b'Conferences and eventsNewsBurke Minsley (USGS): Mississippi Valley AEM interpretation Anand talked about incorporating uncertainty into electromagnetic modelling and summarised discussions on the topic over the last decade. We were given an interesting rundown on Bayesian theory by starting with prior beliefs and ending with different beliefs, made different by the EM data. The difference (misfit) between measured and modelled data gives you the likelihood of your belief, and the smaller your misfit, the more likely is the model. With this, you update your prior belief to produce an updated posterior. Through the talk, we were also shown the importance of doing sensitivity tests and how these would help us assess if data are sensitive to the feature we are interested in. It is a good idea to carry out these tests Burkes talk was on the Mississippi Alluvial Plain (MAP) project, thebefore embarking on paying thousands of dollars for a survey, largest integrated AEM effort for groundwater resource mappingor burning thousands of CPU hours on an inversion product. so far in the USA. An interesting survey was discussed where theyAn example of practical use was shown on two AEM datasets, a used both a fixed-wing time-domain (TEMPEST) system and ahelicopter and a fixed-wing, acquired over the Menindee Lakes. frequency-domain (RESOLVE) AEM system. The acquisition wasThe ensemble of conductivity models from both systems closely interwoven to allow the systems to complement each other. Theresembles the measured geo-electric layers measured via derived conductivity models extracted from both instrumentsdownhole conductivity logs.remarkably showed a seamless transition in their nationalNeil Foley (University of Montana): Geophysical identification hydrogeological grid. A 1 km x 1 km x 5 m vertical thicknessesofsubsurface water in the McMurdo Dry Valleys Region,mesh USGS national product was derived, from which maps andAntarcticasections were presented. The presentation showed a remarkable correlation of subsurface images with known geology. The conclusion was that the results and data from this AEM survey will support several stakeholders and can be used in diverse scientific and societal applications such as geology, water, hazards, minerals, ecosystems, climate and infrastructure.Aaron Davis, presented by Tim Munday (CSIRO): AEM inversion with a hydrological perspectiveNeil took us on a field trip to Blood Falls in the Taylor Glacier in Antarctica and demonstrated how water (in its liquid form) is a particularly good target for AEM in the cryosphere, given that the presence of solute (salt) lowers the freezing point of water. In particular, this makes AEM the perfect tool for detecting intra-glacial-lake systems which harbour extremophile life forms, some of which are excellent proxies Tim gave an overview of CSIROs current capabilities andfor life on Mars. The discovery of some of these waters in presented work where CSIRO is engaged in the EM space.Antarctica are extensive and reflect the geologic history of During the talk some case studies and examples were shown,the region.ranging from larger-scale studies like the Perth basin to postage-stamp scale smaller areas like a study in the South GoulburnTim Munday (CSIRO): Inverting for and/or stripping of airborne IP Island in the Northern Territory, where the whole islands waterand SPM - consequences for the geological interpretation of AEM supply is groundwater-dependent and is under constant threatdata.of saltwater intrusion under changing sea levels. CSIRO also presented a portal for service provision and data delivery.Anandaroop Ray (Geoscience Australia): Incorporating uncertainty into electromagnetic inversionTim showed two approaches of dealing with what has been attributed to be a superparamagnetic effect (SPM) in AEM data, which appears to be more prevalent in the newer high-powered 29 PREVIEW OCTOBER 2021'