부산대학교 도서관

We investigated the influence of the 2016 Kumamoto earthquake on groundwater quality at 12 sampling points in the area near its seismic centre. We statistically evaluated the difference in the measured values of each water-quality index before and after the earthquake based on bi-weekly or monthly monitoring data for three years across the earthquake area. We also visualised water-quality characteristics using a hexa-diagram (Stiff diagram) and statistically evaluated differences before and after the earthquake using non-hierarchical cluster analysis. The results showed that there was not a large variation in water-quality characteristics as represented by the hexa-diagram shape. However, statistical analysis showed a significant difference at nine sampling points, suggesting earthquake influence on groundwater quality. In addition, it is possible that the influence of the earthquake appeared later in a groundwater-discharge area. On the other hand, no topographic relationship between the location of the sampling points and seismic centre or the fault was shown; thus, it is likely that groundwater quality varied at arbitrary points within the study area where slip on the fault was observed.