Italian seismic amplification factors for peak ground acceleration and peak ground velocity

Ground motion modification over large areas is generally evaluated by focusing on sourceeffects disregarding local lithostratigraphic site conditions. Hence, amplification maps ofpeak ground acceleration and peak ground velocity are proposed to improve the forecast ofground motion on a national scale. Topological information about litho-type successionsand soil mechanical behaviour were retrieved from the Italian database of seismicmicrozonation and more than 30 million of seismic site response analyses were performedto quantify the amplification factors (i.e. the ratio between expected ground motion at thesite of interest and that at the outcropping engineering bedrock). The maximum value ofthe amplified peak ground acceleration on the Italian territory results in about twice asmuch as the value expected at the outcropping of the engineering bedrock. Finally, damagescenario maps based on the amplified ground motion could be produced as a supportingtool for urban planning and emergency system management.