Observing this "backscatter" phenomenon through a technique called Distributed Acoustic Sensing (DAS), the 20 km long cable was turned into a bed of 10,000 motion sensors that could detect seismic activity with picometer precision.
Working from a beachside shack on California's Monterey Bay, Nate Lindsey fired a stream of infrared laser pulses down a long fiber-optic cable extending onto the ocean floor. The miles-long cable had been there for a decade...but Lindsey, a geoscientist at UC Berkeley, was trying something new
Scientists discovered California’s newest known offshore faults by borrowing a garden hose-size fiber optic cable that spans the seafloor of Monterey Bay and turning it into an ad-hoc seismic array….
At the Lawrence Berkeley National Laboratory, Dr. Jonathan Ajo-Franklin is using dark fiber to measure seismic signals. Dr. Ajo-Franklin’s team gained permission to access a section of a dark fiber network between Sacramento and Calusa, California.