Fig. 4

Seismic parameters estimated from observational data subjected to 200,000 iterations of MCMC analysis. a Sampling distribution projected onto a 2D plane. Relationship between moment ratio and \({f}_{c1}\), b \({f}_{c1}\) and \({f}_{c2}\), and c moment ratio and \({f}_{c2}\). Dark blue areas indicate results assuming an F-distribution, and yellow areas indicate results assuming a normal distribution. Cyan and orange dots indicate the best point of the calculation, 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 ratio for each seismic station, average of all spectral ratios, and the theoretical spectral ratio based on the maximum likelihood value. h Estimated stress drops for 20 events from a cluster assuming an F-distribution. Red circles indicate the results obtained from large earthquakes, and blue triangles indicate results obtained from small earthquakes. The thin bars indicate 95% confidence interval obtained from the variation of the accepted sampling. i Estimated stress drops for 20 events from a cluster assuming a normal distribution. Red circles indicate results obtained from large earthquakes, and blue triangles indicate results obtained from small earthquakes