Parameterization of a Composite Attenuation Relation for the Dead Sea Area Based on 3-D Modeling of Elastic Wave Propagation

3-D simulations of elastic wave propagation generated by earthquakes with magnitudes between 5.5 and 7.0 are used to parameterize strong ground motion attenuation relations for the Dead Sea Rift (DSR) graben structure. The results show that standard attenuation relations with an isotropic distance parameter are inadequate for a graben structure with a deep sedimentary trough. A new strategy is devised for the parameterization of attenuation relations in graben structures by looking at the statistical properties of 53 simulated earthquakes of variable magnitudes located at various sites along the western boundary fault of the DSR graben. An exemplary attenuation relation is designed from the synthetics for the 1 Hz spectral acceleration, modifying the Joyner-Boore-type parametrization by adding coefficients suited for three different source-to-sensor configurations: within the graben, beyond the graben and path unaffected by the graben structure.