engleski

Calibration of the Wiechert seismographs relative to a reference seismometer

The horizontal 1000 kg Wiechert seismograph has been calibrated on the basis of a comparison of its records to the ones that were obtained by the reference seismometer. The resulting magnification curve shows notable deviations from the theoretical one. Its most prominent feature is a sudden magnification increase observed for frequencies above 5 Hz, which is attributed to frame oscillations excited by the seismic waves. Also, the observed average response curve exibits larger magnification for frequencies below the resonance frequency. The results indicate a non-linear behaviour of the Wiechert instrument related to the degree of impuliveness of the excitation.

Seismograph calibration; historical instrumentation; Wiechert seismograph

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