Rupture processes and Coulomb stress changes of the 2017 Mw 6.5 Jiuzhaigou and 2013 Mw 6.6 Lushan earthquakes

Since the 2008 great M w 7.9 Wenchuan earthquake, two destructive earthquakes, the 2013 M w 6.6 Lushan earthquake and the 2017 M w 6.5 Jiuzhaigou earthquake, struck the eastern margin of the Tibetan Plateau, causing many casualties and significant property damage. The rupture processes and Coulomb stress change of the Lushan and Jiuzhaigou earthquakes are investigated in this study. The general patterns of the slip models of the two events are similar, where the slip is concentrated around the hypocenter and the primary ruptured zone extends about 20 km along strike. The rupture zone of the 2017 Jiuzhaigou earthquake spans a depth range of 4–16 km with a peak slip of ~ 115 cm, whereas the rupture zone of the 2013 Lushan earthquake is concentrated at 8 to 20 km depth with a peak slip of 125 cm. The coseismic static Coulomb stress changes induced by the two events are computed with the obtained slip models. The Tazang fault and the northern extremities of the Minjiang and Huya faults were strongly loaded by the Jiuzhaigou earthquake, whereas the Lushan earthquake mainly affected its surrounding faults. Therefore, we infer that the seismic hazard potential in these regions has probably been increased further, and the Lushan earthquake did not contribute significantly the occurrence of the Jiuzhaigou earthquake. Additionally, we also compute the stress changes imparted by the 2008 Wenchuan earthquake. The computed stress changes in both events’ hypocenters exceed the trigger threshold (0.1 bar), which suggests that the Wenchuan earthquake played a pivotal role in the occurrence of these two earthquakes.