Mathematical Modeling of Transient Electromagnetic Sounding Signals for Monitoring the State of Permafrost


 –The study is aimed at theoretical development and scientific substantiation of a high-resolution transient electromagnetic (TEM) geophysical technique for monitoring the state of permafrost. The electromagnetic monitoring configuration includes spatially distributed sounding systems for surface and borehole locations of the field sources and receivers. Changes in the electrophysical properties of the earth can be traced for the cases of both ground thawing and freezing. We developed the theory of TEM signals modeling, upon which created an algorithm for rapid and accurate numerical simulation of the electromagnetic field. The signals are scrutinized from the various sounding systems in the basic earth models as function of registration time. We show how the features associated with a spatial arrangement of frozen rocks appear on the EMF diagrams. It follows that a set of the measured data enables visual detection of the boundary between frozen and thawed rocks.