A New Technique for Low Magnetic Latitude Transformation: Synthetic Model Results and Examples

SUMMARY Traditional methods for processing low magnetic latitude data below ±25° magnetic latitude do not fully resolve anomaly location and may distort the anomaly shape leading to misinterpretation of the data, as well as loss of certain directional anomalies. The principal objective of our research was to develop a new filter that would better position anomalies, reduce anomaly distortion and provide good anomaly shape while attempting to recover structures parallel to the declination direction. The MTC-LML Filter (Modulus of Total Component at low magnetic latitudes) is based on the calculation of the Modulus of the three magnetic components of the main field (one vertical and two orthogonal horizontal). To test the MTC-LML Filter, a set of synthetic models were constructed composed of complicated magnetic bodies each with different strike directions and depths. Each model was designed to address a specific aspect of the low magnetic latitude problem. The results of synthetic modelling for the MTC-LML Filter were compared with synthetic models of standard transformations and techniques for dealing with low magnetic latitude data. Practical applications of the MTC-LML Filter were then made using survey data. The filter results for synthetic model and survey data, show better location and shape of model source bodies when compared to the existing standard transformations and techniques. The MTC-LML Filter provides an improved transformation of the data with reliable location and shape of the anomalies above the source, reduced anomaly distortion and better recovery of structure parallel to the declination direction.