Giuseppe Mercalli

Giuseppe Mercalli
Giuseppe Mercalli
Born	May 21, 1850
Died	March 19, 1914(1914-03-19) (aged 63)
Nationality	Italian
Fields	Volcanology
Known for	Mercalli intensity scale

Giuseppe Mercalli (May 21, 1850 – March 19, 1914) was an Italian volcanologist and Catholic priest. He is best remembered for the Mercalli intensity scale for measuring earthquakes.

Born in Milan, Mercalli was ordained a Roman Catholic priest and soon became a professor of the Natural Sciences at the seminary of Milan. The Italian government appointed him a professor at Domodossola, followed by a post at Reggio di Calabria. He was professor of geology at the University of Catania in the late 1880s and finally was given a post at the Naples University. He was also director of the Vesuvius Observatory until the time of his death.

He is best remembered for the Mercalli intensity scale for measuring earthquakes which, in modified form, is still used today. Unlike the Richter magnitude scale, which measures the energy released by an earthquake, the Mercalli intensity scale measures the subjectively assessed effects of an earthquake. It is poorly suited for measuring earthquakes in sparsely populated areas but ideal for comparing damage done by various tremors, and is useful in earthquake engineering. The scale in use today assigns indices ranging from I - "Not felt, except by a few under favorable conditions", to XII - "Damage total; objects thrown into the air."

Giuseppe Mercalli also observed eruptions of the volcanoes Stromboli and Vulcano in the Aeolian Islands. His descriptions of these eruptions became the basis for two indices in the Volcanic Explosivity Index: 1 - Strombolian eruption, and 2 - Vulcanian eruption. He also photographed Vesuvius immediately after its eruption in 1906.