Geometrical and structural setting of landslide dams of the Central Alborz: a link between earthquakes and landslide damming

The combination of remote sensing observations, geological field investigations and geomorphological mapping and measurements along with faults and landslides inventory were employed to identify the landslide-dams of Alborz Mountain belt in northern Iran. The study comprises main landslide-dams of Central Alborz, including those with saturated and dried lakes. Valasht, Chort, Shoormast, Evan, Tar, Havir and Imamza-e-Ali were the lakes discovered as being formed by a landslide-damming process. Several other ancient lakes were identified as the remnants of breached and dried landslide-dams. The geometry and structural setting of each case is described; however, more investigations are required to evaluate the potential hazards for downstream populations. Most of these cases are believed to be co-seismic or earthquake-induced landslide dams formed due to large ( M : ~7.0) known historical and derived pre-historic earthquakes. This paper emphasizes the relationship between active faulting, fault valleys and slope instability that leads to fault valley blockage by landslide. The recommendation from this study is that more consideration of active structures is needed in tectonically active regions, where the fault damage zones are more susceptible to slope instability due to progressive deformation and earthquakes.