GIS-based earthquake-triggered landslide hazard zoning using contributing weight model

Abstract

Earthquake-triggered landslides have aroused widespread attention because of their tremendous ability to harm people’s lives and properties. The best way to avoid and mitigate their damage is to develop landslide hazard maps and make them available to the public in advance of an earthquake. Future construction can then be built according to the level of hazard and existing structures can be retrofit as necessary. During recent years various approaches have been made to develop landslide hazard maps using statistical analysis or physical models. However, these methods have limitations. This study introduces a new GIS-based approach, using the contributing weight model, to evaluate the hazard of seismically-induced landslides. In this study, the city and surrounding area of Dujiangyan was selected as the research area because of its moderate-high seismic activity. The parameters incorporated into the model that related to the probability of landslide occurrence were: slope gradient, slope aspect, geomorphology, lithology, base level, surface roughness, earthquake intensity, fault proximity, drainage proximity, and road proximity. The parameters were converted into raster data format with a resolution of 25×25m² pixels. Analysis of the GIS correlations shows that the highest earthquake-induced landslide hazard areas are mainly in the hills and in some of the moderately steep mountainous areas of central Dujiangyan. The highest hazard zone covers an area of 11.1% of the study area, and the density distribution of seismically-induced landslides was 3.025/km² from the 2008 Wenchuan earthquake. The moderately hazardous areas are mainly distributed within the moderately steep mountainous regions of the northern and southeastern parts of the study area and the hills of the northeastern part; covering 32.0% of the study area and with a density distribution of 2.123/km² resulting from the Wenchuan earthquake. The lowest hazard areas are mainly distributed in the topographically flat plain in the northeastern part and some of the relatively gently slopes in the moderately steep mountainous areas of the northern part of Dujiangyan and the surrounding area. The lowest hazard areas cover 56.9% of the study area and exhibited landslide densities of 0.941/km² and less from the Wenchuan earthquake. The quality of the hazard map was validated using a comparison with the distribution of landslides that were cataloged as occurring from the Wenchuan earthquake. 43.1% of the study area consists of high and moderate hazardous zones, and these regions include 83.5% of landslides caused by the Wenchuan earthquake. The successful analysis shows that the contributing weight model can be effective for earthquake-triggered landslide hazard appraisal. The model’s results can provide the basis for risk management and regional planning is.