A Restudy of Existing Graphical Methods of Interpreting Magnetic Data and their Application to Interpreting the Results of Magnetic Surveys Across the Los Angeles Basin

Citation

Quigley, Milner Darwin (1950) A Restudy of Existing Graphical Methods of Interpreting Magnetic Data and their Application to Interpreting the Results of Magnetic Surveys Across the Los Angeles Basin. Engineer's thesis, California Institute of Technology. doi:10.7907/KWMD-SQ93. https://resolver.caltech.edu/CaltechTHESIS:02262010-092659807

Abstract

This thesis discusses the historical development of the methods of magnetic interpretation and explains why greater emphasis should be placed on graphical methods. Many graphical methods have been published but only one of them, Pirson's Polar Diagram method, has widespread application to all magnetic interpretive problems. The Polar Diagram method is especially applicable to magnetic problems of a regional nature where the disturbing body is very irregular in shape and cannot be approximated by a second order geometric form. A disturbing body of this description is present in the Los Angeles Basin. Previous attempts to match the observed magnetic anomaly curves across the Los Angeles Basin with the theoretical calculated curves by numerical methods have failed to obtain a close comparison. The Polar Diagram method makes it possible to obtain a superposition of the calculated curves over the observed curves except in the vicinity of the Palos Verde Hills. The superposition was obtained only after there was complete agreement between the existing geologic, gravity; and seismic information along the profile across the Basin. The Polar Diagram method is one of the quickest and most straight forward of the graphical methods to use. It is applicable to most magnetic problems where the direction of the induced magnetism is parallel to the direction of the remanent magnetism.

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