Reppel-Bocholt Fault Zone.
Composite source BECS002 consists of the east-dipping Reppel and Bocholt faults (Figure S2). The distance between both faults is generally less than 2.5 km. The geomorphic expression is less pronounced than at the Bree fault scarp (BECS001) further south, becoming even less distinct towards the Belgian/Dutch border in the north. In the Netherlands, the likely counterpart of the Bocholt fault has been mapped (as the “Feldbiss fault”; Vandenberghe, 1990), but the prolongation of the Reppel fault is not known. An interpreted cross section based on vertical electric soundings and borehole data (Vandenberghe, 1990) shows that the northern end of the Bocholt fault consists of several strands spanning a ~2 km wide zone. This could be due to the intersection with the Veldhoven fault (NLCS004), but it is also possible that one of the strands corresponds with the Reppel fault, and that mapping is incomplete in this area.
None
Not much information is available for the northern sections of the SW border fault zone. Vandenberghe (1990) published an interpreted profile based on vertical electric soundings and boreholes across the northern part of the Reppel-Bocholt fault zone, showing 37.5 m of vertical offset for the base of the Middle Pleistocene Sterksel Formation. It is not clear whether or not the lower part of this formation is present in this area, so we assume an age of 0.78 – 1.1 Ma for this horizon. These ages correspond to vertical displacement rates of 0.034 – 0.048 mm/yr. This is comparable to the deformation rate that can be inferred from a depth map of the base Quaternary horizon in Worum et al. (2004).
| ID | Fault section | Offset (m) | Time period | Deformation rate (mm/yr) | Reference |
|---|---|---|---|---|---|
| 15 | Displacement of base Miocene on seismic reflection profiles | 325 – 375 | Since Miocene (23 Ma) | 0.014 – 0.016 | Based on data from Demyttenaere and Laga (1988) |
| 16 | Displacement of base Quaternary | ~120 | Since 2.58 Ma | ~0.047 | Based on data from Worum et al. (2004) |
| 14 | Displacement of base of Sterksel Fm | 37.5 | Since 0.78 – 1.1 Ma | 0.034 – 0.048 | Based on data from Vandenberghe (1990) |
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