On April 1, 2022, a website called This Song is Sick posted an article that stated that the State of Colorado had discovered an active Volcano underneath the popular Red Rocks Amphitheatre. Despite some valid points stating that the state of Colorado did “diligent tectonic tests,” the article was posted on April Fools and is indeed FALSE.
The article ends stating “April Fools! This entire article is satire, in celebration of our favorite day on the internet. Enjoy!”
Origination: The article was an April Fool's joke
So there you have it, there is no volcano underneath the Red Rocks Amphitheatre known at the time of writing.