The 2016 Kaikōura Earthquake Revealed by Kinematic Source Inversion and Seismic Wavefield Simulations: Slow Rupture Propagation on a Geometrically Complex Crustal Fault Network

Abstract

The 2016 Kaikōura (New Zealand) earthquake generated large ground motions and resulted in multiple onshore and offshore fault ruptures, a profusion of triggered landslides, and a regional tsunami. Here we examine the rupture evolution using two kinematic modeling techniques based on analysis of local strong‐motion and high‐rate GPS data. Our kinematic models capture a complex pattern of slowly (Vr < 2 km/s) propagating rupture from south to north, with over half of the moment release occurring in the northern source region, mostly on the Kekerengu fault, 60 s after the origin time. Both models indicate rupture reactivation on the Kekerengu fault with the time separation of ~11 s between the start of the original failure and start of the subsequent one. We further conclude that most near‐source waveforms can be explained by slip on the crustal faults, with little (<8%) or no contribution from the subduction interface.

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

“…Increasing the value of D c and decreasing the stress drop through σ hmin / σ v from those in Model S by less than a few percent do not lead to the triggering of slip on Upper Kowhai. Since the dynamic triggering occurs or not is related to a bifurcation point in the solution space in the range of admissible parameter values, these can be regarded as two plausible scenarios, with the former one consistent with the Kaikoura earthquake observation (Holden et al, ).…”

“…The 2016 Kaikoura earthquake in the northern South Island of New Zealand was one of the most complex faulting events ever observed. The geometrical complexity of the faults ruptured during the earthquake was captured by field surveys (Clark et al, ; Litchfield et al, ; Nicol et al, ), kinematic inversions using interferometric synthetic aperture radar, and GPS data (Hamling et al, ; Xu et al, ) and strong motion records (Y. F. Bai et al, ; Cesca et al, ; Holden et al, ; Kaiser et al, ; Wang et al, ), suggesting that the rupture was initiated near the southwestern end, propagated through a large number of subparallel and conjugate faults extending over 150 km, and terminated at the northeastern end. Although the involvement of the Hikurangi subduction interface is still debated (e.g., Y. F. Bai et al, ; Cesca et al, ; Holden et al, ; Wang et al, ; Xu et al, ), the source models of the Kaikoura earthquake show heterogeneous slip distributions with the maximum slip on Kekerengu fault (Hamling et al, ; Holden et al, ; Xu et al, ).…”

Triggered Slow Slip and Afterslip on the Southern Hikurangi Subduction Zone Following the Kaikōura Earthquake

“…Some suggest that rupture of the subduction interface contributed >50% of the earthquake's moment (Bai et al, 2017;Duputel & Rivera, 2017;Hollingsworth et al, 2017;Wang et al, 2018), while others suggest a much smaller contribution from the subduction zone (<30%; Clark et al, 2017;Hamling et al, 2017), if any (Cesca et al, 2017;Holden et al, 2017;Xu et al, 2018). Some suggest that rupture of the subduction interface contributed >50% of the earthquake's moment (Bai et al, 2017;Duputel & Rivera, 2017;Hollingsworth et al, 2017;Wang et al, 2018), while others suggest a much smaller contribution from the subduction zone (<30%; Clark et al, 2017;Hamling et al, 2017), if any (Cesca et al, 2017;Holden et al, 2017;Xu et al, 2018).…”

“…The M W 7.8 Kaikōura earthquake struck just after midnight on 14 November 2016 (NZ local time), rupturing at least a dozen faults in the northern South Island of New Zealand over~90 s Holden et al, 2017; Figure 1). The complex network of faults that ruptured has defied conventional wisdom regarding multifault rupture.…”

Coseismic and postseismic deformation associated with the 2016 Mw 7.8 Kaikoura earthquake, New Zealand: fault movement investigation and seismic hazard analysis

“…The inset in the bottom right shows the distribution of aftershocks (M > 3, from the GeoNet earthquake catalogue) occurring after the mainshock the rupture complexity along a transpressional plate boundary . Seismological and geodetic inversion models indicate that coseismic rupture not only occurred on shallow crustal faults but also at the Hikurangi subduction interface with small-scale thrusting-dominated movements Holden et al 2017). Clustered aftershocks were mainly concentrated in mainshock rupture regions (Fig.…”