What scale is used to assess earthquake strength based on human perception?

The Intensity Scale is utilized to assess earthquake strength based on human perception and the effects experienced by individuals and structures. This scale takes into account the subjective experience of shaking intensity, the extent of damage to buildings, and the observable effects on people and the environment. The most commonly used version is the Modified Mercalli Intensity (MMI) Scale, which categorizes the intensity of shaking from I (not felt) to XII (total destruction).

This scale differs from the Richter Scale, which measures the energy released at the source of the earthquake and provides a quantitative measure of the earthquake’s magnitude, not based on human experience. Similarly, the Magnitude Scale specifically quantifies the size of an earthquake in terms of the seismic waves recorded, while the Seismic Scale is not a standard term used in seismology. The focus of the Intensity Scale is on perception and the resulting impact on communities, making it the correct choice for this question.