Effect of very low frequency on H/V

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Here, it is displayed how the H/V can be influenced but a low frequency content in the signal. For that purpose, we merge two different signals:

Merging signals.png

  • one at a site having a resonance frequency around 1 Hz
  • one displaying a low frequency component within [0.1-0.2 Hz]

Following the Sesame recommandations, to define a 1 Hz frequency for H/V processing, a 10 seconds window should be enough.

Then the merged signal is computed in a H/V and Spectrum way with 20, 60 and 100 second.

At first, the processing has been done without high pass filter. In this case, the 1 Hz peak appears only with the 100 seconds windowing.

No high pass filter.png

Later on, another processing has been done with a 0.5 Hz high pass filter. In this case, the 1 Hz peak appears directly with a 20 seconds windowing.

High pass filter.png