Figure 3 . (a) Record section of transverse component seismograms used in this study. Shown is the amplitude of ground displacement in red and blue for positive and negative polarities, respectively, with a color intensity proportional to the absolute value. The seismograms have been aligned to the S wave at time 0. (b) The arrival times of S, ScS, and SS (black lines), S150, S410 and S660 (blue dashed lines), and the SS-precursors S150S, S410S and S660S (green dashed lines) have been computed for PREM for a source depth of 20 km.