Quick Identification of Regional Earthquake-Induced Landslides Based on Sharp NDVI Change

Landslides triggered by earthquake lead to substantial loss of life and damages to property. It was necessary and important to locate and plot out the landslides immediately after earthquake for quick victims rescuing. In addition, it is significant to map potential landslides for planning settlement and mitigating geological disaster. Landslide often results in sharp land cover changes in forested or bushed area, which can be easily detected by airborne or satellite-based remote sensing techniques. The region that landslide takes place is often inaccessible for field observation because of the accompanied temporary failure in transportation and communication. Therefore, remote sensing can be adopted to collect spatial information of landslide efficiently and quickly. By taking Wenchuan Earthquake as an example, this paper advanced one quick methodology to extract primary regional landslides with 8-day MODIS NDVI and terrain slope information. The threshold of temporal NDVI jump (value of 0.4) was introduced to discriminate landslide induced sharp NDVI decline from seasonal variations of vegetation cover, while slope information can be used to further confirm land cover change caused by landslide. In addition, the result emphasizes that region with slope over 15o is exposed to high landslide risk, which should be carefully taken into account in settlement and transportation planning.