Earthquake intensity's qualitative measure. Uses a linear empirical scale based on seismic phenomenon's observed effects. Earthquake intensity plots on a scale I to XII. Roman numerals are used in contrast to the Richter scale, the measure of earthquake magnitude. In 1902 the Italian geologist Giuseppe Mercalli (1850-1914) defined this method. In 1956 Charles Richter developed the US version known as the Modified Mercalli.