Physics-Based Numerical Simulations of Regional Seismic-Wave Propagation Controlled by the Complex Geology of the Dead Sea Fault

ABSTRACT

Long, mature continental transform faults are commonly associated with complex fault geometries and deep sedimentary basins that strongly influence rupture dynamics, wave propagation, and regional ground motions. Although these effects have been extensively documented for data-rich systems such as the San Andreas and North Anatolian faults, they remain poorly constrained along the Dead Sea fault (DSF) due to the scarcity of strong-motion recordings. This study addresses this gap using large-scale, 3D physics-based simulations to investigate ground-motion characteristics along the northern DSF, a region that hosts deep pull-apart basins and exhibits a significant seismic moment deficit. We simulate nine Mw 7 strike-slip rupture scenarios on three major DSF segments using a detailed 3D geological velocity model and finite-difference wave propagation up to 3 Hz. More than 32,000 three-component synthetic seismograms are generated on a dense spatial grid. The simulations reveal pronounced basin-controlled amplification, strong rupture directivity, and marked directionality of horizontal ground motions, with peak ground velocity ratios between fault-normal and fault-parallel components spanning more than an order of magnitude. Near-fault pulse-like motions are frequently observed, with dominant pulse periods of 2–6 s. Regression analyses using a simplified ground-motion model (GMM) show that while established directivity predictors capture component-specific effects, significant positive residuals persist within the deep sedimentary basins, indicating additional amplification mechanisms not represented by conventional site parameters. Importantly, directivity effects largely cancel in the geometric-mean horizontal component, suggesting that commonly used orientation-independent intensity measures may underestimate hazard for near-fault structures. These results demonstrate the critical role of 3D basin and rupture effects along the DSF and highlight the need for nonergodic, region-specific GMMs. The synthetic database developed here provides a foundational step toward such models in data-limited tectonic environments.