Yellowstone National Park's many thermal mineral springs and geysers are features of the volcanic activity underneath the ground. Scientists at NASA are convinced that the threat of a supervolcano erupting from the magma chamber under Wyoming, Montana, and Idaho is greater than the threat of an asteroid or comet hitting the earth.
When Nasa scientists came to consider the problem, they found that the most logical solution could simply be to cool a supervolcano down. A volcano the size of Yellowstone is essentially a gigantic heat generator, equivalent to six industrial power plants. Yellowstone currently leaks about 60-70% of the heat coming up from below into the atmosphere, via water which seeps into the magma chamber through cracks. The remainder builds up inside the magma, enabling it to dissolve more and more volatile gases and surrounding rocks. Once this heat reaches a certain threshold, then an explosive eruption is inevitable.