The above seismograms were recorded at 40 samples per second from GS-13 short period vertical (sz), N/S (sn), and E/W (se) seismometers in the walk in vault near Leonard, Oklahoma. The E/W motion was so large that the S phase appears to have clipped. The straight line before P does not indicate zero earth noise. It appears as a straight line because the large motion from the earthquake caused the entire seismograms to be scaled down.
The above East-West earth motion seismogram was made from 200 samples/second produced by a Guralp CMG-1TD seismometer at 830 m depth in the Crosstimbers borehole. The samples were earth velocty, but they were transformed to earth acceleration to emphasize higher frequencies (the transformation is fft. divide by omega, inverse fft). Unlike the E/W velocity seismogram from a GS-13 seismometer (third down from top of this page), the Guralp E/W velocity did not clip. The acceleration spectrogram (color) shows both P and S energy almost up to 90 hertz. There is also a persistent "layer" above 80 Hertz due to waves scattered from crustal irregularities surrounding Leonard. The higher thinner layer may be an artefact of processing. The left hand scale on the spectrogram (color) is in Hertz. The 2200 to 2300 scales on the bottom of both spectrogram and seismogram are arbitrary seconds from the beginning of an archive file.
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