Simulation of seismic hazard parameters and earthquakes source mechanisms along the Red Sea rift, western Saudi Arabia

Abstract Well-recorded earthquakes located along the rift axis of the Red Sea, western Saudi Arabia, were investigated. These events are among the most significant recorded between 1997 and 2024 in this seismic zone. The moment tensor inversion, using full waveform data, was applied to determine the rifting mechanism and parameters of the investigated earthquakes. The optimum double-couple mechanism for investigated earthquakes revealed normal faulting with minor strike slip movement along the red sea spreading axis. The most recent earthquakes were felt in nearby cities, prompting a study to understand the fault mechanisms and assess the impact of strong ground motion parameters on western Saudi Arabian cities, which have rapidly developed along the Red Sea’s active rifting system. The stochastic simulation method, based on the site spectral model, was used to estimate the effects and strong ground motion parameters of the most recent and significant earthquakes in the western cities of Saudi Arabia: one on June 16, 2020 ( <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:msub> <m:mrow> <m:mi>M</m:mi> </m:mrow> <m:mrow> <m:mi mathvariant="normal">L</m:mi> </m:mrow> </m:msub> </m:math> {M}_{{\rm{L}}} = 5.5), and another on April 14, 2023 ( <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:msub> <m:mrow> <m:mi>M</m:mi> </m:mrow> <m:mrow> <m:mi mathvariant="normal">L</m:mi> </m:mrow> </m:msub> </m:math> {M}_{{\rm{L}}} = 4.5). The results suggest that Al-Muwaileh and Duba cities experienced peak ground accelerations of 9.113 and 8.673 cm/s 2 from the June 16, 2020, earthquake and 2.347 and 1.707 cm/s² from the April 14, 2023, earthquake, respectively. The pseudo-seismic spectral acceleration values were 2.282 × 10 1 and 2.379 × 10 1 cm/s 2 in Duba and Al-Muwaileh, respectively, for the June 16, 2020, earthquake and 4.837 and 6.752 cm/s 2 for the April 14, 2023, earthquake.