Coulomb stress changes associated with the M7.3 Maduo earthquake and implications for seismic hazards

On May 21, 2021, the M7.3 Maduo earthquake occurred within the Bayan Har Block, one of the most seismically active regions in the Tibetan Plateau. This aroused attention to the seismic hazards in this block. Understanding the stress transfer to adjacent faults is important for assessing seismic hazards. In this study, based on the elastic dislocation theory and a multi-layered lithospheric model, we calculate the Coulomb failure stress changes caused by this event on the adjacent major faults and identify the segments that experienced significant increases in stress. Our preliminary results show that five segments, including the middle segment of the Dari Fault, the Tuosuo Lake segment, the Maqin–Maqu segment, the western segment of the Dari Fault, and the Yushu segment of the Garze–Yushu Fault, experienced significant increases in co-seismic stress, which exceed the proposed threshold (1 ​× ​104 ​Pa) for triggering an earthquake. The stress change pattern associated with the post-seismic viscoelastic relaxation effect is substantially consistent with that caused by the co-seismic effect. The segments with high combined (co-plus post-seismic) stress changes are identical to those indicated by the co-seismic stress increase. Based on the stress change in this study and those of previous studies on seismic activity and fault stress evolution, we emphasize the seismic potential of the Maqin–Maqu segment, the Tuosuo Lake segment, and the middle-west segments of the Dari Fault, which should receive increased attention.