Shallow Landslide Susceptibility Assessment in the High City of Antananarivo (Madagascar)

Abstract

The urban area of Antananarivo hosts the most important built Cultural Heritage sites, recently inscribed in the UNESCO World Heritage tentative list: the High City of Antananarivo, built on top of the Analamanga hill and encompassing the Rova royal complex together with several important Churches and Cathedrals. During the first months of 2015 the city was severely affected by geo-hydrological hazards due to heavy cyclonic rain, resulting in flooding in the Ikopa river plain area and widespread shallow landslides along the Analamanga hill slopes. This event caused thousands of evacuees and casualties, showing the vulnerability of the site to geo-hydrological hazards. Field data and remote sensing data interpretation were combined in order to produce a detailed geological-geomorphological map in order to understand the processes acting in the Analamanga hill area. With the aim of analyzing the landslide-prone areas with respect to the High City Cultural Heritage and structures a shallow landslide susceptibility map was also created. The obtained maps will provide management-planning tools to be used as a first step towards a risk reduction strategy in the High City UNESCO Core Zone and the surrounding Buffer Zone.