## 4 Discussion
(2012), where the author found the presence of a high-density and high-susceptibility body that was 10 km wide, at 4-7 km depth. The presence of this body agrees very well with the inferred low seismic attenuation in that portion of the crust. [PERSON] et al. (2012) explained the presence of the deduced high-density/susceptibility body with the presence of an intrusive body within the sedimentary sequence, as outlined by the presence of minor outcrops of mafic intrusive rocks along the GP coastline. The observed northeastward-decreasing trend (toward the zone labeled C in Figure 8c) correlates well with the evidence of an anomalous absence of seismic activity in this sector at a depth of up to 20 km. In this frame, in the Northeastern sector of the GP, the low \(Q_{c}\) in the upper/intermediate crust could be representative of ductile behavior, a speculation that deserves further investigation. We did not find any correlation with major surface fault lineaments of the area, as depicted in Figure 1.  
In Figure 8c, at greater depths (24 km and 32 km), down to about 35 km, a high \(Q_{c}\) anomaly (labeled D, in Figure 8c) appears in the easternmost sector of the GP. In this area, seismicity is deeper, as can be also observed in Figure 2. With respect to the previous 2D mapping of \(Q_{c}\)([PERSON] et al., 2018), the easternmost part of the GP is covered by a seismic network, and it is now included in our results. It is very interesting that, in Figure 8c, in the two deepest map sections (24 km and 32 km), \(Q_{c}\) shows a decreasing trend (toward label E in Figure 8c) toward the southwest: in this sector, at a depth greater than 18 km, seismicity is not present ([PERSON] et al., 2018), the Adriatic Moho is shallower ([PERSON] et al., 2018) and the crustal rheology has a ductile behavior ([PERSON] et al., 2018). All these independent observations agree well with the result of a lower \(Q_{c}\) (zone labeled E, in Figure 8c). At the same depth, the easternmost sector of the GP is seismogenic ([PERSON] et al., 2018) and in a fragile regime ([PERSON] et al., 2018; [PERSON] et al., 2018), and this agrees with the observed higher \(Q_{c}\) (zone labeled D, in Figure 8c). As discussed in a previous study ([PERSON] et al., 2018), with increasing \(f_{c}\), \(Q_{c}\) shows the effect of the intrinsic and scattering attenuation of back-scattered body waves coming from deeper portions of the lithosphere ([PERSON], 2011). At a higher frequency, in Figure 8c, it can be observed that, with increasing depth, \(Q_{c}\) tends to decrease. This behavior can be ascribed to the effect of the intrinsic attenuation that increases with the sampled Earth volume. In confirmation of this behavior, as we plotted in Figure 9, the \(Q_{c}\) trend with the source-to-receiver distance of \(r\), with \(f_{c}\) = 12 Hz and \(t_{L}\) = 30 s, the linear decreasing trend of \(Q_{c}\) (\(r\)) that confirms this hypothesis can be clearly observed. In summary, from the \(Q_{c}\) tomography at \(f_{c}=12\) Hz (Figure 8c), it can be observed that in the upper/intermediate crust, \(Q_{c}\) decreases toward the northeast (trend toward the C zone); in the lower crust, \(Q_{c}\) increases toward the northeast (trend from the zone with label D to the zone labeled E). Therefore, the intermediate crust would act as a separation interface between these two trends of \(Q_{c}\) in opposite directions. The attenuation maps confirm the high heterogeneity of the GP crust, as already evinced from the analysis of seismicity and the stress field ([PERSON] et al., 2018; [PERSON] et al., 2018).