When you think of volcanoes in the United States, Hawaii likely comes to mind. However, America's most dangerous volcano isn't on an island.

Mount St. Helens sits just miles from the city of Seattle, and has erupted regularly throughout the past century. It last erupted on May 18, 2017, but scientists have picked up subterranean activity recently near the volcano.

Steve Olson, Author of "Eruption: The Untold Story of Mount St. Helens" discusses the likelihood of another eruption in the near future. He also takes a look at some of the other active volcanoes in the United States.

If a volcano erupts near a large city like Seattle, it would not only be dangerous for the people who live there, but very costly for the businesses located in the area. Olson discusses the economic impact that an eruption would have.