Yellowstone Caldera

Yellowstone The oldest identified caldera near McDermitt, Nevada–Oregon,  Yellowstone super-volcano is one of the most dynamic sites on earth, this volcano would be devastating for the United States as an estimated 87,000 people would be killed instantly and two-thirds of the U.S land would be destroyed 

Millions of years ago, a source of immense heat known as a hotspot formed in the Earth's mantle below what today is Yellowstone. Roughly 600,000 years ago, the hotspot pushed a large plume of magma toward the Earth's surface. This caused the crust to just upward.