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Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
04 Apr 2017
Review status
This discussion paper is under review for the journal Natural Hazards and Earth System Sciences (NHESS).
Methodology for Earthquake Rupture Rate estimates of fault networks: example for the Western Corinth Rift, Greece
Thomas Chartier1,2, Oona Scotti2, Hélène Lyon-Caen1, and Aurélien Boiselet1,2,a 1Laboratoire de géologie, Ecole Normale Supérieure, CNRS UMR 8538, PSL Research University, Paris, 75005, France
2Bureau d’Evaluation des Risques Sismiques pour la Sûreté des Installations, Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France
anow at: Axa Global P&C, Paris, 75008, France
Abstract. Modelling the seismic potential of active faults is a fundamental step of probabilistic seismic hazard assessment (PSHA). An accurate estimation of the rate of earthquakes on the faults is necessary in order to obtain the probability of exceedance of a given ground motion. Most PSHA studies consider faults as independent structures and neglect the possibility of multiple faults or fault segments rupturing simultaneously (Fault to Fault -FtF- ruptures). The latest Californian model (UCERF-3) takes into account this possibility by considering a system level approach rather than an individual fault level approach using the geological , seismological and geodetical information to invert the earthquake rates. In many places of the world seismological and geodetical information long fault networks are often not well constrained. There is therefore a need to propose a methodology relying only on geological information to compute earthquake rate of the faults in the network. In this methodology, similarly to UCERF-3, a simple distance criteria is used to define FtF ruptures and consider single faults or FtF ruptures as an aleatory uncertainty. Rates of earthquakes on faults are then computed following two constraints: the magnitude frequency distribution (MFD) of earthquakes in the fault system as a whole must follow an imposed shape and the rate of earthquakes on each fault is determined by the specific slip-rate of each segment depending on the possible FtF ruptures. The modelled earthquake rates are then confronted to the available independent data (geodetical, seismological and paleoseismological data) in order to weigh different hypothesis explored in a logic tree.

The methodology is tested on the Western Corinth Rift, Greece (WCR) where recent advancements have been made in the understanding of the geological slip rates of the complex network of normal faults which are accommodating the ~15 mm/yr North-South extension. Modelling results show that geological, seismological extension rates and paleoseismological rates of earthquakes cannot be reconciled with only single fault rupture scenarios and require hypothesising a large spectrum of possible FtF rupture sets. Furthermore, in order to fit the imposed regional Gutenberg-Richter MFD target, some of the slip along certain faults needs to be accommodated either with interseismic creep or as post-seismic processes. Furthermore, individual fault’s MFDs differ depending on the position of each fault in the system and the possible FtF ruptures associated with the fault. Finally, a comparison of modelled earthquake rupture rates with those deduced from the regional and local earthquake catalogue statistics and local paleosismological data indicates a better fit with the FtF rupture set constructed with a distance criteria based on a 5 km rather than 3 km, suggesting, a high connectivity of faults in the WCR fault system.

Citation: Chartier, T., Scotti, O., Lyon-Caen, H., and Boiselet, A.: Methodology for Earthquake Rupture Rate estimates of fault networks: example for the Western Corinth Rift, Greece, Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2017-124, in review, 2017.
Thomas Chartier et al.
Thomas Chartier et al.
Thomas Chartier et al.


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