自己組織化マップを用いた東北地方太平洋沖地震に伴う東京における地下水位の変動特性評価

抄録

Groundwater observation wells have been bored in 40 sites in Tokyo Metropolis. Large fluctuations of unconfined and confined groundwater levels were observed after the 2011 off the Pacific coast of Tohoku earthquake at 98 observation wells in Tokyo. In this study, the characteristics of groundwater level fluctuation caused by the earthquake were evaluated using Self-Organizing Maps (SOM). The SOM has been suggested as a nonlinear classification method. As for the results, the SOM analysis succeeded in visualizing the characteristics of groundwater level fluctuation. Eight fluctuation patterns were identified for the characteristics of unconfined and confined groundwater level fluctuation. In addition, by comparing the results of the SOM with the visual inspection of fluctuation time series, it is shown that the SOM is successfully and objectively almost the same as the fluctuation patterns after the earthquake.