Rapid Estimation of Disaster Losses by Physics-based Simulation for the M6.8 Luding Earthquake on September 5, 2022

An M6.8 earthquake occurred in Luding, Sichuan province, China on September 5, 2022. Since towns and villages in the earthquake-stricken area are densely populated, the earthquake caused severe fatalities and economic losses. Rapid estimation of earthquake intensity and disaster losses is significantly important for post-earthquake emergency rescue, scientific anti-seismic deployment, and the reduction of casualties and financial losses. Therefore, we make a preliminary rapid estimation of the earthquake intensity and disaster losses in the aftermath of the Luding earthquake. The seismic intensity represents the distribution of earthquake disasters and the degree of ground damages and can be directly converted from the peak acceleration velocity (PGV) map. To obtain a reliable PGV distribution map of this earthquake, we combined the finite-fault model constrained by seismic observations, with the complex three-dimensional (3D) geological environment and topographical features to perform strong ground motion simulation. Then, we compared the consistency between the simulated ground motion waveforms and observations, indicating the plausibility and reliability of simulations. In addition, we transformed the PGV simulation results into intensity and obtained a physics-based map of the intensity distribution of the Luding earthquake. The maximum simulated intensity of this earthquake is IX, which is consistent with the maximum intensity determined from the post-earthquake field survey. Based on the simulated seismic intensity map of the Luding earthquake and the earthquake disaster loss estimation model, we rapidly estimated the death and economic losses caused by this earthquake. The estimation results show that the death toll caused by this earthquake is most probably in the range of 50-300, with a mathematic expectation of 89 The government should launch a Level II earthquake emergency response plan. The economic losses are likely to be in the range of 10-100 billion RMB, with a mathematical expectation of 23.205 billion RMB. Such seismic intensity simulations and rapid estimation of disaster losses are expected to provide a preliminary scientific reference for governments to carry out the targeted deployment of emergency rescue and post-disaster reconstruction.