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▲▲Figure 17. A trench in a residential property in Heathcote. Groundwater table was not evident even up to a depth of 2 m below theground surface.100Percent finer by weight (%)806040Huntsbury(Port Hills)Trench 2m (Eastern Tce)Trench 1m (Eastern Tce)Porritt Park20Seabreeze(Bexley)North KaiapoiWilsons st(St. Martins)00.001 0.01 0.1 1 10Grain size (mm)▲ ▲ Figure 18. Comparison of grain size distribution curves of ejected sands from different sites in Christchurch and soils from unliquefiedsubsurface sites near the Heathcote River.why the extent of liquefaction along the Heathcote River wasminor compared to that near the Avon River.CONCLUDING REMARKSAlthough the M 7.1 Darfield earthquake caused liquefactionin Christchurch and adjacent areas, the M 6.3 Christchurchearthquake induced more widespread liquefaction and causedmore serious damage to infrastructure. Liquefaction and reliquefactionwere observed in areas with high potential to liquefy,such as natural deposits close to major streams, rivers, andwetlands as well as loose or uncompacted fill. Experiences fromcase histories all over the world have highlighted the effect ofliquefaction on buildings and buried structures, but the scale ofdamage experienced in Christchurch following the 2010 and2011 events was unprecedented and may be the greatest everobserved in an urban area. Moreover, the short time intervalbetween the two large earthquakes presented a very rare oppor-Seismological Research Letters Volume 82, Number 6 November/December 2011 917