APPLICATION OF METHODS OF ELECTRICAL EXPLORATION WITH CONTROLLED SOURCES FOR DETECTING CAUSES OF SUB-PASS-LOCATION PROCESSES DEVELOPMENT

Abstract

The relevance of the work is caused by insufficiency of knowledge on the reasons of development of suffusion processes expressed as land surface failures menacing to infrastructure of industrial production in Caspian Depression. The aim of the research is to determine the near-surface and deep geoelectric structure of the site of manifestations of suffusion-subsidence formations to identify possible causes of their occurrence. Object of the research are suffusion-subsidence formations in the form of funnel-shaped earth surface dips with a depth of 1 to 6 m in an amount of 15 pieces located in three practically parallel zones. Methods The entire volume of field data is obtained by three different depth methods of geoelectrics: electrotomography, vertical electric sounding, non-stationary electromagnetic sounding. Processing, interpretation, visualization of data were carried out using interactive simulation and inversion software packages ERA, EMS, Zond, Res2D, ERTLab. The justification of the results is based on the analysis and comparison of the obtained geoelectric data with a priori geological data. Results. Based on the results of the work done, with depths of up to 400–500 m, sections and maps of electrical resistivity distribution at different depths, three-dimensional geoelectric models for both the near-surface and the deep part of the section were constructed. As a result of geological interpretation of the data, the zones were identified (according to the resistivity parameter) to which the existing funnels were confined, the direction of removal of the destroyed (washed out) rocks was determined. The authors identified the structures related to the zones of development of suffusion-subsidence processes, and stated possible reasons for their formation. Conclusions. The paper demonstrates high efficiency of the complex of electromagnetic methods used on the site with the destructive phenomena. It is concluded that the main mechanism for funnels formation is associated with leaching of limestone and salt «cement» from the N-Q sediments, with further unloading into deeper watered horizons. This complex can be recommended at the solution of similar tasks in other regions where there are zones of manifestation of suffusion processes, and also for monitoring their development.

Keywords

• geoelectric structure
• vertical electric sounding
• electrotomography
• non-stationary electromagnetic sounding
• suffosion processes