Viscoelastic Coulomb Stress from Historical Earthquakes on the 2022 Luding M_S6.8 Earthquake and Its Static Stress Triggering on Neighboring Faults

We investigated the influence of historical earthquakes on the 2022 Luding M_S6.8 earthquake and its subsequent effects. We computed the viscoelastic Coulomb stress changes induced by these historical seismic events using the rupture model of historical earthquakes and the layered Maxwell viscoelastic medium model. Our findings indicate that the Luding earthquake was brought forward approximately 29 years ago because of several historical earthquakes. Specifically, the 1923 Renda M_S7.3 earthquake, the 1933 Diexi M_S7.5 earthquake, the 1973 Luhuo M_S7.3 earthquake, the 2008 Kangding M_S5.1 earthquake, the 2008 Wenchuan M_S8.0 earthquake, the 2014 Kangding M_S6.3 earthquake, and the 2014 Kangding M_S5.8 earthquake resulted in events of 117.61, 26.67, 84.51, 0.27, 0.91, 7.64, and 3.17 years, respectively. Conversely, the 1936 Mabian earthquake swarm, the 1984 Litang M_S7.3 earthquake, the 1955 Kangding M_S7.5 earthquake, and the 2013 Lushan M_S7.0 earthquake delayed its occurrence by 39.89, 22.43, 144.23, and 4.89 years, respectively. Furthermore, by employing the half-space homogeneous elastic model and the rupture characteristics of the Luding earthquake, we compute the coseismic Coulomb stress changes in neighboring faults. Our results reveal increased Coulomb stress in the Xianshuihe fault (excluding its southern segment), the Anninghe fault, the Zemuhe fault, the Daliangshan fault, the southern segment of the Longmenshan fault, the northern segment of the Mabian‒Yanjin fault, and the Xiaojinhe fault. Conversely, we observed stress decreases in the southern segment of the Jinshajiang fault, the central and eastern segments of the Longriba fault, the Mabian-Yanjin fault (excluding its northern segment), and the southern segment of the Xianshuihe fault.