A geostatistical modelling of empirical amplification functions and related site proxies for shaking scenarios in central Italy

This work aims at identifying and modelling statistical dependencies between empirical amplification functions of sites in central Italy and the main geological and
geophysical characteristics of the region, within a geostatistical analysis framework. The empirical functions, named δS2S, are estimated by decomposing the re
siduals of the median predictions of a non-ergodic ground motion model of elastic acceleration response spectra developed for the reference region. To select the
model that best describes the spatial variability of the data, the performance of stationary and non-stationary spatial models is compared, the latter being able to
constrain the prediction of the empirical functions to physical quantities available in the region and descriptive of the geology, topography and geographical location
of the site. Finally, we obtain optimal models of δS2S, for each spectral ordinate, parameterised as a function of geographical coordinates and an input map of shear
wave velocity in the upper 30 m (Vs30) constructed ad hoc by combining information gathered from two high-resolution maps available for the region. The
methodology allows the development of a new practice-oriented framework for the empirical estimation of site amplification, which can be adopted for the gen
eration of shaking scenarios in the context of regional hazard and seismic risk assessment.