Yellowstone super volcano
Im suprised people dont pay more attention to it, being that this thing will be our doom. Most experts agree that it is overdue to blow up(could happen by the time Im done writing this) and when it does humanity will most likely die out. Within a thousand miles of the park, everything will be simply gone. What follows is even worse, the ash will block out the sun and then it is high time to say goodbye.
-Be wary of the earth, for when it angers you will know power.-
or something like that...