I think "survivable" is to be understood on a civilization scale, not for individuals. It would definitely be a calamitous event with massive loss of life - but

I think "survivable" is to be understood on a civilization scale, not for individuals. It would definitely be a calamitous event with massive loss of life - but if you survive the attack itself and can feed yourself and otherwise survive for a few months perhaps, you would have decent odds. I think.