New perspectives in the study of active faults in metropolitan France: the "Active faults France" research axis

Metropolitan France shows a strong structural heritage and a low deformation rate. However, destructive earthquakes can occur there. Active faults are therefore a priority research topic for our societies. In this article and as part of a national effort to identify the still largely fragmentary knowledge, the team of researchers involved in this study stresses that major efforts from the active tectonics and paleoseismology community are needed to generate robust data, especially on the many faults that are not yet studied.

This is the objective of the "Failles ACTives France" (FACT) axis launched in the framework of the Action Sismicité Transverse (ATS) of the Resif-Epos consortium [Masson et al. 2021]. Here are presented some recent investigations carried out along presumed active faults and under study in the mountainous areas of France, their forelands and plains.

These new results implement new approaches and tools, and allow to characterize their quaternary activity and to propose new research tracks to improve our knowledge. The first option may be to continue on the "historical earthquake trail", studying faults in their immediate vicinity. However, given the long recurrence intervals of earthquakes, it is also necessary to go beyond, by targeting inherited structures of more than 5 km with a morphological signature on the surface, or affecting plio-quaternary sedimentary basins. The definition of new targets to be studied in priority, as well as the implementation of complementary approaches, implies a close collaboration between university researchers throughout the country, institutional scientists, with their regional and regulatory knowledge, and finally by industry/stakeholders, with the knowledge of the facilities to be protected. Close collaboration with neighboring countries (Belgium, Germany, Italy and Spain) is also established to cover transnational geological objects and themes.

Reference

Jean-François Ritz, Stéphane Baize, Laurence Audin, Christine Authémayou, Fabien Graveleau, Caroline Kaub, Pierre Lacan, Frédérique Leclerc, Christophe Larroque, Kevin Manchuel, Jean-Louis Mugnier, Maria Ortuño, Magali Rizza, Riccardo Vassallo , Pierre Antoine, Pierre Arroucau , Jérémy Billant, Laurent Bollinger, Matthieu Ferry, Charlotte Fillon, Laurent Geoffroy, Hervé Jomard, Pascal Le Roy, Jean-Luc Locht, Sébastien Migeon, Clément Perrin, Julie Perrot, Gueorgui Ratzov, Klaus Reicherter, Olivier Soubigou, Christophe Vergniault , Marc Viaplana-Muzas, Jérôme Van der Woerd , (2021), New perspectives in studying active faults in metropolitan France: the “Active faults France” (FACT/ATS) research axis from the Resif-Epos consortium, Comptes Rendus. Géoscience, DOI.