The impact of landslides to the landscape evolution in the island of Andros

This paper presents the impact of landslide phenomena to the landscape evolution of Andros Island. The morphology of Andros Island,was highly affected by tectonism (extensional deformation) in combination with the highly weathered metamorphic rocks of the Cycladic metamorphic massif. These are the two main reasons for the landslide phenomena in the island. The landslides on the island have a specific distribution following the slopes with high angles. These are located on high altitude areas very close to the major tectonic structures, or on the side slopes of highly eroded valleys due to the running water action. The results of the fieldwork and the terrain analysis showed that the landslides are divided into three distinctive groups, corresponding to their scale and their formation conditions. The oldest (1^st) group of landslides affects very large parts of mountain slopes that have been moved downwards due to driving forces connected with the tectonic evolution of the area and the deformation faults, but also with the action of weathering and erosion processes. The geological formation of the slope parts is responsible for the generation of the intermediate (2nd) group of landslides. All landslides included in this group of mass movements are manifested in sites which consist of schists with marble intercalations and marble bodies. These formations are intensively fractured. The youngest (3^rd) group includes all the synchronous landside phenomena. These landslide phenomena, which affect linear technical works and urban areas, are connected with the geomorphologic conditions, climatic regime as well as human activities, and are presented in many places over the island, mainly during of high precipitation periods.