Imagine turning internet cables into super-sensitive ears for the Earth. Well that’s exactly what scientists did to study the Mendocino earthquake off California in 2024.
They placed a laser device at the Arcata Police Station and used the building’s fiber–optic line to feel tiny shakes. The study, which was carried out by James Atterholt at the USGS and published in the journal Science, demonstrates how fiber optic seismic monitoring combined with distributed acoustic sensing (DAS) can quickly determine the location of an earthquake, its magnitude, and the fault’s breaking mechanism.
In areas where regular seismometers are scarce or seafloor monitoring is too costly, the plan is to “listen” through existing telecom cables from firms like Google, Amazon, and AT&T.
If scientists have access to these networks, “earthquake early warning could be dramatically improved tomorrow,” according to Emily Brodsky of the University of California, Santa Cruz. The method may also helped in the investigation of slow warning indicators that precede large earthquakes like the 2011 Tohoku earthquake and tsunami, which resulted in the Fukushima nuclear accident, and the 2014 Chilean earthquake.
The fiber trick’s operation
The technique is known as distributed acoustic sensing (DAS). A box measures minute variations in the light that bounces back after sending laser light down a fiber-optic cable. These modifications result from tiny compressions and stretches in the cable, which are brought on by ground vibrations. Scientists can “image” a quake in real time by interpreting those wiggles.
Before the Mendocino earthquake, the DAS unit at the Arcata Police Station had been operational for over two years. When it did, the fiber captured enough information to map the location, magnitude, and rupture length of the quake. James Atterholt stated, “This is the first study that is imaging an earthquake rupture process from an earthquake that’s this large.” “This demonstrates that there is potential to enhance earthquake early warning alerts with telecom fibers,” he continued.
Another uncommon phenomenon discovered by the study was a “supershear” rupture, in which the fault break travels faster than the waves produced by the earthquake. Atterholt likened it to a sonic boom produced by “a fighter jet exceeding the speed of sound.”
Atterholt also pointed out that although supershear earthquakes can alter the intensity of shaking, “we haven’t really nailed down why some earthquakes go supershear and why some don’t.”
Why this might alter early warning
Imagine the miles and miles of fiber-optic cables that are already installed. Scientists could add thousands of “virtual” sensors without excavating if they could “borrow” those networks from Google, Amazon, and AT&T for a short time. Emily Brodsky stated: “There isn’t a technical obstacle there. The Atterholt study proves that.”
“There are legitimate concerns,” Brodsky clarified. They are concerned that someone might place an instrument on something that is very valuable to them. They fear that the cables may be damaged or that someone may be listening. However, “it’s pretty clear that having that data is also in the public safety interest, so that is a problem that needs to be solved at the regulatory level.”
It’s important to note that this fiber sensing would supplement conventional seismometers rather than replace them, and it typically doesn’t disrupt internet traffic. There are limitations in the technical realm: DAS can currently travel up to 90 miles offshore, according to Jiaxuan Li of the University of Houston. Other places, however, are already benefiting from the technology.
One network, earthquake warnings, safer communities
Global seismic alerts warnings could be improved by using fiber optic seismic monitoring with internet cables. Its effectiveness is demonstrated by the Mendocino earthquake study, and with industry and scientific backing, DAS could transform telecom networks into life-saving protectors.