Failed Patagonian tableland: landslides distribution and controls

Argentinian Patagonia is formed mostly by tableland relief created by Cenozoic basaltic efusions, general uplift and relief inversion. The tableland is vastly effected by landslides. Using TanDEM-X we manually maped 30 000 km2 of landslides in the Patagonian tableland and conducted spatial analysis of their distribution and controls. Based on relative dating to lava efusions, glaciation and paleoshorlines we propose, that the landslide activity in the region spans across several millions of years. In contrary to general knowledge of landslide distribution, most of the landslides in the Patagonian tableland are located in low-seismicity, tectonicaly stable, semiarid to arid conditions. We propose, that the leading landslide distribution control is the tableland stratigraphy: basaltic caprock overlaying weak sedimentary and volcanoclastic rocks. The caprock protects the underlying weak rocks and thus it becomes elevated above the surroundings over time, forming plateaus and mesas. As long as the topography of the formed tableland becomes high enough to laterally expose underlaying weak rocks, the tableland margins becomes unstable and collapse. It starts as lateral spreading a rotational landslides and later often evolve to flow-like mass movements. Many of the plateaus and mesas in the Patagonian tableland are fringed by almost continuous landslides. Some mesas are already completly consumed by landslides. This study helps to understand distribution and evolvement of landslides in volcanic tablelands.