Changes in Widespread Aquifer Properties caused by a Magnitude 6 Class
Earthquake evaluated using InSAR Analyses
Abstract
The correlation between surface displacements and groundwater level
changes has been widely used to understand aquifer properties and their
site characteristics; however, the underlying mechanism of various
correlation types and influence of earthquakes has not been fully
investigated. In this study, we examine correlations in Osaka and Kyoto,
Japan, over 4 years including the period of the June 18, 2018, Mw 5.6
northern Osaka earthquake surface displacement from InSAR analyses and
groundwater level monitoring data. Both positive and negative
correlations were identified at groundwater level observation stations.
Based on the different types of correlations, we propose a new
conceptual aquifer model that drives the opposite interaction between
the surface displacement and the groundwater level change. We further
reveal that sites with negative correlations increased after the
earthquake, suggesting that the earthquake increased the groundwater
recharge rate as a result of increases in aquifer transportation
properties such as permeability and porosity.