TXT-tool 3.081-1.1: An Integrated Model Simulating the Initiation and Motion of Earthquake and Rain-Induced Rapid Landslides and Its Application to the 2006 Leyte Landslide

Abstract

An earthquake and rainfall induced rapid landslide claimed more than 1000 people in the province of Southern Leyte, the Philippines on 17 February 2006. Landslide hazard assessment based on the simulation of initiation and motion of landslides has a great significance in practice to prepare and mitigate such disasters in the future. This research presents a new integrated computer model (LS-RAPID) simulating the initiation and motion of landslides triggered by rainfalls and/or earthquakes using the landslide parameters obtained from the undrained dynamic loading ring shear apparatus. This model LS-RAPID was developed from the geotechnical model for the motion of landslides (Sassa in Proceedings of 5th international symposium on landslides, “Landslides”. Balkema, Rotterdam, vol 1, pp 37–56, 1988) and its improved simulation model (Sassa et al. in Landslides 1(3):221–235, 2004b) and new knowledge obtained from a new dynamic loading ring shear apparatus (Sassa et al. in Landslides 1(1):7–19, 2004a). The model well simulated the development process of progressive failure to a rapid motion and the entrainment of deposits in the runout path. The combination of field investigation and ring shear test’s results on the 2006 Leyte landslide suggested that this landslide was triggered by both effects of pore pressure increase due to rainfall and seismic forces due to a very small earthquake. The application of this simulation model could well reproduce the initiation and the rapid long runout motion of the Leyte landslide.