There's never going to be 100% safety when storing your private keys, or with anything else for that matter.  I saw the video of the Beirut blast, and you'd have to have your HW wallet or flash drive or piece of paper with your seed words on it buried pretty deep if you were storing any of those things near the blast zone--and even then, what's to keep rescue workers or the cleanup crews from stumbling across your stash before you do?

This is definitely one of the disadvantages of crypto, that you truly own your own money.  There's not a bank that's insuring it, and it's not stored on some corporation's server like stocks and other digital investments are.  If your private keys get blown up or lost or stolen, you're screwed. 

As an aside, I can't believe there were only around 100 casualties in that blast.  It looked like it would have killed a lot more people than that, though I don't know how dense the population was in that particular area at the time.  Scary stuff.