The role of splay faulting in increasing the devastation effect of tsunami hazard in Makran, Oman Sea

There are both far- and near-field tsunamis that need to be considered for the Oman Sea region, and in addition, the landslide as a minor source requires special attention. The Makran subduction zone originated in the Cretaceous as part of the closing Tethyan seaways. It bent and broke oceanic sediments into an accretionary wedge that extends nearly 400 km northward from the present deformation front. The historical records indicate one unambiguous Makran tsunami in the east. It was generated in 1945 in the eastern part of the subduction zone. As for the tsunami, it reportedly reached heights of 12-15 m in Pasni, just north of the earthquake's epicenter. There and in Karachi, its largest waves came ashore late enough, so it was suggested to be associated with landslides. But an alternative explanation that is the objective of this paper is the splay faults that exist in the Makran accretionary margin may have caused this late arrival and increase the run-up height observed in the near-field region after the initial tsunami. Several case studies indicated that splay faults are associated with subduction zones in the world. They develop within the sedimentary sequences as sediments are being added from the upper plate. The superimposed effect of splay faulting on tsunami wave heights in the near-field has also been observed in many mega-tsunami events. Thus, as mentioned above, to achieve this, first, we must identify and map the splay faults in the region, so, 2D seismic reflection data, which belongs to the National Iranian Oil Company, gathered in the Oman Sea in 2000 has been utilized. The result of this interpretation has been presented in map showing the major splay and normal faults, in the south and north, respectively. It is strongly suggested that the result of this study is to be utilized in future comprehensive tsunami hazard assessments in the region.