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Measurement of Seafloor Rayleigh Ellipticity From Unoriented Seismic Data and Its Significance for Seismic Imaging in the Ocean

Description: 

Observations of seafloor Rayleigh ellipticity play a important role in seismic imaging in the ocean. To extract these observables from arbitrarily oriented ocean-bottom seismometer data, we introduce an orthogonal-regression-based approach for measuring waveform amplitude ratios between the unoriented horizontal and vertical components of surface waves. These amplitude ratios are subsequently used to calculate the Rayleigh ellipticity and determine the sensor orientation angle.

The robustness of our method is validated through applications to both unoriented OBS data and well-oriented on-land seismic data. By directly deriving Rayleigh ellipticity from the unoriented three-component data, our approach circumvents challenges associated with surface wave non-great-circle effects and uncertainties in OBS sensor orientation angles.

Overall the Rayleigh ellipticity measurements from our method are systematically higher than those by conventional analysis and show less uncertainties. Our analyses suggest that the Rayleigh ellipticity curve (14–60 s), which could be retrieved from the raw broadband OBS data, is effective to constrain the oceanic lithosphere structure. The potential of seafloor Rayleigh ellipticity for seismic imaging in the ocean is evidenced by a case study of the Japan Basin, the Sea of Japan. Considering the insufficient station coverage in the ocean, the single-station measurement of seafloor Rayleigh ellipticity is of significance for OBS community.

Session: ESC-SSA Joint Session:Seismology in the Global Oceans: Advances in Methods and Observations [Poster]

Type: Poster

Date: 4/15/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Sanxi

Student Presenter: No

Invited Presentation: 

Poster Number: 1

Authors