CORRELATION COEFFICIENTS AND THEIR USE IN THE PREDICTION OF MEAN ANOMALIES

The correlation of point anomalies with the separation between them was investigated by means of the correlation coefficient. Correlation curves for free air anomalies were established in Ohio and Finland, and for Bouguer anomalies in Ohio alone. The individual curves showed a wide variation, but the curve obtained by meaning the values of a particular correlation coefficient from the individual curves gave a reasonably smooth curve that turned negative at 107 km in Ohio and 147 in Finland. Various equations were applied to these mean curves to find an analytical representation. A satisfactory representation was found from a third order polynomial representation. Tests of the prediction formulas for free air anomalies were carried out using circles of 20 and 40 km in radius. An accuracy analysis was made by comparing the predicted mean anomaly with a true mean anomaly. Based on 14 points in Ohio a mean error of one prediction was 4 mgals and on 15 points in Finland was 3 mgals for R40 km. In both cases this was an increase in the accuracy of mean anomaly above that if the mean anomaly was simply taken as the point anomaly at the center of the circle. Author