Implementation of the Singular Points Method for Gravity Data by Fast Fourier Transforms

Abstract

i»?The singular points method was originally implemented using a Fourier series associated with the singular point, and it only can be used to interpret the profile data. In this article, the original algorithm is modified using fast Fourier transforms (FFTs) to eliminate the deficiencies in the Fourier series approach. Meanwhile, we implement the three-dimensional (3-D) computation of the singular points method for interpretation of gravity grid data using FFTs. The same as the standard algorithm, the new algorithm also can be used to estimate the depths of causative sources by means of downward continuation in conjunction with determining the point at which the field becomes singular. It is tested on synthetic models, with satisfactory results. Then we applied it to a real gravity data profile from the Qian-An area in Northeast China, and the 3-D computation was applied to the grid data from Dian-Nan in Yunnan province, which was digitalized from a previously published paper (Liu, 2007). Compared with the drilling data and other previous research results, this algorithm demonstrates feasibility and validity of the semi-automatic interpretation.