Source of the 2023 Morocco Earthquake (Mw6.8) inferred by analysis of Seismic and Geodetic Data

On September 8, 2023, at 22:11 UTC, a seismic event of magnitude Mw6.8 (according to the USGS) occurred near the village of Talat N’Yaaqoub, Al Haouz province, in the High Atlas region of Morocco. This earthquake had a profound impact, violently shaking the entire area within a radius of over 70km from the epicentre. More than 78,000 buildings were severely damaged, resulting in approximately 5,600 injuries and around 3,000 fatalities. A considerable portion of the affected population resides in buildings seismically vulnerable and limited access to resources for mitigating such risks. This incident stands out as a significant earthquake in a region characterized by a low deformation rate and generally considered to have low seismic activity. Testimonies collected by CSEM reveal that the seismic vibrations were felt not only in the High Atlas but also by people in a wider area extending to Algeria, southern Spain, and Portugal.

This study presents the preliminary results obtained from a comprehensive investigation of the earthquake's source. The analysis is based on the interpretation of seismic and geodetic data, employing a combination of the following methods: (1) inversion of the seismic moment tensor to determine fault plane geometry and hypocenter depth, (2) waveform inversion using a finite source model to assess spatiotemporal slip distribution, (3) modeling of surface strain field produced by the slip distribution model. The validation of the rupture model was performed by comparing the synthetic surface deformation field with the observed field obtained through the geospatial InSAR method.

Acknowledgement: The work was supported by the Portuguese Foundation for Science and Technology (FCT) project UIDB/04683/2020 - ICT (Institute of Earth Sciences).