The 13 November 2016 Kaikoura, New Zealand Earthquake: rupture process and seismotectonic implications

Abstract

The 13 November 2016 Kaikoura earthquake occurred in the northeastern coastal region of the South Island, New Zealand. The Mw 7.8 mainshock generated a complex pattern of surface ruptures, and was followed within about 12 hours by three moderate shocks of Mw ≥ 6.0. Here we use teleseismic waveforms to invert for the source rupture of the Kaikoura earthquake. The resulting slip‐distribution model exhibits insignificant slip near the hypocenter and three pockets of major slip zones with distinct senses of motion. The mainshock started from a rupture near the hypocenter, grew into thrust on shallow crustal faults ~50 km northeast of the hypocenter, and then developed into two slip zones: a deeper one with oblique thrust and a shallower one with almost purely right‐lateral strike‐slip. Locations of the thrust and strike‐slip motions in the slip‐distribution model agree well with reported coastal uplifts and horizontal offsets. The overall slip pattern is dominated by horizontal motion, especially at shallow depth, due to the partitioning of thrust and strike‐slip motions above the subduction zone megathrust. Aftershock distribution suggests that most aftershocks tend to occur near the edges of the major slip zones of the mainshock. This observation on aftershock locations may provide useful information for seismic hazard assessments after large earthquakes.

Source complexity of the 2016 <i>M</i>_W7.8 Kaikoura (New Zealand) earthquake revealed from teleseismic and InSAR data

“…In fact, at least 12 mapped and unmapped faults with varieties of focal mechanisms were involved in this event (Hamling et al, ; Kaiser et al, ), and most of them were of strike‐slip types. Duputel and Rivera () employed three strike‐slip events and one thrust‐slip event in order to explain the main feature of ground motion, and thought the first event around the epicenter should be of the strike‐slip type and the thrust‐slip event should be at the northern end; but we feel strongly that the purely thrust event should be under all the strike‐slip events, that more strike‐slip events should be on northern area (around asperity B) than on the southern area (around asperity A), and that a possible model should be like the one shown in Figure , which is similar to the model proposed by Lo et al (). Of course, more comprehensive investigation and study will be required in order to clarify this.…”

“…We think there are two possible causes. One is that the InSAR observation itself has been in question because of its special geographical location, and the other is that our simple plane model is incapable of explaining the InSAR observation along the coastal line, which previous studies have revealed to be largely dominated by local tectonics (Hamling et al, ; Cesca et al, ; Lo et al, ) .…”

“…doi: 10.26464/epp2018029 319 tion along the coastal line, which previous studies have revealed to be largely dominated by local tectonics (Hamling et al, 2017;Cesca et al, 2017;Lo et al, 2018) . Hamling et al (2017) employed multiple types of observed data to support a multi-fault rupture model, which has become the most complex ever recorded, and Kaiser et al (2017) believed the earthquake rupture was extremely complex.…”

A Fuzzy-Logic Approach for Optimized and Cost-Effective Early Warning System for Tsunami Detection

“…For instance, an earthquake of 7.5 triggered by an underwater landslide caused a tsunami on 28 September 2018 in Indonesia; 22 buoys connected to the seafloor had not been functioning for 6 years due to a lack of funding [4]. On the other hand, New Zealand has a DART sensor system of 12 sensors, which is further connected to other global partners for the real transmission of data [5]. Although using satellites is one of the commonly used technologies for tsunami detection, it can take up to five minutes to issue an early warning after tsunami detection [6].…”