Innovative Use of Fiber Optic Cables Enhances Offshore Seismic Monitoring

In a groundbreaking study, researchers from the University of Washington have successfully utilized fiber optic cables to monitor seismic activity along the ocean floor, presenting a novel approach to understanding tectonic movements without disrupting existing telecommunications. This technique, known as Distributed Acoustic Sensing (DAS), was first developed in Alaska and later tested off the Oregon coast, as detailed in their recent publication in "Seismological Research Letters" on February 28, 2025.

The Pacific Northwest is home to an extensive seismic monitoring network comprising over 600 stations. These stations play a crucial role in tracking tectonic and volcanic activities, especially in light of the significant seismic threat posed by the subduction of the Juan de Fuca plate beneath the North American plate in the Cascadia Subduction Zone. Traditional methods of monitoring underwater faults have often fallen short of providing detailed analyses, necessitating innovative solutions to enhance data collection from these remote locations.

The research team, led by Marine Denolle, an associate professor in the Earth and Space Sciences Department at the University of Washington, leveraged the existing fiber optic cable infrastructure that forms part of the Ocean Observatory Initiative’s Regional Cabled Array. Unlike prior experiments that relied on inactive or "dark" fibers, this study demonstrated the ability to collect data from live cables without interfering with their primary telecommunications function.

According to Denolle, "What we created is the starting point of any earthquake analysis. Once our AI algorithm enhances the data, we can actually use the wiggles to do science." The researchers utilized data from 285 earthquakes that occurred in Alaska's Cook Inlet in 2023 to train their AI algorithms, enabling them to identify previously undetectable seismic events.

Qibin Shi, a co-author and former postdoctoral researcher at the University of Washington, now a seismologist at Rice University, emphasized the significance of this research, stating, "A well-trained model will identify earthquakes that the human eye cannot see. This marks the first step toward a general-purpose foundational model for earthquakes."

The findings from the Oregon test site further validated the team's approach, allowing them to trace earthquake signals back to specific regions of the ocean floor and improve the precision of earthquake location detection. Denolle noted, "It’s the closest we can get to where the action is, which is vital for scientific inquiries and for early tsunami and earthquake warnings."

The implications of this research are profound, not only enhancing our understanding of plate tectonics but also improving the capabilities of early warning systems that can alert communities to impending natural disasters. The portable nature of the DAS system, requiring minimal computing power, allows for rapid deployment and data collection, as evidenced by the recent three-day experiment in Oregon, which produced substantial datasets.

The research team is currently negotiating permanent installations for their monitoring systems and is exploring partnerships to further develop this technology. Denolle concluded, "We’re going to understand plate tectonics by studying small earthquakes, and this system gives us unprecedented access to that data."

This study was supported by the National Science Foundation, the U.S. Geological Survey, the David and Lucile Packard Foundation, and the University of Washington Geohazard Initiative, among others. The datasets generated from this research are publicly accessible, marking a significant step forward in seismic monitoring capabilities and data utilization for scientific advancement.