Permafrost

Key words: Alaska, oil exploration, climate change, tundra, natural resource decision making,
active layer
The new radio wave technology for researches and 3D-geoelectrical
mapping of underground inter-well space in permafrost massif
V.A. Istratov 1 , A. Kuchmin 1 , A.D. Frolov 2
(1.Radionda Ltd, Moscow, Russia;
2.Scientific Council on Earth Cryology, Russian Academy of Sciences, Moscow, Russia)
Abstract: As many problems in the geophysical studies require the reliable values of frozen
formation electric characteristics, the suitable methods giving a possibility to determine these
properties in situ are of considerable interest. The radio wave geo-introscopy (RWGI)
performed in boreholes is one of such method developed in Russia. It permits to obtain the
effective (i.e. characterizing the electromagnetic wave propagation in real geological situation)
values of electric resistivity and dielectric permittivity as well as the regularities in theirs spatial
changes within the massif under study. The paper contains the main principles of RWGI, a brief
description of the modern special borehole equipment, procedures of the measurements,
principles of data special processing and some results of RWGI application in several sites of
monitoring of Western Yakutia cryolithozone.
Sufficiently high resistivity of frozen massifs allows inter-borehole radiowave
investigations at the high frequencies 1 – 31 MHz to a range up to hundred meters (in
continuous permafrost,). The frozen - thawed sediment boundaries are clearly detectible and
may be confidently localized due to contrasts of their electrical properties. The same is also true
for inhomogeneities of geological structure and lithology.
3-D geoelectric survey of cross-hole space was performed using radio waves with two
parameters found complementing each other when interpreted from geological position:
resistivity and dielectric permittivity.
Such a survey shows a high resolution, it permits a comprehensive differentiation of
geological sequence and provides reliable information on the rock and soil electrical
characteristics in situ.
The considered methods are an effective way to solve various problems of geocryology,
engineering geology and hydrogeology, including those related to ecological-geophysical
monitoring of permafrost state changes result to technogenic impact.
Keywords: electrical prospecting, radiowave, crosshole tomography, permafrost.
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