The period range where waves of a bit different periods in the same time arrive is called Airy phase. The broad spectrum is summed up here so that the amplitudes are higher.
By comparing the results both with PREM and the spectrograms, the Airy phase is well visible at the fundamental modes of all three components at the spectrograms.
The periods of main group of Love waves at radial and at vertical components exactly fit the periods of these waves at tire transverse component, but the Airy phase at the "wrong" components is shifted to the lower group velocities.
The shape and Airy phase of the estimated fundamental modes dispersion curves correspond well with PREM-curves but the curves are shifted to a longer period range.
Fundamental Rayleigh mode at the transverse component is estimated only for the periods shorter than the Airy phase period (about 20-30 s) so the filtered seismogram shows shorter periods (10 s) coming before the longer ones.
There is no Airy phase observed at the transverse component and only a trace of it at the vertical and the radial component.