Fig. 7

Maps showing time lags between the observed and synthetic inter-station Green’s functions in two frequency ranges, 0.125–0.177 and 0.177–0.250 Hz, assuming a single force in the directions R+ and T+ at stations UEMC03, UEMC06, UEMC09, and UEMC15. The red (blue) circle indicates that the synthetic arrives later (earlier). The radius of the circle corresponds to the amplitude of the time lag