oa Heterogeneity in The Lower Crust and the Process by which Intraplate Earthquakes Are Generated

The generating process of the 1984 Western Nagano Prefecture, Japan Earthquake is estimated as follows. Aseismic quasi-static slips occurred on the S-wave reflector. The slips produced a dilatational stress field near the mainshock fault and the dilatational stress decreases the normal stress and increases the shear stress on the fault. Then, slips began to be generated on the fault plane just above the S-wave reflector. It is thought that aseismic slips generate both the strength reduction and stress concentration on the mainshock fault.