Coulomb Stress Transfer and Future Earthquake Hazard from the 2025 Mw 7.7 Myanmar Earthquake: Implications for the Sagaing Fault and Shan Plateau

Abstract On 28 March 2025, a major Mw 7.7 right-lateral strike-slip earthquake ruptured the Sagaing fault (SF) in Myanmar, causing significant casualties and infrastructure damage. The long-term stress evolution of the SF since 1897 has been strongly influenced by coseismic and postseismic Coulomb failure stress change (ΔCFS) associated with this event. These stress changes are evaluated using the PSGRN/PSCMP software combined with a multilayered viscoelastic model. Our results indicate that the earthquake significantly loaded the northern and southern tips of its rupture and several adjacent faults (e.g., the Kyaukme, Loi Kwi, Lancang, and southern Nantinghe faults), with ΔCFS increases exceeding the commonly used 10 kPa (0.1 bar) earthquake-triggering threshold in some areas. Postseismic viscoelastic relaxation is projected to further enhance stress accumulation in these regions over the coming decades. The exceptionally long coseismic rupture (∼500 km) observed in this event significantly exceeds predictions from empirical magnitude-scaling relationships, highlighting the unique propensity for long, narrow ruptures on structurally mature fault zones. Comparisons among multiple coseismic slip models further show that models with larger magnitudes provide systematically better fits to far-field Global Navigation Satellite System observations, whereas smaller magnitude models fail to reproduce the observed deformation field. Furthermore, analysis of the historical earthquake sequence reveals persistent Coulomb stress accumulation on the northern segment of the SF, indicating a potential for future large earthquakes (Mw∼7.3–7.7). This research provides critical insights into stress-triggering mechanisms and refines the seismic hazard assessment for central Myanmar.