Hybrid Empirical Ground Motion Model for Pga and 5% Dampedlinear Elastic Response Spectra from Shallow Crustal Earthquakes in Stable Continental Regions: Example for Eastern North America

The widespread application of the hybrid empirical method (HEM) has made it a viable approach for developing ground motion prediction equations in regions where there are few strong motion recordings but there are ample weak motion data from small-magnitude earthquakes. The HEM uses empirical estimates of ground motion in one region (the host region) to provide estimates of ground motion in another region (the target region) by taking into account the differences in stress drop, source properties, crustal damping, regional crustal structure, and generic site conditions (amplification and damping) between the two regions. Empirical ground motion estimates in the host region are transferred to the target region using regional adjustment factors derived from stochastic simulation. In this study, I used the formal mathematical framework of the HEM and an updated seismological model for eastern North America (ENA) to derive a tentative set of updated ENA hybrid empirical hard-rock ground motion estimates for PGA, PGV and 5% damped linear elastic response spectra. For the preliminary results presented in this paper, I estimated ground motions in ENA (the target region) from a new empirical ground motion prediction equation developed for WNA (the host region). The seismological parameters that were used to develop the regional adjustment factors were taken from recent studies of weak motion data in the two regions. The preliminary results identified several issues and uncertainties that will need to be addressed or resolved before an updated reliable hybrid empirical ground motion prediction equation can be developed for ENA.