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Geotechnical characterization of marine sediments remains an outstanding challenge for offshore energy development, including foundation design and site selection of wind turbines and offshore platforms. We demonstrate that passive distributed acoustic sensing (DAS) surveys offer a new solution for shallow offshore geotechnical investigation where seafloor power or communications cables with fiber-optic links are available. We analyze Scholte waves recorded by DAS on a 42 km power cable in the Belgian offshore area of the southern North Sea. Ambient noise crosscorrelations converge acceptably with just over one hour of data, permitting multimodal Scholte wave dispersion measurement and shear-wave velocity inversion along the cable. We identify anomalous off-axis Scholte wave arrivals in noise crosscorrelations at high frequencies. Using a simple passive source imaging approach, we associate these arrivals with individual wind turbines, which suggests they are generated by structural vibrations. While many technological barriers must be overcome before ocean-bottom DAS can be applied to global seismic monitoring in the deep oceans, high-frequency passive surveys for high-resolution geotechnical characterization and monitoring in coastal regions are easily achievable today.
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This content will become publicly available on February 28, 2026
Distributed Acoustic Sensing for Whale Vocalization Monitoring: A Vertical Deployment Field Test
Abstract There is growing interest in floating offshore wind turbine (FOWT) technology, where turbines are installed on floating structures anchored to the seabed, allowing wind energy development in areas unsuitable for traditional fixed-platform turbines. Responsible development requires monitoring the impact of FOWTs on marine wildlife, such as whales, throughout the operational lifecycle of the turbines. Distributed acoustic sensing (DAS)—a technology that transforms fiber-optic cables into vibration sensor arrays—has been demonstrated for acoustic monitoring of whales using seafloor telecommunications cables. However, no studies have yet evaluated DAS performance in dynamic, engineered environments, such as floating platforms or moving vessels with complex, dynamic strain loads, despite their relevance to FOWT settings. This study addresses that gap by deploying DAS aboard a boat in Monterey Bay, California, where a fiber-optic cable was lowered using a weighted and suspended mooring line, enabling vertical deployment. Humpback whale vocalizations were captured and identified in the DAS data, noise sources were identified, and DAS data were compared to audio captured by a standalone hydrophone attached to the mooring line and a nearby hydrophone on a cabled observatory. This study is unique in: (1) deploying DAS in a vertical deployment mode, where noise from turbulence, cable vibrations, and other sources posed additional challenges compared to seafloor DAS applications; (2) demonstrating DAS in a dynamic, nonstationary setup, which is uncommon for DAS interrogators typically used in more stable environments; and (3) leveraging looped sections of the cable to reduce the noise floor and mitigate the effects of excessive cable vibrations and strain. This research demonstrates DAS’s ability to capture whale vocalizations in challenging environments, highlighting its potential to enhance underwater acoustic monitoring, particularly in the context of renewable energy development in offshore environments.
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- Award ID(s):
- 2103137
- PAR ID:
- 10586190
- Publisher / Repository:
- GeoScienceWorld
- Date Published:
- Journal Name:
- Seismological Research Letters
- Volume:
- 96
- Issue:
- 2A
- ISSN:
- 0895-0695
- Page Range / eLocation ID:
- 801 to 815
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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