Coastal Restoration Trust of New Zealand

Coastal Dune Ecosystem Reference Database

An application of liquefaction hazard evaluation in urban planning Conference Paper

Anderson, C.; McMorran, T.
Journal / Source
Pacific Conference on Earthquake Engineering
In planning for a new town at Pegasus Bay, 30 km north of Christchurch, the risk of seismic liquefaction was considered and evaluated. URS New Zealand Limited evaluated the likelihood of liquefaction within the soils beneath the areas proposed for residential development. The liquefaction assessment was developed using the results of a geological site investigation and a seismic hazard evaluation based on a Probabilistic Seismic Hazard Assessment. This paper describes how the results of recent earthquake hazard research were incorporated into the analyses and an assessment of design criteria for liquefaction mitigation in the proposed residential subdivision. The study demonstrates that liquefaction could occur at the site during the 50 year design life of the houses and commercial buildings, and that current New Zealand codes and standards require that countermeasures be provided during the subdivision design phase. It also demonstrates that the Alpine Fault is not the most critical earthquake source in terms of the liquefaction effects predicted for the site. An assessment of the mitigation options demonstrates that it is possible to construct the subdivision with a lower risk of liquefaction than comparable sites in eastern Canterbury.