A realistic 3-D resistivity model explaining anomalous large magnetotelluric phases: the L-shaped conductor model

作者：Ichihara Hiroshi^*; Mogi Toru

来源：Geophysical Journal International, 2009, 179(1): 14-17.

DOI：10.1111/j.1365-246X.2009.04310.x

• Numerical solutions
• Magnetotelluric

P>Anomalous large off-diagonal phases exceeding 90 degrees pose a major issue impeding the accurate interpretation of magnetotelluric data due to the inadequacy of 1-D or 2-D resistivity models in explaining them. In this study, we propose a realistic 3-D resistivity model to explain anomalous phase data through the use of an L-shaped conductor model. The model presented here consists of a large, elongated conductor (a regional conductor) and a small, square conductor attached to a longer side of the regional conductor. In this model, telluric current is locally reversed and hence out of the ordinal quadrant phase is derived at the edge of the local conductor. Although conventional distortion analyses for galvanic distortion cannot remove anomalous phase problem, we showed that some impedance parameters are not distorted by the anomalous telluric current. Because the 'L' shaped conductor model is simple and broadly applicable to realistic resistivity distributions, it represents an important contribution to the construction of an appropriate model to explain various magnetotelluric data, including anomalous phase data.

• 出版日期2009-10
• 单位中国地震局地震研究所