Ground Surface Deformation Caused by the M-w 5.8 Early Strong Aftershock following the 13 November 2016 M-w 7.8 Kaikoura Mainshock

The M-w 7.8 Kaikoura earthquake on 13 November 2016 is one of the most complex events ever recorded, with surface rupture found on more than a dozen faults. Within about 10 minutes after the mainshock, an M-w 5.8 event occurred and caused an 8 cm static displacement at high-rate Global Positioning System (GPS) station KAIK, which was not accounted for in previous mainshock studies. In this article, we focus on the M-w 5.8 aftershock including (1) relocating the hypocenter using the hypo2000 method, (2) conducting a grid search for its point-source mechanism and centroid location using seismic waveforms at four nearby stations, (3) inverting finite-fault models of this event based on grid-searched fault mechanism, and (4) calculating the surface ground deformation and estimating the deformation in the line of sight (LoS) directions of the ascending and descending Advanced Land Observation Satellite-2 (ALOS-2). Although we are not able to resolve the ruptured fault of the M-w 5.8 aftershock because of limited observation data, we estimate that this event can generate 10-20 cm ground surface displacement and affect the ground displacement observed on the Interferometric Synthetic Aperture Radar (InSAR) data near the Kaikoura Peninsular.