Horizontal displacement effect in tsunami wave generation in the western Makran region

Abstract

The current silent status of the western segment of the Makran Subduction Zone (MSZ), also known as the western Makran, is an opportunity to examine different aspects of a tsunami hazard for this region. In this study, we compute the contribution of the horizontal coseismic displacement of the sea bottom due to earthquakes in the western Makran. This contribution is usually ignored in conventional tsunami generation modeling. We also estimate the evolution of tsunami wave energy and the influence of horizontal seabed displacements on the energy. Moreover, the effect of source parameters variation on tsunami amplitude and on the contribution of the horizontal seabed movement is investigated. Our numerical results show that due to the mild bathymetry gradient of the western Makran region, the effect of horizontal displacements is low. We estimate a 4% increase in maximum tsunami wave amplitude by the influence of the horizontal motion. Also, the contribution from horizontal seabed displacements leads to almost a 9% increment in tsunami wave energy. In addition to local bathymetry, the importance of horizontal seabed deformation can be affected by the fault rake, width and location. These are the main parameters causing uncertainty in the present study.