The earthquake was centered 9 miles west-southwest of Trinidad, Colorado and 180 miles south of Denver.
Prior this earthquake there were three smaller ones earlier in the day - a 3.0, 4.6, and 2.9.
As of 7:30 AM Tuesday there have been 7 aftershocks ranging from magnitude 2.5 to 3.5.
This is the most powerful Colorado earthquake since 1973 when a 5.7 magnitude struck the northwest part of the state, about 50 miles north of Grand Junction.
There are reports of minor damage to homes in the Trinidad area. Groceries also fell of shelves at stores.
Officials are also investigating reports of rockslides on area roads but this has not been confirmed.