Fig. 7
Plot of ln(ε2 + 1) against frequency for the determination of the parameter γ. The regression line (grey line) is derived from a quadratic least-squares fit of Eq. (3) in “Teleseismic fluctuation wavefield method” section. a Fit of ln(ε2 + 1) versus frequency for Event 2010.02.15.21.51 with γ = 0.67 Hz−2. b Fit of stacked ln(ε2 + 1) for all the events with ⟨γ⟩ = 0.36 Hz−2. The grey area represents the interval of data stack with ± 1 − σ error (σ denotes the standard error)