Can dematerialised shares be erased from the depositary database?

Hello guys,

I have a question that is bothering me. As you all know more than 99% of securities does not have a physical form but is dematerialised.

Now imagine a powerful solar flame that destroys all electronic data or a nuke that destroys New York City. Would that mean that the ownership of all dematerialised securities is gone? It reminds me of the Mr. Robot series and what happened there. Please tell me I am wrong.