Geotechnical seismic analysis evaluates the response of the ground to expected seismic action, identifying potential amplifications, differential settlements, liquefaction and co-seismic slope failures. Its importance is critical in high-seismicity areas, where dynamic soil properties control the actual demand transmitted to structures during an event.
Key dynamic parameters are the shear-wave velocity Vs and maximum shear modulus Gmax, obtained through MASW, downhole, crosshole or cyclic triaxial testing. Site seismic classification per local codes (IBC, ASCE 7, Eurocode 8) determines design spectra applicable to the planned structure.
Liquefaction potential in saturated granular soils is evaluated through simplified methods (Seed-Idriss, Boulanger-Idriss) calibrated with CPT or SPT, complemented with nonlinear analyses when criticality justifies. Effects —settlements, bearing capacity loss, lateral spreading— must be mitigated through densification, stone columns or piling depending on the case.
Seismic microzonation integrates regional geology, detailed geophysics and numerical models to deliver spectral response maps applicable to urban planning and critical infrastructure design. Its elaboration requires extensive campaigns, validation with real event records and periodic review as seismic evidence accumulates.