EXTREME SURFACE RUPTURE COMPLEXITY AND FAULT KINEMATICS REVEALED BY DIFFERENTIAL PHOTOGRAMMETRY OF THE 2016 KAIKŌURA, NEW ZEALAND EARTHQUAKE

The 2016 Kaikōura, New Zealand earthquake produced the most complex surface rupture ever documented. Here, we refine field-mapped ruptures in remote, mountainous terrain of the northeastern South Island and calculate near- and far-field 3D displacements from iterative closest point (ICP) differencing of multi-temporal point clouds produced from aerial photography. Complex patterns of folding, block rotations and extrusions, and displacement transfer across segments can be attributed to the relative immaturity, within the stress regime of the modern plate boundary, of faults south of the Hope Fault. This configuration leads to partitioning of transpressional deformation onto the numerous inherited Cretaceous and active basement structures to negotiate a rupture path that is kinematically consistent with the modern plate boundary. The quantification of rupture complexity from this earthquake and a previous global compilation provides a new upper limit of complexity for various surface rupture lengths, and suggests that overall, oblique-mechanism earthquakes are primed for more geometric and kinematic complexity than other ruptures. The potential for similar events to occur along other plate boundary zones highlights the need to fully capture the limits of rupture complexity using constraints from geology and high-resolution, multi-temporal elevation datasets.