The relationship between main geological hazard and topography in the Himalayan seismic belt: A case study in the Xigaze area, Tibet

The Himalayas is a huge mountain formed by the collision between the Eurasian plate and the Indian Ocean plate.In the history, there were many earthquakes with magnitude of 7 or more, which caused a large number of secondary geological disasters, and formed complex and diverse landform.Based on the previous data, field surveys and remote sensing interpretation, combined with the geomorphological map of the Himalayas seismic belt (Xigaze section), the powerful data management and spatial analysis capabilities of GIS were used to analyze major geological hazards in the Xigaze area and make maps of geological hazards and density contour.The results show that the main geological disasters are concentratedly distributed in five areas.The main geological disasters occur in strongly denudated and undulating mountains and periglacial extremely undulating mountain landforms, followed by valley plain and moraine hills.Other geomorphic features have less developmental hazards.Landslides and collapses are prone to occur on sunny slopes below 3500 m (90°~270°), and are most sensitive on the southeast-trending slope.Landslides and collapses are prone to occur at slopes of 15°~45° and 35°~90° respectively.Debris flow disasters occur most often in valleys with basin area less than 5 km², relative elevation difference greater than 100 m, and the longitudinal slope greater than 212.56‰.They are especially developed in V-shaped valleys.