Fig. 9

Modelled stress state at the geothermal project Poing where seismicity up to Ml 2.1 has been recorded. The left panel shows a depth vs. stress plot with \(\text{S}_\text {Hmax}\) (red), \(\text{S}_\text {v}\) (green), and \(\text{S}_\text {hmin}\) (blue). The average values are the bold lines, a standard deviation of one sigma (strongly shaded) and two sigma (lightly shaded, approximately 95% probability of the stress state to be within these bounds) is shown for \(\text{S}_\text {Hmax}\) and \(\text{S}_\text {hmin}\). The target depth at − 2503 m below sealevel is indicated by the bold black horizontal line. The right panel shows a Mohr–Coulomb diagram at target depth. The differential Mohr circle (\(\text{S}_1\)–\(\text{S}_3\)) is indicated in blue and \(\text{S}_1\)–\(\text{S}_2\) and \(\text{S}_2\)–\(\text{S}_3\) are indicated in grey. The averages are indicated by bold lines, the standard deviation of one sigma by a strong shaded area and of two sigma by a lightly shaded area. A standard failure envelope (black) is included for reference with a friction coefficient of \(\mu\) = 0.6 and a cohesion of C = 10 MPa. Failure envelopes for Malm dolomite (orange, C = 13 MPa, \(\mu\) = 1.4) and limestone (blue, C = 11.9 MPa, \(\mu\) = 1.3) reported by Hedtmann and Alber (2018) are also shown