Source Characteristics of the 2017 Ms 7.0 Jiuzhaigou, China, Earthquake and Implications for Recent Seismicity in Eastern Tibet

• Published in: Journal of geophysical research. Solid earth 2019-05, Vol.124 (5), p.4895-4915
• Main Authors: Liu, Gang, Xiong, Wei, Wang, Qi, Qiao, Xuejun, Ding, Kaihua, Li, Xingxing, Yang, ShaoMin
• Format: Article
• Language: English
• Subjects: Coulomb stress change; Deformation; Deformation mechanisms; Earthquake damage; Earthquakes; Fault lines; Geophysics; Global positioning systems; GPS; Interferometric synthetic aperture radar; Jiuzhaigou earthquake; joint inversion; Local communities; Migration; Nucleation; Positioning systems; SAR (radar); Satellite navigation systems; Seismic activity; seismic risk; Seismicity; Slip; source characteristics; Synthetic aperture radar
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2018JB016340

On 8 August 2017, a strong earthquake occurred on an unmapped extension of the Huya fault, Sichuan, China, causing severe damage to local communities. This event highlights the northward migration of major earthquakes along a single strike‐slip fault. We analyze the source characteristics with Global Positioning System (GPS)/ Interferometric Synthetic Aperture Radar static displacements and high‐rate GPS/teleseismic dynamic motions. Our analyses show a complex slip pattern characterized by two patches with a mean slip of 0.6 m and predominantly strike‐slip components. Slip propagates at a rupture speed of approximately 3.2 km/s for about 30 km in length and 20 km in width. Given a slip rate of 0.5 mm/year derived from GPS observations, the mean slip of 0.6 m inferred from the slip model suggests a recurrence interval of ~1,000 years for this earthquake and alike on the Huya fault. The Coulomb stress increase of 0.82 bar caused by preceding earthquakes promoted the failure of the northern Huya fault in 2017. In particular, the nucleation of this event was partially facilitated by the 2008 Wenchuan earthquake and postseismic deformation. Long‐term slip deficits on most parts of the Huya fault have been balanced largely by a series of strong earthquakes since the early 1970s. As yet, a few of seismic gaps remain hazardous during the final stage of one seismic cycle. In particular, the ongoing postseismic relaxation will hasten further the 20‐ to 25‐km long segment in the Jiuzhaigou National Natural Reserve closer to failure in a moderate size earthquake. Key Points Two patches with 0.7 m strike‐slip near the surface for 25 km long are identified on the northern Huya fault The fault failure in 2017 was promoted by recent earthquakes, especially the 2008 Wenchuan earthquake through the postseismic deformation A 20‐ to 25‐km long section proximal to the Jiuzhaigou National Park is encouraged to fail to end the seismic cycle of the Huya fault