Multiple-Fault, Slow Rupture of the 2016 Mw 7.8 Kaikoura, New Zealand, Earthquake: Complementary Insights from Teleseismic and Geodetic Data

We investigate the complex rupture properties of the 2016 M-w 7.8 Kaikoura earthquake by jointly inverting teleseismic body-wave and regional Global Positioning System (GPS) coseismic deformation data within a multifault model. We validate our results by forward modeling recorded Interferometric Synthetic Aperture Radar (InSAR) interferograms. Our study reveals the complementary depth-dependent contributions of teleseismic and local geodetic data to the cumulative slip distribution. The resulting joint inversion model of the rupture process and slip pattern explains both the far-field (teleseismic data) and near-field (GPS and InSAR data) observations. The model highlights variable rupture velocity throughout the sequence, with an initial high-velocity (2.25 km/s) pulse followed by slow (similar to 1.5 km/s) yet significant reverse and transverse motion on faults stretching at least 160 km to the north of the origin. We map significant thrust motion on a dipping plane representing the combined effects of the Hope, Hundalee, and Jordan thrust faults as well as large strike-slip motion along the Kekerengu and Needles faults. The mainshock also ruptured the deep portion of the subduction interface at a velocity of 1.0 km/s.