Recently, scientists have reevaluated their model of the Yellowstone caldera (also called a supervolcano or megavolcano), estimating that there is 50% more magma beneath the surface than previously thought and that the magma is contained within a single large chamber. Yellowstone National Park is, technically, a volcano in the process of preparing to explode once again, generating 1,000-3,000 earthquakes a year and displaying thermal activity on the surface--the last time it erupted was 640,000 years ago, though there have been smaller events as geologically recent as 70,000 years ago.
Are there any volcanoes in your region? Have you ever been to Yellowstone?
----The Golden Eagle