MORPHODYNAMIC AND STRUCTURAL ANALYSIS OF TAMDA LANDSLIDE DAM (MIDDLE ATLAS, MOROCCO)

Large landslides are the regular natural hazards frequent in the mountainous areas. They often defined as the movement of a mass of rock sufficient to forms a landslide dam or barrier lake, which obstruct the river water flow. The “Tamda” lake, located 15 km to the north of the Jbel Bouyablane summit, is a natural dam formed by landslide blocked Tmorghot wadi and modified the water circulation and sedimentation. This landslide seem to be triggered by a superposition of several geological factors (predisposition and trigger).In fact, the predisposition inherent in the structural and tectonic setting (strike, dipand fault planes) of the Eastern Middle Atlas allow to determine the nature and the form of the mass movement. In addition, the dissolving and the undermining due to the water flow, and the seismic activity related to the central Middle Atlas great fault, are the main triggering causes of this ground instability phenomena. In addition, seismic activity related to the central Middle Atlas fault, the dissolution and basal undermining by water flow are the main causes of Tamda landslide.