Indeed, even that natural disaster happens in a whole country at once, the damage will still not affect the communications and internet access in the world, as crypto is located in cloud of space, accessible with the use of internet worldwide. The only disaster that I can imagine that will really paralyze the crypto is when satellites in space will be destroyed or incapacitated by any reason.
There's something wrong in our space if that happens and that will be the end of Crypto if the internet is paralyzed because Cryptocurrency is internet base, you take away the internet and that's the end of everything on blockchain, no transaction no mining all totally stopped, but if it's only earthquake in one area we are still can transact.