A new geostatistical model for shear wave velocity profiles

A consistent procedure is required to deal with uncertainties in seismic hazard studies. In particular, uncertainties in shear wave velocity (VS) profiles are important for 1D numerical simulations of site response conducted within a probabilistic framework. This work proposes a new geostatistical model for shear wave velocity profiles. The main characteristic of the model is the separation of the random variables space and time. The model is calibrated using a database of surface wave tests compiled for this purpose. The flexibility of the model is then demonstrated by presenting a first prototype version for down-hole tests. The proposed geostatistical model is validated through an application to a real case study at Mirandola (Italy), one of the sites included in the InterPACIFIC project. The results show a significant improvement in the management (i.e., treatment) of uncertainties for ground response analyses, compared to the methods usually adopted for this purpose. The new geostatistical model allows for a rigorous quantification of the uncertainties introduced in the hazard study; these uncertainties depend on both the characteristics of the investigated site and the performed test. It is also shown that the randomization procedure provides a set of profiles which are fully consistent with the independent experimental “site signatures” available at the site.