As a volcano erupts in the Caribbean, meet Coloradoâs lone active volcano Lee Siebert, 1999 (Smithsonian Institution) During the mid-Holocene, a maar was formed in central Colorado near the junction of the Colorado and Eagle Rivers west of the Gore Range. Today, this is known as Dotsero. and last updated 2021-04-09 17:52:11-04 EAGLE COUNTY, Colo. â As an ash cloud rose 6 miles above an erupting volcano in the Caribbean Friday morning, an active volcano sat quiet and still in the Rocky Mountains of Colorado. Could it see a similar fate anytime soon? Spoiler: Nope. Not for a very, ve...