Geotechnical aspects of the 2016 Kaikōura earthquake on the South Island of New Zealand
Date
2017-06-30Authors
Stringer, Mark E.
Bastin, Sarah
McGann, Christopher R.
Cappellaro, Claudio
Kortbawi, Maya El
McMahon, Rebecca
Wotherspoon, Liam. M.
Green, Russell A.
Aricheta , Jason
Davis, Ross
McGlynn, Leigh
Hargraves, Sally
Ballegooy, Sjoerd Van
Cubrinovski, Misko
Bradley, Brendon A.
Bellagamba, Xavier
Foster, Kevin
Lai, Carlo
Ashfield, Dan
Baki, Abdul
Zekkos, Adda
Lee, Robin
Ntritsos, Nikolaos
Metadata
Show full item recordAbstract
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 post-event 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.