Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 17, 1585-1593, 2017
https://doi.org/10.5194/nhess-17-1585-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
20 Sep 2017
Transposing an active fault database into a fault-based seismic hazard assessment for nuclear facilities – Part 2: Impact of fault parameter uncertainties on a site-specific PSHA exercise in the Upper Rhine Graben, eastern France
Thomas Chartier1,2, Oona Scotti1, Christophe Clément1, Hervé Jomard1, and Stéphane Baize1 1Bureau d'Evaluation des Risques Sismiques pour la Sûreté des Installations, Fontenay-aux-Roses, 92262, France
2Today at Département de Géosciences, Ecole Normale Supérieure, Paris, 75005, France
Abstract. We perform a fault-based probabilistic seismic hazard assessment (PSHA) exercise in the Upper Rhine Graben to quantify the relative influence of fault parameters on the hazard at the Fessenheim nuclear power plant site. Specifically, we show that the potentially active faults described in the companion paper (Jomard et al., 2017, hereafter Part 1) are the dominant factor in hazard estimates at the low annual probability of exceedance relevant for the safety assessment of nuclear installations. Geological information documenting the activity of the faults in this region, however, remains sparse, controversial and affected by a high degree of uncertainty. A logic tree approach is thus implemented to explore the epistemic uncertainty and quantify its impact on the seismic hazard estimates. Disaggregation of the peak ground acceleration (PGA) hazard at a 10 000-year return period shows that the Rhine River fault is the main seismic source controlling the hazard level at the site. Sensitivity tests show that the uncertainty on the slip rate of the Rhine River fault is the dominant factor controlling the variability of the seismic hazard level, greater than the epistemic uncertainty due to ground motion prediction equations (GMPEs). Uncertainty on slip rate estimates from 0.04 to 0.1 mm yr−1 results in a 40 to 50 % increase in hazard levels at the 10 000-year target return period. Reducing epistemic uncertainty in future fault-based PSHA studies at this site will thus require (1) performing in-depth field studies to better characterize the seismic potential of the Rhine River fault; (2) complementing GMPEs with more physics-based modelling approaches to better account for the near-field effects of ground motion and (3) improving the modelling of the background seismicity. Indeed, in this exercise, we assume that background earthquakes can only host M  <  6. 0 earthquakes. However, this assumption is debatable, since faults that can host M  >  6. 0 earthquakes have been recently identified at depth within the Upper Rhine Graben (see Part 1) but are not accounted for in this exercise since their potential activity has not yet been described.

Citation: Chartier, T., Scotti, O., Clément, C., Jomard, H., and Baize, S.: Transposing an active fault database into a fault-based seismic hazard assessment for nuclear facilities – Part 2: Impact of fault parameter uncertainties on a site-specific PSHA exercise in the Upper Rhine Graben, eastern France, Nat. Hazards Earth Syst. Sci., 17, 1585-1593, https://doi.org/10.5194/nhess-17-1585-2017, 2017.
Publications Copernicus
Download
Short summary
We perform a fault-based PSHA exercise in the Upper Rhine Graben to quantify the relative influence of fault parameters on the hazard at the Fessenheim nuclear power plant site. Sensitivity tests show that the uncertainty on the slip rate of the Rhine River fault is the dominant factor controlling the variability of the seismic hazard level, greater than the epistemic uncertainty due to ground motion prediction equations (GMPEs).
We perform a fault-based PSHA exercise in the Upper Rhine Graben to quantify the relative...
Share