Dynamic viability of the 2016 Mw 7.8 Kaikōura earthquake cascade on weak crustal faults

We present a dynamic rupture model of the 2016 M w 7.8 Kaikōura earthquake to unravel the event’s riddles in a physics-based manner and provide insight on the mechanical viability of competing hypotheses proposed to explain them. Our model reproduces key characteristics of the event and constraints puzzling features inferred from high-quality observations including a large gap separating surface rupture traces, the possibility of significant slip on the subduction interface, the non-rupture of the Hope fault, and slow apparent rupture speed. We show that the observed rupture cascade is dynamically consistent with regional stress estimates and a crustal fault network geometry inferred from seismic and geodetic data. We propose that the complex fault system operates at low apparent friction thanks to the combined effects of overpressurized fluids, low dynamic friction and stress concentrations induced by deep fault creep. The 2016 Kaikōura earthquake in New Zealand raised the discussion about how a complex fault system operates. Here the authors propose a dynamic rupture scenario that reproduces key characteristics of the event and show that the fault system works at low apparent friction.