For the evaluation of the effect on groundwater drainage works, it is essential to grasp actual conditions for mitigation of ground water increase and lowering of basis groundwater level. Authors developed an analysis method which can evaluate characteristic peculiarity of correlation between each integrated precipitation and individual event for ground water increase. In this new method, each fluctuation of ground water level is integrated from the beginning of increasing to the end of decreasing, and treated as a simple statistic. Through case studies, it became clear that regression line has become low-gradient, if groundwater drainage works has been effective.
Strong-motion characteristics during the 2011 Tohoku earthquake are summarized. The major characteristics are：1）predominant at short periods and large accelerations are observed in wide area, 2）significant spatial variation due to the differences of substructure conditions, and 3）very long duration due to wide faulting rupture area.