Three-Dimensional Surface Deformation in the 2016 M W 7.8 Kaikōura, New Zealand, Earthquake From Optical Image Correlation: Implications for Strain Localization and Long-Term Evolution of the Pacific-Australian Plate Boundary Robert Zinke, James Hollingsworth, James Dolan, Russ van Dissen To cite this version: Robert Zinke, James Hollingsworth, James Dolan, Russ van Dissen. Three-Dimensional Surface De- formation in the 2016 M W 7.8 Kaikōura, New Zealand, Earthquake From Optical Image Correla- tion: Implications for Strain Localization and Long-Term Evolution of the Pacific-Australian Plate Boundary. Geochemistry, Geophysics, Geosystems, AGU and the Geochemical Society, 2019, 20 (3), pp.1609-1628. 10.1029/2018GC007951. hal-02416376 HAL Id: hal-02416376 https://hal.archives-ouvertes.fr/hal-02416376 Submitted on 1 Sep 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Copyright RESEARCH ARTICLE Three‐Dimensional Surface Deformation in the 2016 MW 10.1029/2018GC007951 7.8 Kaikōura, New Zealand, Earthquake From Optical Key Points: • Correlation of high‐resolution Image Correlation: Implications for Strain optical satellite imagery reveals 3‐D ‐ surface deformation patterns of the Localization and Long Term Evolution ō 2016 MW 7.8 Kaik ura earthquake fi ‐ • Kinematic analysis shows slip on of the Paci c Australian Plate northern faults was subparallel to plate motion but slip on southern Boundary faults was transpressional Robert Zinke1 , James Hollingsworth2 , James F. Dolan1 , and Russ Van Dissen3 • Comparison of Kekerengu fault field measurements with image 1Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA, 2Université Grenoble Alpes, correlation measurements reveals 3 up to ~36% distributed deformation Université Savoie Mont Blanc, CNRS, IRD, IFSTTAR, Grenoble, France, GNS Science, Lower Hutt, New Zealand Supporting Information: ‐ ‐ • Supporting Information S1 Abstract We generated dense, high resolution 3 D ground displacement maps for the 2016 MW 7.8 • Supporting Information S2 Kaikōura, New Zealand earthquake—the most geometrically and kinematically complex rupture yet • Table S1 — • recorded from stereo WorldView optical satellite imagery using a new methodology that combines subpixel Table S2 ‐ ‐fi • Table S3 image correlation with a ray tracing approach. Our analysis reveals fundamental new details of near eld • Table S4 displacement patterns, which cannot easily be obtained through other methods. From our detailed correlation • Table S5 ‐ ‐ • maps, we measured fault slip in 3 D along 19 faults at 500 m spacing. Minimum resolvable horizontal slip Table S6 ‐ • Table S7 is ~0.1 m, and vertical is ~0.5 m. Net slip measurements range from <1 to ~12 m. System level kinematic • Figure S1 analysis shows that slip on faults north of the Hope fault was oriented primarily subparallel to the Pacific‐ • Figure S2 Australian plate motion direction. In contrast, slip on faults to the south was primarily at high angle to the • Figure S3 • Data Set S1 plate motion and secondarily parallel to plate motion. Fault kinematics are in some locations consistent with • Data Set S2 long‐term uplift patterns, but inconsistent in others. Deformation within the Seaward Kaikōura Range may • Data Set S3 • indicate an attempt by the plate boundary fault system to geometrically simplify. Comparison of published Data Set S4 fi ‐ • Data Set S5 eld measurements along the Kekerengu fault with our correlation derived measurements reveals that ~36% of surface displacement was accommodated as distributed off‐fault deformation when considering only field measurements of discrete slip. Comparatively, field measurements that project previously linear features Correspondence to: (e.g., fence lines) into the fault over apertures >5–100 m capture nearly all (~90%) of the surface deformation. R. Zinke, [email protected] 1. Introduction Citation: The 2016 M 7.8 Kaikōura, New Zealand, earthquake produced one of the most spatially and kinematically Zinke, R., Hollingsworth, J., Dolan, J. F., W & Van Dissen, R. (2019). complex ruptures ever recorded. The mainshock occurred shortly after midnight, local time, on 14 November Three‐dimensional surface deformation 2016, near the town of Waiau in northern South Island, New Zealand (Cesca et al., 2017; Kaiser et al., 2017; ō in the 2016 MW 7.8 Kaik ura, New Litchfield et al., 2018; Nicol et al., 2018). The focal mechanism indicated a nondouble couple source, with Zealand, earthquake from optical image fi ‐ correlation: Implications for strain signi cant right lateral and reverse motion (e.g., www.globalcmt.org/; Duputel & Rivera, 2017, localization and long‐term evolution of Hollingsworth et al., 2017, Kaiser et al., 2017). The rupture propagated northeastward for approximately fi ‐ the Paci c Australian plate boundary. 1.5 min, with peak moment release occurring at ~60 s or later (e.g., Cesca et al., 2017; Holden et al., 2017; Geochemistry, Geophysics, Geosystems, 20, 1609–1628. https://doi.org/10.1029/ Hollingsworth et al., 2017). Fault rupture with surface displacements >1 m was reported along more than 2018GC007951 15 onshore and offshore faults (some of which were oriented ~90° to each other), resulting in a total surface trace length of ~180 km (Stirling et al., 2017; Litchfield et al., 2018; this study). Debate remains as to what role Received 17 SEP 2018 the subduction megathrust fault played in the earthquake, though it is generally presumed that it, or some Accepted 9 FEB 2019 Accepted article online 15 FEB 2019 other deep thrust fault, contributed to the overall moment release and likely aided rupture propagation Published online 28 MAR 2019 through the complex network of faults (Bai et al., 2017; Cesca et al., 2017; Clark et al., 2017; Duputel & Rivera, 2017; Hamling et al., 2017; Hollingsworth et al., 2017; Litchfield et al., 2018; Wang et al., 2018). Immediately following the 14 November mainshock, teams of field geologists began measuring surface deformation resulting from the rupture (Clark et al., 2017; Kearse et al., 2018; Langridge et al., 2018; Litchfield et al., 2018; Nicol et al., 2018; Stirling et al., 2017; Williams et al., 2018). These measurements pro- ©2019. American Geophysical Union. vide key insights into the spatial distribution, kinematics, and complexity of slip in the event. Due to the lim- All Rights Reserved. itations of measurable geomorphic and linear cultural features, however, the field measurements of ZINKE ET AL. 1609 Geochemistry, Geophysics, Geosystems 10.1029/2018GC007951 displacement tend to be clustered, leaving large gaps in their spatial coverage. Furthermore, many field mea- surements could only be projected into the fault zone over relatively narrow (several‐meter‐wide) fault‐ perpendicular widths, thus potentially missing a component of the total fault offset (Dolan & Haravitch, 2014; Milliner et al., 2015, 2016; Rockwell et al., 2002; Shelef & Oskin, 2010; Zinke et al., 2014). To help over- come these limitations, field measurements were often supplemented by remotely sensed data sets, including light detection and ranging (lidar) and interferometric synthetic aperture radar (InSAR). Simultaneously, geo- detic and seismological studies examined broad‐scale patterns of deformation (Bai et al., 2017; Cesca et al., 2017; Hamling et al., 2017; Holden et al., 2017; Hollingsworth et al., 2017; Kaiser et al., 2017; Morishita et al., 2017; Wang et al., 2018; Xu et al., 2018). Although measurements from these studies helped to constrain coarse patterns of surface deformation and to infer fault structure and slip at depth, they lacked the spatial resolution necessary to characterize finer‐scale patterns of surface slip variability or details of the fault zone structure. The limitations of these various geological and geophysical data sets highlight the need for a means of determining fine‐scale, spatially continuous patterns of surface deformation across broad spatial areas, which can link detailed surface deformation patterns with the smoother slip distributions inferred at depth. In this study, we take advantage of very high resolution (~0.5 m) stereo preearthquake and postearthquake WorldView optical satellite images to retrieve a homogeneous 3‐D ground‐surface displacement field in the vicinity of the 2016 Kaikōura earthquake rupture using a new optical image correlation (OIC) methodology. These deformation maps provide the most detailed, seamless, and comprehensive view of surface displace- ment to date, with independent measurements computed every 32 m (with no smoothing imposed through regularization). From these maps, we measured fault‐parallel, fault‐perpendicular, and vertical displace- ments along mapped surface faults. These measurements allow us to determine the kinematics of the rup- tured faults and in turn assess the kinematic consistency between the 2016 earthquake and long‐term patterns of fault deformation expressed in the landscape. Furthermore, our data allowed an opportunity to compare OIC‐derived estimates of near‐field (distributed and localized) displacement