Correlation between Coulomb stress changes imparted by large historical strike-slip earthquakes and current seismicity in Japan

To determine whether current seismicity continues to be affected by large historical earthquakes, we investigated the correlation between current seismicity in Japan and the static stress changes in the Coulomb Failure Function (ΔCFF) due to eight large historical earthquakes (since 1923, magnitude ≥ 6.5) with a strike-slip mechanism. The ΔCFF was calculated for two types of receiver faults: the mainshock and the focal mechanisms of recent moderate earthquakes. We found that recent seismicity for the mainshock receiver faults is concentrated in the positive ΔCFF regions of four earthquakes (the 1927 Tango, 1943 Tottori, 1948 Fukui, and 2000 Tottori-Ken Seibu earthquakes), while no such correlations are recognizable for the other four earthquakes (the 1931 Nishi-Saitama, 1963 Wakasa Bay, 1969 Gifu-Ken Chubu, and 1984 Nagano-Ken Seibu earthquakes). The probability distribution of the ΔCFF calculated for the recent focal mechanisms clearly indicates that recent earthquakes concentrate in positive ΔCFF regions, suggesting that the current seismicity may be affected by a number of large historical earthquakes. The proposed correlation between the ΔCFF and recent seismicity may be affected by multiple factors controlling aftershock activity or decay time.