A Report on the 2012 Seismic Sequence in Emilia (Northern Italy)

Since mid-May 2012, an energetic seismic sequence has affected the northern part of Italy and specifically a wide sector of the Po River Plain. The sequence has been dominated by two main events: a) Mw = 5.9 occurred near Finale Emilia on May 20th at a depth of 6.3 km, and b) Mw=5.8 occurred near Cavezzo on May 29th at a depth of 10.2 km (earthquake location are obtained Istituto Nazionale di Geofisica e Vulcanologia, http://iside.rm.ingv.it/). The effects of the two main shocks can be summarized as follows: - damage to infrastructures (roads, pipelines) essentially because of the occurrence of liquefaction phenomena or soil failure; - damage to very old constructions (especially churches and bell towers – masonry and brickworks); - recent constructions such as barns and industrial premises have collapsed. These constructions were mainly isostatic structures not designed to withstand earthquakes. The paper deals with the following arguments: - seismological aspects, mainly related to the seismo - tectonic framework, the source mechanisms, and the comparison between the observed seismic motion and that expected on the basis of the National Map of Seismic Hazard; - identification and mapping of the soil failures (liquefaction) and induced damage with special emphasis on the geomorphologic structures showing the presence of ancient riverbeds; - description of the structural damage regarding the historical buildings and the modern industrial buildings. In conclusion the report try to explain the reasons for the large damage observed in the case of both ancient and modern constructions.