The Afar Depression, a region of active extensional tectonics and volcanism in the northeastern section of the Ethiopian Rift, hosts a high-enthalpy geothermal area, the Ayrobera geothermal field. High temperatures recorded from wells drilled in this area suggested the existence of this geothermal system. In this study, magnetotelluric data acquired from 199 stations in Ayrobera at different times since 2007 were inverted to produce a new resistivity distribution model to image geothermal structures. Our new 3-D magnetotelluric model revealed three main resistivity features: a near-surface conductive first layer (C1) interpreted as clay-rich sediment at shallow depths down to 600m and basaltic rocks (600–1200 meters) corresponding to the smectite–zeolite zone, followed by a high resistivity region (R1 and R2) below the C1 conductive layer, associated with high-temperature alteration minerals such as chlorite and epidote. The chlorite and epidote were detected below 800 meters in the deep well TD-3, drilled in the southern section of the Ayrobera geothermal field. Fumaroles with high temperatures recorded on the surface near the NW–SE faults (F1 and F2) and hot ground anomalies from shallow ground temperature measurements above the resistive zones (R1 and R2) indicate an upflow region underneath the Ayrobera field. This also implies the possibility of two reservoirs within the resistive zones (R1 and R2) inside the fractured Afar Stratoid Series. At depth, the resistivity model reveals another conductive region (C2) below 8 km, interpreted as a partial melt (heat source) based on previous studies including seismic and geochemical analysis.

埃法尔低谷是埃塞俄比亚裂谷东北部活跃的伸展构造和火山活动区，拥有高焓地热区，即艾罗贝拉地热场。从该地区钻探的井中记录到的高温表明该地热系统的存在。在这项研究中，对自2007年以来在不同时间从Ayrobera的199个站点采集的大地电磁数据进行了反演，以生成一个新的电阻率分布模型来对地热结构进行成像。我们新的3-D大地电磁模型揭示了三个主要的电阻率特征：浅层导电第一层（C1）解释为深至600m的浅层富含粘土的沉积物，而玄武岩（600-1200米）对应于绿土-沸石区域，然后是C1导电层下方的高电阻率区域（R1和R2），与高温蚀变矿物（如绿泥石和附子）有关。在Ayrobera地热田南部钻探的TD-3深井下方800米以下检测到了绿泥石和附子。在西北-东南断层（F1和F2）附近的表面上记录有高温的喷气孔，以及在电阻带（R1和R2）上方的浅层地面温度测量值引起的热地面异常，表明在Ayrobera场下方是一个上流区。这也暗示了在断裂的Afar Stratoid系列内部的电阻带（R1和R2）内可能有两个储层的可能性。在深处，电阻率模型显示了8 km以下的另一个导电区域（C2），根据先前的研究（包括地震和地球化学分析）将其解释为部分熔体（热源）。