Two earth tremours were felt in Barga this morning. The first one was just before 11am and was measured at 2.8 on the Mercalli scale. The second, an hour later was larger – reaching 3.2 on the Mercalli scale. No damage has been reported and most people only noticed the earth tremour by the electric lights swinging slighty.
The Mercalli scale originated with the widely used simple ten-degree Rossi-Forel scale, which was revised by Italian volcanologist Giuseppi Mercalli in 1883 and 1902. In 1902 the ten-degree Mercalli scale was expanded to twelve degrees by Italian physicist Adolfo Cancani The scale was later modified and published in English by Harry O. Wood and Frank Neumann in 1931 as the Mercalli-Wood-Neuman (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 Scale and commonly abbreviated MM or Io.
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