GNGTS 2017 - 36° Convegno Nazionale

48 GNGTS 2017 S essione 1.1 occurred and new knowledge has been acquired. Seismic networks have been implemented, the Po Plain and the Northern Apennines have been affected by several seismic sequences and new studies have been performed. This allowed us to acquire a considerable amount of new data and to better characterize the tectonic structures. Therefore, we considered necessary to update the first edition of the seismotectonic map, expanding the study area (Figs. 1 and 2; Martelli et al. , 2017). The extension of the studies on a larger area became necessary because some geological processes, although far, may influence the safety of the territory and activities in the region. For instance, the strong earthquakes that struck the northern Po Plain/south Alpine margin (1117, 1222, 1695), Mugello (1919) and Garfagnana (1920) caused serious damage in Emilia-Romagna. To compile a seismotectonic map it is essential to identify and represent the active tectonic structures. According to the purposes of the map, among which is to provide regional-scale data and information to plan more detailed specific studies, we decided to adopt a broad definition of the term “active”, confirming the one adopted in the previous edition. We therefore mapped as “active” those structures that show clear evidence of influence on the evolution of the present morphological landscape or have deformed stratigraphic horizons not older than 450 ky (age of the base unconformity of Upper Emilia-Romagna Synthem). Structures showing minor or not certain evidence of morphological influence on the evolution of the present landscape or deformation of stratigraphic units not older than 450 ky have been mapped as “potentially active”. The new map. To realize the new map, in addition to the verification of data published in 2004, specific studies and new surveys were carried out. Seismologic data. To better characterize the seismicity of the Emilia-Romagna we considered earthquakes located in a larger area than the regional territory. In the map we represent the epicenters of earthquakes with a M≥4 and the available focal mechanisms. Symbol size is proportional to the magnitude; the color of the focal mechanisms is indicative of the focal depth. Fig. 1 - The new seismotectonic map of the Emilia-Romagna Region and surrounding areas (simplified version).