Tectonic consequences and source characterization of the December 27, 2022 earthquake on the western coast of the Gulf of Suez

Abstract On December 27, 2022, a moderate earthquake (M L = 5.0) struck the western coast of the Gulf of Suez at 28.03° N and 33.47° E. The event was felt up to 500 km away and was recorded by the Egyptian National Seismological Network (ENSN) and the Egyptian National Strong Motion Network (ENSAN). The epicenter was located about 53 km from a previous M L = 5.1 earthquake that occurred in June 2013. This study determines the source parameters, focal mechanism, and moment tensor of the December 27, 2022 earthquake to better understand its rupture characteristics and tectonic context. Displacement spectra were analyzed to estimate the long-period spectral level and corner frequency, from which the seismic moment was derived (1.96 × 10 2 ⁰–1.44 × 10 22 dyne·cm) and converted to moment magnitude. The estimated source radius ranged from 136 to 254 m, with stress drop values between 2.3 MPa and 61.3 MPa. The corner frequency, inversely related to rupture duration, varied from 5.2 Hz to 9.8 Hz. Moment tensor analysis of the mainshock and three aftershocks (M L ≈ 4.0) revealed predominantly normal faulting with minor strike-slip components, aligned mainly along NNW–SSE and NW–SE directions. This mechanism is consistent with the regional tectonic framework and previously reported fault structures of the Gulf of Suez. The results contribute valuable information for updating seismic hazard assessments in this economically strategic region.