The results of the stress tensor analysis for the P- and T-axes of the focal mechanisms of large earthquakes that occurred in the source region since 1943. (a) The histogram of the R-value, (b) the distribution of the estimated principal stress axes, and (c) the distribution of the observed P- and T-axes. In (b), red solid dots show the azimuth and plunge of the maximum compression axis σ1, blue circles show those of the minimum stress axis σ3, green triangles show those of the intermediate stress axis σ2. In (c), red solid dots show the P-axes and blue circles the T-axes. Black symbols denote the axes for the best stress model.