Impact of Main Boundary Thrust (MBT) on Landslide Susceptibility in Garhwal Himalaya: A Case Study

In Garhwal Himalayan region, seismicity plays a major role in inducing mass movement. Especially at places where active faulting occurs, multiple and retrogressive slope failures have been observed. The active tectonism of the Himalayan collision zone makes the whole mountain chain fragile and instable. In this context, an endeavor has been made in the present study to correlate the impact of Main Boundary Thrust (MBT) on the overall landslide susceptibility for a 74-km stretch of NH 7 in the Garhwal Himalaya, using statistical models of landslide susceptibility zonation (LSZ) mapping. The results of the study show that slope angle, road network and distance from MBT are the most crucial landslide causative parameters in the study area, with statistical contribution of 26%, 20% and 18%, respectively. The study also produces an accurate LSZ map for this stretch of NH 7, which shows that almost 30% of the area has high to very high degree of landslide susceptibility. The prepared LSZ map will be of practical significance for institutionalizing any future landslide mitigation programs in the study area.