A snapshot of the decomposed forward wavefield for an isotropic source at approximate location (−20 km, −40 km). Pz and Sx are the vertical component of (u)_P and the horizontal component of (u)_S, respectively. This snapshot is from 5.92 s after the origin time. The direct P wave is visible in the Pz panel, and the converted Ps waves are visible in the Sx panel. Note that the colour scale has been modified for second panel to ensure that the smaller amplitude S waves are clearly visible.