• Title/Summary/Keyword: phisical scale modeling

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A Study on Topographic Effects in 2D Resistivity Survey by Numerical and Physical Scale Modeling (수치 및 축소모형실험에 의한 2차원 전기비저항 탐사에서의 지형효과에 관한 연구)

  • Kim Gun-Soo;Cho In-Ky;Kim Ki-Ju
    • Geophysics and Geophysical Exploration
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    • v.6 no.4
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    • pp.165-170
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    • 2003
  • Recently, resistivity surveys have been frequently carried out over the irregular terrain such as mountainous area. Such an irregular terrain itself can produce significant anomalies which may lead to misinterpretations. In this study, topographic effects in resistivity survey were studied using the physical scale modeling as well as the numerical one adopting finite element method. The scale modeling was conducted at a pond, so that we could avoid the edge effect, the inherent problem of the scale modeling conducted in a water tank in laboratory. The modeling experiments for two topographic features, a ridge and a valley with various slope angles, confirmed that the results by the two different modeling techniques coincide with each other fairly well for all the terrain models. These experiments adopting dipole-dipole array showed the distinctive terrain effects, such that a ridge produces a high apparent resistivity anomaly at the ridge center flanked by zones of lower apparent resistivity. On the other hand, a valley produces the opposite anomaly pattern, a central low flanked by highs. As the slope of a terrain model becomes steeper, the terrain-induced anomalies become stronger, and moreover, apparent resistivity can become even negative for the model with extremely high slope angle. All the modeling results led us to the conclusion that terrain effects should be included in the numerical modeling and/or the inversion process to interpret data acquired at the rugged terrain area.