地磁感应研究的最初成果之一是探测到在球对称的地球地震波C层中,由岩石的相变而引起的电导率增加(Lahiri和Price 1939)。在六十年代,作为大地电磁法实际应用的一个结果,这些区域的,甚至局部地区的电导率增加的深度的变化资料才能予以对比。由于包括的深度很大(大约为几百公里)、所以数据相当分散。最近,为了避免地表附近的畸变效应, One of the first results of geomagnetic induction studies was the detection of an increase in electrical conductivity due to the phase transition of rocks in a spherical symmetry Earthquake C (Lahiri and Price 1939). In the 1960s, as a result of the practical application of the MT method, the changes in the depth of conductivity increase in these regions, and even in some regions, can be compared. The data is fairly decentralized due to the deep depths (about a few hundred kilometers) included. Recently, in order to avoid the distortion effect near the surface,