The intensity of an earthquake is a measure of its effects on people, structures, and the land at a particular place. The United States uses the Modified Mercalli Intensity Scale to measure earthquakes' intensity. Its twelve levels are identified by Roman numerals.

Levels V, VI, and VII describe the intensities of Colorado’s big quakes.

Mercalli Intensity Level
V Felt by nearly everyone; many awakened. Some dishes, windows broken.
VI Felt by all; many frightened. Some heavy furniture moved. Damage slight.
VII Everyone frightened. Damage considerable in poorly built or badly designed structures, slight to moderate in well-built ordinary structures.