Tectonic patterns in the northern Red Sea region

Abstract

Seismological evidence for northern Red Sea tectonics follows from analysis of the March 31, 1969, earthquake. Source parameters are derived from polarities and amplitudes of P waves, spectral amplitudes of Rayleigh waves, and strain steps recorded at the Eilat Observatory. All the data over this wide spectral window point to a single solution that is consistent with known strike of faults in the epicentral region and the geotectonic hypothesis of the rotational movement of Arabia and Sinai relative to the African continent. The solution consists of a shear dislocation of 1 meter and fault area of 450 km2 at a mean depth of 10 km, dipping about 45° to the east-northeast with a strike parallel to the Red Sea axis. The motion is normal sinistral with both dip-slip and strike-slip components. The trend of motion is about 10° northeast. This implies an opening of the Red Sea at the source by some 50 cm along a front of 30 km, and yields a drift rate of the order of a few millimeters per year during this century. The direction of trend lines up with the axis of the Gulf of Eilat and the Jordan rift valley.