# Trans-dimensional Bayesian inversion of airborne electromagnetic data for 2D conductivity profiles

Rhys Hawkins^{1}

^{3}Ross C. Brodie

^{2}Malcolm Sambridge

^{1}

^{1} Research School of Earth Sciences, Australian National University, Canberra, ACT 2601, Australia.

^{2} Geoscience Australia, Canberra, ACT 2609, Australia.

^{3} Corresponding author. Email: rhys.hawkins@anu.edu.au

*Exploration Geophysics* - https://doi.org/10.1071/EG16139

Submitted: 11 November 2016 Accepted: 30 January 2017 Published online: 24 February 2017

## Abstract

This paper presents the application of a novel trans-dimensional sampling approach to a time domain airborne electromagnetic (AEM) inverse problem to solve for plausible conductivities of the subsurface. Geophysical inverse field problems, such as time domain AEM, are well known to have a large degree of non-uniqueness. Common least-squares optimisation approaches fail to take this into account and provide a single solution with linearised estimates of uncertainty that can result in overly optimistic appraisal of the conductivity of the subsurface. In this new non-linear approach, the spatial complexity of a 2D profile is controlled directly by the data. By examining an ensemble of proposed conductivity profiles it accommodates non-uniqueness and provides more robust estimates of uncertainties.

**Key words:** airborne electromagnetic inversion, Bayesian, non-uniqueness, trans-dimensional, uncertainty.

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