Stochastic strong ground motion simulation of intermediate depth earthquakes: the cases of the 30 May 1990 Vrancea (Romania) and of the 22 January 2002 Karpathos island (Greece) earthquakes

Stochastic finite-fault simulation is used to simulate the acceleration time histories of two intermediate depth ( h∼90 km) earthquakes, which occurred on 30 May 1990 in Vrancea (Romania) and on 22 January 2002 near Karpathos island in Greece. Site amplification functions were used for all stations included in the simulation process. For the Romanian earthquake, peak acceleration values were observed at the more distant from the epicentre stations. In Romania, strong anisotropy in Q-values was observed along the NE–SW direction (along strike of the fault) compared to the normal to the strike of the fault direction. Specific site corrections were required for the station in Bucharest, employing the H/ V ratio technique, to refine the site-specific amplification function and achieve better match of the simulated spectra. In the Aegean Sea region, average values for attenuation and site amplification functions were used for all stations with overall satisfactory results. Any unmatched discrepancies between observed and simulated spectra would require further accurate knowledge of the site characteristics.