Lawrence Livermore National Laboratory researchers were able to capture quakes of unprecedented precision, using fiber optic sensing along unused telecommunication lines, according to a US geological survey.
Fiber optic sensing technology turned ordinary telecom fibers, normally carrying internet traffic, into sensitive seismic sensors. Tiny bends and vibrations in the cables, once considered “noise” for telecom companies, now provide detailed information about how earthquakes move beneath the surface.
By using distributed fiber optic sensing earthquakes, scientists gain a magnified window into the shifting crust of Earth.
Converting Fiber Cables into Sensor Arrays
Optical fiber, one of modern science’s great inventions, transmits light with high efficiency. Even slight vibrations along the cable can disrupt the light, which telecom engineers usually try to avoid.
“Yet what’s noise to telecommunications is data to us,” says Zhongwen Zhan, geophysicist at Caltech.
Technology was first adapted by the oil industry in the 1990s for drilling, but today seismologists use a fiber optic sensing system called an interrogator.
“Basically, a big box with a laser and a computer,” says James Atterholt of the US Geological Survey. To convert fiber optic sensing solutions for seismic change into thousands of mini seismometers.
In December 2024 a magnitude 7 quake struck Cape Mendocino, and this setup captured the rupture’s intricate movements, including a rare supershear speed that briefly exceeded the speed of sound.
“The actual demonstration of it in a proven case shows that it can improve earthquake early-warning systems,” points out Brad Lipovsky, a geophysicist at the University of Washington.
The system depends on fiber optic sensors in telecom cables already buried underground.
Increasing Seismic Knowledge in Cities
There are limitations to urban seismology: traditional instruments are expensive and challenging to install.
“You have limited resources, so you can’t buy too many of them, and it’s hard to get access into populated areas,” says Gene Ichinose of Lawrence Livermore National Laboratory.
Using a Distributed Acoustic Sensing system, each 10-m section of the distributed acoustic sensing (DAS) fiber optic cables acts as a virtual seismometer.
In a test that lasted for a month along an 80-mile corridor between San Francisco and Sunnyvale, researchers captured the activity equivalent to 8,000 instruments. They recorded subtle vibrations from passing trains to a small 3.9 magnitude earthquake near Dublin, California.
“It can be used for landslide monitoring, volcanic monitoring, and that data is available quickly…having enough cables in the right spot provides that timeliness,” Amy Williamson from the UC Berkeley Seismology Lab added
Collected via fiber optic sensing cable and underground fiber optic cable, this high-resolution data could show hidden fault lines under urban centers, identify infrastructure at risk, and track small foreshocks ahead of major quakes.
As Ichinose sums it up, “There’s a lot of excitement…we’re really excited, because I think this is going to revolutionize how we record seismic data,” showing the potential that fiber optic cabling and telecom fiber optics have for reshaping earthquake monitoring.
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