Rapid Estimation of Earthquake Disaster Loss Based on Physical Simulation and Empirical Statistics—A Case Study of the 2021 Yangbi Earthquake

At present, seismic prediction technology is still not available. Scientific decision-making and rescue after an earthquake are the main means of mitigating the immediate consequences of earthquake disasters. If earthquake emergency response level, fatalities, and economic losses can be estimated rapidly and quantitatively, this estimation will provide timely, scientific guidance to government organizations and relevant institutions to make decisions on earthquake relief and resource allocation, thereby reducing potential losses and more conducive to the implementation of social activities such as post-disaster reconstruction and reinsurance. To achieve this goal, a rapid earthquake disaster loss estimation method is proposed herein, based on a combination of physical simulations and empirical statistics. The numerical approach was based on the three-dimensional curved grid finite difference method (CG-FDM), implemented for graphics processing unit (GPU) architecture, to rapidly simulate the entire physical propagation of the seismic wavefield from the source to the surface for a large-scale natural earthquake over a 3-D undulating terrain. Simulated seismic intensity data were used as input for the earthquake disaster loss estimation model to estimate the fatality, economic loss, and emergency response level. The estimation model was developed by regression analysis of the data on human loss, economic loss, intensity distribution, and population exposure from the composite damaging earthquake catalog. We used the 2021 Ms 6.4 Yangbi earthquake as a study case to provide estimated results. The number of fatalities estimated by the model was in the range of 0–10 (five expected fatalities). The most probable economic loss range was 1–10 billion RMB (the expected economic loss was 4.862 billion RMB). Therefore, Level IV earthquake emergency response plan should have been activated (the government actually overestimated the damage and activated a Level II emergency response plan). The local government finally reported three deaths and 3.32 billion RMB economic losses during this earthquake, which is consistent with the model predictions.