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Triple junction kinematics accounts for the 2016 M_w 7.8 Kaikoura earthquake rupture complexity

Shi, Xuhua and Tapponnier, Paul and Wang, Teng and Wei, Shengji and Wang, Yu and Wang, Xin and Jiao, Liqing (2019) Triple junction kinematics accounts for the 2016 M_w 7.8 Kaikoura earthquake rupture complexity. Proceedings of the National Academy of Sciences of the United States of America, 116 (52). pp. 26367-26375. ISSN 0027-8424. PMCID PMC6936559. doi:10.1073/pnas.1916770116.

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The 2016, moment magnitude (M_w) 7.8, Kaikoura earthquake generated the most complex surface ruptures ever observed. Although likely linked with kinematic changes in central New Zealand, the driving mechanisms of such complexity remain unclear. Here, we propose an interpretation accounting for the most puzzling aspects of the 2016 rupture. We examine the partitioning of plate motion and coseismic slip during the 2016 event in and around Kaikoura and the large-scale fault kinematics, volcanism, seismicity, and slab geometry in the broader Tonga–Kermadec region. We find that the plate motion partitioning near Kaikoura is comparable to the coseismic partitioning between strike-slip motion on the Kekerengu fault and subperpendicular thrusting along the offshore West–Hikurangi megathrust. Together with measured slip rates and paleoseismological results along the Hope, Kekerengu, and Wairarapa faults, this observation suggests that the West–Hikurangi thrust and Kekerengu faults bound the southernmost tip of the Tonga–Kermadec sliver plate. The narrow region, around Kaikoura, where the 3 fastest-slipping faults of New Zealand meet, thus hosts a fault–fault–trench (FFT) triple junction, which accounts for the particularly convoluted 2016 coseismic deformation. That triple junction appears to have migrated southward since the birth of the sliver plate (around 5 to 7 million years ago). This likely drove southward stepping of strike-slip shear within the Marlborough fault system and propagation of volcanism in the North Island. Hence, on a multimillennial time scale, the apparently distributed faulting across southern New Zealand may reflect classic plate-tectonic triple-junction migration rather than diffuse deformation of the continental lithosphere.

Item Type:Article
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URLURL TypeDescription CentralArticle
Shi, Xuhua0000-0003-0636-5708
Wang, Yu0000-0003-3589-9274
Wang, Xin0000-0002-6180-0058
Additional Information:© 2019 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND). Contributed by Paul Tapponnier, November 6, 2019 (sent for review September 30, 2019; reviewed by Vincent Courtillot and Gilles Peltzer). PNAS first published December 10, 2019. Data Availability: All data are available in the main text or cited resources mentioned in the text. We thank New Zealand’s National Institute of Water and Atmospheric Research (NIWA) for providing publicly available 250-m-resolution bathymetry; GeoNet ( for providing seismicity catalog data; and GNS Science (New Zealand) for providing the active fault database, earthquake rupture maps and reports, and continuous GPS data. The Smithsonian Institution provided the world volcano information. We thank Christina Widiwijayanti and Lilu Cheng for collecting the volcano information. X.S. acknowledges support from Funds for International Cooperation and Exchange of the National Natural Science Foundation of China (Grant 41720104003), the AXA Research Fund, and the Hundred Talents Program of Zhejiang University (188020*194221903/011/005). P.T. acknowledges a research grant (ZDJ2019-19) from the Institute of Crustal Dynamics, China Earthquake Administration, where this work was finalized. This research was also supported by the Earth Observatory of Singapore, Nanyang Technological University, through its funding from the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence initiative. Author contributions: X.S. and P.T. designed research; X.S. and P.T. performed research; X.S., P.T., T.W., S.W., Y.W., X.W., and L.J. analyzed data; and X.S. and P.T. wrote the paper. Reviewers: V.C., Institut De Physique Du Globe De Paris; and G.P., University of California, Los Angeles. The authors declare no competing interest.
Group:Seismological Laboratory
Funding AgencyGrant Number
National Natural Science Foundation of China41720104003
Zhejiang University188020*194221903/011/005
China Earthquake AdministrationZDJ2019-19
Earth Observatory of SingaporeUNSPECIFIED
Nanyang Technological UniversityUNSPECIFIED
National Research Foundation (Singapore)UNSPECIFIED
Ministry of Education (Singapore)UNSPECIFIED
Subject Keywords:New Zealand; triple-junction migration; Kaikoura–Kermadec sliver plate; Kaikoura earthquake; rupture complexity
Issue or Number:52
PubMed Central ID:PMC6936559
Record Number:CaltechAUTHORS:20191210-150356265
Persistent URL:
Official Citation:Triple junction kinematics accounts for the 2016 Mw 7.8 Kaikoura earthquake rupture complexity. Xuhua Shi, Paul Tapponnier, Teng Wang, Shengji Wei, Yu Wang, Xin Wang, Liqing Jiao. Proceedings of the National Academy of Sciences Dec 2019, 116 (52) 26367-26375; DOI: 10.1073/pnas.1916770116
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100269
Deposited By: Tony Diaz
Deposited On:11 Dec 2019 03:04
Last Modified:16 Nov 2021 17:52

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