Shear-wave velocity structure of the Sinai subplate from receiver function analysis

Abstract

SUMMARY Teleseismic data observed at seven broad-band stations located in and adjacent to the Sinai subplate were analysed using the receiver function method for estimating the velocity structure of the crust and upper mantle. The receiver function method is based on the analysis and interpretation of P‐S converted phases and associated surface multiples that originate at seismic discontinuities beneath the receiver. The main converted P‐S phases are from the base of a near-surface sedimentary layer located in the upper crust, at the Moho, in the subMoho upper mantle, at the 410- and 660-km seismic discontinuities. The velocity structure of the crust and the upper mantle varies within the Sinai subplate. A complicated crustal structure is suggested for the Cyprus arc, which marks the northern boundary of the Sinai subplate, with a Moho depth of 28 km. In the area of the Dead Sea Fault (DSF), which marks the eastern boundary of the Sinai subplate, Moho depth increases from north to south from approximately 27 km beneath station MRNI located in northern Israel to approximately 34 km beneath station EIL located north of the Gulf of Aqaba. Away from the DSF, a crustal thickness of 34‐36 km is indicated at HITJ located in the Arabian Plate and KEG located in the African Plate. A low-velocity zone (LVZ) beginning at approximately 60-km depth is inferred beneath stations located close to the DSF. This boundary is interpreted as the lithosphere‐asthenosphere boundary (LAB). The shallow LAB may be the top of a highly deformed mantle zone and may have facilitated the formation of the DSF some 15 Ma.