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本文从理论上计算了和断层面相垂直的阶状断层上的大地电流场及其梯度变化。借助于第一和第三类椭圆积分,采用施瓦兹——克利斯托里弗尔保角变换方法就可以获得边值问题的闭型解。假定基底的电阻率为无穷大,而沉积盖层的电阻率和厚度都是有限的.基底的断层间距为S,落差为h_2和h_3。为了模拟大地电流场,我们假定在无限远处有一对无限长的线电源。从计算结果来看,大地电流场的梯度对探测和解决断层面来说似乎是一个更好的参数。在断层的落差只是覆盖层总厚度(H)的10％的情况下,如果构造面的埋深和断层面间距几乎相等时,所得结果将趋于零.当然落差更大时,其结果更容易趋于零。断层的位置和地表梯度极值的关系取决于地质构造所有的几何参数。由大地电磁测深资料得到的覆盖层总厚度所提供的待解地质构造,从大地电流剖面及梯度也可以获得关于几何参数的定量解释.所作的计算是用Burrougs—6700计算机进行的。
In this paper, the earth current field and its gradient change on the step-shaped fault perpendicular to the fault plane are theoretically calculated. With the help of the first and third elliptic integrals, closed-form solutions of the boundary value problem can be obtained by using the Schwartz-Kristoffer-Filler transformation method. Assuming that the resistivity of the substrate is infinite, the resistivity and thickness of the deposited caprocks are finite, and the substrate has a fault spacing of S and a gap of h_2 and h_3. In order to simulate the earth current field, we assume that there is a pair of infinite line power at infinity. From the calculation results, the gradient of the earth current field seems to be a better parameter for detecting and solving the fault plane. If the fault’s fall is only 10% of the total cover thickness (H), the result will tend to be zero if the depth of the structural face is approximately the same as the fault face spacing. Tends to zero. The relationship between the position of the fault and the extreme value of the surface gradient depends on all the geometric parameters of the geological structure. Quantitative interpretation of geometrical parameters can also be obtained from the geoelectric current profiles and gradients from the geologic tectonics provided by the total overburden thickness obtained from the magnetotelluric data from the earth and calculations made using the Burrougs-6700 computer.