PREDICTION OF STRONG MOTIONS FROM FUTURE EARTHQUAKES CAUSED BY ACTIVE FAULTS – CASE OF THE OSAKA BASIN

A methodology is proposed for estimating strong ground motions from scenario earthquakes caused by active faults. We summarize the procedure that is currently used to characterize earthquake rupture models for the prediction of ground motions, based on geological investigations of capable earthquake faults and seismological studies of source models. Total fault lengths of scenario earthquake would be evaluated from survey of segmentation and grouping of active faults for a long-term prediction of seismic activity. The fault widths are evaluated based on the thickness of seismogenic zones from the cut-off depth of small earthquakes. The seismic moment of the capable faults are estimated by the empirical relationship between the source areas and seismic source, then average slips are automatically constraint from the seismic moment and source area. The scaling relations of modeling slip heterogeneity constructed based on a statistical analysis of the source inversion of crustal earthquakes ranging from about 6 to 7 in moment magnitude(Mw) (Somerville et al.,1999). We use a set of parameters to quantify in a deterministic manner the distribution of asperities satisfying the heterogeneity of slip on the fault surface and its two-dimensional Fourier transform of the k-squared model by Herrero and Barnard(1994). The procedure proposed here is applied for estimating strong ground motions from hypothetical large earthquakes in the Osaka metropolitan area.