Quantitative Risk Assessment of a Tsunami Induced by the Averroes Fault (Alboran Sea): Case of Martil City, the Mediterranean Coast of Morocco

Abstract

The Mediterranean coast of Morocco is potentially exposed to tsunamis, such as the one triggered by the Algerian Djijelli earthquake in 1856, also known as the most destructive event in the region. This type of coastal hazard could have disastrous effects on several cities along the Mediterranean coast, such as Martil, which is located near the main sources of tsunamis in the Alboran Sea and receives large numbers of national and international tourists each year. This work intends to simulate the potential tsunami of Averroes faults, corresponding to a magnitude Mw = 7.0 earthquake and to estimate the property and life losses. We used the Nonlinear Shallow Water with Nested Grids (NSWING) code integrated into Mirone software to simulate the tsunami phenomenon, combining a series of bathymetric and topographic grid layers with an initial water elevation generated using Mansinha formulations and assuming instantaneous seabed motion. For this investigation, we considered a scenario associated with a potential seismic source for the Averroes fault located in the Alboran Sea. The simulation results obtained reveal that the maximum water height at the regional scale of the Alboran Sea exceeds 1 m. On the other hand, on a local scale in the study area of the Martil city, the flow depth varies between 0.5 and 7 m, with a flooded surface area of 70 km². In addition, the arrival time of the first tsunami waves exceeds 40 min. Material losses could reach 3.72 M$, while the loss of life could be as high as 31,000 victims. The results should be useful to policymakers in developing tsunami protection and raising coastal community awareness of tsunami risks in Morocco.