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Effect of seismogenic depth and background stress on physical limits of earthquake rupture across fault step-overs

Bai, Kangchen and Ampuero, Jean-Paul (2017) Effect of seismogenic depth and background stress on physical limits of earthquake rupture across fault step-overs. Journal of Geophysical Research. Solid Earth, 122 (12). pp. 10280-10298. ISSN 2169-9313. https://resolver.caltech.edu/CaltechAUTHORS:20171115-094842752

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Abstract

Earthquakes can rupture geometrically complex fault systems by breaching fault step overs. Quantifying the likelihood of rupture jump across step overs is important to evaluate earthquake hazard and to understand the interactions between dynamic rupture and fault growth processes. Here we investigate the role of seismogenic depth and background stress on physical limits of earthquake rupture across fault step overs. Our computational and theoretical study is focused on the canonical case of two parallel strike-slip faults with large aspect ratio, uniform prestress and friction properties. We conduct a systematic set of 3-D dynamic rupture simulations with different seismogenic depth, step over distance, and initial stresses. We find that the maximum step over distance H_c that a rupture can jump depends on seismogenic depth W and strength excess to stress drop ratio S, commonly used to evaluate probable rupture velocity, as H_c ∝ W/S^n, where n = 2 when H_c/W < 0.2 (or S > 1.5) and n = 1 otherwise. The critical nucleation size, largely controlled by frictional properties, has a second-order effect on H_c. Rupture on the secondary fault is mainly triggered by the stopping phase emanated from the rupture end on the primary fault. Asymptotic analysis of the peak amplitude of stopping phases sheds light on the mechanical origin of the relations between H_c, W, and S, and leads to the scaling regime with n = 1 in far field and n = 2 in near field. The results suggest that strike-slip earthquakes on faults with large seismogenic depth or operating at high shear stresses can jump wider step overs than observed so far in continental interplate earthquakes.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/2017JB014848DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2017JB014848/abstractPublisherArticle
ORCID:
AuthorORCID
Bai, Kangchen0000-0002-9788-6404
Ampuero, Jean-Paul0000-0002-4827-7987
Additional Information:© 2017 American Geophysical Union. Received 10 AUG 2017; Accepted 9 NOV 2017; Accepted article online 15 NOV 2017; Published online 23 DEC 2017. This work was funded by NSF CAREER award EAR-1015698 and by the Southern California Earthquake Center (Contribution 7964), which is funded by National Science Foundation Cooperative Agreement EAR-82081033462 and U.S. Geological Survey Cooperative Agreement G12AC20038. We thank Julian Lozos, an anonymous reviewer and Associate Editor Yoshi Kaneko for their constructive suggestions to improve this manuscript. All data generating figures in this paper are available at https://drive.google.com/open?id=0B-S2bwIdZxdfYkRhTzF4NXdRWWs.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-1015698
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-82081033462
USGSG12AC20038
Subject Keywords:fault step-over; rupture dynamics; earthquake; seismogenic depth; friction; ground motion
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center7964
Issue or Number:12
Record Number:CaltechAUTHORS:20171115-094842752
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20171115-094842752
Official Citation:Bai, K., & Ampuero, J.-P. (2017). Effect of seismogenic depth and background stress on physical limits of earthquake rupture across fault step overs. Journal of Geophysical Research: Solid Earth, 122, 10,280–10,298. https://doi.org/10.1002/2017JB014848
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83217
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:15 Nov 2017 22:40
Last Modified:03 Oct 2019 19:03

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