Trend analysis of geophysical data

Abstract

Trend analysis of aeromagnetic data has been treated in a few publications during recent years. In this paper a short review is given of the methods used and results from comparisons between different methods. It is attempted to make a more general use of one of the methods presented—the triangle method—on all sorts of geophysical data, including terrain analysis. By the aid of a computer programme for rectangular grid systems the trend analysis is easily performed. The results are given as frequency polygons and polar diagrams, and a discussion is made over the reliability of the resulting frequencies. The amount of information from one analysis can be increased by using two different lengths of the class intervals and by operating with two grid spacings. The triangle method is tested with random and dependent data. Finally an example related to the treatment of gravimetric, magnetic, and topographic maps over a small survey area is presented.