Figure 4

Left panels: high-pass filtered (cut-off period of 2 h) sea level time series (in m) spanning the period from 0400 UTC 15th January 2022 to 1600 UTC 19 January 2022. The location of the stations is shown in Fig. 1, and the distance to Tonga is indicated in each plot. Central panels: wavelet power spectrum (in log₁₀ (m²)) of the non-filtered sea level series at the same locations. In both, left and central panels, the black arrows indicate the arrival time of the different atmospheric wave front passages, while the red arrow plotted for Kawaihae station, in the Pacific Ocean, shows the arrival time of the tsunami wave. Right panels: spectral energy (in log₁₀ (m²)) of the SLOs recorded during each passage (1st in solid blue, 2nd in dashed red, 3rd in dashed green and 4th in dashed purple) and the mean spectral energy of the station, computed from a 1-year record (solid black line). The energy spectra have been estimated by averaging the WPS over a 1 h period centered at each passage time. The gray patch indicates the 95% significance level of the colored spectra, which has been estimated as in Ref.²³ (the significance level is smaller for the background spectra, since it has been estimated by averaging a 1-year time series).