SI-Hex: a new catalogue of instrumental seismicity for metropolitan France

Michel Cara (1) , Yves Cansi (2) , Antoine Schlupp (1) , Pierre Arroucau (3) , Nicole Béthoux (4) , Eric Beucler (3) , Stéphane Bruno (2) , Marie Calvet (5) , Sébastien Chevrot (5) , Alexandra Deboissy (1) , Bertrand Delouis (4) , Marylin Denieul (1) , Anne Deschamps (4) , Cécile Doubre (1) , Julien Fréchet (6) , Stéphanie Godey (7) , Olivia Golle (3) , Marc Grunberg (1) , Jocelyn Guilbert (2) , Méric Haugmard (3) , Liliane Jenatton (8) , Sophie Lambotte (1) , Delphine Leobal (2) , Christophe Maron (4) , Véronique Mendel (6) , Sophie Merrer (2) , Marie Macquet (3) , Arnaud Mignan (1) , Antoine Mocquet (3) , Marc Nicolas (2) , Julie Perrot (9) , Bertrand Potin (8) , Olivier Sanchez (8) , Jean-Paul Santoire (2) , Olivier Sèbe (2) , Matthieu Sylvander (5) , François Thouvenot (10) , Jerome van Der Woerd (11) , Katia van Der Woerd (1)

1 IPGS - Institut de physique du globe de Strasbourg
2 LDG - Laboratoire de Détection et de Géophysique (CEA)
3 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]
4 GEOAZUR 6526 - Géoazur
5 DTP - Dynamique terrestre et planétaire
6 IPGS-Sismologie - Sismologie (IPGS)
7 EMSC/CSEM - European Mediterranean Seismological Centre
8 Mécanique des failles
9 LDO - Domaines Océaniques
10 ISTerre - Institut des Sciences de la Terre
11 IPGS-DGDA - Dynamique globale et déformation active (IPGS)

The aim of the SI-Hex project (acronym for « Sismicité Instrumentale de l’Hexagone ») is to provide a catalogue of seismicity for metropolitan France and the French marine economic zone for the period 1962–2009 by taking into account the contributions of the various seismological networks and observatories from France and its neighbouring countries. The project has been launched jointly by the Bureau Central Sismologique Français (CNRS-University/BCSF) and the Laboratoire de Détection et de Géophysique (CEA-DAM/LDG). One of the main motivations of the project is to provide the end user with the best possible information on location and magnitude of each earthquake. So far, due to the various procedures in use in the observatories, the different locations and magnitudes of earthquakes located in the SI-Hex zone were presenting large discrepancies. In the 2014 version of the catalogue, 1D localizations of hypocentres performed with a unique computational scheme and covering the whole 1962–2009 period constitute the backbone of the catalogue (SI-Hex solutions). When available, they are replaced by more precise localizations made at LDG or, for recent times, by the regional observatories within: 1) the French Alps, 2) the southernmost Alps and the Mediterranean domain including Corsica, 3) the Pyrenees, and 4) the Armorican massif. Moment magnitudes Mw are systematically reported in the SI-Hex catalogue. They are computed from coda-wave analysis of the LDG records for most Mw>3.4 events, and are converted from local magnitudes ML for smaller magnitude events. Finally, special attention is paid to the question of discrimination between natural and artificial seismic events in order to produce a catalogue for direct use in seismic hazard analysis and seismotectonic investigations. The SI-Hex catalogue is accessible on the web site www.franceseisme.fr and contains 38,027 earthquake hypocentres, together with their seismic moment magnitudes Mw.

Keywords: Discrimination; Magnitude; Seismicity; Seismic hazard; Seismotectonics; France

Domains: Geophysics [physics.geo-ph]

Michel Cara, Yves Cansi, Antoine Schlupp, Pierre Arroucau, Nicole Béthoux, et al.. SI-Hex: a new catalogue of instrumental seismicity for metropolitan France. Bulletin de la Société Géologique de France, 2015, 186 (1), pp.3-19. ⟨10.2113/gssgfbull.186.1.3⟩. ⟨insu-01153693⟩