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Subduction initiation with vertical lithospheric heterogeneities and new fault formation

Mao, Xiaolin and Gurnis, Michael and May, Dave A. (2017) Subduction initiation with vertical lithospheric heterogeneities and new fault formation. Geophysical Research Letters, 44 (22). pp. 11349-11356. ISSN 0094-8276. doi:10.1002/2017GL075389.

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How subduction initiates with mechanically unfavorable lithospheric heterogeneities is important and rarely studied. We investigate this with a geodynamic model for the Puysegur Incipient Subduction Zone (PISZ) south of New Zealand. The model incorporates a true free surface, elasto-visco-plastic rheology and phase changes. Our predictions fit the morphology of the Puysegur Trench and Ridge and the deformation history on the overriding plate. We show how a new thrust fault forms and evolves into a smooth subduction interface, and how a preexisting weak zone can become a vertical fault inboard of the thrust fault during subduction initiation, consistent with two-fault system at PISZ. The model suggests that the PISZ may not yet be self-sustaining. We propose that the Snares Zone (or Snares Trough) is caused by plate coupling differences between shallower and deeper parts, the tectonic sliver between two faults experiences strong rotation, and low-density material accumulates beneath the Snares Zone.

Item Type:Article
Related URLs:
URLURL TypeDescription
Mao, Xiaolin0000-0002-8410-4629
Gurnis, Michael0000-0003-1704-597X
May, Dave A.0000-0003-2471-7498
Additional Information:© 2017 American Geophysical Union. Received 22 AUG 2017; Accepted 24 OCT 2017; Accepted article online 30 OCT 2017; Published online 20 NOV 2017. X. M. and M. G. were supported by the National Science Foundation through awards EAR-1247022, EAR-1645775, and OCE-1654766. D. A. M. acknowledges financial support from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement 279925. Computations carried out on the NSF XSEDE systems, made possible by TG-EAR160027. We thank Magali Billen for her detailed review and constructive suggestions. Additional information for this article can be found in the supporting information. Source data for Figures 3 and 4 are available at
Group:Seismological Laboratory
Funding AgencyGrant Number
European Research Council (ERC)279925
Subject Keywords:subduction initiation; fault formation; phase change; force balance; subduction zone; surface process
Issue or Number:22
Record Number:CaltechAUTHORS:20171030-143556755
Persistent URL:
Official Citation:Mao, X., Gurnis, M., & May, D. A. (2017). Subduction initiation with vertical lithospheric heterogeneities and new fault formation. Geophysical Research Letters, 44, 11,349–11,356.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82786
Deposited By: Tony Diaz
Deposited On:30 Oct 2017 21:47
Last Modified:15 Nov 2021 19:53

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