Application of the critical stress concept and uncertainty analysis of the determined S
gradient. (A) Comparison of the effective stress ratios σ1/σ3 for Bruchsal calculated for the Shmin magnitudes of the leak-off tests LOT-2023 (green line) and LOT-2245 (red line) in GB2. The vertical dashed line represents the critical σ1/σ3 ratio of 4.68, i.e., the maximum stress ratio for which the critical stress concept is valid. The blue line shows corrected stress ratios for LOT-2245 to be consistent with the critical stress concept (see text). (B) Overview of maximum possible rock density for derived Shmin magnitudes with respect to fulfilling the criteria for the critical stress concept.