This study examines the distribution and amount of placer deposits enriched with heavy minerals along the coastal region of Odisha, India utilizing a combination of geoelectrical techniques. Abundant heavy mineral placers have been identified along the southern coast of Odisha. However, while geological investigations have been conducted, there is a notable absence of geophysical analyses in this specific area. To ascertain both the horizontal and vertical extensions of heavy mineral placer deposits, a comprehensive investigation was undertaken, involving the execution of 23 ERT (Electrical Resistivity Tomography) and TDIP (Time-Domain Induced Polarization) profiles within the designated study zone. These profiles unveiled substantial heavy-mineral zones spanning from shallow layers to depths of approximately 10-15 m. Two primary patterns of mineralization were discerned: firstly, dispersed occurrences which manifested closer to the surface, characterized by irregular black patches of minerals; secondly, concentrated mineralization found at moderate to significant depths, hinting at concealed or buried deposits. Considering the presence of conductive minerals (ilmenite, magnetite) within the beach placers of the study locale, the application of ERT and IP methods proved to be viable. Additionally, the mineralization trends exhibited variance as one traversed from the southwest to the northeast within the study area. Notably, the resistivity of the heavy minerals ranged from 0.1 to 1.1 Ωm, coupled with chargeabilities surpassing 20 mV/V. Significantly, the arrangement of alternating heavy mineralization layers within the sand formations implied the potential presence of stratal anisotropy. Consequently, a specialized code was developed and implemented to perform 2D anisotropic inversion of the ERT data. The application of this anisotropic inversion rectified the depth estimations for concealed pockets of heavy mineralization. While conventional isotropic inversion suggested a concealed mineralization pocket at depths of 15-32 m, the anisotropic inversion revealed that the same mineral-bearing strata existed at depths of 16–28 m.

Approaches to magnetotelluric monitoring of variations in apparent resistivity and electromagnetic emission that may serve as earthquake precursors are considered. Monitoring of apparent resistivity is advised in the range 7–300 Hz, where natural electromagnetic fields exhibit stable behavior, while at lower frequencies the behavior of the electrotelluric and magnetic fields should be analyzed. We present results of studies aimed at identifying active faults and searching for stress–strain sensitive zones for installing measurement equipment based on the registration of tidal variations in apparent resistivity. The features of apparent resistivity anomalies preceding earthquakes in China based on direct current measurements are discussed. Based on the analysis of natural electromagnetic field monitoring in the ULF and ELF ranges in China, the anomalies recorded prior to several recent earthquakes are considered. Before the Yangbi earthquake (2017) and the series of Yangbi (2021) and Ninglang (2022) earthquakes, variations in apparent resistivity were observed that have a pulsed behavior and probably are manifestations of electromagnetic emission. Possible sources of these anomalies are active faults located near the monitoring stations.