Preliminary Geometry, Displacement, and Kinematics of Fault Ruptures in the Epicentral Region of the 2016 Mw 7.8 Kaikōura, New Zealand, Earthquake

Three‐Dimensional Surface Deformation in the 2016 MW7.8 Kaikōura, New Zealand, Earthquake From Optical Image Correlation: Implications for Strain Localization and Long‐Term Evolution of the Pacific‐Australian Plate Boundary

“…Stewart area, west of the northern Leader fault and north of the eastern stretch of The Humps fault (Figure ). Uplift produced by faulting and folding in this area in 2016 is consistent with long‐term uplift patterns expressed as high hills (Nicol et al, ; this study). Though we note that the topography of the NCD is at least partially controlled by bedrock structure that predates the Neogene faulting we investigate here (Nicol et al, ; Rattenbury et al, ), the uplift patterns resulting from the 2016 earthquake evince the influence of active faults in controlling the relief of this area.…”

“…For our analyses, we scaled our slip measurements in proportion to the net slip, such that larger net displacement values are more represented than smaller ones. Generally, our kinematic orientation measurements (summarized for each fault in Figure S3) reflect the broader deformation patterns shown in Figure and agree with broad‐scale field observations of deformation and uplift (Clark et al, ; Kearse et al, ; Langridge et al, ; Litchfield et al, ; Nicol et al, ; Stirling et al, ; Williams et al, ). Deviations from the overall fault plane attitudes and kinematics stem primarily from local fault structural complexities, such as restraining or releasing bends and steps, which occur at all observable length scales (≤100 to >10 km).…”

“…Debate remains as to what role the subduction megathrust fault played in the earthquake, though it is generally presumed that it, or some other deep thrust fault, contributed to the overall moment release and likely aided rupture propagation through the complex network of faults (Bai et al, ; Cesca et al, ; Clark et al, ; Duputel & Rivera, ; Hamling et al, ; Hollingsworth et al, ; Litchfield et al, ; Wang et al, ). Immediately following the 14 November mainshock, teams of field geologists began measuring surface deformation resulting from the rupture (Clark et al, ; Kearse et al, ; Langridge et al, ; Litchfield et al, ; Nicol et al, ; Stirling et al, ; Williams et al, ). These measurements provide key insights into the spatial distribution, kinematics, and complexity of slip in the event.…”

“…Red faults show our mapping of the ground‐surface (or shallow subsurface) rupture in the 2016 earthquake based on gradients in our correlation maps; the Needles fault ruptured the seafloor (Kearse et al, ) but is not considered here. Black star is the epicenter of the 14 November 2016 mainshock (Nicol et al, ). Black lines are active faults (from Langridge et al, ) on which we did not observe surface rupture, though the Hikurangi megathrust may have ruptured at depth.…”

Dynamic Rupture Simulation Reproduces Spontaneous Multifault Rupture and Arrest During the 2016Mw7.9 Kaikoura Earthquake

“…The eastern Humps fault is favorably oriented (Figure c). This could explain why the rupture may have easily propagated or jumped to the eastern Humps fault from the actual hypocenter a few kilometers south of the fault (Nicol et al, ). The difference between the actual and assumed hypocenters also implies that the current simulation may lack this initial rupture process.…”