Fig. 5

Examples of single-station microtremor measurements acquired along line A–B (top to bottom) in Fig. 3. a H/V ratios and their confidence interval. b Individual spectral components of motion in logarithmic scale. The red rectangle highlights the frequencies where 2D resonance peaks are observed and corresponds to the zoomed plot in c). The grey and black circles mark the 2D resonance peaks on the x and y instrumental components, while the grey square marks the minimum on the vertical spectral components at the 1D resonance frequency. c Plot of individual spectral components and their confidence interval zoomed around the presumed 2D resonance modes marked by arrows. Amplitudes are normalized with respect to the absolute maximum peak amplitude within the red box to better appreciate their decay towards the valley edges