Enhancing post-seismic landslide susceptibility modeling in China through a time-variant approach: a spatio-temporal analysis

Abstract

The pre-phase landslides will have a legacy effect on future landslides, changing the landslide susceptibility. This study attempts to establish a reasonable post-seismic landslide susceptibility model and analyze the spatio-temporal characteristics of landslide susceptibility in the Jiuzhaigou MS7.0 earthquake-struck region. Firstly, an integrated ‘space-ground’ monitoring technology is used to establish a multi-temporal post-seismic landslide dataset. Then, the buffer analysis method documents the spatio-temporal characteristics of post-seismic landslides. Thirdly, the distance is selected as an indicator to quantify the legacy effect. An improved time-variant model is established to evaluate the post-seismic landslide susceptibility. Finally, the spatio-temporal characteristics of landslide susceptibility are generalized, to sum up the changing law. Our results show that the post-seismic landslides are gradually closer to the pre-phase landslides with time. Distance is a critical factor in measuring the impact of pre-phase landslides on future landslides, which can improve the assessment accuracy of the post-seismic landslide susceptibility model. After a large seismic event, the correlation between landslide susceptibility and earthquakes gradually weakens. Post-seismic landslide prevention should focus on the pre-phase landslide expansion triggered by rainfall. Moreover, it should clean up the landslide deposits in time and reasonably dredge the debris flows to avoid secondary geological disasters.