The static effect is a commonly-existent technical problem in MT method, and its influence could lead to an unacceptable result of the observation data. According to the distinguishing method, correction method and the data collection system, the authors put forward a spatial-domain topological processing method based on the original data. Through the analysis of the cause and representation of the static effect and the superposition characteristics of electric field components, the authors began with the essence of space sampling and completed the formula for obtaining the topological curve, finally got the observation result with different pole distances at the same site and found out the implicit observation information in the observation system of continuous arrays. According to the analytical result of theoretical model, the authors established the model of all the possible static migrations of the record site with the change of pole distance in different parts of local inhomogeneous body and, in addition, established the basic topological result graphic display and interpretation method including using sites to do pseudo-section processing and using the fixed frequency result of all sites in a profile painting pseudo-planar graph. The authors also compiled the software of topological processing and finished this new method of using topological processing method to analyze the static effect of MT both in theory and in application. The test result proves that the topological processing could improve the quality of data. With this technique, the discrimination of static effect could begin with many aspects, could find out the spatial distribution of the distorted electrical field caused by local inhomogeneous body, and could find out the location and spatial distribution of the local inhomogeneous body, thus providing researchers with real information on the surface electric structure. The topological processing could also get the result of changing arrays, and this means the emerging of a new method for inhibiting interference.
Weidelt P.The inverse problem of geomagnetic induction[J].Zeitschrift Fuer Geophysik, 1972, 38: 257-289.
[2]
Jones A G.On the equivalence of the "Niblett" and "Bostick" transformations in the magnetotelluric method[J]. Journal of Geophysics, 1983, 53: 72-73.
[3]
Jones A G.Static shift of magnetotelluric data and its removal in a sedimentary basin environment[J]. Geophysics, 1988, 53(7): 967-978.
[4]
Torres-Verdín C, Bostick F X Jr. Principles of spatial surface electric field filtering in magnetotellurics: Electromagnetic array profiling (EMAP)[J].Geophysics, 1992, 57(4): 603-622.
[5]
Jones A G.The problem of current channeling: a critical review[J].Geophysical Surveys, 1983, 6: 79-122.
[6]
Singer B S.Correction for distortions of magnetotelluric fields: limits of validity of the static approach[J].Surveys in Geophysics, 1992, 13(4-5): 309-340.
[7]
Ogawa Y.On two-dimensional modeling of magnetotelluric field data[J].Surveys in Geophysics, 2002, 23(2-3): 251-273.
[8]
Tournerie B, Chouteau M.Deep conductivity structure in Abitibi, Canada, using long dipole magnetotelluric measurements[J].Geophysical Research Letters, 1998, 25(13): 2317-2320.
[9]
Tournerie B, Chouteau M.Analysis of magnetotelluric data along the Lithoprobe seismic line 21 in the Blake River Group, Abitibi, Canada[J].Earth, Planets and Space, 2002, 54(5): 575-589.
[10]
Tournerie B, Chouteau M, Marcotte D.Magnetotelluric static shift: Estimation and removal using the cokriging method[J].Geophysics, 2007, 72(1): F25-F34.
[11]
Kaufman A A.Tutorial distribution of alternating electrical charges in a conducting medium[J].Geophysical Prospecting, 1985, 33(2): 171-184.
[12]
Le Mouel J L, Menvielle M. Geomagnetic variation anomalies and deflection of telluric currents[J].Geophysical Journal International, 1982, 68(3): 575-587.
[13]
Wannamaker P E.Resistivity structure of the northern Basin and Range[C].//Eaton G P. The role of heat in the Development of Energy and Mineral Resources in the Northern Basin and Range Province. Geothermal Resources Council Special Report. 1983: 345-362.
[14]
Wannamaker P E, Hohmann G W, Sanfilipo W A.Electromagnetic modeling of three-dimensional bodies in layered earths using integral equations[J].Geophysics, 1984, 49(1): 60-74.
[15]
Swift C M.A magnetotelluric investigation of an electrical conductivity anomaly in the southwestern United States[D].Massachusetts: Massachusetts Institute of Technology, 1967.
[16]
Word D R, Smith H W, Bostick F X Jr. An investigation of the magnetotelluric tensor impedancemethod[R].Texas: Texas Univ Austin Electronics Research Center. 1970.
[17]
Sternberg B K, Washburne J C, Pellerin L.Correction for the static shift in magnetotellurics using transient electromagnetic soundings[J].Geophysics, 1988, 53(11): 1459-1468.
[18]
Berdichevsky M N, Vanyan L L, Dmitriev V I.Methods used in the U.S.S.R. to reduce near-surface inhomogeneity effects on deep magnetotelluric sounding[J].Physics of the Earth and Planetary Interiors, 1989, 53(3-4): 194-206.
[19]
Bahr K.Interpretation of the magnetotelluric impedance tensor: regional induction and local telluric distortion[J].Journal of Geophysics, 1988, 62(2): 119-127.
[20]
Groom R W, Bailey R C.Decomposition of magnetotelluric impedance tensors in the presence of local three-dimensional galvanic distortion[J].Journal of Geophysical Research, 1989, 94(B2): 1913-1925.
