GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 2.3 523 calculation, for which we use an approach based on the maximization of the signal-to-noise ratio by using a technique recently proposed by Malagnini and Munafò (2018), Malagnini and Dreger (2016) and Munafò et al. (2016). We calculate the moment magnitude, Mw, of each single event present in the data set, separating the contribution of the seismic source, the site and the regional crustal attenuation (namely, body-wave geometrical spreading g(r), crustal attenuation parameter Q(f), residual systematic attenuation parameter k , as in Munafò et al. , 2016). Using this approach it is possible to estimate Mw in a clear and unambiguous manner. Among a number of sites in which we expect to implement the proposed analyses, we are particularly interested in considering as case study the Cavone oil field (Emilia Romagna region, Italy) because of the availability of microseismic data that has been shared within the context of the experimental implementation of the National Guidelines for monitoring (ILG, Indirizzi e Linee Guida), and according to the agreement among the MISE, INGV, Assomineraria and Società Padana Energia. The Cavone oil field is located in the E–W trending sector of the Ferrara arc belonging to the external fold-and-thrust system of the Northern Apennines belt, completely buried by thick Quaternary sediments of the Po plain. The Cavone oil field produces from a Mesozoic carbonate reservoir at a depth of about 2900m. The reservoir lies within an anticline displaced by reverse faulting, in a fold-fault system verging North, intersected by thrust faults oriented E-W. This site has been thoroughly investigated by different teams after the 2012 Emilia seismic sequence to evaluate the potential of triggering/inducing seismic events by the industrial activities carried out at the field (wastewater reinjection in particular). For example, the report Fig. 1 - Seismicity distribution of about 1000 earthquakes recorded between 2010 and 2017 by the Cavone oil field seismic network (green triangles) in the area. Blue dots show the locations of the earthquakes, pink triangles indicate the Italian National Seismic Network operated by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the red squares indicate the main cities. Three cross sections (1, 2, 3) show the earthquake distribution at depth along the dotted lines in the main map.