Sustained Changes in Well Water Levels Following a Large Earthquake: Possible Evidence of Permeability Decreases in a Shallow Groundwater System

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 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. Sustained increases in well water levels in midstream areas, as well as sustained decreases in downstream areas, resulted from decreases in permeability. These decreases in permeability were possibly caused by consolidation of liquefied sediments following the earthquake.