## 4 Discussion
### Holocene Deposits  
A possible correlation between subsidence and Holocene sediments compaction was investigated focusing on the lithological features, thickness and stratigraphic architecture of the Holocene deposits.  
We analyzed 200 boreholes (Demanio Idrico Prov. Cosenza, [82, 83]) and literature data [57, 61, 65] to define lithology, vertical-lateral variations and thickness of the post-LGM deposits. An isopach map of the Holocene succession superimposed with the Envisat Vertical component was generated (Figure 9a). The greater vertical displacement values are located in the area of the Holocene deposits accumulation but the larger subsidence rates do not correspond to the major depozones.  
To well investigate the second topic, we compared each Vertical displacement value of with the corresponding thickness of the Holocene deposits (Figure 9b).We also performed a comparison between thickness and vertical component in correspondence of each borehole, if SAR data are available (Figure 9c).  
The analysis reveals that the Holocene sediments compaction does not play a dominant role in the subsidence of the SP area, on the contrary as described for other delta plains [5, 7].  
Subsidence rates of 3-5 mm/yr induced by to the Holocene deposits consolidation due to phreatic and confined water tables drop are calculated by [66] and are not sufficient to justify the vertical displacements inferred by SAR data.  
Although the minor role of Holocene deposits compaction, the boreholes analysis highlights a clear influence of the lateral variations of the sediments lithology for the subsidence phenomena. In detail, we took into account the ground deformation patterns from ascending and descending Envisat data, and the boreholes into the Saraceno and Satanasso alluvial fans areas (Figure 10a), considering the thickness of fine-grained (silt and clay) deposits (Figure 10b,c). Greater ground velocities are usually retrieved close to the boreholes recording a major thickness of fine-grained sediments while the lower values are in correspondence of the coarse-grained (gravel and sand) deposits which made up the alluvial fan bodies. Thus, the lateral variation of the fine-grained materials thickness creates differential land subsidence.  
Figure 7: **(a)** Location of the used wells and seismic profiles. **(b)** Isopach map of the Plio-Quaternary succession with the distribution of the Envisat Vertical component. **(c)** Comparison between the thickness of the Plio-Quaternary succession and ground velocity, based on the Envisat Vertical component, along one of the analyzed profiles (its trace in Figure 7a). The discontinuous lines for the InSAR profile are due to missing data in the ascending and/or descending original velocity maps due to coherence lack.  
Figure 8: Correlation between (**a**) ascending and (**b**) descending velocities with the thickness of the Plio-Quaternary succession.  
Figure 9: (**a**) Envisat Vertical component overlapped to the Holocene deposits isopach map. (**b**) Scatter plot Envisat Vertical component _vs_. Holocene deposits thickness inferred from isopach map. (**c**) Comparison between Holocene sediments thickness and Envisat Vertical component in correspondence of each borehole.