Scientists Saw an Earthquake in Incredible DetailUsing Telecom Cables

"The same optic fibers that pulse with the world's Internet traffic are now listening to the pulse of the planet, picking up earthquake tremors in better detail than traditional seismic networks do. In a recent Science study, researchers used 15 kilometers of telecom fiber near Mendocino, Calif., to record the region's biggest earthquake in five yearscapturing in fine detail how the magnitude 7 rupture started, slowed and sped up, accelerating even faster than the speed of sound."

"The oil industry adopted this technology in the 1990s, deploying specialized fiber-optic cables to detect temperature, pressure and vibration during drilling. James Atterholt, a seismologist at the U.S. Geological Survey, hoped to adapt such observations to an actual earthquake. In May 2022 Atterholt and his team set up a device called an interrogatorbasically a big box with a laser and a computer, he saysto send beams of light through an unused fiber on a coastal telephone cable."

Fifteen kilometers of coastal telecom fiber near Mendocino, California, recorded a magnitude-7 earthquake with finer spatial detail than traditional seismic networks. The fiber captured how the rupture initiated, slowed, and then accelerated, including episodes of acceleration exceeding the speed of sound. Optical fibers reflect tiny changes when ground vibrations perturb microscopic imperfections, and those reflections can be read by an interrogator that sends laser pulses through unused telecom strands. The oil industry previously used fiber-optic sensing for drilling. Repurposing existing telecom cables allows high-resolution, distributed acoustic sensing of earthquakes along long distances.

Read at www.scientificamerican.com