Mercalli intensity scale
The earthquake of 13 January 1915 (also known as the earthquake of Avezzano) affected the Marsica area, situated in the interior of Abruzzo. It was one of the most catastrophic earthquakes to occur in world territory, leaving 120,000 victims in Avezzano and surrounding areas. While the mainshock occurred at 7:48 AM local time and was judged to be X ("Extreme") on the Mercalli intensity scale, the initial aftershock was estimated to be VII ("Very strong") on the Mercalli intensity scale and was felt throughout all of central Italy.