Imaging the shallow structure of the dipping slab and crustal thickness variations in the western Makran Subduction Zone

We apply the S-wave receiver function method to data from a temporary seismic network deployed in the western Makran region to obtain constraints on the geometry of the subducting and overriding plates. A migrated depth section of receiver functions shows a shallow northward-dipping slab with depth increasing from ۳۰ km in the coastal region to about ۱۰۰ km beneath the Taftan volcano. The continental Moho of the overriding plate is also observable in our profile. Beneath the northern part of the profile, in the Sistan Suture Zone, the crust is about ۴۰ km thick, increasing to approximately ۵۶ km beneath the Taftan volcano. We also present modeling of crustal thickness variations across the region using the joint inversion of P-wave receiver functions and fundamental mode Rayleigh wave group dispersion data. Our modeling confirmed the presence of a thick crust beneath the Taftan. The map of continental Moho variation also revealed a thick crust (۵۰ km) in the southern part of Sistan zone near the Saravan Fault. In this area, which has experienced moderate to large earthquakes, the depth of oceanic Moho is between ۵۵ and ۶۳ km. Furthermore, our modeling of the oceanic Moho depth variation along the coastal Makran shows the oceanic crust is the thinnest beneath Chabahar and increases in thickness towards the Makran-Zagros transition zone.

کلیدواژه ها:

Subduction ، Makran ، Receiver function ، Slab ، Taftan ، Moho