Fig. 2
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40623-017-0746-8/MediaObjects/40623_2017_746_Fig2_HTML.gif)
H/Vs, imaginary parts of the Green’s functions, and medium responses of Love and Rayleigh waves of target two-layered (V s2 = 3V s1) and the corresponding cap-layered medium (V sCap = 2V s2, Depth = 10λ 0). Upper left: FW H/V (thick black), SW H/V (gray) and ellipticity (thin black) of fundamental mode of Rayleigh waves for target two-layered medium. Upper middle: imaginary parts of the Green’s functions in the horizontal component for FW (thick black), SW (gray) of target two-layered medium, and for SW (red), Love waves (blue) and Rayleigh waves (brown) of cap-layered medium. Upper right: imaginary parts of the Green’s functions in the vertical component for FW (thick black), SW (gray) of target two-layered medium, and for SW (red) of cap-layered medium. Lower left: medium responses (dot) of Love waves of target two-layered medium and those (solid curves) of cap-layered medium. Lower middle: horizontal medium responses (dot) of Rayleigh waves of target two-layered medium and those (solid curves) of cap-layered medium. Lower right: vertical medium responses (dot) of Rayleigh waves of target two-layered medium and those (solid curves) of cap-layered medium. The numbers denote the orders of normal modes of surface waves, e.g., 0 denotes the fundamental mode (black), 1 denotes the first higher mode (red), 2 the second higher mode (blue), 3 the third higher mode (cyan), 4 the fourth higher mode (thin black) and 5 the fifth higher mode (purple)