On 16/12/2020 12:09, John Walliker wrote:
On Friday, 11 December 2020 at 01:08:38 UTC, Graham. wrote:

Are the submarine fibre optic cables vulnerable? If so, what's the
mechanism?

Long-distance submarine fibre-optic cables have repeaters which are
powered by high-voltage dc supplies at each end. Induced voltages
in the power conductors might, in principle, cause problems.

John


Although given the cost of a failure, you might expect pretty good
protection right at the end. Would standard "lightning" protection (for
induction from ground currents) work?