Yamamoto Shun, Koike Katsuaki, Yamashiki Yosuke Alexandre, Shimada Jun
Graduate School of Advanced Integrated Studies in Human Survivability, Kyoto University, Kyoto, Japan.
Graduate School of Engineering, Kyoto University, Kyoto, Japan.
Sci Rep. 2023 Dec 21;13(1):22916. doi: 10.1038/s41598-023-50133-0.
This study presented the first attempt to detect precursory changes in groundwater level before the 2016 Kumamoto Earthquake. This detection was achieved by accurately determining the relationship between long-term groundwater level fluctuation and crustal deformation over 16 years through analysis of groundwater level time-series data acquired at 17 sites within the study area. Here, we show that the observed groundwater levels were lower than the modelled levels in aquifers composed of porous strata (Togawa lava and part of the pre-Aso volcanic rocks), and that there were larger differences until 2014, which diminished until the occurrence of the Kumamoto Earthquake. The initial reduction in the modelled groundwater level and the latter recovery were most likely caused by crustal strain relaxation associated with the large 2011 earthquake off the Pacific coast of Tohoku (M 9.0) and the strain accumulation prior to the 2016 Kumamoto Earthquake.
本研究首次尝试探测2016年熊本地震前地下水位的前兆变化。通过分析研究区域内17个站点采集的地下水位时间序列数据，准确确定了16年间长期地下水位波动与地壳变形之间的关系，从而实现了这种探测。在此，我们表明，在由多孔地层（户川熔岩和阿苏火山前岩石的一部分）组成的含水层中，观测到的地下水位低于模拟水位，并且在2014年之前差异更大，在熊本地震发生前这种差异逐渐减小。模拟地下水位的最初下降和随后的回升很可能是由与2011年东北太平洋沿岸大地震（M 9.0）相关的地壳应变松弛以及2016年熊本地震前的应变积累引起的。
