Whirlibird, If Yellowstone does go off no one knows how fast it will happen. Studies from the past eruptions show that it may take from 7 to 14 days for the total eruption. So there is some time to go somewhere else if you leave the minute you hear of an eruption. Also if you read the history of all of the eruptions you will find that each one was located in a different area miles away from each other. So it all depends were the eruption happens too.