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|Died||March 19, 1914(aged 63)|
|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 which is still used today.
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 and finally a post at the Naples University. He was also director of the Vesuvius Observatory until the time of his death.
The Mercalli intensity scale, unlike the Richter magnitude scale, measures not the energy released by an earthquake but the effects an earthquake had on a given area. This makes it poorly suited for measuring earthquakes in sparsely populated areas but ideal for comparing damage done by various tremors. The Mercalli scale, which has been widely used in earthquake engineering, gives a rating from I to XII, where I is felt only by a few people and XII has near total damage, few or no masonry structures remain standing, and objects are thrown into the air.
Giuseppe Mercalli also witnessed the eruptions at the Aeolian Islands of Stromboli and Vulcano. His description of the two volcanic eruptions is used by volcanologists everywhere. He also photographed Vesuvius immediately after its eruption in 1906.
In 1914, Mercalli burnt to death under suspicious circumstances, allegedly after knocking over a paraffin lamp in his bedroom. He is thought to have been working through the night, as he often did (he once was found working at 11 a.m. when he had set an examination, upon hearing which he replied, “It surely can't be daylight yet!”), when the fatal accident occurred. His body was found, carbonized, by his bed, holding a blanket which he attempted to use to fend off the flames. The authorities, however, stated a few days later that the professor was quite possibly murdered by strangling and soaked in petrol and burned to conceal the crime because they determined that money now worth about $1,400 was missing from the professor's apartment.
Mercalli was the author of two intensity scales. The first (Mercalli, 1883), was according to Davison (1921) a mere adaptation of the Rossi–Forel scale. It has six degrees unlike the ten degrees of the Rossi–Forel scale. Now, it is largely forgotten. Mercalli's second scale (Mercalli, 1902), has ten degrees (unlike the twelve degrees that are wrongly claimed on many websites) and is basically an expansion of the descriptions states in the Rossi–Forel scale.
In 1904, the ten-degree Mercalli intensity scale was expanded to twelve degrees by Italian physicist Adolfo Cancani, who added two extra degrees at the top of the scale (the degrees XI (catastrophe) and XII (enormous catastrophe)). It was later completely rewritten by the German geophysicist August Heinrich Sieberg and became known as the Mercalli–Cancani–Sieberg (MCS) scale. The Mercalli–Cancani–Sieberg scale was later modified and published in English by Harry O. Wood and Frank Neumann in 1931 as the Mercalli–Wood–Neumann (MWN) scale. It was later improved by Charles Richter, the father of the Richter magnitude scale. The scale is known today as the Modified Mercalli intensity scale or Modified Mercalli intensity scale and is abbreviated MM or MMI.
- Howell, Jr., B. F. (2003), "Biographies of interest to earthquake and engineering seismologists", International Handbook of Earthquake & Engineering Seismology, Part B, Volume 81B (First ed.), Academic Press, p. 1761, ISBN 978-0124406582
- "PROF. G. MERCALLI BURNED TO DEATH; Famous Director of Vesuvian Observatory Upsets Oil Lamp Upon Himself". The New York Times. March 20, 1914.
- Cancani A (1904) Sur l’emploi d’une double echelle sismique des intensitès, empirique et absolue. Gerlands Beitr Geophys 2:281—283
- Davison, C. (1921) On scales of seismic intensity and on the construction of isoseismal lines. Bull. Seismol. Soc. Am. 11:95—129
- Mercalli, G. (1883) Vulcani e fenomeni vulcanici in Italia. In: Negri G, Stoppani A, Mercalli G (eds) Geologia d’Italia. Vallardi, pp 217–218
- Mercalli, G. (1902) Sulle modificazioni proposte alla scala sismica De Rossi–Forel. Boll Soc Sismol Ital 8:184—191