b'AEM 2023Short abstractsfrom 3000 NIA up to 1 000 000 NIA magnetic moments (threecombinations and estimates the signal-to-noise ratio of the different AEM systems were used) in La Runion volcanic island.resulting decays. The estimation of the signal-to-noise ratio is Subsequently, a 3D geological model of the first km beneathperformed using the singular value decomposition filtering the Plaine des Fougres was built, in order to constrain 3Dwhich has proven to be effective in identifying and removing hydrogeological modelling. This approach allowed for thenoise affecting an AEM dataset.correlation of different datasets, providing a comprehensive image of the subsurface and enabling a greater hydrogeologicalThe supervised stacking method is applied on the raw data. It understanding. It was used to position the route of a deep- has been tested on two AEM datasets, acquired in Reunion and water drainage gallery and has great potential for applicationsAuvergne (France), where EM noise is high, and resistivity can in other areas. easily exceed 1000 m in some places. The results show that the presented method improves the signal-to-noise ratio and can reduce sferics and certain noises from man-made installations. HiQGA: Open source deterministic and probabilisticIt provides less noisy decays for post-processing and offers new AEM inversion possibilities for processing AEM dataAnandaroop Ray1, Richard Taylor2, Ross Brodie1, Yusen LeyCooper1, Neil Symington1 and Negin F. Moghaddam2 Airborne magnetics as structural guide in the 3D inversion of Airborne EM data1. Geoscience Australia, Symonston2. Formerly at Geoscience Australia, Symonston Carsten Scholl, Stephen E Hallinan, Marianne Parsons and The High Quality Geophysical Analysis (HiQGA) packageTomKimurais a framework for geophysical forward modelling,CGG, Milano, LOMBARDIA, ItalyBayesian inference, and deterministic imaging. A primary focus of the code is production inversion of airborneAirborne Magnetics and Electromagnetics surveys are widely electromagnetic (AEM) data from a variety of acquisitionused in mineral resource exploration. Beyond the sensitivity of systems. Adding custom AEM systems is simple using aboth to certain mineral deposits, magnetics serves as a useful modern computational idea known as multiple dispatch.proxy for geological structure.For probabilistic spatial inference from geophysical data,We extend our previous work on cross-gradient, structurally-only a misfit function needs to be supplied to the inferenceguided 3D EM inversions to use two-dimensional gradients engine. For deterministic inversion, a linearisation ofderived from pre-processed magnetic grids as a structural guide the forward operator (i.e., Jacobian) is also required. Forin inversions of AEM data sets.fixed wing geometry nuisances, probabilistic inversion is carried out using Hierarchical Bayesian inference, andWe compare 3D resistivity inversion results obtained with this deterministic inversion for these nuisances is done usingstructural guiding approach to those without, for AEM data BFGS optimisation. The code is natively parallel, andrecorded in a survey in New Brunswick, Canada.inversions from a full day of production AEM acquisition can be inverted on thousands of CPUs within a few hours. ThisThis structurally-guided 3D inversion method using magnetics allows for quick assessment of the quality of the acquisitiondata is generic and can be applied to inversion of other and provides geological interpreters preliminary subsurfacegeophysics data such as ground electromagnetics, etc.conductivity images and associated uncertainties. These images are used to create subsurface models for a rangeBGR helicopter-borne frequency-domain EMpast, of applications from natural resource exploration to itspresent, futuremanagement and conservation.Bernhard SiemonSupervised stacking to improve the signal-to-noiseBundesanstalt fr Geowissenschaften und Rohstoffe, Hannover, ratio of AEM data LOWER SAXONY, GermanyPierre-Alexandre Reninger The German Federal Institute for Geosciences and Natural BRGM, Orlans, REGION CENTRE-VAL DE LOIRE, France Resources (BGR) has been conducting airborne geophysical surveys worldwide for more than four decades. Most of these AEM method has proven to provide useful information onairborne surveys applied frequency-domain heli-copter-borne the subsurface for many applications. However, measuredelectromagnetics (HEM) in combination with magnetic and decays are affected by many noises, limiting its effectivenessradiometric measurements.and which may prevent to acquire usable data, especially in resistive environments. Stacking techniques are applied in anHEM surveys served and still serve as acquisition of baseline attempt to improve the signal-to-noise ratio. However, stackingdata for a number of applications in mineral, groundwater all decays falling within a stack interval can be ineffective,and soil exploration. After starting with anomaly detection given the nature of noises that can affect the data from decayin mineral exploration surveys, the focus was set to to decay. To a lesser extent, arbitrarily increasing the stackgroundwater surveys during the following decades. Spatial size may also be ineffective, especially in an anthropisedmapping of freshwater resources, seawater intrusion, environment. Stacking is generally done without any realsubmarine fresh-water outflows, and buried valleys are control on the data taken into account. some typical applications. Recently, environmental issues have gained more and more importance. Therefore, BGR This paper introduces a supervised stacking method that stacksconducted most of the current surveys in Germany. These decays falling within a stack interval considering differentprovided not only resistivity distributions, but also estimated 63 PREVIEW AUGUST 2023'