Coulomb stress transfer from the 2025 MW 7.7 Myanmar earthquake to active faults in southwestern Yunnan, China: Implications for seismic hazard

On 28 March 2025, a strong MW 7.7 earthquake struck the seismic gap in the central section of the Sagaing Fault in Myanmar, causing significant damages and casualties in Myanmar and neighboring countries. Major earthquakes like this are expected to transfer stresses to nearby active regions and change their seismic hazards in the near future. In this study, based on a stratified viscoelastic model and a coseismic slip model, we calculated the co- and post-seismic Coulomb stress change (△CFS) imparted by the MW 7.7 Myanmar earthquake to the main active faults in the adjacent southwestern Yunnan region in China. Our results show that five fault segments experience up to 3 kPa of coseismic stress increase, including the Longling-Lancang Fault, the Nantinghe Fault, the Menglian Fault, the Heihe Fault, and the Red River Fault, respectively. The pattern of postseismic △CFS is similar to that of coseismic △CFS, suggesting that with the increasing elapsed time, the stress level continues to increase in these fault zones. The coseismic auxiliary stress fields show that the orientation of the principal tensile stress is predominantly NE-SW in the northern part of the southwestern Yunnan region, and shows clockwise rotation to NW-SE in the south. This stress regime controls the additional slip motion, consistent with that reflected by the coseismic shear stress change. Combined with other geophysical and geodetic data, we propose that more attention should be paid to the Longling-Lancang Fault, the Nantinghe Fault, the Menglian Fault, and the Heihe Fault, potential candidates for the next strong earthquakes in this region.