LIKELIHOOD OF EARTHQUAKE-INDUCED LANDSLIDE DAMMING IN UTTARAKHAND HIMALAYAS

Abstract

Earthquake-induced landslide dams are hazardous geological structures which may induce catastrophic and cascading impacts on livelihood in mountainous terrains upon breaching. Seismological monitoring of landslides has potential applications in identifying the occurrence of landslide dams upstream and can serve as an early warning system for consecutive cascading hazards. However, the research study on the likelihood of earthquake-induced landslide damming in the Himalayas is very limited, and it has uncertainties in field identification. This study presents a framework for analysing the possibility of earthquake-induced landslide damming. In the 20th century, we did not experience a large earthquake with a magnitude greater than Mw 6. However, if it happens in Uttarakhand, it could trigger large landslides, landslide damming, breaching of the landslide dams, and flash flood-like situations, which will damage human beings and properties. The study aimed to explore the correlation between earthquakes and the creation of landslide dams, analyzing how earthquakes initiate landslide damming and the subsequent impacts of such dams on the surrounding environment. Using a statistical approach (frequency ratio method), this study creates a Landslide Susceptibility Map (LSM) and an Earthquake-Induced Landslide Susceptibility Map (EILSM) for the research area in Uttarakhand, India. EILSM has been prepared through Probabilistic Seismic Hazard Analysis (PSHA) to find the hotspot areas so that we can arrange proper mitigation measures to reduce the damage to livelihood and properties. With the help of historical earthquake-induced landslide data, few landslide dams were identified. Then, a 2D numerical simulation for a selected landslide damming process was performed to understand its effects and characteristics. The findings of this study could be useful in proposing appropriate guidelines and potential mitigation measures to minimize the losses to individuals residing in downstream areas and prevent property damage.