6th Colloquium on historical earthquakes & paleoseismology studies

Toward a better characterization of small to moderate earthquakes seismological pattern in Northeastern France

24 Oct 2018, 13:45

35m

Han-sur-Lesse

Poster Preference Session 1 Posters Poster Session 1

Speaker

Alexandra Renouard (Université de Strasbourg, CNRS, IPGS/EOST, UMR7516, 5 rue René Descartes, 67100 Strasbourg, France)

Description

Seismic risk assessment in intraplate regions with low surface deformation, such as Northeastern France, and its border countries of Germany and Switzerland, faces important challenges related to vulnerability due to the : high density of population, numerous industries with sensitive activities (nuclear power plants, mines, quarry blasting, chemical and bacteriological industries), and fragile historical heritage to protect. However, despite being located at the middle of the western Europe, seismic hazard estimation in our study area remains poorly constrained, especially because of lack of knowledge on active structures’ identification and the nature of the processes responsible for earthquakes. Furthermore, the regional seismicity encompasses significant historical and recent earthquakes (intensity up to IX and X), together with a regular activity heterogeneously distributed over the whole region, and affecting all the main geologic domains : the Upper Rhine Graben, the ancient massifs of the Vosges and the Black Forest, the Jura mountains with the molassic basin and the Alps. We focus here on the small events, whose the space time evolution and the statistic analysis are important criteria to characterise the seismic behaviour of the region and its potential seismogenetic structures. By taking advantage of an exceptional, recently densified seismic network (development of temporary stations (2015-2020) in the framework of the European AlpArray project, reinforcing the growing permanent national networks of France, Germany, Switzerland and Belgium), we are building a new seismic catalog following a methodology specifically adapted to this network and its low level of detection, the current regional seismicity and the large amount of waveforms analysed. Doing so, we reduce the magnitude of completeness and access to more accurate hypocentral localizations and magnitude estimations, which are crucial for the seismic event classification and a better characterisation of the seismic behaviour of the region.