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 9:00 AM - 10:15 AM 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:Takashi Tonegawa(Research and Development center for Earthquake and Tsunami, Japan Agency for Marine-Earth Science and Technology), HyeJeong Kim(Earthquake Research Institute, University of Tokyo)

9:15 AM - 9:30 AM

[SSS04-02] High-resolution seismic constraint on the seafloor sediments using teleseismic body waves of multiple components of ocean bottom seismometers: method and practice

*HyeJeong Kim1, Hitoshi Kawakatsu1,2, Takeshi Akuhara1, Nozomu Takeuchi1 (1.Earthquake Research Institute, The University of Tokyo, 2.Institute of Earth Sciences, Academia Sinica)

Keywords:ocean bottom seismometers, seafloor sediment, teleseismic body waves

The seafloor sediment layer, a sequence of materials from the top water-saturated sediment to the consolidated sedimentary rock above a basement, is a ubiquitous feature of the ocean. The seismic signals recorded by the ocean bottom seismometers are influenced by the seafloor sediments. An accurate prediction of the influence of the sediment layer on the passive seismic records of the ocean bottom seismometers is possible by knowing its seismic structure. Kim et al. (2022; JpGU) presented a new method that constrains the seafloor sediment in a high resolution using the radial and vertical component records of teleseismic body waves. The method is advanced to employ the autocorrelation function of the pressure component upon incident teleseismic P wave. The method can constrain parameters regarding both the S-wave velocity (VS) and the P-wave velocity (H/VP, ρVP) of the multi-layered sediment, where H and ρ are the thickness and density of a layer, respectively. The method applied to a station in NW Pacific showed agreements with the direct measurements of the ocean drilling section and the structure constrained by controlled source surveys. The method can resolve thinner sediment layers (∼50 m) than the other previous methods with different types of passive seismic data (e.g., Ruan et al., 2014). In the presentation, we will present the results of the method applied to broadband ocean bottom seismometers from Japan and the US of the Pacific Ocean. Moreover, the effects of the sediment layer on the passive ocean bottom seismology will be discussed.