Ellipticity of Rayleigh waves in basin and hard-rock sites in Northern Italy

摘要: We measure ellipticity of teleseismic Rayleigh waves at 95 seismic stations in Northern Italy, for wave period between 10 and 110 s, using an automatic technique a large volume high-quality recordings from over 500 global earthquakes that occurred 2008–2014. Italy includes wide range crustal structures, the deep Po Plain sedimentary basin to outcropping crystalline rocks Apennines Alps. It thus provides excellent case studying influence shallow earth structure on polarization surface waves. The measurements show spatial correlation with geological features region, such as high associated regions low velocity values faster, hard rock Alps Apennine mountains. Moreover, observed also relate thickness basement, highlighted by differences beneath Apennines. Comparison observations predicted reference model region substantial fit, particularly T ∼ 38 s data. Discrepancy shorter suggests slight modifications are needed, could help better constrain region. Predictions larger than factor four or more transition retrograde prograde motion periods 10–13 is plain. Analysis corresponding real data indicates possible detection particle motion, but weak earthquake signals mixed ambient noise predicted, short, periods. Detection polarity inversion joint analysis may provide further, stringent, constraints basins.