A very broad-band stochastic source model used for near source strong motion prediction

• Published in: Geophysical research letters Vol. 25; no. 7; pp. 1063 - 1066
• Main Authors: Berge, Catherine, Gariel, Jean-Christophe, Bernard, Pascal
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01-04-1998; American Geophysical Union
• Subjects: Earth sciences; Earth, ocean, space; Earthquakes, seismology; Engineering and environment geology. Geothermics; Exact sciences and technology; Internal geophysics; Natural hazards: prediction, damages, etc; algorithms; broad-band spectra; high frequency; simulation; ground motion; earthquakes; Green function; stochastic models; active faults; fault displacements; fault planes; prediction; synthetic seismograms; seismic risk
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/98GL00732

The simulation of near‐source ground motion requires the calculation of ground motion in a very broad‐band frequency range (typically from 10 s to 0.1 s). However, the calculation of complete Green's function is too time consuming for high‐frequency simulations. We present a method to obtain very broad‐band synthetic seismograms, combining the kinematic spectral source model of Bernard et al., [1996], and an algorithm, based on the wavenumber technique of Bouchon and Aki, [1977]. High‐frequency radiations are evaluated with ray theory and a broad‐band dislocation defined on a finely discretized fault plane. The low‐frequency radiations due to the near‐ and intermediate‐fields are calculated with the complete field algorithm on a low‐wavenumber filtered dislocation. This dislocation is defined on a coarse grid over the fault, hence significantly reducing the computing time. We apply this method to compute the ground motion at a station located near an extended fault, where the near‐, intermediate‐ and far‐field radiations are important.