Human vulnerability to quick shallow landslides along road: fleeing process and modeling

Abstract

Throughout the history, many lives have been lost due to landslides. Understanding the process of human flight during landslide events is important in assessing the risks posed by future landslides. This study proposes a model for simulating human flight from a quick shallow landslide along a road, quantifies the flight success rate, and identifies the crucial variables that impact flight efficiency. A questionnaire survey was undertaken along a stretch of highway near Yingxiu, China to collect information regarding human responses and behavior in the face of landslide events. The factors influencing human flight are classified into factors related to the evacuees, the landslide intensity, and the flight path. Subsequently, a flight model is proposed to simulate the movements of people randomly located along a road threatened by landslides. Various components of “available time” and “demand time” for escaping from the landslide affected area are treated as random variables. Based on this model, probability analysis is conducted to estimate the flight success rates of the people at risk when fleeing from landslides of various intensities. Sensitivity analysis shows that the pre-failure time and the response time are the most important factors in the flight process. Finally, comparison between the flight success rates from two existing methods and those from the new model is made.