HR: 0800h
AN: NG41B-0523    [Abstracts]
TI: Hybrid zoneless probabilistic seismic hazard analysis: Test and first application to SW Germany
AU: * Chan, C
EM: han@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, D-14473, Germany
AU: Gruenthal, G
EM: ggrue@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, D-14473, Germany
AB: Zoneless approaches are one option to assess probabilistic seismic hazard (PSHA). They rely simply on smoothing the epicenter locations of past events according to the fractal distribution of earthquakes in space without defining seismic source zones. However, some shortcomings are connected with these zoneless approaches. Sometimes, one cannot apply one single magnitude completeness, especially when the study area covers different catalogue areas, where different completeness patterns are valid. Furthermore, the characteristic depths of the strongest earthquakes generally differ over larger areas. With respect to these two reasons, a hybrid approach for zoneless PSHA is introduced in this study; i.e. a combination of a zoneless approach with a seismic source model based solely on the large scale geological architecture. This large scale model meets the requirements of introducing different magnitude completeness. But the probability of the earthquake occurrence is based on a pure zoneless approach. Then, instead of a time set of magnitude completeness for the entire studying area, as it is the standard procedure for zoneless approaches, various time sets for different large zones are considered. Another innovation of our approach is to take into account the actual depth of each earthquake rather than assuming a certain weighting set of depths. We apply the hybrid zoneless approach to the SW part of Germany, which represents one of the highest seismicity areas in the country. The use of area specific magnitude completeness and actual depths of all events clearly results in a more realistic PSHA. Furthermore, we compare the results of the hybrid zoneless approach with the results of a recent study using a zone-based methodology. The zone-based approach shows more significant contrasts in the study area; i.e the hybrid zoneless approach provides a rather smoothed pattern. This corresponds to comparisons between zoneless and zone-based approaches by previous studies.
DE: 0468 Natural hazards
DE: 0902 Computational methods: seismic
DE: 3245 Probabilistic forecasting (3238)
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting