Keywords:deep geological repository of high-level radioactive waste, plate interaction for a long time, geological strain rate, simulation of crustal deformation, visco-elastic heterogeneity
The basic framework for assessment of deep geological repository of high-level radioactive waste is extrapolation of the crustal deformation over the past a few hundred-thousand years. However, the quantity and reliability of information for crustal deformation vary from era to era and from area and area. The crustal deformation predicted by extrapolation includes a certain level of uncertainty. Japanese islands have received crustal shortening due to the subduction of oceanic plates for a long time, which is characterized by complicated topography and crustal deformation as a result. In this study, we try to establish the method to estimate the crustal deformation for a long period, using the crustal strain rate in geological time scale (geological strain rate) and numerical simulation considering visco-elastic or elasto-viscoplastic behavior of the crust and upper mantle. At first, we report geological strain rate estimated from active fault database of Japan which is collected by National Institute of Advanced Industrial Science and Technology. Next, we report the result of numerical simulation to account for the anomalous crustal deformation around the source region of earthquake swarms by introducing visco-elastic material.
This study was carried out under a contract with Agency of Natural Resources and Energy (ANRE), part of Ministry of Economy, Trade and Industry (METI) of Japan as part of its R&D supporting program for developing technology of geological disposal of high-level radioactive waste.