The 1995 Kobe, Japan, earthquake: A long-delayed aftershock of the offshore 1944 Tonankai and 1946 Nankaido earthquakes

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Abstract
The 1995 Kobe earthquake produced predominantly right-lateral slip along the northeast-southwest-trending Nojima fault approximately 200 km landward of the Nankai trough, southwest Japan. The last major earthquakes along the Nankai trough, the M8.0 1944 Tonanakai and M8.2 1946 Nankaido earthquakes, involved about 4 m of interplate slip, each releasing about 100 years of accumulated stress from the northwest-southeast convergence of the Philippine Sea (PHS) plate. By calculating the change in Coulomb failure stress on the Nojima fault due to 1944/46 to 1995 postseismic relaxation of a thin low-viscosity channel beneath southwest Japan, we show that stress diffusion from the 1940s interplate earthquakes increased the likelihood of future failure on the Nojima fault by slowly but progressively unloading the normal stress on the fault over a 50-yr period.