Ultrastable laser interferometry for earthquake detection with terrestrial and submarine cables

TLDR

Seismic networks detect earthquakes on continents, but most of Earth's surface lies under oceans where installing seismometers is difficult. The authors propose using intercontinental fiber optic cables as ocean‑bottom strain sensors to dramatically improve earthquake recording. They detect small strain changes from seismic waves by sending laser light through in‑use fiber optic cables with ultrastable lasers. They show that ordinary submarine telecommunication cables can detect earthquakes, demonstrating that intercontinental fiber optic cables can serve as ocean‑bottom strain sensors. Marra et al., Science, this issue, p.

Abstract

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