Two regions of seafloor deformation generated the tsunami for the 13 November 2016, Kaikoura, New Zealand earthquake

Abstract

The 13 November 2016 Kaikoura, New Zealand, Mw 7.8 earthquake ruptured multiple crustal faults in the transpressional Marlborough and North Canterbury tectonic domains of northeastern South Island. The Hikurangi trench and underthrust Pacific slab terminate in the region south of Kaikoura, as the subdution zone transitions to the Alpine fault strike‐slip regime. It is difficult to establish whether any coseismic slip occurred on the megathrust from on‐land observations. The rupture generated a tsunami well recorded at tide gauges along the eastern coasts and in Chatham Islands, including a ~4 m crest‐to‐trough signal at Kaikoura where coastal uplift was about 1 m, and at multiple gauges in Wellington Harbor. Iterative modeling of teleseismic body waves and the regional water‐level recordings establishes that two regions of seafloor motion produced the tsunami, including an Mw ~7.6 rupture on the megathrust below Kaikoura and comparable size transpressional crustal faulting extending offshore near Cook Strait.

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).…”

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

“…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, ).…”

Subduction Thermal Regime, Slab Dehydration, and Seismicity Distribution Beneath Hikurangi Based on 3‐D Simulations

“…Large earthquakes have struck the Hikurangi margin offshore the eastern North Island of New Zealand, such as the 1931 M7.8 earthquake at Hawke's Bay, where six subsidence events have occurred over the past 7,000 years based on micropaleontological evidence (Cochran et al, ; Hayward et al, ). Along the Hikurangi trough, the Cretaceous Hikurangi Plateau that subducts beneath the Australian plate (Figure a) is thought to combine rupture of the interface and adjacent crustal faulting (e.g., Bai et al, ; Cochran et al, ). The national seismic hazard model for New Zealand uses geological models and seismological data to suggest that large to great earthquakes could occur on the subduction interface on the order of every 600–2,000 years (Stirling et al, , ).…”