Fig. 4
From: Significant P wave conversions from upgoing S waves generated by very deep earthquakes around Japan
Comparison of synthetic waveforms for the R component of ground velocity for a 600-km-deep source, for modifications of the ak135 model with varying near surface structure. The top trace includes 5 km of sea water on top of a 7 km crust with recording at the seabed, and the other traces represent progressively thickening continental crust up to 50 km thickness. Four epicentral distances are shown: a 878 km (7.89°) where the P and S phases are produced solely by upgoing waves, b 1535 km (13.80°) where there is interference between waves that have left the source both upwards and downwards to produce more complex waveforms, c 2083 km (18.73°) where sP becomes a distinct phase and d 2467 km (22.19°) where sP is as large as or larger than the S phase. At the larger distances, there is a clear separation of converted phases