In addition to sending films, emails, and tweets, fiber-optic cables that go through the ground, along the seafloor, and into our houses have other uses. Anywhere the wire reaches the ground, these signals can also capture ground vibrations as small as a nanometer. Fiber-optic cables have long been used for unanticipated purposes, but only a small number of military and commercial applications have taken use of it.
In a pilot study at the University of Washington, fiber optic sensing is being investigated for seismology, glaciology, and even urban surveillance. The new UW Photonic Sensing Facility is supported in part by a $473,000 grant from the M.J. Murdock Charitable Trust, a non-profit organization based in Vancouver, Washington. It has three decoder devices, or "interrogators," that use photons traveling through a fiber-optic cable to detect ground motions as small as 1 nanomeeter.