Fig. 1

a 2D conceptual model of the geology at Rittershoffen. The sedimentary cover is investigated from geological studies from Vidal et al. (2017) and Aichholzer et al. (2016). The granite below 2.5 km deep is assumed to be the same as in the Soultz-sous-Forêts site (Dezayes et al. 2005a, b). b Temperature–depth profiles obtained from logs run in the Rittershoffen wells (GRT-1, GRT-2) after drilling operation over (Baujard et al. 2017). The background colors correspond to the four layers homogenized at the scale of about 100 m and considered in the model (\(e_1\), \(e_2\), \(e_3\) and \(e_4\) correspond to the layer thicknesses, \(e_1\) is inverted during the back analysis; \(e_2\) = 2.2  km - \(e_1\) ; \(e_1\) + \(e_2\) + \(e_3\) = 3.9 km ; \(e_1\) + \(e_2\) + \(e_3\) + \(e_4\) = 5.4 km)