The Yellowstone caldera is not dead, only sleeping. When we were there this summer, we learned that, among other things, the Mud Volcano has recently come to life again after being still for many years. And now there's an earthquake swarm going on there, with a dozen 3.0 + quakes in the last couple days. Pretty creepy. If that supervolcano were to go off, it would be a truly Cataclysmic Event.