Fig. 3

Fitting of different functions: a VEI 7. b VEI 6. c VEI 5. d VEI 4. e M ≥ 7.0. f M ≥ 6.5. g M ≥ 6.0. h M ≥ 5.5. i M ≥ 5.0. j M ≥ 4.5. k M ≥ 4.0. Light blue dots show the observed recording rate calculated with equation 1 with the window size of 8. Blue lines are fitted exponential and double exponential functions (Table 3). Orange dashed lines are the under-recording probability function (Coles and Sparks 2006; Deligne et al., 2010). Red dashed lines are the modified Omori’s law. Green dashed lines are the Weibull distribution. The under-recording probability function, the modified Omori’s law and the Weibull distribution are fitted by minimizing the square error between the functions and the time series of observed recording rate (light blue dots) in logarithmic scale