Japan Geoscience Union Meeting 2023

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[E] Oral

S (Solid Earth Sciences ) » S-SS Seismology

[S-SS04] Seismological advances in the ocean

Mon. May 22, 2023 10:45 AM - 12:00 PM 106 (International Conference Hall, Makuhari Messe)

convener:Tatsuya Kubota(National Research Institute for Earth Science and Disaster Resilience), Takashi Tonegawa(Research and Development center for Earthquake and Tsunami, Japan Agency for Marine-Earth Science and Technology), Yukihiro Nakatani(Nansei-Toko Observatory for Earthquakes and Volcanoes, Graduate School of Science and Engineering, Kagoshima University), Chairperson:Yukihiro Nakatani(Nansei-Toko Observatory for Earthquakes and Volcanoes, Graduate School of Science and Engineering, Kagoshima University), Tatsuya Kubota(National Research Institute for Earth Science and Disaster Resilience)

11:45 AM - 12:00 PM

[SSS04-10] Characteristics of Low-Frequency Horizontal Noise of Ocean-Bottom Seismic Data

*Chao An1, Chen Cai2, Lei Zhou1, Ting Yang3 (1.Shanghai Jiao Tong University, 2.Sun Yat-sen University, 3.Southern University of Science and Technology)

Keywords:Ocean-bottom seismometer, horizontal noise, tilt noise

Horizontal records of ocean-bottom seismographs are usually noisy at low frequencies (< 0.1 Hz). The noise source is believed to be associated with ocean-bottom currents that may tilt the instrument. Currently there has been little literature that quantitatively discusses the mechanism and characteristics such noise. In this article, we analyze in-situ ocean-bottom measurements by rotating the data horizontally and evaluating the coherency between different channels. Results suggest that the horizontal noise consists of two components, random noise and principle noise whose direction barely changes in time. The amplitude and the direction of the latter are possibly related to the intensity and direction of ocean-bottom currents. Rotating the horizontal records to the direction of the principle noise can largely suppress the principle noise in the orthogonal horizontal channel. In addition, the horizontal noise is incoherent with pressure, indicating that the noise source is not ocean surface water waves (infragravity waves).