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Integration and influence of paleoseismic and geologic data for the seismic hazard evaluation in the Catalan coastal ranges, Spain |
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| Authors: | Aníbal Ojeda Kuvvet Atakan Eullia Masana Pere Santanach María-Jos Jimnez Mariano García-Fernndez |
| Institution: | a Institute of Solid Earth Physics, University of Bergen, Allégten 41, N-5007, Bergen, Norway b Dept. Geodinàmica i Geofísica, Universitat de Barcelona, Zona Universitaria de Pedralbes, Barcelona 08028, Spain c Institute of Earth Sciences, Jaume Almera, CSIC, Barcelona, Spain |
| Abstract: | In this study, the influence of paleoseismic and geologic data in the seismic hazard estimation for the Catalan coastal ranges is analysed. We computed the probabilistic seismic hazard using area seismic sources with a Poissonian assumption for the earthquake occurrence. For the computations, a previously published attenuation relationship based on European strong motion data was applied. The resulting hazard estimates show similarities to the previous assessments in the region. These results were then used as a reference for comparison with other new models. In order to analyse the influence of the paleoseismic data three different models were tested. Since the number of faults that are investigated in detail are few, the same area sources that were used in the Poissonian assumption were kept in all three new models. In addition, the new paleoseismic data with faults expressed as line sources were used. In this case, a cyclic earthquake occurrence was assumed. The three models were based on the paleoseismic data with different assumptions on the time elapsed since last event. The time elapsed was set to 0, 10 and 85% of the recurrence interval in each model. The results are presented as maps showing the difference between the three models and the reference model with the Poissonian assumption. The results are given in horizontal peak ground acceleration contour maps for different return periods, also taking into account large return periods as high as 25,000 years. This is done to demonstrate the effect of large recurrence intervals found for some of the active faults. In general, we observe that for short return periods (<1000 years), the Poissonian assumption of earthquake occurrence is probably sufficient and provides a robust estimate of the hazard. However, for longer return periods (>5000 years) the effects of the paleoseismic data become increasingly significant. In order to estimate the true seismic hazard potential of this apparently low seismicity area, long-term behaviour of the possible active faults in the region needs to be investigated systematically. |
| Keywords: | Seismic hazard evaluation Paleoseismology Characteristic earthquake Renewal model Spain Catalan coastal ranges |
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