Tsunami runup and tide-gauge observations from the 14 November 2016 M7.8 Kaikōura earthquake, New Zealand

Abstract

The 2016 Mw 7.8 Kaikōura earthquake was one of the largest earthquakes in New Zealand’s historical record, and it generated the most significant local source tsunami to affect New Zealand since 1947. There are many unusual features of this earthquake from a tsunami perspective: the epicentre was well inland of the coast, multiple faults were involved in the rupture, and the greatest tsunami damage to residential property was far from the source. In this paper, we summarise the tectonic setting and the historical and geological evidence for past tsunamis on this coast, then present tsunami tide gauge and runup field observations of the tsunami that followed the Kaikōura earthquake. For the size of the tsunami, as inferred from the measured heights, the impact of this event was relatively modest, and we discuss the reasons for this which include: the state of the tide at the time of the earthquake, the degree of co-seismic uplift, and the nature of the coastal environment in the tsunami source region.