Undersea Internet Cables Could Be Key to the Future of Earthquake Detection

Considering that 70 percent of the planet is covered by oceans, we don't have all that many underwater earthquake sensors. Though there's plenty of seismic activity that happens out in the middle of the ocean, most detection equipment is located on land, with the exception of a few offshore sensor projects in Japan, the U.S., and Canada.

To get better earthquake data for tremors and quakes that happen far from existing sensors, a group of scientists in the UK, Italy, and Malta suggest turning to the internet. As Science News reports, the fiber-optic cables already laid down to carry communication between continents could be repurposed as seismic sensors with the help of lasers.

The new study, detailed in a recent issue of Science, proposes beaming a laser into one end of the optical fiber, then measuring how that light changes. When the cable is disturbed by seismic shaking, the light will change.

This method, which the researchers tested during earthquakes in Italy, New Zealand, Japan, and Mexico, would allow scientists to use data from multiple undersea cables to both detect and measure earthquake activity, including pinpointing the epicenter and estimating the magnitude. They were able to sense quakes in New Zealand and Japan from a land-based fiber-optic cable in England, and measure an earthquake in the Malta Sea from an undersea cable running between Malta and Sicily that was located more than 50 miles away from the epicenter.

Seismic sensors installed on the sea floor are expensive, but they can save lives: During the deadly Japanese earthquake in 2011, the country's extensive early-warning system, including underwater sensors, was able to alert people in Tokyo of the quake 90 seconds before the shaking started.

Using existing cable links that run across the ocean floor would allow scientists to collect data on earthquakes that start in the middle of the ocean that are too weak to register on land-based seismic sensors. The fact that hundreds of thousands of miles of these cables already crisscross the globe makes this method far, far cheaper to implement than installing brand-new seismic sensors at the bottom of the ocean, giving scientists potential access to data on earthquake activity throughout the world, rather than only from the select places that already have offshore sensors installed.

The researchers haven't yet studied how the laser method works on the long fiber-optic cables that run between continents, so it's not ready for the big leagues yet. But eventually, it could help bolster tsunami detection, monitor earthquakes in remote areas like the Arctic, and more.