Abstract Based on elastic dislocation theory and lithosphere layered viscoelastic model, we analyze the influence of the co-seismic and post-seismic stress of the Yushu earthquake on the Zaduo earthquake. Additionally, we discuss the stress influence of Yushu and Zaduo earthquakes on the major active faults about seismic risk in the study area. The result shows that the co-seismic stress increased 1.476 kPa on the epicenter of the 2016 Zaduo earthquake. During the 6 years between the two earthquakes, post-seismic Coulomb stress enhanced regional stress in the area, and released stress in the stress shadow; the epicenter of the Zaduo earthquake is always located in the area of enhanced stress. When the Zaduo earthquake occurred, the Coulomb stress increased 3.902 kPa on the epicenter of the Zaduo earthquake. The results of different models show that the occurrence of Yushu earthquake promoted the occurrence of Zaduo earthquake. The co-seismic rupture of Zaduo earthquake only affected the stress state of a small area around the epicenter, which made a high stress area in the northwest of Zaduo fault zone. The co-seismic and post-seismic effect of Yushu earthquake significantly enhanced the stress state of the Yenuoka-Jielong segment, Batang-Luoxu segment, Dangjiang segment, the middle segments of Batangxiang and Wudaoliang-Qumalai faults. The northwest seismic gaps of Ganzi-Yushu fault, including the Yenuoka-Jielong and Batang-Xianggu segments, retain arelatively high seismic hazard.
