Fig. 3

Original records a and de-tided waveforms b of the 20 July 2017 Bodrum–Kos tsunami in Bodrum (Turkey) and Syros (Greece). c, d Spectra and spectral ratios at these two stations. tsu and back represent tsunami and background signals, respectively. e The enlarged view of the green rectangle shown in (b). In (e), the seafloor uplift of ~ 2 cm looks occurring 30 s before the earthquake time. Obviously, the uplift occurred simultaneously at the earthquake origin time (red vertical line); the 30 s shift can be attributed to the temporal resolution of the instrument