FIGURE 2. Imaging discontinuities with waveforms from individual stations.

Blue lines show SV waveforms deconvolved and migrated in single bins for stations LMN, HRV, PAL, LBNH, BINY in two back-azimuth bins, and SSPA. A positive phase corresponds to a velocity increase with depth, while a negative phase indicates a velocity decrease with depth. Coloured arrows indicate phases from the base of the lithosphere (green), the Moho (dark blue), crustal reverberations (yellow and magenta), and, for station HRV, a discontinuity at 61 km depth (light blue). Error bars corresponding to two standard deviations (grey lines) were calculated with bootstrap tests in which a random 20% of the events in the bin were randomly replaced by another 20%, and the deconvolved, migrated waveforms were recalculated 100 times. Horizontal black lines correspond to the lithosphere–asthenosphere boundary as determined by surface wave models, defined as the greatest negative velocity gradient (LMN²³, all others²⁴). Synthetic waveforms corresponding to the models obtained by inverting the data are shown for HRV and LMN (red lines). Crustal phase amplitudes were not included in these inversions and are therefore the one aspect of the synthetic waveforms that do not match the data (Supplementary Information, section 2).