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Probabilistic seismic hazard assessment of Switzerland: best estimates and uncertainties

Wiemer, Stefan ; Giardini, Domenico ; Fäh, Donat ; Deichmann, Nicholas ; Sellami, Souad

In: Journal of Seismology, 2009, vol. 13, no. 4, p. 449-478

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    Titre
    • Probabilistic seismic hazard assessment of Switzerland: best estimates and uncertainties
    Auteur
    • Wiemer, Stefan. Swiss Seismological Service, Institute of Geophysics, Sonneggstrasse 5, ETH Zurich, NO, 8092, Zurich, Switzerland
    • Giardini, Domenico. Swiss Seismological Service, Institute of Geophysics, Sonneggstrasse 5, ETH Zurich, NO, 8092, Zurich, Switzerland
    • Fäh, Donat. Swiss Seismological Service, Institute of Geophysics, Sonneggstrasse 5, ETH Zurich, NO, 8092, Zurich, Switzerland
    • Deichmann, Nicholas. Swiss Seismological Service, Institute of Geophysics, Sonneggstrasse 5, ETH Zurich, NO, 8092, Zurich, Switzerland
    • Sellami, Souad. Swiss Seismological Service, Institute of Geophysics, Sonneggstrasse 5, ETH Zurich, NO, 8092, Zurich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Journal of Seismology, 2009, vol. 13, no. 4, p. 449-478. Springer Netherlands
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:314652
    Summary
    We present the results of a new genera tion of probabilistic seismic hazard assessment for Switzerland. This study replaces the previous intensity-based generation of national hazard maps of 1978. Based on a revised moment-magnitude earthquake catalog for Switzerland and the surrounding regions, covering the period 1300-2003, sets of recurrence parameters (a and b values, M max ) are estimated. Information on active faulting in Switzerland is too sparse to be used as source model. We develop instead two models of areal sources. The first oriented towards capturing historical and instrumental seismicity, the second guided largely by tectonic principles and express ing the alterative view that seismicity is less stationary and thus future activity may occur in previously quiet regions. To estimate three alterna tive a and b value sets and their relative weighting, we introduce a novel approach based on the modified Akaike information criterion, which allows us to decide when the data in a zone deserves to be fitted with a zone-specific b value. From these input parameters, we simulate synthetic earthquake catalogs of one-million-year duration down to magnitude 4.0, which also reflect the difference in depth distribution between the Alpine Foreland and the Alps. Using a specific predictive spectral ground motion model for Switzerland, we estimate expected ground motions in units of the 5% damped acceleration response spectrum at frequencies of 0.5-10Hz for all of Switzerland, referenced to rock sites with an estimated shear wave velocity of 1,500m/s2 in the upper 30m. The highest hazard is found in the Wallis, in the Basel region, in Graubünden and along the Alpine front, with maximum spectral accelerations at 5Hz frequency reaching 150cm/s2 for a return period of 475years and 720cm/s2 for 10,000years