Variability of kinematic source parameters and its implication on the choice of the design scenario

The near-fault seismic motion recorded during recent earthquakes (Chi Chi earthquake, 1999; Parkfield 2004) showed the high spatial variability of the motion. This variability is controlled by the fault geometry, the rupture process complexity and also by the propagation and site effects. As a result of these observations, the earthquake scenarios can be largely influenced by the vicinity of the seismic source, and the number of available recordings is still not enough to infer a robust parameterization of the ground motion to be used for retrieving multi-parametric predictive equations. In this study we modeled scenarios from different rupture models of a fault similar to the 1980 Irpinia, Italy, earthquake source (Mw 6.9). A discrete wavenumber-finite element technique (COMPSYN; Spudich and Xu, 2002) was used to compute full-wave displacement and velocity time series in the low-frequency band. We investigated the inter and intra event variability as a function of different source rupture parameters (rupture velocity, slip distribution, nucleation point, source time function), whose values depend on the degree of knowledge of the physical model controlling the process. The probability density functions of the simulated ground motion parameters, such as PGD and PGV, can be used to identify a specific scenario matching the engineering requests.