Repeated major episodes of tectonic deformation, lateral spread and liquefaction in christchurch during the canterbury earthquake sequence of 2010-2011

Abstract

The Canterbury Earthquake Sequence of 2010-2011 caused regional tectonic subsidence and uplift. The observed slip distributions and fault locations were used to develop models of the 3-D tectonic deformation throughout the region, for each earthquake. The earthquake sequence also triggered widespread liquefaction causing subsidence and localized lateral spreading. These were both mapped by land damage assessment teams for the Earthquake Commission. Land was categorized on the basis of observed land and foundation damage to differentiate the amounts of geotechnical investigation and foundation design effort required to address the potential for liquefaction. Aerial LiDAR (light detection and ranging) surveys were used to quantify the surface deformations and, by subtracting the estimated vertical tectonic movements, the subsidence attributable to liquefaction, which correlated well with areas observed to be affected by liquefaction. Horizontal ground surface movements were also estimated using sub-pixel correlation of pairs LiDAR data sets. Horizontal movements within the soil layers were estimated by subtracting the tectonic movements, which correlated well with lateral spreading observations.