Vast quantities of liquefaction ejecta repeatedly inundated properties during the 2010-2011 Canterbury earthquake sequence in New Zealand, resulting in differential ground surface subsidence and significant damage to buildings and urban infrastructure. There are strong spatial correlations between the occurrence of ejected sediment with groundwater pressure in deep aquifers. When geotechnical testing sites are grouped according to liquefaction vulnerability indices (to control variance relating to shaking strength, water table depth, and soil profile strength), places where ‘minor’ and ‘moderate-severe’ liquefaction occurred during the Mw6.2 Christchurch earthquake had distinctly higher aquifer pressure than sites where liquefaction was not observed. Together with observations of earthquake-induced pressure changes and inferred transfer of groundwater from deep aquifers to shallower levels, an interpretation is that leakage from aquifers with artesian (above ground) pressure provided an additional driving mechanism for surface manifestation of water and sediment. It is surmised that above-ground aquifer pressures further promoted suffusion and piping along fractures, flow-pathways and liquefied horizons. The Mw6.2 Christchurch earthquake is presented as an example where leakage of artesian groundwater likely contributed to the near-surface liquefaction-induced ground damage. The process can result in underprediction of liquefaction vulnerability so needs to be considered when evaluating potential for earthquake-induced liquefaction and ground damage wherever groundwater is confined.

在2010年至2011年新西兰的坎特伯雷地震序列中，大量的液化喷射物反复淹没，导致地面沉降差异很大，并对建筑物和城市基础设施造成重大破坏。在深层含水层中，喷射沉积物的发生与地下水压力之间存在很强的空间相关性。当根据液化脆弱性指数对岩土工程测试地点进行分组（以控制与震动强度，地下水位深度和土壤剖面强度有关的差异）时，在克赖斯特彻奇6.2级地震中发生“轻微”和“中度-严重”液化的地方的含水层压力明显高于未液化的位置。结合地震引起的压力变化的观测结果以及推断的地下水从深层含水层向浅层的转移，可以解释为自流（高于地面）压力的含水层的渗漏为水和沉积物的表面表现提供了额外的驱动机制。据推测，地上含水层的压力进一步促进了沿裂缝，流动通道和液化层位的注水和管道输送。以克赖斯特彻奇Mw6.2地震为例，自流地下水的渗漏可能导致近地表液化引起的地面破坏。该过程可能导致对液化脆弱性的低估，因此在评估地下水受限的地方引起地震引起的液化和地面破坏的可能性时，需要考虑这一点。