FMHex20: An earthquake focal mechanism database for seismotectonic analyses in metropolitan France and bordering regions

We present a compilation of over 1700 focal mechanisms for nearly 1300 earthquakes in metropolitan France and bordering regions of Western Europe. It is based on both published and unpublished sources (articles, reports, observatory websites) for which the focal mechanism solutions have been verified for internal consistency, corrected in cases of minor errors and rejected in cases of major inconsistencies between the parameters. The database, labeled FMHex20, is a first version and should be regularly updated in the future as part of an ongoing effort within the Seismicity Transverse Action of the French Resif research infrastructure. We also present first-order seismotectonic analyses for the whole metropolitan France and for two regions (Western France and Northern Alps-Jura-Vosges) to illustrate how the FMHex20 database can serve as a basis for geodynamic or seismic hazard zonation studies. Combined with complementary datasets, it can improve our understanding of the kinematics of potentially active faults, including in very-low-strain-rate regions as is the case for most of France.

Automated summary

This study compiles over 1700 focal mechanisms for nearly 1300 earthquakes in metropolitan France and bordering regions, based on verified sources for geodynamic and seismic hazard zonation studies. The FMHex20 database will be regularly updated to enhance understanding of potentially active faults kinematics.