Exploration on the relationship between earthquake-triggered landslides and tectonics in the Himalayan Subduction Zone

Abstract

Most major earthquakes worldwide occur within subduction zones, but there is a death of studies on earthquake induced landslides in subduction zones. the Mw7.8 earthquake that jolted Nepal on April 25, 2015, the first strong earthquake in the Himalayan Subduction Zone in nearly 70 years, triggered a large landslide event, and the area served as a good venue for conducting research on earthquake-triggered landslides in Himalayan Subduction Zones. Based on remote sensing interpretation and field investigation, 2,072 sets of earthquake-triggered landslide information were obtained, revealing that the Nepalese earthquake-triggered landslides are distributed between 1,000-3,000 m above sea level, in the transition area between the High Himalaya and the Low Himalaya, basically along the Main Central Thrust, with a large topographic drop; The dominant distribution range of landslide slope values is 35-40°; the dominant distribution range of aspect values is 120-200°, which is closely related to the horizontal deformation field. The basic characteristics of earthquake-triggered landslides in the Himalayan Subduction Zone are initially discussed: The landslide points are clearly distributed in a faceted pattern and are closely associated with deep, low-dip fault rupture surfaces; the landslides are all located in the upper plate, and are easily induced by the inertia of seismic motion on slopes with slopes that are oriented in the same direction as the reverse thrust of the upper plate.