I would like to point out that some of the disasters you name are cyclical events, that happen on fairly predictable patterns... I live near the New Madrid fault and it goes off every few hundred years in a big way. The last series of big quakes was 1809-1810 I think, and the Mississippi river changed course, lakes drained and disappeared, etc etc. People from St Louis to Memphis half expect it go again any day now. The people who lived through it probably thought it was the end of the world. It wasn't.