Habu, Mammoth Mountain in California is another semi-active volcano that may be due to blow on a 100,000 year clock, I’m too lazy to google the figures but IIRC while not quite Yellowstone size seems capable of covering Los Angeles 300 miles away with a foot or more of ash, probably even more so for Las Vegas, and do no good at all for the thousands of tourists visiting it at any time, bathing in the hot springs and all between ski runs or summer hikes. Had a number of 5.x and I think 6.x quakes there a few years ago, I believe it’s been mostly quiet more recently.

Uh-oh, CO2 emissions, too!

http://en.wikipedia.org/wiki/Mammoth_Mountain