Holistic inversion of frequency-domain airborne electromagnetic data with minimal prior information

Ross Brodie; Malcolm Sambridge

doi:10.1071/EG08110

RESEARCH ARTICLE

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Holistic inversion of frequency-domain airborne electromagnetic data with minimal prior information

Ross Brodie ¹ ³ Malcolm Sambridge ²

+ Author Affiliations

- Author Affiliations

¹ Australian National University & Geoscience Australia, Research School of Earth Sciences, Bldg 61 Mills Road, Acton, ACT 0200, Australia.

² Australian National University, Research School of Earth Sciences, Bldg 61 Mills Road, Acton ACT 0200, Australia.

³ Corresponding author. Email: ross.c.brodie@ga.gov.au

Exploration Geophysics 40(1) 8-16 https://doi.org/10.1071/EG08110
Submitted: 18 August 2008 Published: 27 February 2009

Abstract

The holistic inversion approach for frequency domain airborne electromagnetic data has previously been employed to simultaneously calibrate, process and invert raw frequency-domain data where prior information was available. An alternative formulation has been developed, which is suitable in the case where explicit prior information is not available. It incorporates: a multi-layer vertically-smooth conductivity model; a simplified bias parameterisation; horizontal smoothing with respect to elevation; and cluster computer parallelisation. Without using any prior data, an inversion of 8.0 million data for 3.4 million parameters yields results that are consistent with independently derived calibration parameters, downhole logs and groundwater elevation data. We conclude that the success of the holistic inversion method is not dependent on a sophisticated conceptual model or the direct inclusion of survey-area specific prior information. In addition, acquisition costs could potentially be reduced by employing the holistic approach which largely eliminates the need for high altitude zero-level measurements.

Key words: airborne, calibration, electromagnetic, holistic, inversion, MPI, parallelisation.

Acknowledgments

The Riverland data were acquired by the South Australian Salinity Mapping and Management Support Project, which is jointly funded by the Commonwealth and South Australian Governments under the National Action Plan for Salinity and Water Quality. We thank that Project for permission to publish this work. The inversions were carried out on the Terrawulf computational facility which is supported through the AuScope initiative. AuScope Ltd is funded under the National Collaborative Research Infrastructure Strategy (NCRIS), an Australian Commonwealth Government Programme. We also thank Geoscience Australia for supporting this research. Brodie publishes with the permission of the CEO of Geoscience Australia.

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