Tsunami impact assessment for low-lying cities along the Northern Atlantic coast of Morocco using MIRONE software

Abstract

The Northern Atlantic coastline of Morocco is potentially exposed to tsunamis, like that triggered by the large Lisbon event (November 1st, 1755), also known as the most destructive event in Moroccan history. In this work, we used MIRONE software to simulate tsunami phenomenon in the Southwest Iberian Margin region, combining a series of bathymetric and topographic grid layers with an initial water elevation generated using Mansinha's formulations and assuming an instantaneous seabed movement. For this investigation, we considered four scenarios, associated with four potential seismic sources for the 1755 earthquake located in the Gulf of Cadiz. Thus, for each scenario, we obtained a map showing the results of the simulation (distance traveled, wave displacement speed, evolution of wave heights from offshore to coastal areas and arrival travel times). These maps showed that cities like Mohammedia, Casablanca and El-Jadida, were important stakes that could be impacted by a tsunami originating from these sources. For these cities, we thus determined the traveling water columns and the inland distances that could be reached by this inundation. The results show that these cities are potentially threaten by maximum water elevation exceeding 20 m in some locations, with a worse scenario characterized by flow depth and inundation distance ranging from 6 m to 10, and 1.8 km–4.6 km, respectively. These results should also be useful for the authorities, emergency, and decision planners to develop tsunami protection and risk awareness among the coastal communities of Morocco.