On 17/12/2020 12:00, mechanic wrote:
On Wed, 16 Dec 2020 04:09:55 -0800 (PST), 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.

Induced how? From sunspots? Salt water is a conductive medium so
should shield most of the length. All a bit like the hydrogen scare
in the 1980s.

If it were to happen then it would be a big solar flare with a coronal
mass ejection in the direction of the Earth. There are satellites
watching for any such events.

1989 was the last one big enough to take down significant parts of
Canada's national grid. Smaller local events don't make the news.

https://www.nasa.gov/topics/earth/fe..._darkness.html

There has been nothing even close to the Carrington event in 1859 though.

https://www.raeng.org.uk/publication...er-full-report

As a crude rule of thumb if you can see a bright aurora in the southern
parts of the UK then it is getting close to being enough to cause trips
somewhere in North America. Magnetic north is much closer to them.

--
Regards,
Martin Brown