Abstract
We constructed a system for detecting preseismic changes in groundwater levels that uses a combination of long-term observation and analysis of groundwater, a poro-elastic theory, and the pre-slip model. This system is now in operation and is contributing to the national project for prediction of the Tokai earthquake. To apply this system to Tonankai and Nankai earthquakes, we constructed an integrated groundwater observation network in and around Shikoku and the Kii Peninsula (Japan). This network is now being used to observe and study groundwater and crustal deformation. Since 2002, we have also been carrying out international cooperative hydrological research for earthquake prediction in Taiwan to help minimize the damage caused by earthquakes in Southeast Asia. We underestimated the magnitude of the 2011 Tohoku earthquake, which was one of the factors that brought about the severe damage in and around the Tohoku area. Therefore, we should examine scientifically the reasons for the underestimation, and advance earthquake prediction research.
