The Mercalli scale measures the intensity of these from I to XII
Details of how these scales compare are discussed by Rick Aster on page 8 and
... [DOC] [TLE] Introduction to the Earthquake Intensity Database | NCEI [PAR] Intensities are evaluated using the Modified Mercalli Intensity Scale of 1931, 
which ... ranging from intensity I, barely perceptible, to intensity XII, total damage.