New fiber cable can hear footsteps 25 miles away

British scientists have turned a fiber-optic cable into a super-microphone that can pick up the sound of a footstep 25 miles away, The Independent reports. The technology can also detect sounds perpendicular to the cable up to 15 feet away.

The eavesdropping system, adapted from military sonar and submarine technology, is aimed at improving security along borders, railways, airports and pipelines. It also has major implications for counterterrorism and police investigations

The OptaSense system was developed by QinetiQ, a former British defense agency that was privatized. The Independent writes that it's been tested "on railways to prevent vandals or thieves trespassing on high-speed lines as well as to counter terrorism. It has been deployed by several blue chip oil companies to protect energy pipelines which run through some of the most lawless and remote regions of the world."

Here's how it works:

The system works by picking up tiny seismic waves detected under the ground by the fibre optic cable which carries an optical pulse sent from a central computer. Virtual “microphonesâ€