Fig. 5

Source parameters calculated from observational data subjected to 400,000 iterations of MCMC analysis. a Sampling distribution projected onto a 2D plane. Relationships between moment ratio and \({f}_{c1}\), b \({f}_{c1}\) and \({f}_{c2}\), and c moment ratio and \({f}_{c2}\). The dark blue areas indicate results assuming an F-distribution, and the yellow areas indicate results assuming a normal distribution. Cyan and orange circle indicate the highest likelihood values from the F- and normal distribution calculations, respectively. d Histogram of the sampling in \({f}_{c1}\), e \({f}_{c2}\), and f moment ratio. g Spectral ratios of the 7th event in Table 1. Gray, black, and red curves, respectively, indicate spectral ratios for each seismic station, an average of all spectral ratios, and the theoretical spectral ratio according to the highest likelihood values. h Estimated stress drops for 20 events in a cluster assuming an F-distribution. Red circles indicate results obtained from large earthquakes, and blue triangles indicate results obtained from the smaller earthquake. The thin bars indicate a 95% confidence interval obtained from the variation of the accepted sampling. i Estimated stress drops assuming a normal distribution. Red circles indicate results obtained from large earthquakes, and blue triangles indicate results obtained from smaller earthquakes.