A new seismotectonic interpretation of the Mw 6.8 Al Haouz earthquake (Morocco) proposed by IGG researchers
On 8 September 2023, the magnitude Mw 6.8 Al Haouz earthquake occurred the strongest earthquake ever instrumentally recorded in Morocco. It caused around 3,000 casualties and devastating damage. The epicentral area was located in the Western High Atlas about 75 km southwest of Marrakech. In a recently published article, IGG researchers provided an alternative seismotectonic interpretation of the Al Haouz earthquake based on original field data collected during several years of geological-structural research in the Moroccan High Atlas.
The Mw 6.8 earthquake was likely generated by rupture along a newly formed north-dipping high-angle fault, linking pre-existing fault planes belonging to an orogen-scale WSW-ESE transpressional shear zone. The role of asthenospheric upwelling and the tectonic models generally proposed for the Cenozoic evolution of the Atlas region have been also discussed. The new analysis highlighted that the geological evolution and seismotectonic structure of the Moroccan High Atlas are largely governed by the oblique convergence of tectonic plates. On the contrary, the impact of asthenospheric uplift, if present, remains limited and may influence exclusively the geomorphological evolution of the Western High Atlas, but cannot explain the seismotectonic and geological features observed today at the surface, which are instead effects of transpressional tectonics.
Bibliographic reference
Malusà M.G., Ellero A., Ottria A. (2024). Tectonics of the Mw 6.8 Al Haouz earthquake (Morocco) reveals minor role of asthenospheric upwelling. Tectonophysics, 891, 230533, https://doi.org/10.1016/j.tecto.2024.230533.
For information: Alessandro Ellero, CNR-IGG (a.ellero(at)igg.cnr.it), Giuseppe Ottria, CNR-IGG (g.ottria(at)igg.cnr.it).
