Comment on egusphere-2022-823

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.