Post-Earthquake People Loss Evaluation Based on Seismic Multi-Level Hybrid Grid: A Case Study on Yushu Ms 7.1 Earthquake in China

People loss is one of the most important information that the government concerns after an earthquake, because it affects appropriate rescue levels. However, existing evaluation methods often consider an entire stricken region as a whole assessment area but disregard the spatial disparity of influencing factors. As a consequence, results are inaccurately evaluated. In order to address this problem, this paper proposes a post-earthquake evaluation approach of people loss based on the seismic multi-level hybrid grid (SMHG). In SMHG, the whole area is divided into grids at different levels with various sizes. In this manner, the effciency of data management is improved. With SMHG, disaster statistics can be easily counted under both the administrative unit and per unit area. The proposed approach was then applied to investigate Yushu Ms7.1 earthquake in China. Results revealed that the number of deaths varied with different exposure grids. Among all the different grids, we found that using the 50x50 exposure grid can get the most satisfactory results, and the estimated number of deaths was 2,203, with an 18.3% deviation from the actual loss. People loss results obtained through the proposed approach were more accurate than those obtained through traditional GIS-based methods.