17235395), which integrates structural components from geological maps, previous neotectonic databases and fault-specific studies. Our objective is to provide a new, well documented, and modular fault database. Multiple structural representations per fault are presented, allowing the end-user to choose from the various parameter value options. With an end purpose of identifying the most relevant faults for seismic hazard assessment, we build a series of indices which allow fault prioritization: the Importance index (I), the Documentation index (D) and, the Seismogenic Potential index (SP). The first classifies faults into major, secondary and minor based on the source's description of the structure; the second analyses the quantity of information known for each fault; the last intends to decipher seismically active faults by integrating the age of the last documented rupture, the spatial correlation with seismic flux and, the spatial correlation with geodetic strain. SEFPAF may have various applications, amongst them we illustrate the first step towards the development of a fault model for seismic hazard analysis: we identify relevant faults to model by adjusting the index criteria and, propose idealized geometries for a set of 20 faults which can subsequently be used as composite seismogenic sources.