大地电磁资料的分形特征

FRACTAL FEATURES OF THE MTS DATA

分形理论是研究一类无规则、非线性但具有自相似性的无序系统。这个无序系统的维数一般是分数。分数维的大小可以反映系统的复杂性，揭示系统的本质规律。本文利用功率谱分析法来揭示大地电磁资料的分形特征，并简单分析分数维在大地电磁中的地质意义。发现当地下电性分布均匀时，电、磁场分量的自功率谱都服从对数坐标轴上的线性分布；而遇到电性不均匀体时，功率谱的线性发生畸变。

Fractal theory is used to study an irregular, non linear system which is characterized by self similarity. The dimension of the system is fraction. The fractional dimension reflects the complicity and essential features of the system. In this paper, the authors tries to intoduce the fractal theories to Magnetoteleuric Sounding. The Power Spectrum method was used to study a case and a low resistivity layer was found successfully. The conclusion is that if the media underground is homogeneous, the distribution of the Power Spectrum will be linear on bi logarithmic coordinate axes and if any abnormal body occurs underground, the linearity will be deformed, downward for low resistivity body and upward for high resistivity.