Jogyura Landslide: Impact of Main Boundary Thrust, a Case Study from Central Himalaya

The Himalayan mountain range, divided by deep and active thrusts, is a region of highly sensitive to tectonic stability. The Main Boundary Thrust (M.B.T.) defines the boundary of the Lesser Himalaya against Outer Himalaya. In this, an old landslide was reactivated during monsoon period in 1992 and the area is now experiencing frequent slides throughout the year affecting 50–60 ha of area. On an average 1–2 ha of land is being swept away every year in the area. The existence of Main Boundary Thrust (MBT), toe erosion by Nihal River, loading of slope crest (intensive settlement and agricultural processes and village path), regular and heavy water discharge in slided area, highly jointed rocks, low vegetation cover, high monsoonal precipitation and thin soil cover were found to be foremost causative factors. Major anthropogenic activity i.e. construction of ‘cart-track’ amid the critical slope had promoted vulnerability of the area. The land conservation measures adopted by Soil Conservation Department and Forest Department also proved futile. Rambans Plants (agave americana) and Chari hurbs (Sorghum bicolor) are being planted by the inhabitants for land conservation. Various recommendations are proposed.