Observation of earthquake-induced changes in well water levels provides
an opportunity to study the effects of seismic activity on the
groundwater system. In this study, we used data from a plain-scale well
network in the alluvial Canterbury Plain of New Zealand's South Island
to document sustained and complex changes in well water levels,
following the 2010 Darfield earthquake. We interpret that the sustained
increases in well water levels in the midstream area, as well as
sustained decreases in the downstream area, resulted from decreases in
plain-scale permeability. These decreases in permeability were caused by
the consolidation of the liquefied sediments following the earthquake.
These results may provide a better understanding of the effects of large
earthquakes on groundwater systems and resources, especially in
liquefaction areas.