Predesign, failure and displacement mechanisms of large rockslides in the Annapurna Himalayas, Nepal

The paper analyses and compares four major mass movements (rockslides and rock avalanches) with volumes of 1 to 5 km(3) around the Annapurna Himalayan region from engineering, geological, quaternary geological, and geomorphological viewpoints. It shows how paleotectonic and neotectonic predesign, as well as morphological overprint caused by glacial activities, are the main preparatory causal factors for the sliding events. That is why giant failures of mountain crests have mainly occurred in areas of tectonic activity. The mechanism of failure, and displacement of the resulting large mass movements also strongly depends on this litho-tectonic predesign and continues in giant translational rockslides in which the primary rock structure or fabric is preserved, but shattered by mechanical stress during the sliding event. (c) 2005 Elsevier B.V. All rights reserved.