Empirical testing of a simplified approach for the estimation of 1D litho-stratigraphical amplification factor

To allow a widespread application of seismic microzonation studies in Italy, simplified cost effective procedures are required. To this purpose, regional abacuses allowing the evaluation of 1D litho-stratigraphical amplification phenomena based on a small set of cheap surface measurements have been proposed. These abacuses were initially elaborated by extensive one-dimensional numerical simulations of a wide set of representative seismo-stratigraphic configurations testified in the study area. In order to test effectiveness of the abacuses in use in the Marche Region (Central Italy), seismic amplification estimates deduced from this tool have been compared with outcomes of detailed seismic response studies carried out at a number of sites included in the area affected by the 2016–2017 seismic sequence in Central Italy. This analysis indicated that abacuses provide reliable estimates in the most part of the area except a specific geological domain where available subsoil information was not exhaustive when abacuses were initially formulated. Then, abacuses where partially reformulated by obtaining outcomes in line with independent observations. This in general, testifies the accuracy of the simplified approach but also the requirement for accurate field-testing before their widespread application.