The magnitude Mw7.8 ‘Kaikōura’ earthquake occurred shortly after midnight on 14 November 2016. This paper
presents an overview of the geotechnical impacts on the South Island of New Zealand recorded during the postevent
reconnaissance.
Despite the large moment magnitude of this earthquake, relatively little liquefaction was observed across the
South Island, with the only severe manifestation occurring in the young, loose alluvial deposits in the
floodplains of the Wairau and Opaoa Rivers near Blenheim. The spatial extent and volume of liquefaction ejecta
across South Island is significantly less than that observed in Christchurch during the 2010-2011 Canterbury
Earthquake Sequence, and the impact of its occurrence to the built environment was largely negligible on
account of the severe manifestations occurring away from the areas of major development.
Large localised lateral displacements occurred in Kaikōura around Lyell Creek. The soft fine-grained material in
the upper portions of the soil profile and the free face at the creek channel were responsible for the accumulation
of displacement during the ground shaking. These movements had severely impacted the houses which were
built close (within the zone of large displacement) to Lyell Creek. The wastewater treatment facility located just
north of Kaikōura also suffered tears in the liners of the oxidation ponds and distortions in the aeration system
due to ground movements.
Ground failures on the Amuri and Emu Plains (within the Waiau Valley) were small considering the large peak
accelerations (in excess of 1g) experienced in the area. Minor to moderate lateral spreading and ejecta was
observed at some bridge crossings in the area. However, most of the structural damage sustained by the bridges
was a result of the inertial loading, and the damage resulting from geotechnical issues were secondary