Illuminating tremors in the deep

Abstract

Telecommunication cables on the seafloor monitor seismic activity The paucity of seismic stations in the ocean limits sustained seafloor seismic and pressure observations that are needed for rapid earthquake detection, early warning of damaging ground shaking, and tsunami prediction and verification. Because establishing infrastructure in the oceans is expensive, there is a big advantage to methods that use undersea telecommunication cables. On page 931 of this issue, Zhan et al. (1) describe a new approach to monitor earthquakes, oceanic swell, and potential tsunamis. It relies on observing changes in the polarization of the light that is used to transmit data through the optical fibers in cables on the seafloor. This approach requires no new infrastructure or instrumentation, but instead relies on utilizing observations already made to extract the telecommunications data received at the end of the cable. The finding should spur implementation of an array of cable sensing technologies for geophysical monitoring.