Engineering and geological capabilities of the remote inductive sensing method in the study of sedimentary rocks in Southern Yakutia (using the example of the Kyurgellyakh railway station)

Using the remote inductive sensing method at a frequency of 1.125 MHz in the transition zone with transmitter–receiver spacings of 5–50 m, the attenuation of the harmonic electromagnetic field of a vertical magnetic dipole was studied in frozen sedimentary rocks in Southern Yakutia within the area of the Kyurgellyakh railway station. The investigations were carried out at depths of 6–12 m under conditions of discontinuous and island permafrost. Two main tasks were solved: the first task consisted of quantitatively assessing the strength of sedimentary rocks using a regression equation relating rock strength to the electromagnetic field attenuation characteristics; the second task involved mapping the boundaries of tectonic zones based on field attenuation anomalies exceeding 4 dB/m and identifying zones of mechanical stress concentration at the intersections of tectonic lineaments, reflecting intense tectonic activity in past geological time. The error in calculating rock strength with a confidence level of 80.0% is ±27.7%, which is comparable to the permissible laboratory error of ±20.0%. According to drilling data, the tectonic zones represent linear block depressions with a depth of 5–10 m or more. They are filled with fractured and weathered dolomites interbedded with limestones or with clays of the ancient weathering crust. The obtained results expand the engineering geological capabilities of the remote inductive sensing method in studying the structure and state of sedimentary rocks. The proposed approach, based on the analysis of electromagnetic field attenuation, is recommended for use alongside traditional electrical sensing methods in engineering-geological zoning of areas in Southern Yakutia designated for construction, with the aim of identifying tectonically weakened zones that are unfavorable for the siting of engineering structures.