Microtremor H/V spectral ratio in two sediment-filled valleys in western Liguria (Italy)

In this paper, the H/V spectral ratio method is applied to ambient noise recordings collected along 4 profiles crossing two alluvial plains located in western Liguria (Northwestern Italy). The results point out that important amplifications occur on both the alluvial plains. In the Argentina plain amplifications affect mainly the 2-5.Hz frequency band, whereas in the Prino plain the highest amplifications occur at nearly 10-11.Hz. Moreover, in the Prino valley, the peaks of spectral ratio appears to be directly related to the alluvial fill thickness whereas in the Argentina valley the amplifications seem to be due to a shallow portion of the Quaternary sediments. Finally, important amplifications are also measured in correspondence of a landslide, having a thikness up to 6 m, located on the western slope in the Prino valley.