Application of B and Li isotope systematics for detecting chemical disturbance in groundwater associated with large shallow inland earthquakes in Kumamoto, Japan

Abstract

Copyright © 2021 by The Geochemical Society of Japan. caused by such contamination is sometimes enhanced by anthropogenic activities such as excessive pumping of groundwater (Smith et al., 2018; Jasechko et al., 2020). In addition, natural disasters such as large earthquakes can also trigger these problems. By analyzing the major ion concentrations, trace element concentrations, and stable isotope ratios of water molecules, several studies have described changes in the natural composition of groundwater in response to seismotectonic activities (Tsunogai and Wakita, 1995; Manga and Rowland, 2009; Barberio et al., 2017; Skelton et al., 2019). However, these changes have been rarely described using stable isotope ratios of dissolved trace elements (Poitrasson et al., 1999; Schuessler et al., 2016). The detailed mechanisms and processes of hydrochemical changes in the regional groundwater system of Kumamoto region of southern Japan in response to the Mw 7.0 Kumamoto crustal earthquake of 2016 were previously investigated using a high-resolution well monitoring network. The results suggested that a co-seismic groundwater drawdown surrounding the epicenter was Application of B and Li isotope systematics for detecting chemical disturbance in groundwater associated with large shallow inland earthquakes in Kumamoto, Japan