Abstract
On August 5, 2010, local severe rain in Ladakh Region of northwestern India caused debris avalanches, which became an unprecedented catastrophe in which more than 200 people lost their lives and more than 400 went missing. These disasters originated primarily from Leh District in Ladakh Region; the heaviest damage occurred in the Choklamsar developing area located within the alluvial fan near the central city of the district. This study aims to clarify why considerable damage occurred, especially in the Choklamsar developing area, and to discuss transition of mountain disasters.