Preprints
https://doi.org/10.5194/egusphere-2022-823
https://doi.org/10.5194/egusphere-2022-823
 
04 Oct 2022
04 Oct 2022

OBS noise reduction from horizontal and vertical components using harmonic-percussive separation algorithms

Zahra Zali1,2, Theresa Rein1, Frank Krüger1, Matthias Ohrnberger1, and Frank Scherbaum1 Zahra Zali et al.
  • 1University of Potsdam, Institute of Geosciences, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
  • 2GFZ German Research Centre for Geosciences, Potsdam, Germany

Abstract. Records from ocean bottom seismometers (OBS) are highly contaminated by noise, which is much higher compared to data from most land stations, especially on the horizontal components. The high energy of the oceanic noise at frequencies below 1 Hz complicates the analysis of the teleseismic earthquake signals recorded by OBSs.

Previous studies suggested different approaches to remove low frequency noises from the data, but mainly focused on the vertical component. The records of horizontal components, crucial for the application of many methods in passive seismological analysis of body and surface waves could not be much improved in the teleseismic frequency band. Here we introduce a noise reduction method, which is derived from the harmonic-percussive separation algorithms used in Zali et al., (2021) in order to separate long-lasting narrowband signals from broadband transients in the OBS signal. This leads to significant noise reduction of OBS records on both the vertical and horizontal components and increases the earthquake signal to noise ratio without distortion of the broadband earthquake waveforms. This is proved through synthetic tests by measuring SNR and cross-correlation coefficient where both showed significant improvement for different realistic noise realizations. The application of denoised signals in surface wave analysis and receiver function is discussed through synthetic and real tests.

Zahra Zali et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-823', Anonymous Referee #1, 14 Nov 2022
    • AC1: 'Reply on RC1', Zahra Zali, 17 Nov 2022
  • RC2: 'Comment on egusphere-2022-823', Anonymous Referee #2, 22 Nov 2022
    • AC2: 'Reply on RC2', Zahra Zali, 28 Nov 2022

Zahra Zali et al.

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Short summary
The Investigation of the global Earth's structure benefits from the analysis of ocean bottom seismometer (OBS) data that allow an improved seismic illumination of dark spots of crustal and mantel structures in the oceanic regions of the Earth. However, recordings from the ocean bottom are often highly contaminated by noise. We developed an OBS noise reduction algorithm, which removes much of the oceanic noise while preserving the earthquake signal and doesn’t introduce waveform distortion.