TITLE:
Plausible Northern Extension of Los Humeros Caldera Geothermal Field and Correlation of Density and Electrical Resistivity within the Collapsed Structure
AUTHORS:
Román Alvarez, Miguel Camacho-Ascanio
KEYWORDS:
Los Humeros Caldera, 3D Gravity Inversions, Geothermal Resources, Magneto-Telluric Soundings, Satellite-Derived Gravity
JOURNAL NAME:
Engineering,
Vol.17 No.12,
December
23,
2025
ABSTRACT: Los Humeros is a Pleistocene caldera in the eastern portion of the Trans Mexican Volcanic Belt, exploited for geothermal resources for over five decades, presently providing over 90 MWe. We model the gravity field, obtaining 3D density models from high-resolution (220 m) satellite-derived gravity data and compare these models with geological and magneto-telluric descriptions detailed elsewhere. An additional comparison with a geological E-W section indicates that the most voluminous caldera formations coincide with a low-density region extending from the surface to below 6 km bsl that is likely associated with the caldera activity. Interpretation of three additional density cross-sections leads us to infer that the magmatic system feeding Los Humeros also has a component surfacing 12 km north of the center of the caldera, a result that is first disclosed here. Comparison of the density distributions with three corresponding electrical resistivity profiles obtained elsewhere from magneto-telluric soundings shows that low-resistivity regions prevail above 1 km asl where high-density pockets alternate with low-density regions. High-resistivity regions can be associated with high- or low-density regions. Vertical channels ⁓2 km wide extending 6 - 8 km, of intermediate resistivity (150 - 300 ohm-m), appear in three resistivity profiles analyzed. In one case, it coincides with a low-density region (3) and in the others appear associated with fractured regions pertaining to the resurgent activity. We find that the magma chamber is not directly located under Los Humeros caldera; it is rather displaced ⁓7 km to the north of the location of the caldera. Comparison with two shallow resistivity profiles shows that geothermal fluids induce propylitic alterations in high- and low-density regions.