VSP radial component geophone data from a vibrator-source (using a sweep of 6-120 Hz and offset 490 ft) in the Bakken shale showing downgoing, first-arriving P-waves and later and more dipping converted downgoing S-waves (from Huang, 2016). 

Contexts in source publication

Context 1

... first, let's check the evidence of S-waves in the subsurface. Even a seismic source with a small offset can generate down-going P-to-S conversions (Figure 1). Moving the source laterally farther away from receiving well can generate large P-to-S conversions (Figure 2) where there are strong conversions from the top of anhydrite and salt. ...

Context 2

... VSP are used to record the full in-situ elastic wavefield. From this, we often extract the PS response and integrate it with well logs (Figure 9) and surface seismic results to provide a very compelling interpretation ( Figure 10). We can also analyse the true amplitude with offset response (because we've measured both the downgong and upcoming waves). ...

Context 3

... can also extract the true AVO response from PP and PS reflections. In a case from the Ross Lake heavy oilfield, we find that the field data amplitudes with offset match those synthetically generated quite well (Figure 11). This suggests that full waveform modeling and iteratively matching the earth model to the data seems realistic. ...