Method Of Low-attitude Reduction To The Pole Applying To The Magnetic Data Of Cambodia

In general, the method of reduction to the pole which we use at the low latitudedistrict can be sorted in two ways, one is used in the space domain the other is in thefrequency domain. When in the frequency domain we can get what we want quickerand simpler than in the space domain so the reduction to the pole method in frequencydomain is widely used in the present. Nevertheless, instead of eliminating the noisemost of the reduction to the pole methods merely suppress it. Though the noise canaffect the result of reduction to the pole, it is not the key cause, we can not get asatisfying result just by suppressing the noise. In this paper we have used five kinds ofreduction to the pole method-one is in the space domain called equivalent sourcetechnique method, whose specific ideas are using the dipole layer whose direction isthe same with the local magnetization and the way of the dipole arrangement is linedaccording to an exact rule to replace the actual underground magnetic body. This iscalled the equivalent source technique method. This method actually regards theproblem of the reduction to the pole as a linear inverse problem, this method can getthe dipole moment of per unit length by solving the linear equation which containedthe actual magnetic data we measured, then following the equivalence principle ofsuperposition we make the direction of the dipole vertically downward and then wecan acquire the result of the reduction to the pole. The other four is in the frequencydomain respectively called suppression filter method, hyperbolic sine method, directdamping method and pseudo inclination method-which we apply to the model wedesign and then to the magnetic data from a small area of north Cambodia. In the finalpart of the paper we compare the result which we got before and choose a better onein these five methods, due to the short of the geological information in this area wehave to choose the better method only by the shape and amplitude of the magneticanomaly without considering whether it fits the geological conditions.