Fig. 15
From: High-resolution mini-seismic methods applied in the Mont Terri rock laboratory (Switzerland)
Evolution of a BdZ derived from IVM in borehole BRC2. Apparent vp distribution for receivers R1–R3 and BdZ corrected vp. a vpR1 > vpR2 ≥ vpR3 indicate a negative radial vp gradient (egg-like shell). b Repetition of IVM 20 h later shows vpR1 < vpR2 < vpR3 indicative of a disturbed borehole wall. c BdZ corrected vp for both cases are similar. d Qualitative visualisation of the BdZ via CMP related vpR3–vpR1. e As d but 20 h later