"Looking at the maps, the earthquake occurred in an area where we do not expect a strong acceleration of the ground", explains Lucia Luzi, director of the Milan branch of the Istituto nazionale di geofisica e vulcanologia (Ingv). The epicenter, the first evaluations, it was placed between Corsico and Pear, 6 kilometres west of the capital, while the depth where it is triggered is estimated to be around 56 km away. "Under the milan area there are several faults, and then the territory is no exception compared to the rest of Italy that is the whole of seismic risk — continues the scientist —. However, the last earthquake the more significant of the area was recorded in 1951 in Lodi and he had reached a magnitude of 5.4 on the Richter scale. In the Milan area, historically, you feel more resentment of the other earthquakes that occur far away, like the one of 2012 in Mirandola. Looking to the past centuries, a similar effect to that of today can be seen in 1473, with the uncertainties of the case, of course."
The push toward the North
in order To explain the origin of the current event there is a need in general to the thrust exerted by the african plate towards the North, against the continental plates of europe which, then, is divided into plates smaller as that of the adriatic which, in their turn, exert pressures in different directions. "Therefore, in this geological context, the whole of the area from Piedmont to Friuli-Venezia Giulia", explains Carlo Doglioni, president of the Ingv, "undergoes a contraction from the north to the south that can go from less than a millimetre per year in the lombardy area, about two millimetres to the area of friuli". "But the tectonic structures are varied between them, and also that of 1951 it was different than the present," continues Lucia Luzi. "The faults in the area of milan are so different and for now the activity has been contained as history shows. Certainly the most dangerous areas of the peninsula along the Apennines; but we can not exclude anything. The shock in the Milanese, being generated directly in the subsoil, has been more briefly but more intensely, while the other, of resentment come to the epicenter and farther away are more long in time".
Among other things, for the earthquake of 1951 there was controversy because some believed then that the cause was linked to the extraction of oil carried out by Eni. Instead, the checks carried out later", states the president Doglioni, "have demonstrated the absence of any connection, his origin was much more in depth." In the area of northern Italy, Lombardia is included, the evaluations of the national Institute of geophysics and volcanology recorded in the history of the past millennium 110 earthquakes significant, from Piedmont to Friuli-Venezia Giulia, starting from that of Brescia, of the 1065. The most destructive hit Verona in 1117, reaching a magnitude of 6.7 on the Richter scale.
The hazard map
In 2004, the national Institute of geophysics and volcanology has developed the first seismic hazard map of the territory, and then with increasingly prevalent and sophisticated is updated by providing the appropriate guidance for the earthquake-resistant buildings. At the local level, then, the Regions do further detail work with the maps of the microzonizzazione. But these have not yet been realized in many areas of the peninsula.