Fig. 3

Results of stress tensor inversion in regions N, C, and S for a the period before (11 March 2011 to 3 June 2002) and b the period after (11 March 2011 to 31 December 2017) the Tohoku earthquake. The locations of these regions are shown in Fig. 1b. The left panel shows stress tensor inversion results. Red, green, and blue dots correspond to the 95% confidence regions of the σ₁, σ₂, and σ₃ axes, respectively, and red, green, and blue circles correspond to the best-fit solutions of the same axes, respectively. The right panel shows the frequency distributions of stress ratio R, where R = (σ₁ − σ₂)/(σ₁ − σ₃), for the respective regions