Usually breaks are caused by humans (ships pulling anchors, sabotage/spying). Sometimes they're natural (caused by wildlife, ocean floor movement, flaws in the cable design).

Fixes usually take a few hours if they happen at the endpoints, or weeks if they happen somewhere under the ocean.

Interestingly, spying breaks always involve three simultaneous breaks in the cable. The cable is broken at two points, and then broken at a third point in the middle to put spy equipment. They do this so the people operating the cable can't tell where the spy equipment was inserted, since otherwise you can tell where a cable is broken or being tampered with by sending light down the cable and seeing how long before light reflects off the broken bit and comes back to the end.

Using statistical methods, you can see how frequently you'd expect a cable to break at different points along it's length simultaneously, and it happens a lot more than raw chance would suggest.

This is not true. Submarine cable installations generally have a lifespan of 20-25 years although that's even being extended now to 30 years with advances in WDM gear. Also in water deeper than 1500 meters the cables are typically laid on the ocean floor. This is done because it is beyond the limit of trawl fishing anchors.

>"Interestingly, spying breaks always involve three simultaneous breaks in the cable. The cable is broken at two points, and then broken at a third point in the middle to put spy equipment."

Yeah this is not true at all. Where did you get this from? Fiber cables can be tapped by simply adding a bend radius to the cable which allows it to leak. [1], Further you can shoot a light down both ends of a fiber and easily discern that there is more than one break in the cable.

[1] https://www.thefoa.org/tech/ref/appln/tap-fiber.html

IIRC at BSidesLV last year there was a vendor selling optical splicing modules which were rather difficult to detect using this technique.

Per wikipedia: > Still, cable breaks are by no means a thing of the past, with more than 50 repairs a year in the Atlantic alone,[48] and significant breaks in 2006, 2008, and 2009.

Can you further explain this part? It sounds so out there with undersea cable.

The only thing I can think of is that wildfire cause erosion in soil which wash off into the sea and damage the end point?

Things like a whale getting entangled in it, and then using all its strength to get free, breaking the cable.

Submarine cable is buried when it's at depths of 2000 Meters or less. It is done so using jet-plow technology. Beyond depths of 2000 meters the cable simply sinks to floor and rests there. It most certainly does not hang across a valley the way high tension power lines do above ground. Also cable routes are carefully planned to avoid trenches wherever possible. Where that's not possible it's simply sunk by its' own weight down to the ocean floor.

I'd expect cables in shallow water in fishing areas to be broken more often than deep floating cables in the middle of the Atlantic.

I've never heard that they break the cables, but rather "bend" them so that light leaks out of the fibre.

-- Gen. Michael Hayden (retired), former Director of both the CIA and NSA.

Not everyone treats long haul as secure until they learn the hard way. Few are big enough to find out.

https://www.computerworld.com/article/2541664/fishermen-pull...

Of course there are also accidental breakages and other things. That is to say there are many root causes, not necessarily intuitive.

If you can go thousands of miles across the Pacific and be "quite stable", and a shallower, shorter run through similar ocean floor and ship traffic conditions between HK and the Philippines suffers fewer outages than one to Vietnam, yeah, censorship seems like a pretty reasonable conclusion.

Imagine if your job is to drive the tractor on the beach that would "chop" the cable up once or twice every year...

This is less the case for people using other providers.

This is silly, the internet at night is slow simply because there are too many people are using it at the same time. Bandwidth is not limitless, and they are shared for the same neighborhood.

Also, having a 100Mbps internet plan doesn't mean you will be guaranteed to have 100Mbps download/upload all the time. There are reason why in VN companies like netnam and cms are selling 50Mbps leased line for 1000+ dollars.

Try to download some highly seeded torrents at the "throttled hours" to see for yourself.

[1] http://texyt.com/vietnam+internet+cable+stolen+by+thieves+00...