Noise Reduction Techniques for Use in Determining Local Geomagnetic Field Changes
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Measurements of the difference in total field ΔF(t) have been made over a 16 km N-S path near Boulder. The behavior observed is quite different from that for an E-W path. The present accuracy of the narrow line rubidium magnetometers used is about 0.01 γ. The N-S variations appear to correlate mainly with variations in H rather than D, and may be associated with either gradients of external fields or currents in shallow conductivity anomalies. More recently three magnetometers have been set up on a straight E-W line so that the ‘second difference’ can be measured, and a transfer function from field component variation to the second difference can be determined. A generalization of this approach will be used for analyzing USGS tectonomagnetic data from California.
KeywordsTotal Field Crustal Stress Noise Reduction Technique Poor Coherence Denver Basin
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