Utilizing distributed acoustic sensing and ocean bottom fiber optic cables for submarine structural characterization

Area of Science:

• Geophysics
• Marine Geology
• Seismology

Background:

• Marine seismic data acquisition is limited by sparse instrumentation.
• Ocean bottom fiber optic cables offer a potential sensing resource.
• Distributed Acoustic Sensing (DAS) can convert these cables into dense seismic arrays.

Purpose of the Study:

• To demonstrate the utility and limitations of marine DAS for submarine structural characterization.
• To apply DAS ambient noise records for high-resolution near-seafloor imaging.
• To investigate shallow geohazards and depositional features in Monterey Bay.

Main Methods:

• Utilized a 20 km section of fiber optic cable offshore of Moss Landing, CA.
• Recorded ambient noise using DAS systems.
• Extracted Scholte waves via interferometry and inverted dispersion curves.
• Generated a 2D shear-wave velocity image of near-seafloor sediments.

Main Results:

• Recovered a high-resolution 2D shear-wave velocity image of shallow sediments.
• Demonstrated that migrating coherently scattered Scholte waves resolve lateral contrasts.
• Identified shallow faults and paleo-channel deposits in Monterey Bay.

Conclusions:

• Marine DAS is a powerful tool for characterizing submarine structures.
• This technique provides improved constraints on shallow geohazards.
• Existing marine cable networks can be leveraged for geophysical exploration.