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The 2010–2011 Canterbury earthquake sequence began with the 4 September 2010, Mw7.1 Darfield earthquake and includes up to ten events that induced liquefaction. Most notably, widespread liquefaction was induced by the Darfield and Mw6.2 Christchurch earthquakes. The combination of well-documented liquefaction response during multiple events, densely recorded ground motions for the events, and detailed subsurface characterization provides an unprecedented opportunity to add well-documented case histories to the liquefaction database. This paper presents and applies 50 high-quality cone penetration test (CPT) liquefaction case histories to evaluate three commonly used, deterministic, CPT-based simplified liquefaction evaluation procedures. While all the procedures predicted the majority of the cases correctly, the procedure proposed by Idriss and Boulanger (2008) results in the lowest error index for the case histories analyzed, thus indicating better predictions of the observed liquefaction response.

a b s t r a c tMagnitude-bound relations are often used to estimate paleoearthquake magnitudes from paleoliquefaction data. This study proposes New Zealand-based magnitude-bound curves that are developed using (a) liquefaction field observations and (b) a newly proposed back-calculation approach that combines the simplified liquefaction evaluation procedure with a regionally appropriate ground motion prediction equation. For (b) both deterministic and probabilistic frameworks are proposed. The magnitude bound curves back-calculated using either the deterministic or probabilistic frameworks are advantageous in that they can be used to predict the spatial distribution of liquefaction in regions where historical liquefaction field observations are limited or poorly documented, and because soil-and site-specific conditions can be incorporated into magnitude-bound analyses. Moreover, curves developed using the probabilistic framework allow for the range of possible causative earthquake magnitudes to be better understood and quantified. To demonstrate the use of the proposed relations, paleoliquefaction features discovered in eastern Christchurch (NZ) are analyzed. The 1869~M w 4.8 Christchurch earthquake and/or 1717~M w 8.1 Alpine Fault earthquake are found to be the most likely candidates amongst known historical and paleoearthquakes for triggering liquefaction over the permissible time range (ca. 1660 to 1905 A.D.). This study demonstrates the potential of the proposed magnitude-bound curves to provide insight in to past, present, and future hazards, proving their utility even in cases of limited evidence. The approach of developing and applying magnitude bound curves proposed herein is not limited to parts of New Zealand, but rather, can be applied worldwide.

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Semi-empirical models based on in situ geotechnical tests have been the standard-of-practice for predicting soil liquefaction since 1971. More recently, prediction models based on free, readily available data were proposed. These “geospatial” models rely on satellite remote-sensing to infer subsurface traits without in situ tests. Using 15,223 liquefaction case-histories from 24 earthquakes, this study assesses the performance of 23 models based on geotechnical or geospatial data using standardized metrics. Uncertainty due to finite sampling of case-histories is accounted for and used to establish statistical significance. Geotechnical predictions are significantly more efficient on a global scale, yet successive models proposed over the last 20 years show little or no demonstrable improvement. In addition, geospatial models perform equally well for large subsets of the data—a provocative finding given the relative time- and cost-requirements underlying these predictions. Through this performance comparison, lessons for improving each class of model are elucidated in detail.