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 (V-s) 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.