'Twogo together': Near-simultaneous moment release of two asperities during the 2016 M<sub>w</sub> 6.6 Muji, China earthquake



Bie, Lidong, Hicks, Stephen, Garth, Thomas, Gonzalez, Pablo ORCID: 0000-0002-1767-1164 and Rietbrock, Andreas
(2018) 'Twogo together': Near-simultaneous moment release of two asperities during the 2016 M<sub>w</sub> 6.6 Muji, China earthquake. EARTH AND PLANETARY SCIENCE LETTERS, 491. pp. 34-42.

This is the latest version of this item.

Access the full-text of this item by clicking on the Open Access link.
[img] Text
2018_Bieetal_EPSL.pdf - Published version

Download (2MB)

Abstract

On 25 November 2016, a Mw 6.6 earthquake ruptured the Muji fault in western Xinjiang, China. We investigate the earthquake rupture independently using geodetic observations from Interferometric Synthetic Aperture Radar (InSAR) and regional seismic recordings. To constrain the fault geometry and slip distribution, we test different combinations of fault dip and slip direction to reproduce InSAR observations. Both InSAR observations and optimal distributed slip model suggest buried rupture of two asperities separated by a gap of greater than 5 km. Additional seismic gaps exist at the end of both asperities that failed in the 2016 earthquake. To reveal the dynamic history of asperity failure, we inverted regional seismic waveforms for multiple centroid moment tensors and construct a moment rate function. The results show a small centroid time gap of 2.6 s between the two sub-events. Considering the >5 km gap between the two asperities and short time interval, we propose that the two asperities failed near-simultaneously, rather than in a cascading rupture propagation style. The second sub-event locates ∼39 km to the east of the epicenter and the centroid time is at 10.7 s. It leads to an estimate of average velocity of 3.7 km/s as an upper bound, consistent with upper crust shear wave velocity in this region. We interpret that the rupture front is propagating at sub-shear wave velocities, but that the second sub-event has a reduced or asymmetric rupture time, leading to the apparent near-simultaneous moment release of the two asperities.

Item Type: Article
Uncontrolled Keywords: near simultaneous failure, Muji earthquake, InSAR, multiple moment tensor inversion, seismic gap
Depositing User: Symplectic Admin
Date Deposited: 13 Aug 2018 11:32
Last Modified: 13 Oct 2023 19:16
DOI: 10.1016/j.epsl.2018.03.033
Open Access URL: https://www.sciencedirect.com/science/article/pii/...
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3024964

Available Versions of this Item