Fig. 6

Source time functions of the VLP event. a The black line is a band-limited source time function directly obtained by the waveform inversion (FSTF), and the dotted line is the deconvolved form of the source time function (DSTF), which is band-unlimited and represents the source process. Gray line is the DSTF, band-pass filtered at 0.1–0.5 Hz, which gives a measure of the goodness of the DSTF such that a better DSTF yields a better fit between the black and gray lines. b Fourier amplitude spectra for the three curves of Fig. 6a