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Optics of an earthquake

Researchers co-opt fiber optic cable as an earthquake detector 


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The makings of a sophisticated earthquake detection system may already exist under our feet. Researchers at Stanford University have shown that the existing fiber optic cables that provide high-speed internet could be harnessed as sensors for detecting the magnitude and direction of seismic events.

In a project dubbed the “fiber optic seismic observatory,” scientists at Stanford’s School of Earth, Energy & Environmental Sciences installed a 3-mile loop of optical fiber underneath the university. Since September 2016 the system has recorded more than 800 earthquakes, from small, man-made temblors to the deadly quake that struck Mexico earlier this year.

The system uses a technology called distributed acoustic sensing, in which laser light is sent down the optical fiber bundle: During an earthquake, a detector measures the amount of light that bounces back due to vibrations or strain in the fiber.

While seismometers are currently more sensitive than the proposed fiber optic array, their coverage is sparse and they are expensive to install and maintain. The Stanford researchers believe a seismic observatory based on telecom cable would be relatively inexpensive to operate.

“Every meter of optical fiber in our network acts like a sensor and costs less than a dollar to install,” Biondo Biondi, a professor of geophysics at Stanford, said in a statement.

The researchers hope to develop a seismic network across the Bay Area to demonstrate that such an array can operate on a citywide scale.

Crack protection

The Pacific Northwest, unlike California, is not known for its earthquakes. For decades, California has required contractors to construct buildings to be earthquake resistant. But buildings in the Pacific Northwest—which sits squarely on the Cascadia Subduction Zone, a region with huge quake potential—could be devastated by a major earthquake.

With the goal of protecting existing structures from temblors, scientists at the University of British Columbia (UBC) in Vancouver, Canada, have developed a way to retrofit older buildings with a special concrete coating that could make them more earthquake resistant.

The product, known as eco-friendly ductile cementitious composite (EDCC), combines cement with polymer-based fibers, fly ash, and other industrial additives. The fibers give the concrete flexibility so it won’t crumble under pressure like traditional concrete or masonry.

The researchers sprayed a 1-centimeter-thick layer of EDCC onto different types of walls and subjected them to seismic shocks as strong as those in the magnitude 9.1 quake that struck Tōhoku, Japan, in 2011. In the tests, the treated walls stayed up while untreated ones collapsed.

The EDCC coating could also be applied to pipelines, sidewalks, and roadways. Later this year an elementary school in Vancouver will get its own coat of the material. —M.C.

Autonomous trucking

If a self-driving truck doesn’t need a driver, why design it with a cab?

Last month, General Motors unveiled a conceptual autonomous cargo vehicle that can operate with or without a cab attached. Powered by hydrogen fuel cell technology, the Silent Utility Rover Universal Superstructure (SURUS) is designed for tough environments such as natural disasters or military conflicts. The vehicle has the ability to accommodate flexible cargo modules, from shipping containers to portable medical facilities.

Each with a range of more than 400 miles, multiple SURUS vehicles could be operated in a leader-follower configuration to reduce manpower requirements, according to GM. —M.C.


Michael Cochrane Michael is a World Journalism Institute graduate and a former WORLD correspondent.

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