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Figure 3 | Earth, Planets and Space

Figure 3

From: Stress state in the upper crust around the source region of the 1891 Nobi earthquake through shear wave polarization anisotropy

Figure 3

An 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.

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