b'AEM 2023Short abstractsDeveloping a fully airborne drone TEM system layer above the conductive cover or at surface in the resistive host is also modelled and compared. The properties chosen Nicklas S. Nyboe and Kristoffer S. Mohr to populate the model are representative of environments encountered in recently inverted surveys for these systems.SkyTEM Surveys, Aarhus N, DenmarkThe model results show that as the waveform turnoff sharpens Aiming at improving the efficiency and versatility of theand the system frequency decreases the sensitivity to shallow near time-domain electromagnetic method for geotechnical andsurface IP effects increases dramatically and suggests that in this environmental applications, we are developing a fully airborneenvironment common in Australia and other deeply weathered small-scale drone TEM system. In this paper we will outline theregions in Africa, the benefits of using these systems to detect main reasonings and design choices leading to the presentdeeper and more subtle conductors are not being realised.system implementation. The development of the complete airborne drone TEM system has involved the development ofA selection of the model results was inverted using the Moksha numerous system parts, which all present their own challenges2.5D inductive only and the joint inductive and IP inversion and optimisations both as individual elements and when workingmethods to determine if these complex models are accurately together. In fact, our development of the airborne drone TEMrecovered.system has essentially progressed in two parallel branches, where one branch has constituted drone and frame developments,The results indicate that it is very difficult or nearly impossible to while the other has constituted transmitter and receiverrecover the original geoelectric section when IP dominates the developments. Practical field tests of the various transmitterinductive signal in this way.and receiver prototypes have typically been performed as minor surveys at various test locations using a scaled-downPassive and active airborne electromagneticsseparate SkyTEM frame towed by a helicopter. We will present former andand combined technical solutions and applicabilitypresent capabilities of the system, primarily exemplified through descriptions of these prototype test surveys. Alexander Prikhodko1, Andrei Bagrianski1, Petr Kuzmin1 and Andrew Carpenter2Geotechnical ground investigations with a small1. Expert Geophysics Limited, Toronto, ON, Canadaairborne TEM prototype system 2. Expert Geophysics Pty Ltd, Perth, WA, AustraliaMartin Panzner1, Andi Pfaffhuber1 and Nicklas Nyboe2 Airborne electromagnetic methods are divided, by primary field 1. EMerald Geomodelling, Oslo, OSLO, Norway sources, into active (with controlled primary field sources) and 2. SkyTEM surveys, Aarhus, Denmark passive (without the ability to control the primary field). Each has pros and cons related to the depth of investigation, bandwidths, In this paper we show how time domain electromagnetic datasensitivity, resolution, terrain clearance requirements, and parasitic from a small airborne prototype system was successfully usedeffects. Expert Geophysics Limited has developed AEM systems for geotechnical ground investigations at a road constructionutilising active and passive principles, separate and combined. site in Central Norway. The measured data were processedThe MobileMT system is an entirely passive system using a remote and inverted with time efficient semi-automatic processingreference technique. The system provides low-noise broadband tools. Subsequently, the resistivity models recovered by AEMdata extracted from natural field audio frequency (AFMAG) and data inversion were automatically interpreted with machinea very-low-frequency (VLF) power spectra. In addition to the learning based algorithms that were trained with geotechnicalpassive field data, but with limited broadband, the TargetEM drilling data. Both the thickness of a sediment layer overlayingsystem measures time-domain data with an active and focused bedrock and the type of sediment was estimated. The measuredsource of the primary transmitting field. The combined (active data and the inverted resistivity models are compared toand passive) airborne electromagnetic system records broadband those from a regular SkyTEM304 system, which was utilisedstreaming data used to extract AFMAG, VLF, and time-domain earlier at the same site. Also, the sediment depth and sedimentcomponents. The natural field data, even in a limited frequency type estimated from the two AEM datasets were compared,range, is valuable in filling the gaps when the time-domain proving the feasibility of such a small airborne TEM system formethod is limitedat mapping highly resistive geological terrains, geotechnical ground of the shallow subsurface. in detecting superconductors, during surveys in rugged relief conditions, and at parasitic effects appearance. In this paper, we A forward model study to investigate 25, 12.5 andpresent the combined active-passive system.6.25 Hz AEM system responses to IP and SPM effects in the regolith AEM imagery down to one kilometre depth: New constraints for geological and hydrogeological Rodney Paterson1 and Jovan Silic2 modeling in volcanic contexts1. Intrepid Geophysics, Brighton, VIC, Australia Anne Raingeard1, Pierre-Alexandre Reninger1, Aurlie Peyrefitte1, 2. Jovan Silic and Associates, Melbourne, Victoria, Australia Guillaume Martelet1, Bertrand Aunay2 and Arnauld Malard32.5D forward modelling has been completed on a series of1. BRGM, Orlans, Francesynthetic electrical property models to evaluate and compare the2. BRGM, St Denis, La Runion, Franceresponses of the 25 Hz Tempest, 25 Hz VTEMplus and 12.5 and3. ISSKA, La Chaux-de-Fonds, Suisse6.25 Hz HeliTEM2 systems to a large tabular conductor buried between 30 and 430 m below 30 m of conductive cover with andWe present the integration of airborne magnetic data and without chargeable IP properties. The response to a surface SPMfive different airborne electromagnetics data sets spanning AUGUST 2023 PREVIEW 62'