Filtering marine magnetic anomalies

When marine magnetic anomalies can be adequately modeled by two-dimensional magnetic structures within one or more plane layers, many interesting manipulations of both models and anomalies are linear filtering operations [Dean, 1958; Bott, 1967; Black and Scollar, 1969; Schouten, 1971]. Linear filters can be applied quickly and accurately by using the fast Fourier transform algorithm [Cooley and Tukey, 1965]. We have applied this algorithm to two broad classes of physically meaningful filters. The first class consists of the filters that together can synthesize theoretical magnetic anomalies, given a magnetic model. The second class consists of filters that are the inverse of the filters in the first class and can be used to resolve the source of an observed anomaly. We shall describe in some detail the two classes of filters and their application to synthesizing theoretical magnetic anomalies and ultimately to resolving two correlating magnetic anomaly sections of the Eltanin 41 track across an asymmetrically spreading area south of Australia [Weissel and Hayes, 1971, 1972].