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Published February 2018 | Published + Supplemental Material
Journal Article Open

Systematic deficiency of aftershocks in areas of high coseismic slip for large subduction zone earthquakes

Abstract

Fault slip during plate boundary earthquakes releases a portion of the shear stress accumulated due to frictional resistance to relative plate motions. Investigation of 101 large [moment magnitude (M_w) ≥ 7] subduction zone plate boundary mainshocks with consistently determined coseismic slip distributions establishes that 15 to 55% of all master event–relocated aftershocks with M_w ≥ 5.2 are located within the slip regions of the mainshock ruptures and few are located in peak slip regions, allowing for uncertainty in the slip models. For the preferred models, cumulative deficiency of aftershocks within the central three-quarters of the scaled slip regions ranges from 15 to 45%, increasing with the total number of observed aftershocks. The spatial gradients of the mainshock coseismic slip concentrate residual shear stress near the slip zone margins and increase stress outside the slip zone, driving both interplate and intraplate aftershock occurrence near the periphery of the mainshock slip. The shear stress reduction in large-slip regions during the mainshock is generally sufficient to preclude further significant rupture during the aftershock sequence, consistent with large-slip areas relocking and not rupturing again for a substantial time.

Additional Information

© 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited. Submitted 7 July 2017; Accepted 16 January 2018; Published 14 February 2018. We thank L. Ye for access to mainshock slip models, which are available from https://sites.google.com/site/linglingye001/earthquakes/slip-models. We thank two anonymous reviewers for helpful suggestions that improved the presentation. Funding: N.W. was supported by the Geological Survey of Israel at the Ministry of Energy and Water Resources. T.L. was supported by NSF grant EAR1245717. Author contributions: N.W. performed the computer analysis. T.L. conceived the analysis of aftershock patterns relative to mainshocks and contributed to the analysis design. E.E.B. and H.K. contributed to the analysis design. All authors contributed to the writing of the paper. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors. The GCMT earthquake catalog is obtained from www.globalcmt.org/CMTsearch.html.

Attached Files

Published - eaao3225.full.pdf

Supplemental Material - aao3225_FigS1.pdf

Supplemental Material - aao3225_FigS4.pdf

Supplemental Material - aao3225_SM.pdf

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Additional details

Created:
August 19, 2023
Modified:
October 18, 2023