Estimation of Ground Motion Characteristics of the September 08, 2023 Morocco Earthquake

The Mw 6.8 Morocco earthquake of 8 September 2023 was the country’s most destructive seismic event in the last six decades, causing widespread devastation and over 3,000 casualties across the High Atlas region. The complete absence of near-field strong-motion recordings has made it difficult to quantify the level of ground shaking and to explain the spatial distribution of damage. In the present earthquake, since the strong ground motions were not recorded within 500 km, there is a necessity to develop simulated acceleration time histories. This study employs the modified stochastic finite-fault method to generate simulated ground motions at 22 representative sites across the affected region. In addition, Fourier amplitude spectra and 5 %-damped response spectra are estimated using simulated ground motion. The results reveal that spectral ordinates exceeded the Moroccan Règlement Parasismique Marocain (RPS:2000-2011) design spectra at short periods (0.1–0.3 s), implying that low-rise unreinforced masonry structures were most vulnerable. In contrast, in certain areas where the simulated spectra remain below code values, structures have suffered severe damage due to poor construction quality and poor enforcement of seismic provisions. The study provides a physically consistent estimate of ground-motion characteristics for the 2023 event and offers valuable insights for post-earthquake damage interpretation, code calibration, and seismic risk mitigation in North Africa.