Coastal rocky slopes instability analysis and landslide frequency-area distribution alongside the road network in west Mediterranean context (Northern of Morocco)

Abstract

The Mediterranean coasts are known for their tourist attractiveness due to its richness in fishing resources and beach resorts as well as landscapes at the level of different ecosystems (forests, rocky and sandy beaches). The construction of the Mediterranean coastal road (RN16), which aims to enhance the tourist value of these resources and to improve access to this coastal region, has triggered an almost radical modification in the development process of this area, where the risks are increasing because of the multiplication of the challenges and the hazards due to the instability of its slopes. These events are mainly the result of marine erosion, the involvement of geological, geomorphological, climatic factors and also anthropic parameters with a strong littoralisation. The study area is characterized by active tectonics translated by the presence of faulting sets affecting the rock mass. The aim of this study is to assess the characteristics of the rock mass and its stability, and to anticipate landslide occurrence frequency with a particular size in a specified region with a certain rock mass quality as well. The methodology followed in this work consists of the elaboration of a complete inventory of landslides, the fracturation analysis and the rock mass engineering conducted to evaluate the stability of the slopes and the statistical analysis of the landslide size distribution. The combination of these two approaches has allowed us to assess qualitatively and quantitatively the landslide hazard on coastal rocky fractured areas.