During the monsoon, whenever there is high-intensity rainfall over a short span of time, landslides can assume alarming proportions within GHNP and cause widespread damage. Aggravating factors can be broadly classified as geological, hydrological, seismological and land use. Almost all landslides involve failure of earth material under shear stress.
Geological landslides are caused by a concomitance of structural deformities ‒ including steep dips, folds and faults ‒ with terrain such as shale, sedimentary and ash beds.
Rainwater causes hydrological landslides by increasing the effective weight of hillside material, lubricating sliding matter such as shale, or weakening hillside strata through moisture intake.
Earthquake intensity and frequency influences the occurrence of landslides, as well as man-made seismological events such as blasting for slate and limestone quarrying.
Human land-use activities leading to landslides include indiscriminate tree felling, overgrazing, unscientific removal of land cover, improper agricultural practices on steep slopes, and improper alignment of roads and mule paths on weak or unstable rock formations.