Giuseppe Mercalli invented the Mercalli intensity scale in 1902 as a way to measure the effects of an earthquake. The scale is based off of the observations of the people who experienced the earthquake.
The Mercalli scale originally rated earthquakes on a 10-degree scale, but was later modified in 1904 to have 12 degrees, ranging from instrumental to catastrophic. The scale was rewritten again by geophysicist August Heinrich Sieberg, and was known as the Mercalli-Cancani-Sieberg scale. This scale was modified and translated into English in 1931 by Harry O. Wood and Frank Neumann, and finally improved by Charles Richter. In modern times, it is known as the Modified Mercalli intensity scale. The Mercalli scale measures the effects of an earthquake, and the popular Richter scale measures the energy of an earthquake.