Stability of the regional stress field in central Japan during the late Quaternary inferred from the stress inversion of the active fault data

摘要

We analyzed 169 geological fault-slip data from 37 active faults in central Japan to investigate the late Quaternary stress field stability. Modern stress states have been documented with unprecedented accuracy; however, their stability over time scales beyond instrumental observations is inadequately understood. Because the stress field has changed in the geological past, we compared present stress conditions in central Japan, determined from geophysical observations, with conditions determined by inverting the fault-slip data from active faults that exhibited cumulative displacement for the past ～10^5 years. The maximum stress axis obtained from fault-slip data trends ESE–WNW. This state of stress accounts for 97% of the data and supports the fact that oblique faults with reverse and strike-slip senses are interlaced in the region. The optimal stress is similar to the present stress state, indicating that the stress field in central Japan has been uniform and stable over the past ～10^5 years.