When I was working for a national UK bank, a while back, a passenger jet crashed within half a mile of our secure data center (placed outside the metropolis, in open country). It caused a major exercise in working out what would have been the effect on our operations if the plane had crashed a few yards closer. The answer, they concluded, would probably have been the disappearance of the bank. They'd never have recovered from the mess, and what is worse, countless thousands of depositors would have been unable to get their money out due to the disappearance of the necessary records of their account. This, in turn, could have caused widespread economic chaos. The bank therefore worked out a new system to enable it to survive such a catastrophe. This was passed on to other financial institutions and has since served well in subsequent natural disasters accidents, and terrorist organizations.