260 Geophysics in Geothermal Exploration Figure 9.2 Constitutive elements of a volcanic hydrothermal system (Darnet et al., 2019). 9.1 Integration of magnetotelluric data A total of 32 MT stations acquired during different periods (Darnet et al. 2019; Dezayes et al. 2023) are available. This dataset includes land MT stations and, for the first time, marine MT stations around the island, providing a more comprehensive image of the geological structures. These 32 stations were inverted using the MININ3D code (Hautot et al., 2000, 2007) to create a 3D resistivity model. The results show a conductive structure overlying a resistive body, with a varying depth interface: 600 m below Moya Beach and 1.6 km below the airport (Figure 9.3). The model shares similarities with Pellerin et al. (1992) but reveals a more complex geometry. This interface can be interpreted as the boundary between a geothermal reservoir and its caprock. In the map view at a depth of 2432 m, the resistive body displays a NW-SE global trend (Figure 9.3). The high quality of the hybrid land and sea MT measurements enabled the construction of a well-constrained 3D image of a potential geothermal target. The 3D resistivity cube is interpreted based on the cross-sections shown in Figure 9.4. These cross-sections reveal a large, highly resistive volume compared to the surrounding host rock, with values ranging between 30 and 60 Ω·m (Figure 9.5). Based on the reference model, this zone corresponds to the reservoir altered by geothermal fluid circulation. Its boundaries can thus be delineated across all the cross-sections. Above the reservoir lies the caprock, characterized by lower resistivity values, below 10 Ω·m. On the profiles, this zone is challenging to identify clearly due
RkJQdWJsaXNoZXIy NjA3NzQ=