re: Un-zipping the continent
Geology is fascinating. Maybe 25 years or so ago, the New Madrid had a mild quake. I lived in Nevada, MO at that time and felt it there, just a few seconds vibration. There is something about the terrain that carries even mild quakes so that you feel them even that far away. I remember reading that if a major one hit New Madrid, we'd feel it all the way up to Kansas City.
I read we're not quite overdue for one so it might be another 100 years or so.