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

¹ Géosciences Montpellier, CNRS, Université de Montpellier, Université des Antilles, Montpellier, France
² CEA DAM Ile-de-France, Bruyères-le-Châtel, France
³ Géoazur, Université Côte d’Azur, CNRS, Observatoire de la Côte d’Azur, IRD, Valbonne, France
⁴ Institut Terre Environnement Strasbourg, École et Observatoire des Sciences de la Terre, CNRS, Université de Strasbourg, Strasbourg, France
⁵ Bureau d’Evaluation des Risques Sismiques pour la Sûreté des Installations, Institut de Radioprotection et Sûreté Nucléaire, Fontenay-aux-Roses, France
⁶ Institut de Recherche en Astrophysique et Planétologie, CNRS, UPS, CNES, Université de Toulouse, Toulouse, France

^* Corresponding author: stephane.mazzotti@umontpellier.fr

Received: 27 April 2020
Accepted: 21 December 2016

Abstract

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 It is based on both published and unpublished sources (articles, reports, observatory websites) for which the focal mechanism solutions have been verified for internal consistency, corrected in cases of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 Résif 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.