A team of researchers identified the Tizi n'Test fault as the likely cause of the 2023 Al Haouz earthquake in Morocco, using advanced methods like DInSAR analysis and Triangular Elastic Dislocation modeling. A group of researchers from Morocco, Italy, and Germany have employed a multidisciplinary approach to identify the fault, a crack or break in the Earth's surface, responsible for the earthquake that struck the Western High Atlas region of Morocco on September 8, 2023. Published on March 6 in the peer-reviewed journal ScienceDirect, the study explores the oblique slip dynamics and strain partitioning characteristics of the region, investigating potential interactions between fault systems at depth. The researchers explain that the main earthquake occurred at a depth of about 28 km. Aftershocks were mostly concentrated near the Tizi n'Test fault (TnTf), showing patterns typical of fault-related seismic activity. Tizi n'Test is a small town and rural commune in Taroudant Province of the Souss-Massa-Drâa region. The mainshock involved a compressive event with two fault planes: one steeply dipping northwest and the other gently dipping southwest. The steep northwest-dipping fault is likely to have experienced a larger amount of movement than the gentler southwest-dipping fault. Tizi n'Test fault as the likely cause of the earthquake Using DInSAR (Differential Synthetic Aperture Radar Interferometry) analysis, a technique that measures ground movement from space, the researchers created displacement maps that revealed an uneven uplift along the Tizi n'Test fault. They also applied a method called Triangular Elastic Dislocation (TDE), a modeling approach that simulates the behavior of faults using geological data and earthquake patterns. The northwest-dipping fault, associated with the Tizi n'Test fault (TnTf), aligned better with the observed ground movement than the southwest-dipping fault, linked to the Jebilet Thrust (JTt), located north of Marrakech and the High Atlas, which played a smaller role. The Jebilet Thrust fault is a major geological structure in the area but was less involved in this particular earthquake. «We propose that the Tizi n'Test fault system is the likely cause of the 2023 Al-Haouz earthquake», concluded the researchers. «We also gained new insights into the possible reactivation of faults at depth», they added. Reactivation refers to the idea that some faults might be re-triggered by changes in stress after an earthquake. The study emphasizes the importance of combining ground observations with advanced modeling to enhance our understanding of the seismic activity and deformation processes in the Western High Atlas region during the 2023 Al Haouz earthquake. By integrating data from different sources, such as satellite images and aftershock patterns, the researchers were able to create a more accurate picture of how the earthquake occurred.
