Central Oregon's Cascade Range. Getty Images Most people, when asked what area in the Cascade Range has spit the most lava and ash out over the past 5,000 years, would answer Mount St. Helens. It is the Cascade volcano that has had the most well-known eruption in US history (its 1980 blast) and is the only volcano in the entire range to have erupted in the past 100 years. So, as this leading question might imply, you'd likely be surprised to find out that Mount St. Helens isn't the leader in volcanic eruptions. In fact, neither is Rainier or Lassen or Hood. In fact, the leader in total volume over the past five millennia doesn't even really have a name---but has dumped 15 cubic kilometers (that's over 3.5 cubic miles) of lava onto the surface of the Earth.