Distributed Slip Model for Forward Modeling Strong Earthquakes

We develop a generic finite-fault source model for simulation of large earthquakes: the distributed slip model (DSM). Six geometric and seven kinematic parameters are used to describe a smooth pseudo-Gaussian slip distribution, such that slip decays from peak slip within an elliptical rupture patch to zero at the borders of the patch. The DSM is implemented to initiate seismic-wave propagation in a finite-difference code. Radiation pattern and spectral characteristics of the DSM are compared with those of commonly used finite-fault models, that is, the classical Haskell's model (HM) and the modified HM with radial rupture propagation (HM-RRP). The DSM accounts for directivity effects in the fault-parallel direction, as well as fault-normal ground motions, and overcomes the unrealistic uniform slip and stress singularities of the Haskell-type models. We show the potential of the DSM to estimate the ground motions of strong earthquakes. We use this model to initiate seismic-wave propagation during the 1927 M-L 6.25 Jericho earthquake and compare calculated macroseismic intensities to reported intensities at 122 localities. The root mean square of intensity residuals is 0.68, with 56% of the calculated intensities matching the reported intensities and 98% of the calculated intensities within a single unit from the reported intensities. The DSM is an essential step toward robust ground-motion prediction in earthquake-prone regions with a long return period and limited instrumental coverage. Online Material: Animation of rupture and wave propagation.