Background: The Atlantic Coast of Morocco is prone to tsunami inundation. Therefore, in this region, earthquakeinduced tsunami hazard has been intensively investigated leading to the development of a number of coastal inundation models. However, tsunami vulnerability remains not well understood to the same extent as the hazard. In this study, we use high-resolution numerical modeling, detailed field survey and GIS-based multi-criteria analysis to assess the building tsunami vulnerability and its sensitivity to the tide variations. Asilah located in the northwestern Atlantic coast of Morocco, where the impact from the 1755 tsunami is well documented, constitutes the area of this study. Results:To model the source-to-coast tsunami processes we used the COMCOT (Cornell Multi-grid Coupled Tsunami Model) numerical code on a set of bathymetric/topographic grid layers (640 m, 160 m, 40 m and 10 m resolutions) with an initial sea-surface perturbation generated using Okada's formulae and assuming an instantaneous seabed displacement. The tsunami source models in this study correspond to four 1755-like earthquake scenarios. Results show that Asilah's built environment is highly vulnerable to the tsunami impact that can range from 1.99 to 2.46 km 2 of inundation area, depending on the source and the tidal level considered. The level of building vulnerability decreases considerably when moving away from Asilah's coastline. Moreover, the variation in the tidal level introduces large change in the modeled tsunami impact and, therefore, affects the level of building vulnerability.Conclusion: Thus, we suggest considering the effect of the tide when simulating tsunami hazard and vulnerability, particularly, in coasts where tidal variations are significant. This study provides hazard and vulnerability maps that can be useful to develop the tsunami awareness of the Moroccan coastal population.

Background: Despite a position along the passive margin of Africa, the Moroccan Atlantic coast is under the influence of the tsunami threat from earthquakes triggered along the Nubia-Eurasia plate boundary. Along Tangier, Asilah, Sale and Mazagao's coasts, tsunami have been described since historic times. The 1755 Lisbon quake triggered a tsunami that struck the shores of Morocco 60 min after the tremor, the waves reaching from 2 to 15 m in amplitude. The coastal sedimentary record, together with other proxies, is now being experienced to discriminate and reconstruct evidence of prehistoric inundation events.

The Al-Hoceima region is threatened by tsunami hazard because of its location in the coastal area of the Mediterranean Sea, besides the shallow seismically active region south of the Alboran Sea. Therefore, the current study presents a novel model to map coastal flooding potential zones due to tsunami wave run-up in Nekor bay using three natural parameters (distance from coastline, altitude and slope) in a geographic information system (GIS) environment. Furthermore, the coastal flooding simulation using 4 scénarios (1, 2, 3, 4m) based on the run-up elevation according to tsunami wave elevation (TWE) literature of the study area is used to confirm the DAS model result, and to estimate the potential impacts. The result of the DAS model revealed that 1 km from the coast to the Nekor plain is the most exposed to the impact of tsunamis generated south of the Alboran Sea. The coastal flooding simulation confirmed the DAS result, and the damage estimation of the urban area and the agriculture was respectively 2 and 98% for run-up 1 m, 3% and 97% for run-up 2m, 4% and 96% for run-up 3m, and for the worst case scenario of 4 m was 3% and 97%. Therefore, the results obtained show that the major potential impact of coastal flooding in Nekor plain is the salinization of agricultural land. Finally, we propose a sustainable solution utilizing a controlled forest along the coast to reduce future tsunami impacts on Nekor bay.

No abstract

No abstract