Figure 3From: Stress state in the upper crust around the source region of the 1891 Nobi earthquake through shear wave polarization anisotropyAn example of shear wave splitting analysis. (a) An example of band-pass (1 to 20 Hz) filtered three component waveform data at station N.IZUH. (b) Original waveforms of band-pass filtered two horizontal components around the S wave. Dashed lines show the time window for particle motion and splitting analysis. (c) Particle motion of two horizontal components. (d) Rotated waveforms of a faster shear wave and a slower one. (e) Contour map of the confidence level by the method of Silver and Chan (1991). The plus sign shows the optimum splitting parameters of δt and ϕ. A contour interval corresponds to the confidence level of two times the standard error. Note that a variation of the confidence level along δt axis finer than a sampling interval (=0.01 s) is artificial.Back to article page