Calibration of path and site effects and simulation of megathrust earthquake scenarios in the Makran subduction zone using stochastic finite fault modeling

The Makran subduction zone, where the Arabian plate is subducting beneath Eurasia, represents a significant seismic hazard due to its potential to generate a megathrust earthquake. To assess this hazard, it is crucial to estimate and calibrate parameters related to the path and site effects of strong ground motion. This study leverages observed strong motion accelerograms from the 2013 Mw 7.8 Saravan earthquake, the largest intra-slab earthquake recorded in the Makran region, to calibrate key parameters using a stochastic finite fault modeling method based on dynamic corner frequency. We focus on parameters such as the quality factor (Q), kappa (κ0), local site amplification (LSA), and crustal amplification (CA), comparing simulated peak ground acceleration and pseudo spectral amplitude with observed data to refine these regional specific parameters. The high level of agreement between simulated and observed results validates the reliability of the calibrated parameters. Simulation of a potential megathrust earthquake, using known source parameters from prior research and the calibrated path and site parameters, indicates that the peak ground acceleration is expected to be highest at the northern edge of the Makran accretionary wedge, the Jaz-Murian basin, and the Sistan suture zone. These findings are essential for seismic hazard assessment and can inform urban planning efforts in the region.