variability in Avonside, New Zealand

Field mapping, LiDAR, and aerial photography are used to map surface liquefaction-induced lateral spreading fissures and aligned sand blow vents formed during the 22 February 2011 Mw 6.2 Christchurch earthquake. Classification of the study area into 164 polygons enables comparison of liquefaction severity metrics including linear liquefaction feature density, ejecta surface area, and horizontal and vertical ground surface displacements with geomorphic metrics including distance from the downslope free-face, surface elevation, sediment type, and the liquefaction potential index (LPI). Preliminary analyses indicate (i) mean fissure density decreases with increasing distance from the free face at distances of 0-50 m, no relationship is observed at distances>50 m, (ii) mean horizontal ground displacement increases with increasing LPI, and (iii) vertical subsidence is invariant with elevation, implying that other factors (e.g. LPI) may contribute to a complex liquefaction strain field. The basic geology and geomorphology are derived from LiDAR and modern river morphology. Comparison of the liquefaction data with geomorphic mapping indicates geomorphic mapping may be applied to determine the likely distribution of sediments susceptible to liquefaction