Numerical Modeling on Ocean-Bottom Seismograph P-Wave Receiver Function to Analyze Influences of Seawater and Sedimentary Layers

It is challenging to apply the receiver function method to teleseisms recorded by ocean-bottom seismographs (OBSs) due to a specific working environment that differs from land stations. Teleseismic incident waveforms reaching the area beneath stations are affected by multiple reflections generated b...

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Main Authors: Wenfei Gong, Hao Hu, Aiguo Ruan, Xiongwei Niu, Wei Wang, Yong Tang
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Journal of Marine Science and Engineering
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Online Access:https://www.mdpi.com/2077-1312/12/11/2053
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author Wenfei Gong
Hao Hu
Aiguo Ruan
Xiongwei Niu
Wei Wang
Yong Tang
author_facet Wenfei Gong
Hao Hu
Aiguo Ruan
Xiongwei Niu
Wei Wang
Yong Tang
author_sort Wenfei Gong
collection DOAJ
description It is challenging to apply the receiver function method to teleseisms recorded by ocean-bottom seismographs (OBSs) due to a specific working environment that differs from land stations. Teleseismic incident waveforms reaching the area beneath stations are affected by multiple reflections generated by seawater and sediments and noise resulting from currents. Furthermore, inadequate coupling between OBSs and the seabed basement and the poor fidelity of OBSs reduce the signal-to-noise ratio (SNR) of seismograms, leading to the poor quality of extracted receiver functions or even the wrong deconvolution results. For instance, the poor results cause strong ambiguities regarding the Moho depth. This study uses numerical modeling to analyze the influences of multiple reflections generated by seawater and sediments on H-kappa stacking and the neighborhood algorithm. Numerical modeling shows that seawater multiple reflections are mixed with the coda waves of the direct P-wave and slightly impact the extracted receiver functions and can thus be ignored in subsequent inversion processing. However, synthetic seismograms have strong responses to the sediments. Compared to the waveforms of horizontal and vertical components, the sedimentary responses are too strong to identify the converted waves clearly. The extracted receiver functions correspond to the above influences, resulting in divergent results of H-kappa stacking (i.e., the Moho depth and crustal average V<sub>P</sub>/V<sub>S</sub> ratio are unstable and have great uncertainties). Fortunately, waveform inversion approaches (e.g., the neighborhood algorithm) are available and valid for obtaining the S-wave velocity structure of the crust–upper mantle beneath the station, with sediments varying in thickness and velocity.
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spelling doaj-art-90e2e046c1c34359bf62abfe6d4cb5e72025-08-20T01:54:02ZengMDPI AGJournal of Marine Science and Engineering2077-13122024-11-011211205310.3390/jmse12112053Numerical Modeling on Ocean-Bottom Seismograph P-Wave Receiver Function to Analyze Influences of Seawater and Sedimentary LayersWenfei Gong0Hao Hu1Aiguo Ruan2Xiongwei Niu3Wei Wang4Yong Tang5Ocean College, Zhejiang University, Zhoushan 316021, ChinaCollege of Civil Engineering and Architecture, Zhejiang University of Water Resources and Electric Power, Hangzhou 310018, ChinaKey Laboratory of Submarine Geoscience, Second Institute of Oceanography, Hangzhou 310012, ChinaKey Laboratory of Submarine Geoscience, Second Institute of Oceanography, Hangzhou 310012, ChinaKey Laboratory of Submarine Geoscience, Second Institute of Oceanography, Hangzhou 310012, ChinaOcean College, Zhejiang University, Zhoushan 316021, ChinaIt is challenging to apply the receiver function method to teleseisms recorded by ocean-bottom seismographs (OBSs) due to a specific working environment that differs from land stations. Teleseismic incident waveforms reaching the area beneath stations are affected by multiple reflections generated by seawater and sediments and noise resulting from currents. Furthermore, inadequate coupling between OBSs and the seabed basement and the poor fidelity of OBSs reduce the signal-to-noise ratio (SNR) of seismograms, leading to the poor quality of extracted receiver functions or even the wrong deconvolution results. For instance, the poor results cause strong ambiguities regarding the Moho depth. This study uses numerical modeling to analyze the influences of multiple reflections generated by seawater and sediments on H-kappa stacking and the neighborhood algorithm. Numerical modeling shows that seawater multiple reflections are mixed with the coda waves of the direct P-wave and slightly impact the extracted receiver functions and can thus be ignored in subsequent inversion processing. However, synthetic seismograms have strong responses to the sediments. Compared to the waveforms of horizontal and vertical components, the sedimentary responses are too strong to identify the converted waves clearly. The extracted receiver functions correspond to the above influences, resulting in divergent results of H-kappa stacking (i.e., the Moho depth and crustal average V<sub>P</sub>/V<sub>S</sub> ratio are unstable and have great uncertainties). Fortunately, waveform inversion approaches (e.g., the neighborhood algorithm) are available and valid for obtaining the S-wave velocity structure of the crust–upper mantle beneath the station, with sediments varying in thickness and velocity.https://www.mdpi.com/2077-1312/12/11/2053ocean-bottom seismographsreceiver functionH-kappa stackingneighborhood algorithm
spellingShingle Wenfei Gong
Hao Hu
Aiguo Ruan
Xiongwei Niu
Wei Wang
Yong Tang
Numerical Modeling on Ocean-Bottom Seismograph P-Wave Receiver Function to Analyze Influences of Seawater and Sedimentary Layers
Journal of Marine Science and Engineering
ocean-bottom seismographs
receiver function
H-kappa stacking
neighborhood algorithm
title Numerical Modeling on Ocean-Bottom Seismograph P-Wave Receiver Function to Analyze Influences of Seawater and Sedimentary Layers
title_full Numerical Modeling on Ocean-Bottom Seismograph P-Wave Receiver Function to Analyze Influences of Seawater and Sedimentary Layers
title_fullStr Numerical Modeling on Ocean-Bottom Seismograph P-Wave Receiver Function to Analyze Influences of Seawater and Sedimentary Layers
title_full_unstemmed Numerical Modeling on Ocean-Bottom Seismograph P-Wave Receiver Function to Analyze Influences of Seawater and Sedimentary Layers
title_short Numerical Modeling on Ocean-Bottom Seismograph P-Wave Receiver Function to Analyze Influences of Seawater and Sedimentary Layers
title_sort numerical modeling on ocean bottom seismograph p wave receiver function to analyze influences of seawater and sedimentary layers
topic ocean-bottom seismographs
receiver function
H-kappa stacking
neighborhood algorithm
url https://www.mdpi.com/2077-1312/12/11/2053
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