Near‐surface electromagnetic responses: geological noise or fractal signals?
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© 2001 Society of Exploration Geophysicists. Based on observations from two distinct settings, a faulted sandstone aquifer and a clay-rich alluvial oodplain, we present evidence that near-surface controlled-source electromagnetic (CSEM) responses are fractal signals. The observed responses are very rough; they do not show the statistical behavior of smoothly varying functions superimposed by random Gaussian noise. This suggests that CSEM signals re ect self-similarity in the underlying, heterogeneous electrical conductivity structure. The process of EM induction in the Earth thus may be regarded as a mapping from a fractal medium to a fractal response. This result poses exciting new challenges for numerical modeling and geological interpretation of CSEM responses in the areas of engineering and environmental geophysics and shallow resource development.
author list (cited authors)
Everett, M. E., & Weiss, C. J.