Modeling seismic rates in France for seismic hazard assessment

2019 (5 to 6 months depending on the student)
Laboratoire(s) de rattachement : ISTerre
Encadrant(s) : C. Beauval and D. Marsan
Contact(s) : Celine.Beauval at univ-grenoble-alpes.fr
Lieu : ISTerre, 1381 rue de la Piscine 38400 Saint Martin d’Hères
Niveau de formation & prérequis : internship M2
Mots clés : earthquake recurrence ; seismic hazard assessment ; declustering, macroseismic intensitie


Modeling seismic rates in France for seismic hazard assessment

The first step in a probabilistic seismic hazard study is the modeling of earthquake recurrence rates from earthquake catalogs. The earthquake catalog used must cover both instrumental and historical periods to be as representative as possible of the seismic potential of the zone. In France, instrumental data covers the last 50 years ; whereas the SisFrance macroseismic database includes information on earthquakes for the last millennium (http://www.sisfrance.net/). Earthquake recurrence models are established from past seismicity in a source zone. They predict the range of earthquakes that can occur in a source zone and the frequencies of these earthquakes. They are used to predict the occurrences of future earthquakes in the seismic hazard study. As they must be representative of long-term seismicity, aftershock sequences are usually retrieved from the catalog. The aim of this internship is twofold :
1) modeling the seismic rates for seismic source zones in France, with a specific focus on the declustering step. Considering different declustering algorithms (e.g. Van Stiphout et al. 2012) the analysis will enable to understand the uncertainties related to each method and the impact on the seismic rates modeled. The impact of other uncertainties, such as the uncertainty on the determination of completeness time windows, will also be quantified.
2) making use of intensity attenuation relationships (e.g. Bakun and Scotti 2006 ; Baumont et al. 2017) to check the consistency between the predicted and observed number of intensities at some selected sites (with and without clustered events). The aim is to evaluate the recurrence models using as a reference the observed history of shaking at given selected sites, with a specific attention on the uncertainties.

Supervisors  : Céline Beauval and David Marsan, at ISTerre
Contacts  : celine.beauval at univ-grenoble-alpes.fr ; david.marsan at univ-smb.fr

Framework  : SERA European project http://www.sera-eu.org/en/home/

Some references  :
• Bakun, W.H. & Scotti, O., 2006. Regional intensity attenuation models for France and the estimation of magnitude and location of historical earthquakes, Geophys. J. Int., 164, 596–610.
• Baumont D, Manchuel K, Traversa P, Durouchoux C, Nayman E, Ameri G (2017) Empirical intensity attenuation models calibrated in Mw for metropolitan France. Bull Earthq Eng.
• Cara M, Cansi Y, Schlupp A et al (2015) Si-Hex : a new catalogue of instrumental seismicity for metropolitan France. Bull Soc Géol Fr 186:3–19. doi:10.2113/qssqfbull.186.1.3.
• Manchuel K, Traversa P, Baumont D, Cara M, Nayman E, Durouchoux C (2017) The French seismic CATalogue (FCAT-17). Bull Earthq Eng.
• Van Stiphout, T., J. Zhuang, and D. Marsan (2012). Seismicity declustering, Community Online Resource for Statistical Seismicity Analysis, doi : 10.5078/corssa-52382934, available at http://www.corssa.org.