Volcano 'shredded' submarine cable, vastly complicating repair job Two boffins from New Zealand's University of Auckland have detailed the extraordinary repair job performed to reconnect the submarine cable connecting the Kingdom of Tonga to the world. Tonga's sole submarine cable connection was severed by an eruption of the Hunga Tonga–Hunga Haʻapai volcano on January 15. Further domestic …
Probably more a case that they didn't know what they would find, and by the time they did they were fairly committed.
I imagine the engineers behind it aren't happy with the solution but given that the main priority was getting the country back online ASAP, choosing to push on with the repairs makes sense. Especially as they didn't have 90km of cable available to replace it with.
They probably also closed the ticket with "recommend for replacement".
Yup. Cable cuts and repairs are one of the main factors for cable lifespan. So the more cuts, the more splicing losses. Eventually that leads to replacing the cable, or segments between repeaters to remove the splice losses. That'll be up to the cable owner(s), who'd need to get new cable and condition it prior to replacing damaged segment(s).
It's all sorts of fun. Designs have cable spans between repeaters (torpedoes) and spacing is based on projected signal losses, plus some safety margin, especially on sections at higher risk of being broken. So if this cable had breaks either side of a repeater, then multiple sections might need replacing.
Age and upgrades can also cause issues. So Neal Stephenson's article mentioned FLAG and FEA. That had a cunning in-service capacity upgrade using some optical-fu and filters. If the same is true for this cable, then it might need more time to spin up more suitable fibre.
Or it could be the cable is there, just in the wrong place. Spares can get held in wet storage, that might also be used to condition it, ie stored around it's expected operating depth. So then cable ships might have to sail to the storage location, load cable, then head for the break. That could mean weeks of sailing time.
Oh, and 'renewables'. Buying and operating cable ships isn't cheap, and they're rather specialist. So some years ago, there were concerns that operators couldn't stay in business unless telco's paid a lot more in O&M. But along came offshore energy projects, and a larger customer base to keep the cable ships afloat. Which also means more competition for those ships, ie if they're laying an HVDC cable, they aren't laying fibre.
It's a fascinating part of telecoms though, and the Porthcurno Cable Museum is a fun place to learn more.
Starlink (and its other LEO sat competitors) have massive potential for internet connectivity for remote islands, boats, cabins in the woods etc. It's even possible that they'd have noticeably better rates than those living in cities because contention would be non-existent.
As for Ukraine, the issue I see there is Russians will develop capabilities to disrupt the service and it might even get lucky and take out the entire system. Russia hacked another sat service on day 1 so they clearly have intent. That aside I think these things will be covertly used although it would be better if there were smaller receivers that weren't so overt and could be operated from batteries and stashed when not in use. Starlink is supposedly producing versions for boats & trucks so maybe they could be repurpose for that task.
Physically the cables are likely to be somewhat interchangeable. They may vary in the number and type of fibres, the voltage rating (for power to the repeaters) and the amount of armouring and tensile strength - but broadly I would suspect that there will be some consistency such that a similar cable could be found.
However the repeater/regenerator units are most likely completely custom to that link. Even if they are manufactured based on a standard type they are likely still customised in some way to the individual system. However, the system plans will always call for a certain number of spares to be made and stored.
Source: I used to work for STC Submarine Systems. Although this was a while ago and I guess things could have changed since then...
Many years ago I worked for a company that provided the positioning systems for such operations & watched the cable being fed from a overhead gantry/conveyor to one of three "cable tanks" while prepping the Sir Eric Sharp* for such a undertaking.
The cable was certainly hefty & was guided by operators into a tight coil to be played out later (1700 tons), I have no idea what that equates to in distance.
Edit, some time after writing this in the edit window a figure of 5KM or Miles popped into my head, I can't swear to its accuracy & if that was the total capacity of the three tanks or just one (I suspect the former).
*IIRC - The date (1989 Commissioning) seems right but I may be confused as after I left the company & joined RACAL, a few years later one of my younger colleagues went to work for C&W as Electronics Tech\Junior officer possibly on that same ship hence the icon as he was taught to use firearms in case of piracy.
https://atlantic-cable.com/Cableships/SirEricSharp/index.htm
Some of these ships can carry 1000's of miles of cable - at least of the thinnest, least armoured stuff that normally makes up the majority of the length. Length considerably reduced as the level of armouring goes up. If I recall correctly, trans-Atlantic links were often done in two main lengths and then perhaps one more short length at each end with the heavily armoured cable.
Having said that, the "Sir Eric"'s CV does suggest that it mostly worked on the shorter length projects, the shore ends and repair missions so perhaps it's not one of the bigger cable ships.
Your memory of 5km or miles is probably a little low but, to be fair, if it was triple armoured cable than actually that could be a per-tank figure. That stuff has a much higher cross sectional area and a reduced bend radius so possibly they wouldn't be able to use all the capacity of the tank either.
Knowing how difficult sub-sea cables are to work on; you have to question the wisdom of such projects as the HV link to Iceland; or Xlink to Morocco.
When the profitability of your entire project dangles on one very credible, and very expensive failure mode with no real options to mitigate that should be cause for some concern.
It's proven difficult enough to do shorter examples in much shallower and less hostile waters. If you can pull it off, fantastic. "If". A more moderate route, say Morocco-Spain and then travelling via existing or expanded networks would surely make more sense and be more maintainable.
One thing I find very surprising is that it still apparently makes economic sense to use fibre comms for countries with comparatively small economies. Not for much longer.
For those interested in more detail about submarine cable systems and their repair, the International Cable Protection Committee has some informative publications on their website: https://www.iscpc.org/publications/
Direct links to:
Submarine cables and the oceans: connecting the world Adobe Acrobat Document (.pdf) - 2.62 MB
A report prepared in collaboration with UNEP (United Nations Environmental Programme), which is designed to provide an objective, factual description of the submarine cable industry and the interaction of submarine telecommunications with the marine environment.
and
About Submarine Telecommunications Cables - 2011 Adobe Acrobat Document (.pdf) - 8.51 MB
PDF version of MS PowerPoint slide show presentation. An informative presentation on submarine telecommunications cables and their role in the modern world.
NN
The TeleGeography stuff is nice, especially if you can afford their commercial stuff.
I quite like Greg's Cable Map. Having both available is luxury.
Neal Stephenson's travel-log/essay on international communications cables is still a good read. Light on juicy technical details, but definitely an engaging read.
Reading this article was part of what got my brother into the cable-laying business, as an undersea surveyor.
The existence of turbidity currents was proven by the 1929 M7.2 Grand Banks Earthquake off the eastern seaboard of Canada.
A series of massive currents slid down the continental shelf slicing twelve Transatlantic cables. The first six to fail were relatively shallow and failed almost immediately with the shock, whilst the remaining cables failed one by one over a period of 13 hours beginning in shallow waters and ending with the deepest cable. The exact moment each failed was recorded and allowed geologists to calculate the speed of the currents at anything up to 100kmh - underwater remember.
The slides were immense, reaching more than 1000km from their origin and moving more than 200km3 of material to the ocean floor. Oh and the cause of the earthquake - like many on the Eastern Seaboard - is very poorly understood.
The cable probably makes a bunch of drops in other countries, you don't want to disturb those to replace the entire cable. You think 60km of cable is pricey, but 1000s km is a lot more and the time for the cable laying ship. Then the bits going ashore at all the other stops are a lot more expensive to build and lay.
Then you have a bunch of repeaters that cost $$$$$$ and aren't exactly next-day delivery.
You might pull forward the business case for the next upgraded cable but you aren't going to rip and replace a working one
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