On September 8, 2023, a powerful earthquake with a magnitude of 6.8 struck western Morocco, causing widespread damage and loss of life in rural communities within the High Atlas Mountains. This event was particularly devastating due to the region’s relative lack of preparedness for such a strong earthquake. While Morocco experiences frequent seismic activity near the Rif Mountains, the High Atlas Mountains, where the earthquake occurred, have been relatively quiet since 1960, leading to a potential underestimation of seismic risks in the area.
Researchers have now shed light on the unusual characteristics of the Morocco earthquake. Their analysis, published in Geophysical Research Letters, revealed that the earthquake originated from a deep fault plane within the Tizi n’Test fault system, located approximately 26 kilometers below the surface. The strongest effects of the rupture occurred at a depth of 12-36 kilometers, leading to displacement of the Moho, the boundary between the Earth’s crust and mantle.
The study’s findings suggest that the earthquake was not primarily triggered by surface faulting, but rather by mantle upwelling, a phenomenon that is also believed to be responsible for the elevation of the High Atlas Mountains. This unexpected origination depth, far from typical plate boundaries, highlights the complex and often overlooked dynamics within intraplate regions.
The authors emphasize the need for more comprehensive seismic hazard models that incorporate data about deeper dynamics within these regions. They also stress the importance of robust seismic monitoring systems, especially in areas with infrequent but potentially devastating earthquakes, like the High Atlas Mountains. By understanding the complexities of these deep-seated processes, we can better prepare for future earthquake risks and mitigate their impact on vulnerable communities.
