Title: Research Assistant Professor
Country/Region: China
Period: 2021/06/16-2022/6/15
Theme: Deciphering the structure of the megathrust in the Hyuga-nada region using data from dense OBS array
Host: Takeshi AKUHARA
Introduction: I’m an observational seismologist at Institute of Geophysics and Geomatics, China University of Geosciences. My primary research interests lie in understanding the dynamics and deformation of the Earth’s interior, and mostly, I dear with the ground vibrations excited by earthquakes or seismic ambient noise and map the crust and uppermost mantle structure. Before moving to ERI, I mainly focus on continental deformations of the tectonically active regions in China. During my stay in ERI, I would like to work closely with my host, Dr. Takeshi Akuhara, and pay attention to the deep structure of the Sea of Japan with data collecting from broadband Ocean Bottom Seismometers (OBS). Specifically, we intend to fully explore the potential of broadband OBS waveforms in imaging the deep lithosphere and asthenosphere, including the sharpness and depth of structural discontinuities. Hopefully our investigations would provide fine constraints to the evolution of the Sea of Japan. I also look forward to meeting more friends in ERI and we may have interesting interactions on each other.
Research Report:
Layered evolution of the oceanic lithosphere beneath the Japan Basin, the Sea of Japan
Sanxi Ai (sanxi.ai@qq.com; aisanxi@cug.edu.cn)
ERI Long-term visiting researcher (2021-2022)
The formation of a new ocean basin provides a unique observational window into the structure and deformation of the oceanic lithosphere. During my stay at ERI, I collaborated with Prof. Akuhara in studying the lithosphere structure of the Japan Basin with broadband ocean bottom seismometers deployed in the eastern Japan Basin, the Sea of Japan (figure 1).
Figure 1. A bathymetry map of the Japan Basin. The red triangles mark the locations of the OBS used in the present study. The insert subplot marks the location of the Sea of Japan, which is located in the northwestern Pacific.
Our study offers detailed 1-D vertically polarized shear-wave velocity models of the young Japan Basin by interpreting S receiver functions, seafloor Rayleigh wave ellipticities and phase velocities in a Bayesian trans-dimensional framework. The models suggest a distinct discontinuity in the mid-lithosphere (figure 2). Additional analyses indicate that the upper layer is characterized by strong positive radial anisotropy, while the lower layer is more isotropic.
Sanxi Ai (sanxi.ai@qq.com; aisanxi@cug.edu.cn)
ERI Long-term visiting researcher (2021-2022)
The formation of a new ocean basin provides a unique observational window into the structure and deformation of the oceanic lithosphere. During my stay at ERI, I collaborated with Prof. Akuhara in studying the lithosphere structure of the Japan Basin with broadband ocean bottom seismometers deployed in the eastern Japan Basin, the Sea of Japan (figure 1).
Figure 1. A bathymetry map of the Japan Basin. The red triangles mark the locations of the OBS used in the present study. The insert subplot marks the location of the Sea of Japan, which is located in the northwestern Pacific.
Our study offers detailed 1-D vertically polarized shear-wave velocity models of the young Japan Basin by interpreting S receiver functions, seafloor Rayleigh wave ellipticities and phase velocities in a Bayesian trans-dimensional framework. The models suggest a distinct discontinuity in the mid-lithosphere (figure 2). Additional analyses indicate that the upper layer is characterized by strong positive radial anisotropy, while the lower layer is more isotropic.
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Fiscal Year: 2021
Fiscal Year: 2021