## 4 Conclusions  
Summarizing all the above, it is possible to come to the following conclusions:  
Figure 13: Modeling results for the case of sand layer: (**a–c**) response spectral acceleration \(SA\) (\(T\), 5%); (**d**) PGA values; (**e**) acceleration amplification curves for offshore case; (**f**) acceleration amplification curves for the onshore case.  
(1) The presented procedure allows developing the NERA algorithm to incorporate the case of porous saturated soils, including those located offshore. The Biot and Gassman models in the seismological low-frequency band are reduced to using the parameters of porous medium for averaging the density of porous soils and calculating the velocity of S-waves in governing equation of the NERA algorithm. In turn, shear modulus degradation curves for undrained undisturbed settings do not depend significantly on the parameters of the porous medium. The water layer above the offshore site also does not affect the response in the case of SH-waves;  
(2) The use of the presented procedure for modeling the response of offshore soft clay layer showed good agreement between the simulated by different methods (NERA, DEEPSOIL (EQL) and DEEPSOIL (MKZ)) and observed spectra on the layer surface. The algorithm allows demonstrating resonances and the effect of the seismic wave amplitude saturation;  
(3) The modeling showed that the response of cohesive and non-cohesive soils with moisture specific both for onshore and offshore sites is explained by effects of resonances and effect of seismic amplitude saturation, which, in turn, depend on the corresponding value of the layer thickness and S-wave impedance for porous saturated soil layer;  
(4) The presented procedure and modeling results can have significant practical usage for studying the influence of parameters of the porous medium on the seismic response of the moist soil deposits. Offshore geophysical and geotechnical studies are quite expensive, especially if a large measurement grid is required. The proposed approach makes it possible to use the analogy method in offshore site response analysis, taking as a basis the main geotechnical parameters of the corresponding coastal soils and adjusting the values of void ratio, water saturation factor and moisture coefficient. In addition, it is also possible to interpolate the values of the parameters of a saturated porous medium on a sparse grid at the offshore area of interest.  
Conceptualization, A.A.K.; methodology, A.A.K.; software, A.A.K.; validation, A.A.K.; formal analysis, A.A.K.; investigation, A.A.K., E.A.R. and M.A.N.; data curation, S.A.K.; writing--original draft preparation, A.A.K.; writing--review and editing, D.A.A.; visualization, A.A.K.; supervision, D.A.A. and S.A.K.; project administration, A.A.K.; resources, S.A.K.; funding acquisition, A.A.K. All authors have read and agreed to the published version of the manuscript.  
This work was financially supported by the Russian Science Foundation (grant 20-77-00034, developing of the algorithm and its approbation), by Russian State Assignment no. 0128-2021-0004 (literature review and editing of the text).  
Not applicable.  
The authors declare no conflict of interest.