ABSTRACT
The Red Sea is a plate boundary separating the Arabian Plate and the African Plate. It extends from the Bab Al-Mandab Strait in the south to the Sinai triple junction in the north. Earthquake activity occurring in the Red Sea could affect several countries such as Ethiopia, Sudan, Egypt, Yemen, and the Kingdom of Saudi Arabia. A plan with a huge budget has been drawn up to develop the northern part of the Red Sea, especially the NEOM project. This plan also includes the construction of the King Salman Bridge. Therefore, the assessment of the seismic hazard (SH) in this seismically active region is necessary for the sustainability of these mega projects. This study presents a probabilistic seismic hazard assessment (PSHA) along the Red Sea coasts. An earthquake catalogue including the available historical records and instrumental seismicity is compiled. It is processed by converting various magnitude types to the moment magnitude (Mw). Repetitions within the compiled catalogue are removed, and then, the catalogue is de-clustered. A completeness test is applied to the compiled catalogue. In addition to the three areal source models, a recently developed fault model is utilized to represent the seismicity along and around the Red Sea. Four ground-motion prediction equations (GMPEs) are used to estimate the ground motion. The SH inputs are implemented through a logic-tree framework, and the resulting Peak Ground Acceleration (PGA) maps and spectral acceleration (SA) maps at 0.2 and 1.0 second for return periods of 475 and 2,475 years illustrate that the maximum acceleration values are concentrated around the East African Rift, the Harrat Lunayyir volcanic field, and the Gulf of Aqaba. Seismic hazard curves for some important cities located on the Red Sea coast are produced and de-aggregated to obtain the magnitude and distance of the earthquake source dominating each seismic hazard curve.
