Effects of geomagnetic field perturbations on the power supply of transoceanic fiber optic cables

There is a growing concern that a big coronal mass ejection event will induce perturbations on the power supply of fiber optic transoceanic cables that may produce a global internet blackout. In this paper we give the expression of the voltage variations that a transient change of the geomagnetic field induces on the voltage of the power supply of a transoceanic fiber optic cable. We show that the transient voltage change is proportional to the magnitude of the magnetic field deviations and not to its time derivative as a direct application of Faraday's law would imply, and this suggests design criteria to protect transoceanic fiber optic systems against big geomagnetic storm events. The presented analysis also enables the classification of existing systems into some that are less sensitive to the weakening of the geomagnetic field occurring during strong geomagnetic storms and others that are more prone to experience an outage when a weakening of the geomagnetic field occurs.