Yellowstone National Park
Most of you know that Pearl (or The Book Whose Name Must Be Changed - more on that later) is set in Montana near Yellowstone.
A premise in the book is that Loki (the evil trickster god in Norse Mythology who is responsible for earthquakes on Earth) is setting up to explode Yellowstone and consequently wreak havoc on the world.
Yellowstone has thousands of mini earthquakes every year, and it also sits on top of a caldera (an active volcano). Which is why we get all the super cool geothermal features there.
Geysers. Fumaroles. Mud pots. Hot springs.
You get the picture.
Scientists are debating when the caldera will erupt next, and here's a little National Geographic video that talks about it: