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Published May 28, 2021 | Supplemental Material + Published
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Multifault Opposing-Dip Strike-Slip and Normal-Fault Rupture During the 2020 M_w 6.5 Stanley, Idaho Earthquake

Yang, Jidong ORCID icon
Zhu, Hejun ORCID icon
Lay, Thorne ORCID icon
Niu, Yufeng
Ye, Lingling ORCID icon
Lu, Zhong ORCID icon
Luo, Bingxu
Kanamori, Hiroo ORCID icon
Huang, Jianping ORCID icon
Li, Zhenchun
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Abstract

On March 31, 2020, an M_w 6.5 earthquake struck near Stanley, Idaho. More than 35% nondouble-couple component in long-period point-source solutions indicate a more complex source than slip on a planar fault. Using an integrative analysis of seismological and geodetic data, we find that the Stanley earthquake ruptured a pair of opposing-dip faults offset by a 10-km-wide step, including an unmapped northern subfault with predominantly strike-slip faulting and a southern subfault subparallel to the Sawtooth fault with predominantly normal faulting. This converging fault geometry allowed the rupture to traverse a surficial 10-km-wide step, which is greater than the limiting dimension (3–4 km) that commonly ceases earthquake ruptures. This study reveals that a composite rupture process with strike-slip and normal faulting is typical for earthquakes located near the northern boundary of the Centennial Tectonic Belt (CTB), which is distinct from the predominantly normal faulting in the central CTB.

Additional Information

© 2021 American Geophysical Union. Issue Online: 19 May 2021; Version of Record online: 19 May 2021; Accepted manuscript online: 04 May 2021; Manuscript accepted: 20 April 2021; Manuscript revised: 14 April 2021; Manuscript received: 12 January 2021. This study is supported by the startup funding of Guanghua Scholar at China University of Petroleum (East China) (20CX06069A) (To Jidong Yang) and UTD faculty startup funding (to. Hejun Zhu). Thorne Lay's research on earthquake is supported by U.S. National Science of Foundation grant EAR1802364. Lingling Ye's research on earthquake is supported by National Natural Science Foundation of China (No. 41874056). Yufeng Niu's research on earthquake is supported by National Natural Science Foundation of China (No. 41901286). Jianping Huang and Zhenchun Li are supported by National Outstanding Youth Science Foundation (No. 41922028), National Natural Science Foundation of China (No. 41874149), and Funds for Creative Research Groups of China (No. 41821002). Data Availability Statement: All data needed to evaluate the conclusions in this study are presented in the paper and supplement materials. Seismological data used in back-projection and finite-fault inversion can be downloaded from https://ds.iris.edu/wilber3/find_event. The 3D crustal velocity model used in back-projection analysis can be downloaded from http://ds.iris.edu/ds/products/emc-us2016/. The aftershock catalog is downloaded from https://earthquake.usgs.gov/earthquakes/search/. Sentinel-1 images used in InSAR analysis are provided by the European Space Agency and can be downloaded from https://search.asf.alaska.edu/#/. We thank two anonymous reviewers and the editor G. Prieto for helpful comments on the manuscript.

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Published - 2021GL092510.pdf

Supplemental Material - 2021gl092510-sup-0001-supporting_information_si-s01.pdf

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Supplemental Material - 2021gl092510-sup-0003-movie_si-s02.mp4

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