Ultrastable laser interferometry for earthquake detection with terrestrial and submarine cables

Submarine fiber optic earthquake detection Seismic networks detect earthquakes and are common on continents, where they are easy to install. However, most of Earth's surface is under the oceans, where placing seismometers is difficult. Marra et al. now find that ordinary submarine telecommunication cables can be used to detect earthquakes. Small strain changes associated with the passage of seismic waves were detected with laser light sent through in-use fiber optic cables by ultrastable lasers. This strategy could turn intercontinental fiber optic cables into ocean-bottom strain sensors, dramatically improving our ability to record earthquakes. Science , this issue p. 486