The occurrence of earthquakes should be avoided in the area of nuclear waste repositories. Since earthquakes preferentially occur on tectonic faults when they are reactivated under the right stress field, an estimation about the reactivation potential of the faults is important. Such an estimation is providede by the so-called slip tendency, which is calculated from the ratio of the maximum resolved shear stress to the normal stress on the fault surface. The SpannEnD-Germany model provides the stress tensor needed to calculate the shear and normal stresses.
In addition, information is required on the geometry of the tectonic faults for which the slip tendency is to be calculated. Based on various criteria, 60 faults were identified that are particularly relevant in the context of the SpannEnD project. Simple geometries were created for these faults depending on whether they are normal faults, thrust faults or strike slip faults. For a selection of the 60 faults, additional seismic sections and geological sections were researched, which were used to create more realistic geometries.
The stress state from the Germany model is mapped onto the created fault geometries and used for the calculation of the slip tendency of the faults. In general, the values lie between 0 and 1. The greater the calculated slip tendency, the more likely the reactivation of the fault and thus the occurrence of an earthquake.
The slip tendency can be compared with the spatial distribution of earthquakes. The map shows the slip tendency of the 60 selected faults at a depth of 8 km, where a majority of earthquakes occurs. In general, regions with increased seismicity correlate with regions of increased slip tendency.