Joint processing of total-field and gradient magnetic data

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Contents Vol 42(3)

doi:10.1071/EG10012

The Bulletin of the Australian Society of Exploration Geophysicists

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Joint processing of total-field and gradient magnetic data

Kristofer Davis ¹ ² ³ Yaoguo Li ¹

¹ Center for Gravity, Electrical, and Magnetic Studies, Department of Geophysics, Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA.
² Present address: UBC-Geophysical Inversion Facility, Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC V6T 1Z4, Canada.
³ Corresponding author. Email: kdavis@eos.ubc.ca

Exploration Geophysics 42(3) 199-206 http://dx.doi.org/10.1071/EG10012
Submitted: 13 April 2010 Accepted: 9 June 2011 Published: 2 September 2011





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Abstract

The processing of aeromagnetic data to account for levelling has been improved using gradient data. Utilising multiple magnetometers allows measurements of magnetic gradients and minimises the diurnal variation and other common-mode noise. We develop an equivalent source technique for jointly processing total-field and gradient data that makes use of a well known but rarely used relationship between the derivatives of the magnetic field and the derivative of its source to relate both datasets to a common equivalent source distribution. This approach treats the observed gradients as an additional and independent dataset instead of being just supplemental information. The direct result of joint processing is a set of enhanced data that incorporates information from both types of observed data as well as a higher signal-to-noise ratio. The methodology of the joint equivalent source processing technique is presented and demonstrated with a field example. Our method diminishes higher frequency noise, accentuates mid-frequency signals, and has higher resolution than that of total-field data alone.

Key words: equivalent source, gradients, joint inversion, magnetics, processing.

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