Monterey Bay Seafloor Experiment
Science & Technology

Illuminating Seafloor Seismology With Existing ‘Dark’ Fiber-Optic Cables and Distributed Acoustic Sensing

Researchers employed 20 kilometers (pink) of a 51-kilometer undersea fiber-optic cable, usually used to speak with an off-shore science node (MARS, Monterey Accelerated Analysis System), as a seismic array to review the fault zones beneath Monterey Bay. Through the four-day take a look at, the scientists detected a magnitude 3.5 earthquake 45 kilometers away in Gilroy, and mapped beforehand uncharted fault zones (yellow circle). Credit score: Nate Lindsey, UC Berkeley

A brand new fault system on the seafloor was found off California’s coast by briefly reworking a pre-existing underwater fiber optic cable into an array of practically 10,000 seismic sensors, in response to a brand new research. The outcomes showcase the potential of leveraging the intensive internet of subsea optical fiber telecommunication cables already spanning the ocean’s flooring to observe and report oceanographic and seismic processes in unprecedented element.

Deep beneath the floor, tectonic forces conspire to fracture and fold the Earth’s crust. These rocks break and transfer at faults. Like geological scars, the floor of Earth is striated with faults; the most important and most full of life — the place rocks are actively snapping and shifting — are chargeable for triggering damaging earthquakes and tsunamis. Mineral deposits like oil and gasoline are sometimes discovered alongside these constructions, too.

Nonetheless, charting Earth’s fault zones is difficult and many stay unknown, notably people who lie on the underside of the ocean. Because of this, offshore seismic hazard potential just isn’t absolutely understood, and details about offshore assets is incomplete.

Distributed Acoustic Sensing (DAS), a sort of fiber-optic sensing that makes use of pulses of laser mild to repeatedly detect slight actions alongside optical fibers, has been used to measure seismic waves and map faults on land. Researchers have steered it might be used to measure seafloor seismic exercise as effectively. Throughout a upkeep window, Nathanial Lindsey and colleagues briefly repurposed an undersea fiber-optic cable — a part of the Monterey Accelerated Analysis System — to gather DAS measurements throughout the continental shelf of California’s coast.

In accordance with Lindsey et al., DAS turned the decade-old cable into the equal of 1000’s of delicate seismic sensors. Over the quick period, the authors had been capable of map a beforehand unknown fault system and observe a number of dynamic tidal and storm-driven processes within the water column above. Philippe Jousset discusses the research in a associated Perspective.

Learn Undersea Fiber-Optic Cables Make Superb Seismic Network for extra info on this research.

Reference: “Illuminating seafloor faults and ocean dynamics with darkish fiber distributed acoustic sensing” by Nathaniel J. Lindsey, T. Craig Dawe and Jonathan B. Ajo-Franklin, 29 November 2019, Science.
DOI: 10.1126/science.aay5881

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