Earlier quoted context omitted.
> I wonder how much data per unit of time this is capable of transporting. The max throughput of fiber optic cables isn't exactly constant. As fiber optic modem and DSP technology improves you can get much higher speeds on 15+ year-old cables than were ever possible when they were laid. Recently I saw an article about researchers getting 300,000 Gbit/s over existing fiber optic cables (though I'm sure that's a long w…
You're referring to single continuous fiber optic cables on land. Long undersea cables incorporate powered repeaters. Those can't be upgraded in situ with improved technology.
Pulling a cable up, cutting a damaged part out of it and putting a new piece in is done all the time to fix damaged cables.