## 5 Conclusions  
This work presents a comparison between the gravity residual anomaly and the H/V predominant period from a long dataset that includes a group of the most important cities in Chile. This comparison is made to find relations between both parameters, and it is analyzed through the geology presented in each site. Key elements found in this analysis are the role played by the local geology characteristics (soil/basement type) and the potential differences between seismic and gravimetric bedrock. The results of the comparison between gravity residuals and H/V predominant period show a direct correlation between both parameters, where the higher the period the higher the negative gravimetric residual. However, this correlation is better when only soft sites are considered, increasing the R\({}^{2}\) value in more than 50% in cities such as Vina del Mar or Santiago, compared to all the sites together. These soft sites are those with seismic classifications of D and E (shear wave velocities lower than 350 m/s or periods higher than 0.4 s), and they correspond, in general, to loose to medium density sands or fine soils such as clays or silts. Considering all the results, we conclude that the ideal conditions for this relation is when a soft soil layer overlies a homogeneous bedrock. Even though this correlation is better over soft sites, the results on these sites present differences in the trend slope and in the variance of the correlation depending on the heterogeneity of the geological background and the depth to the basement. The results show that in zones where there is a heterogeneous basement or soil column, the dispersion of the correlation is higher than in zones where a unique sedimentary process took place. On the other hand, the dispersion is also higher over basins with higher sediment thicknesses, such as Santiago and Mejillones. The linear trend considering all the sites in the study with soft sites presents a good correlation with an R\({}^{2}\) of 0.87. The variability in the trend of every particular site is a function of the soil-bedrock mechanical and geological contrast, thus a general empirical rule cannot be established. Finally, the seismic depths-to-basement obtained through the inversion of the ellipticity curve and through the 1-D relation of Equation (1) are very similar, although the difference is higher (around 20%) when denser soils are considered. The same occurs when the seismic basement is compared with the gravimetric one, where the differences are less than 15% in depth for soft soils and increase up to 30% in denser soils. These results show that both basements can be compared in places with high impedance contrast between soil and bedrock (soft sites). In denser sites with lower impedance contrast, the great part of the H/V curves does not present a clear peak or the peak has a low amplitude; this makes it impossible to estimate a seismic depth-to-basement from this method, as well as to make the comparison with gravity. In general, the gravimetric basement is deeper than the seismic one. However, gravimetric depths-to-basement can be under/over-estimated in zones with a heterogeneous soil column. **Author Contributions:** Data preparation and review, J.M. ; investigation, J.M., E.S. and G.Y. ; writing--original draft preparation, J.M; writing--review and editing, J.M., E.S. and G.Y. ; supervision and validation, E.S and G.Y. All authors have read and agreed to the published version of the manuscript. **Funding:** This study is based upon work supported partially by the CONICYT/FONDEF project D10E1027 and by CIGIDEN (National Research Center of Integrated Natural Disaster Management) CONICYT/FONDAP 15110017. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The data underlying this article will be shared on reasonable request to the corresponding author.