A 3D model of the crustal volume in which the Amatrice earthquake of 24 August 2016 was generated and the subsequent seismic sequence: it is one of the results of the RETRACE-3D project (centRal italy EarThquakes integRAted Crustal model; www.retrace3d.it), a work carried out jointly by the Department of Civil Protection together with the research institutes CNR-IGAG, CNR-IREA, INGV and ISPRA for the development of original products that represent an innovative point of view on the seismotectonics of the Central Apennines.
More than 60 researchers and experts, belonging to the aforementioned institutes or associated universities, contributed to the project, which covered an area of approximately 2.500 km2, straddling the Lazio, Abruzzo, Umbria and Marche regions, affected by over 118.000 events seismic events between 2016 and 2019. Two private companies such as Eni and Total have also agreed to contribute to the project, providing a considerable amount of data (reflection seismic profiles, stratigraphies of deep wells, gravimetric and magnetic data, scientific and technical reports) , the result of their activities in the area, making their own available technical know-how. Furthermore, all the research institutes involved made the contents of their databases available for the project.
The RETRACE-3D project carried out a review of all the geological and geophysical data available in the area affected by the 2016-2017 Central Italy seismic sequence, with the ultimate goal of reconstructing a reliable and coherent 3D geological model of that area and accurately define the three-dimensional distribution in the subsoil of the most relevant geological units and main faults, including seismogenic ones. Certainly challenging but fundamental objectives, as a complete geological model and a detailed 3D image of the crust up to about 10-15 km of depth were lacking for those crucial areas.
The work confirmed once again the need for a three-dimensional approach to fully grasp the existing tectonic complexity. Since the early days of the seismic sequence, the difficulty in trying to relate the surface structural elements with the seismicity alignments observed at depth had in fact appeared quite clear to the scientific community.
The idea for the project was born immediately after the devastating earthquake of 24 August 2016, at the DICOMAC set up in Rieti by the Civil Protection Department, from where emergency management was coordinated. Indeed, one of the peculiarities of the Italian civil protection model is the very close relationship between operational management and the role of the scientific community, immediately involved in the field with monitoring, analysis and evaluation tasks. The guiding principle of the work was the belief that the wider the scientific community involved, the higher the value of the final product.
The added value of the project is that it is a virtuous and easily reproducible model of institutional and scientific collaboration, which includes a constructive public-private synergy. Gods were rarely made available at the same time dataset of such high quality, such a significant level of expertise and the ability to integrate so much information and technical know-how multidisciplinary to study an area such as the one affected by the seismic sequence of Central Italy of 2016-2017. Conceived during a seismic emergency, the project can represent a successful working scheme to be activated quickly in case of similar emergencies, but also applicable in the ordinary to specific areas with high seismicity, preparing geological models in advance, to support more reliable interpretations on the activation of faults and the relative danger.