Fig. 2From: Spatio-temporal characteristics of frictional properties on the subducting Pacific Plate off the east of Tohoku district, Japan estimated from stress drops of small earthquakesa Example of an analyzed waveform of an earthquake with M4.8. The horizontal color bars show three time windows used in obtaining spectra, which were (S0) – 0.50 to 9.73 s, (S1) 0.78 to 11.01 s, and (S2) 2.06 to 12.29 s after the arrival time of S wave. The gray line indicates a time window from 12.00 to 1.77 s before the P arrival, which was used to calculate the noise spectrum in (b). Individual time windows include 1,024 data points. b Waveform spectra for the four time windows marked in (a). c Example of a waveform of an M3.5 earthquake that was used for an EGF. Note that the vertical scale is different from that in (a). d Waveform spectra for the four time windows marked in (c). e Deconvolved spectra with the best-fit omega-squared model. The color lines show deconvolved source spectra, that is, (b) divided by (d), for three individual time windows with a resampling of frequency bands. The black broken line indicates the best-fit omega-squared model with corner frequencies of 1.0 and 2.5 Hz for the analyzed and EGF earthquakes, respectivelyBack to article page