40-1 Seismic Effect on Himalayan Landslides

Session: Geomorphology (Posters)

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Abstract:

Many factors affect slope stability and landslide risk, including seismic activity. Coarse, broad risk mapping often uses general fault proximity as an approximation of seismic factors, while the application of more granular seismic data is often overlooked or similarly generalized. Specific seismic activity is also influenced by several geological factors that also affect slope stability, such as the type of rock or soil. Seismic gaps, long periods without earthquakes, in active seismic areas may reflect an unseen addition to the severity of risk. The study area spans from central Nepal through Sikkim, India. This area on the southern side of the Himalayas experiences frequent seismic events, with some notable gaps, as well as possesses several other contributing risk factors against slope stability, such as monsoonal rains and weak soil or rock. This project investigates the effects of seismicity on a high-risk area, as well as how seismic gaps influence slope risk factors. Seismic data for the selected area was compiled, analyzed, and mapped against other geologic and terrain data to better understand and plan around the seismic effect on slope stability. Satellite imagery and landslide inventories were analyzed to locate and categorize the type of landslides involved, as that provides insight into which factors contributed to the event. Preliminary analysis shows a relationship between geological zones and the distribution and frequency of seismic events, as well as a correlation between that combined risk factor distribution and landslide density. The investigation demonstrates the complexity of relationships between combined risk factors, as well as the need for more accessible data. The continuing investigation requires further detailed analysis of available data to better understand the regional relationships and effects of the involved risk factors.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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