Seismic soil classification of Italy based on surface geology and shear-wave velocity measurements

During an earthquake the seismic wave amplification related to local site conditions can have a significantimpact on the ground motion. In order to account for these local effects some proxies for the soil characteristicsexist; e.g., the average shear-wave velocity of the upper 30 mJ()S,30, or the equivalent shear-wave velocity fromthe ground to the depth of the seismic bedrock when this is less than 30 mJ()S,eq.The aim of this paper is to provide maps of seismic shallow soil classification for Italy accounting for twosources of information: site-specific measurements and large-scale geological maps. The soil maps are obtainedvia a four-step procedure: (1) a database of available site-specific investigations is built, covering (unevenly) thewhole national territory; (2) twenty geo-lithological complexes are identified from the available geologicalmaps; (3) the investigations are grouped as a function of the geo-lithological complex and the distribution ofmeasuredJK,30andJK eq,are estimated; (4) medians and standard deviations of such distributions are assumed tobe representative of the corresponding complexes. The statistics of investigations are used to derive the large-scale soil maps. To make the results of the study available, a stand-alone software has been developed. Despitenot being adequate substitutes of site-specific studies such as microzonation and local site response analyses, theprovided results can be useful for large-scale seismic risk studies