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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 economic 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 damage and can be directly converted from the peak ground 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 estimated results show that the death toll caused by this earthquake is probably 50–300, with a mathematic expectation of 89. Thus the government should launch a Level II earthquake emergency response plan. The economic losses are likely to be 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.

We considered various non‐uniformities such as branch faults, rotation of stress field directions, and changes in tectonic environments to simulate the dynamic rupture process of the 6 February 2023 Mw7.8 Kahramanmaraş earthquake in SE Türkiye. We utilized near‐fault waveform data, GNSS static displacements, and surface rupture to constrain the dynamic model. The results indicate that the high initial stress accumulated in the Kahramanmaraş‐Çelikhan seismic gap leads to the successful triggering of the East Anatolian Fault (EAF) and the supershear rupture in the northeast segment. Due to the complexity of fault geometry, the rupture speed along the southeastern segment of the EAF varied repeatedly between supershear and subshear, which contributed to the unexpectedly strong ground motion. Furthermore, the triggering of the EAF reminds us to be aware of the risk of seismic gaps on major faults being triggered by secondary faults, which is crucial to prevent significant disasters. On 6 February 2023, the south‐central Türkiye was hit by two major earthquakes with magnitudes of Mw7.8 and Mw7.6 respectively. Among them, the complex rupture process and unexpected ground motion of the Mw7.8 event attracted the attention of seismologists. In this paper, the 3D dynamic rupture process of this mainshock is simulated based on complex multi‐fault system and heterogeneous initial stress. And the simulation results are in good agreement with the observations. Our results show that high initial stress is required for the EAF to be triggered. The supershear rupture occurred only in certain fault segments and is unable to sustain itself in a significant area on the fault due to the along‐strike variations in fault geometry and strength. More importantly, the dynamic model suggests that we must be alert to the risk of major fault being triggered by earthquakes on nearby small faults, especially when there are seismic gaps on the major fault. The high initial stress accumulated in the seismic gap leads to the successful triggering of the East Anatolian FaultThe change of fault geometry in the southwest segment prevented the sustained supershear ruptureThe risk of earthquake nucleation on the secondary fault triggering the major fault rupture and the related disaster was highlighted The high initial stress accumulated in the seismic gap leads to the successful triggering of the East Anatolian Fault The change of fault geometry in the southwest segment prevented the sustained supershear rupture The risk of earthquake nucleation on the secondary fault triggering the major fault rupture and the related disaster was highlighted