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.
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Liquefaction Triggering, Consequences, and Mitigation
The moment magnitude (Mw) 7.8 Kaikōura, New Zealand, earthquake triggered relatively
few cases of liquefaction and related phenomena (e.g., lateral spreading) despite the large
magnitude of the event. Cases of severe liquefaction manifestation were confined to localized areas proximal to waterways near the township of Blenheim, in the north-eastern corner of the South Island of New Zealand. The occurrence and non-occurrence of liquefaction within the wider Blenheim area is shown to closely correspond with fluvial geomorphology and associated depositional setting of the sediments. Herein, the distribution of liquefaction within the region is detailed in the context of the geomorphological influences and sedimentologic controls. This work highlights the influence of geomorphic variability on the occurrence of liquefaction, with the aim of improving the assessment of liquefaction hazards for future events worldwide.
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- NSF-PAR ID:
- 10094911
- Date Published:
- Journal Name:
- Proc. Geotechnical Earthquake Engineering and Soil Dynamics V (GEESD V), Liquefaction Triggering, Consequences, and Mitigation (S.J. Brandenberg and M.T. Manzari, eds.), ASCE Geotechnical Special Publication (GSP) 290
- Volume:
- 290
- Page Range / eLocation ID:
- 264 to 272
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1061/9780784481455.026
