This study focuses in the analysis of the internal structure of the upper 3 km of Los Humeros caldera and the relation of electrical and hydrothermal anomalies. For this purpose, we measured, processed, and interpreted 78 broadband magnetotelluric (MT) soundings. We performed a 3D inversion of the data set (ModEM) using all MT soundings, although only half of the available frequencies per sounding due to limited computed power. We also carried out the 2D inversions (NLCG) of the invariant determinant along two orthogonal profiles (EW and NS) crossing the caldera structure; their comparison yields similar resistivity and structural models results. The resistivity modeling is complemented with the results of a joint 3D inversion of an accurate gravity database of 720 stations, and total field aeromagnetic data (SGM) from the caldera crater. The combined results provide novel details about the structure of the shallow geothermal reservoir of the resurgence caldera complex hosting the active hydrothermal system. Density and resistivity models show the existence of a composed crater basin structure separated by an EW high density structure; the northern basin is associated to the LH crater, whereas the southern basin associates to the emergent LP caldera basin. The magnetization model indicates that there is a common source for the magnetic volcanic products observed at the caldera surface, and that the Los Potreros (LP) fault is the more magnetized fault of the geothermal system. The propylic zoning under the geothermal field, which according to the MT model results has resistivities above ∼100 ohm-m, was extrapolated using this and additional criteria to obtain the distribution of other hypothetical propylitic zones of hydrothermal potential.

中文翻译：

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从大地电磁和势场数据看洛斯休姆罗斯火山口和地热储层的浅层结构

这项研究的重点是分析Los Humeros破火山口上部3 km的内部结构以及电热异常之间的关系。为此，我们测量，处理和解释了78种宽带大地电磁（MT）测深。我们使用所有MT测深对数据集（ModEM）进行了3D反转，尽管由于有限的计算能力，每个测深只有可用频率的一半。我们还沿着穿过火山口结构的两个正交剖面（EW和NS）对不变行列式进行了二维反演（NLCG）。他们的比较得出相似的电阻率和结构模型结果。电阻率建模得到了720个站的精确重力数据库的联合3D反演结果以及来自破火山口火山口的全场航空磁数据（SGM）的补充。合并的结果提供了有关活跃水热系统的中部复苏火山口浅层地热储层结构的新颖细节。密度和电阻率模型表明存在由EW高密度结构分隔的组成的火山口盆地结构。北部盆地与LH火山口相关，而南部盆地与新兴的LP火山口盆地相关。磁化模型表明，在火山口表面观察到的磁性火山产物有一个共同的来源，而洛斯波特罗斯（LP）断层是地热系统中磁化程度较高的断层。根据MT模型的结果，地热场下的丙基区带的电阻率在〜100 ohm-m以上，