Effects of volume on travel distance of mass movements triggered by the 2005 Kashmir earthquake, in the Northeast Himalayas of Pakistan

Abstract

The 2005 Kashmir earthquake (Mw 7.6) generated widespread mass movements in the Northeast Himalayas of Pakistan. The mass movements were mainly catastrophic rock avalanches, rockslides, rockfalls and debris falls, ranging in volume from a few hundred cubic meters to hundreds of million cubic meters. Data of 103 mass movement events were collected during field surveys to characterize each event. The mass movements and their travel distances were analyzed, using empirical models, widely adopted in the literature. The empirical approaches were used to analyze the relationships between geometrical parameters like volume, Fahrboschung angle, fall height, surface area, travel path and travel distance. The mobility of mass movements was expressed as the ratio between the height of fall and travel distance as function of volume. The volume was estimated by multiplying the deposit area by average thickness. The Fahrboschung angle showed a decreasing tendency with increasing mass movement volume. In addition, the Fahrboschung angle of mass movements with small volumes was more variable. A strongly correlated linear trend exists between the height of fall and travel distance for all types of the mass movement. Moreover, a weak correlation was found between unconfined and partly confined travel path. The empirical results of the 2005 Kashmir earthquake data are consistent with the previously published data from other parts of the world.