THE SIMULATION OF MAGNETIC VARIATION ANOMALIES USING SINGLE-STATION DATA

Hypothetical event maps of the vertical field derived from single-station magnetic variation transfer functions are biased by the anomalous horizontal fields. An iterative scheme, proposed earlier, is used to estimate and correct for the anomalous fields. The scheme here is applied to single-station transfer functions from 90 sites in southern Scotland and northern England. It converges to a stable solution in four iterations, and the results compare favourably with those predicted in the southern part of the area using measured inter-station transfer functions. The resultant hypothetical event maps of the anomalous horizontal fields show that the Northumberland Trough and Southern Uplands conductivity anomalies are both strikingly linear features which correlate more closely than previously supposed with other geological and geophysical observations.