Pre-seismic and co-seismic deformation of the 2017 Mw 6.5 Jiuzhaigou, eastern Tibet earthquake constrained by GPS and InSAR data

Guojie Meng, Xiaoning Su, Shunying Hong, Xin Zhou, Yanfang Dong, & Chengtao Li

Published August 7, 2018, SCEC Contribution #8305, 2018 SCEC Annual Meeting Poster #127 (PDF)

We investigate pre-seismic and co-seismic crustal deformation of the 2017 Mw 6.5 Jiuzhaigou, which occurred in the eastern boundary of Bayan Har block, Tibet Plateau, using geodetic data. Pre-seismic deformation is in the epicentral area is realized from continuous and campaign GPS data acquired during the 2009-2017 period. The left-lateral strike and extensional rates are 3.0 mm/yr and 3.1 mm/yr, respectively, for the northern extension of the Huaya Fault, where no co-seismic rupture identified along the hidden segment. Strain tensor components show an evident localized strain accumulation in the vicinity of epicenter zone. Co-seismic deformation field is derived by GPS and InSAR data in multiple SAR viewing geometries. The fault geometry models retrieved with multiple inversion methods are highly consistent, showing a source model with a strike of ~154° and a dip angle of ~ 77°. Based on the optimal fault geometry model, the fault slip distribution jointly inverted from InSAR and GPS data shows the slip is mainly concentrated in the depth of 1 - 15 km, and only one slip center appears in the depth of 5 - 9 km with a maximum slip of about 1.06 m. Taking the shear modulus of μ = 32 GPa, the seismic moment derived from the distributed slip model is about 7.85 ×1018 Nm, equivalent to an earthquake of Mw 6.5. Most of the aftershocks with magnitude < M 3 happened in stress shadow area with depth between 5-15 km; whereas, the aftershocks with magnitude ≥ M 3 predominately happened in an area with positive Coulomb stress changes in a depth more than 15 km. The static Column stress triggered by the mainshock significantly increased at the Tazang fault northwest to the epicenter, the hidden North Huya fault and partial segments of Minjiang fault west of the epicenter.

Key Words
The 2017 Jiuzhaigou Mw 6.5 Earthquake; Geodetic Observation; Earthquake Deformation

Citation
Meng, G., Su, X., Hong, S., Zhou, X., Dong, Y., & Li, C. (2018, 08). Pre-seismic and co-seismic deformation of the 2017 Mw 6.5 Jiuzhaigou, eastern Tibet earthquake constrained by GPS and InSAR data. Poster Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy