Using fiber optic cables to signal tsunami events
S. Himmelstein | February 28, 2024
The high-cost specialized buoys deployed by the U.S. to monitor tsunamis in the Pacific Ocean may soon be replaced with a more economical supervisory system based on distributed acoustic sensing (DAS). The technology is less capital intensive relative to the Deep-ocean Assessment and Reporting of Tsunamis (DART) buoy network as it makes use of the existing 1 million miles of fiber optic cables that traverse the ocean floor.
The use of this existing cable network as an early tsunami warning system is being advanced by researchers from Helmholtz Center Potsdam (Germany), University of Michigan and California Institute of Technology. The detection method uses the optical phase changes in Rayleigh backscattered light within an optical fiber to function as thousands of vibration sensors, enabling the fiber to serve as a dense array capable of continuously detecting and analyzing seismo-acoustic signals along tens of kilometers.
The researchers have installed DAS interrogator units in fiber optic telecommunication systems in Alaska, Japan, Spain and Lake Ontario that tap into underwater fiber optic cables. One such device placed in Florence, Oregon, effectively detected a tsunami that originated in an island chain nearly 1,300 miles east of the tip of South America. The DAS network was demonstrated to provide extensive coverage and real-time monitoring capabilities to benefit preparedness and response efforts in coastal communities.
A paper detailing the data collection and analysis methods applied in the DAS system is published in Geophysical Research Letters.