Experimental calculation of the damping ratio in buildings hosting permanent GPS stations during the recent Italian earthquakes

During the recent earthquakes in Italy, the contemporary presence of about 40 permanent GPS and 40 accelerometric stations of the national seismic network made it possible to estimate the value of the damping ratio of the buildings hosting the GPS stations. This value was calculated as the minimum of a function (parabola) constructed step by step from the relations between the ordinates of the pseudo-acceleration spectra extracted from the GPS and accelerometric measurements. For both construction material and building geometry, the results indicate values that differ by at least two percentage points from the values imposed by the technical regulations.