Seismic landslide hazard assessment in the Tianshui area, China, based on scenario earthquakes

This work represents a regional potential seismic landslide hazard assessment for the Tianshui area, southeastern Gansu Province, China. The peak ground accelerations for two specific seismic scenarios (Ms 7.0 and 8.0) are estimated through empirical attenuation relationships. They are then combined with the slope threshold accelerations to calculated cumulative displacements through the Newmark’s sliding rigid-block model. Potentially unstable areas are identified based on the predicted Newmark displacement. The results show that both of the scenarios are capable of producing widespread slope instabilities, mainly loess landslides in the near-fault region, and that the Ms 7.0 earthquake would induce more slope instabilities around Tianshui city. The high-risk zones are concentrated mainly in the loess or mudstone areas with slope greater than 30°, especially on the banks of the Wei River, Xi River, and Niutou River, and pose a threat to the Longhai Railway line and the surroundings of Tianshui city. The potential damage to traffic networks and to built-up areas in Tianshui city is also mapped. These maps represent a preliminary assessment that can be utilized by local government to define the seismic landslide hazard better for future detailed risk evaluation, emergency plans, and engineering design.