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Comment by bladedtoys | Hacker News Reader

I wonder do they just drop the transatlantic cables blindly over the mid-atlantic ridge and hope for the best or check that it's not a hot spot or something.

And four cables connect Alaska to the lower 48? I wonder why.

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I live in southeast AK. An earthquake near Glacier Bay this month broke one of the undersea cables, which caused an outage for customers of one service provider. I had no idea there were multiple cables to southeast, until I read about the response to this incident.

The Capital City Weekly has a good article about the recent incident, which also includes a short history of communication cables in Alaska [0]. Basically a few companies built seabed cables in southeast during the dot com boom, and then there was too much capacity for a while. One company went bankrupt and another company attempted to buy all the capacity, but concerns about a monopoly prevented that deal from going through. Now when there's an outage, companies can lease access from each other until the broken cable gets repaired.

The currents in our coastal channels are significant, with 8-12 foot tidal swings. Those currents, combined with the silty and rocky nature of the ocean floor in much of southeast, makes for a pretty abrasive environment. Add to that a lot of bottom fishing and anchoring, and cables get broken.

As a resident of southeast, I'm happy for the redundancy!

[0] http://www.capitalcityweekly.com/stories/081314/new_12153949...

I wonder why they didn't just lay them along the alcan highway? Surely that would have been a zillion times cheaper.

The alcan highway is pretty long, and passes through some pretty remote regions. You'd have to run cables from the alcan down to Skagway, and then you'd have to run cables underwater to connect the various coastal communities that are on islands, or far from developed roadways. Juneau, Ketchikan, Sitka, Wrangell, Petersburg are all communites with 2,000-30,000 people, and none of those communites connect to the outside world by road.

http://gregorio.stanford.edu/holbrook/CableCosts.html says that cost of undersea cables in the '90s was in the $27k-$56k/km range, with the $27k a bit of an outlier.

Cost estimates for terrestrial cable are harder to come by, and seem depend a lot on things like rights of way (likely not relevant here as a cost), terrain (_very_ relevant), ability to get equipment to the right location, etc. But the numbers I'm seeing on various links from https://www.google.com/search?q=cost+of+laying+fiber+optic+c... are in the $20k to $40k range per kilometer (I took the actual numbers I saw and divided by 1.6) about 5-10 years ago. Figure about 1.4x smaller if you want to adjust for inflation to compare to '90s numbers.

All of which is to say that "zillion" in this case is probably a number somewhere between 1 and 4. Give or take; these are all estimates, obviously. Also not clear to me which is faster to lay, by the way, which might matter in terms of deciding which one to do.

Not to mention that the undersea cable might be shorter, offsetting some of the per-km difference in cost, since it's a lot easier to go straight.

It's easier to lay a subsea cable than to go overland in remote areas. Take a look at the subsea map of Africa as an example. In Africa the subsea links are there because it's too remote to run cables through the jungle or across the Sahara. Additionally terrestrial cables are more frequently cut than subsea cables. In India terrestrial fibers are cut routinely every day to the point that they have to allocate extra repair margin for the links.

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