Scientists Identify Fault Responsible for Morocco’s Deadly 2023 Earthquake

On September 8, 2023, an earthquake of magnitude 6.8 followed by a strong aftershock struck the High Atlas mountain range in Morocco, near Marrakech. The shock was felt well beyond Morocco’s borders, reaching countries such as Spain, Portugal and even Mauritania. According to Moroccan authorities, the toll stands at 2,946 dead and 6,125 injured. The earthquake affected around 660,000 people, leaving 380,000 people permanently or temporarily homeless, with more than 59,000 houses destroyed or damaged.

Nearly two years after this disaster, researchers from Morocco, Italy and Germany have examined fault dynamics and stress distribution in the region, providing insight into how deep fault systems interact, reports ScienceDirect. The epicenter of the earthquake is located about 28 kilometers underground. The aftershocks occurred mainly near the Tizi n’Test fault, a geological structure close to a rural commune in the province of Taroudant. According to the researchers’ explanations, this is a compressional event involving two fault planes, one steeply dipping to the northwest and the other more gently to the southwest.

The northwest fault has likely undergone a more significant movement, they estimate. Using differential radar interferometry (DInSAR), which allows measuring ground displacements, such as glacier movements, the researchers were able to map the displacement along the fault. This analysis showed an asymmetric uplift along the Tizi n’Test fault, confirming its role in the earthquake. Another method used: the triangular dislocation elastic (TDE) modeling approach, a modeling approach that simulates fault behavior using geological and seismic data.

While the Tizi n’Test fault was the main actor, another geological structure, the Jebilet thrust north of Marrakech, appears to be less involved in this particular earthquake, notes the study. This leads the scientists to conclude: "From this correlation, we propose that the Tizi n’Test system is the likely cause of the 2023 Al-Haouz earthquake".