Methods for Geophysical Sensing on Submarine Cables.

We will review basic physics to establish five methods to use subsea optical fiber networks for network resiliency improvements, earthquake and tsunami early warning and climate change: i) Optical interferometry-based, Optical polarization-based, iii) Coherent Rayleigh backscattering; iv) Microwave frequency fiber interferometry, and v) Faraday's law of induction to explain correlation of voltage disturbance and the strength of the geomagnetic perturbation TeleGeography's Interactive Submarine Cable Map. 487 global cables and 1,304 landing stations 1.3+ million km [GRAPHICS] .