Yellowstone National Park in North America is part of a crater of a supervolcano that last erupted 640000 years ago. The supervolcano has erupted 3 times in the last 3 million years. Scientists predict it could erupt at any time now.
The supervolcano at Yellowstone is formed because of a volcanic hotspot. This is where a super hot plume of magma moves towards the Earth’s crust and melts it creating a huge chamber of magma below the ground. The hot spot is static but the Earth’s crust moves over it. Therefore there have been many craters across the US caused by this hot spot.
Yellowstone is a popular tourist attraction with many tourists visiting to see the volcanic features, such as geysers and hot springs. Old Faithful is one example of a geyser.
The video below provides a good overview of what could happen at Yellowstone in the future.