International

Title: Induced Polarization effects in Electromagnetic data: opportunity or waste of time?

Speaker: Francesco Dauti, PhD student at University La Statale of Milan

Date/Time: 30/03/2023 @ 1645

Zoom Registration: https://us02web.zoom.us/webinar/register/WN_6tN9sU_uQNmzPI0s3EaWow

Abstract: 

The possibility to model the Induced Polarization (IP) effects from the time-domain Airborne Electromagnetic (TD-AEM) data has gained considerable interest in the last two decades from both industry and academia. 

Recently, it has been physically demonstrated that IP effects can distort AEM data that, if not recognized and properly treated, can lead to artefacts in the modelled resistivities.   What it is still unclear though is if these distortions can be robustly recovered and modelled, providing useful information on polarisation effects within the ground.

Results on two aspects of airborne IP (AIP) modelling will be discussed:

(i) if modelled AIP effects can give significant information for exploration, and

(ii) if it is possible to measure and model AIP in AEM fixed-wing systems.

Francesco Dauti is a Ph.D. student in exploration geophysics at University La Statale of Milan. He took a bachelor’s and a master’s degree at University of Pisa, in geological sciences and in exploration and applied geophysics. His current research field is about the integration of galvanic and inductive Induced Polarization techniques for mineral exploration, both in terms of modelling, inversion, and interpretation.

Bio:

Francesco Dauti is a Ph.D. student in exploration geophysics at University La Statale of Milan. He took a bachelor’s and a master’s degree at University of Pisa, in geological sciences and in exploration and applied geophysics. His current research field is about the integration of galvanic and inductive Induced Polarization techniques for mineral exploration, both in terms of modelling, inversion, and interpretation.

More details to follow

On Tuesday 19th October, 6:00pm AEDT, ASEG NSW is bringing you a talk by Derecke Palmer (UNSW) titled Is there a seismic refraction signature for sulphide mineralisation?

Although I accepted retirement from UNSW almost two decades ago, I have continued with my longstanding research interests in near surface refraction seismology. The major theme of my research has been full trace processing. Inexorably, full trace processing leads into detailed model building with traveltimes and amplitudes. My presentation addresses three important questions.

The first is “Is there a seismic refraction signature for sulphide mineralisation at the base of the regolith?” The second is: “Will full waveform elastic inversion rapidly replace traveltime acoustic tomographic inversion, and become routine with most geotechnical investigations?” The third is: “Would a detailed analysis of the refraction component of selected regional reflection profiles recorded by GA be useful?” The presentation employs seismic data recorded by GA near a major operational gold mine.

Attendance is by joint Zoom virtual + physical presentation at Geoscience Australia.

Register Here: https://us02web.zoom.us/webinar/register/WN_vdsnFZAuRp2egjpFX1QLbQ

Please bring your own drinks and nibbles if attending online.

Topic: ASEG NSW - talk by Berta Vilacís

Presenter: Berta Vilacís

Date and time: Sep 21, 2022 06:00 PM

Registration: https://us02web.zoom.us/webinar/register/WN_p_jGJ9-ESQaR2j_c9XroWQ

Overview:

Mantle convection is an essential driving force of plate tectonics. It affects the horizontal and vertical motion of the Earth’s surface. The horizontal motion of the lithosphere is observed in the spreading rates, while its vertical motion leaves an imprint the geological record. In particular, positive surface deflections driven by mantle convection create erosional/non-depositional environments, which induce gaps in the stratigraphic record (i.e., hiatus). Modern digital geological maps allow us to map no-/hiatus surfaces at continental scale systematically and use them as a proxy for mantle flow induced dynamic topography. We find that hiatus surfaces change in timescales of geological series. This is consistent with the presence of a weak upper mantle. Also, we find significant differences in the spatial scale of inter-regional hiatus, on the order of 2000-3000 km in diameter, which can be linked by fluid dynamic analysis to active upper mantle flow regions. Our results highlight the importance of geological datasets to further understand geodynamic processes in the deep Earth. Also, they indicate that studies of horizontal and vertical motion of the lithosphere to track past mantle flow would provide powerful constraints for adjoint based geodynamic inverse models of past mantle convection.

Bio:

Berta Vilacís is a PhD student in geodynamics at the Ludwig-Maximillians-Universität München (LMU Munich). She did her bachelor in Physics in the University of Barcelona focusing in applied seismology during her final year. At the same time she got a one-year fellowship in the Catalonia seismic network. After working in maintaining and processing data from the IEC seismic network in 2017, she moved to Munich where she got her MSc in Geophysics by TUM and LMU Munich. In 2019, she started her PhD in Hans-Peter Bunge’s group. Her research focuses in using geological information, such as geological maps, as a way to observe, map and track past mantle convection.

The 8th International Workshop on Airborne Electromagnetics will be held at Fitzroy Island, Queensland Australia, in person between the 4th and 8th September 2023. Fitzroy Island is an unspoilt tropical paradise of rainforest and beaches within the calm sheltered waters of the Great Barrier Reef. The island is a National Park, with walking trails, tropical plants and animals, and abundant marine life.

The Workshop will encompass advances in airborne electromagnetic systems, modelling and interpretation. Case studies covering geotechnical, mining, energy, groundwater and environmental applications will be presented. The event will be a platform to contribute, discuss and learn about airborne electromagnetics and provide a forum for in-depth conversations on the subject area with colleagues from Australia and worldwide.

A four-day program will feature speakers from academia, government and industry, with keynotes delivered by leading experts in their respective streams.

We look forward to welcoming you to the 8th International Airborne Electromagnetics Workshop.

Key Dates

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Title: Mis-adventures of a Mathematician in Industry

Presenter: Audrey Addison

Date: Thursday, 5th May 2022

Time: 12:00 PM Canberra (AEST)

Registration: https://us02web.zoom.us/webinar/register/WN_Zuj0cfuZTT6EgoH9QGm3fw

Abstract:

What does a scientist do?  That question was at the top of my mind as I was finishing up my PhD in Mathematics in 2014.  My plans of teaching at the college level were thwarted by the two body problem, so I turned my focus to industry instead.  What followed was a series of positions in three disparate industries: Oil and Gas, Industrial Engineering and Tech where I found that the more things changed, the more they stayed the same.  In this talk, I’ll share my personal experiences in industry and as a military officer, demonstrate how a mathematician or scientist might find a niche in industry and summarize some lessons learned. 

Bio: 

Audrey Addison has held varied responsibilities throughout her career and has a PhD in Mathematics. She was a Rescue Coordination Center Controller with the US 11th Air Force; Intelligence Officer, US 176th Wing; Research Geophysicist, Chevron, and a Numerical Analysis Software Engineer, Siemens. She currently works as a Software Engineer at Google.

Title: ACT AGM + Tech Talk: Airborne Gravity and gravity gradiometry for a high resolution national gravity grid of Australia

Presenter: Dr Mark Dransfield – Airborne Gravity Consultant

Date: Thursday, 28th April (to be followed by the ACT ASEG AGM)

Time: 1500

Registration: https://us02web.zoom.us/webinar/register/WN_YxPHm9hIQR-FZDUx-8JEog

Abstract:

In 2019, for the first time, the National Gravity Grid included gravity observations from ground gravity, airborne gravimetry and gradiometry, and satellite observations. This is a significant step towards my personal dream of a national gravity dataset sampled at a spacing similar to aeromagnetics' 400 m or better.

One of the many questions to be addressed for the next national gravity grid is the subject of this talk.

With data from such disparate sources, how do we best merge the data into one gravity map to preserve the spatial resolution, accuracy, and precision, and to provide a product of maximum value to the communities that will use it?

I will discuss some of the alternatives and attempt to summarise the advantages and disadvantages of each.

Title: The use of machine learning in processing remote sensing data for mineral exploration

Presenter: Dr. Ehsan Farahbakhsh

Date: Wednesday 20th April 2022

Time: 1800-1900

Registration: https://us02web.zoom.us/webinar/register/WN_2iHaItV9Sk201SP4ZFkPpw

Overview:

The decline of the number of newly discovered mineral deposits and increase in demand for critical minerals in recent years has led exploration geologists to look for more efficient and innovative methods for processing different data types at each stage of mineral exploration. As a primary step, various features, such as lithological units, alteration types, structures, and indicator minerals, are mapped to aid decision-making in targeting ore deposits. Different types of remote sensing datasets, such as satellite and airborne data, make it possible to overcome common problems associated with mapping geological features. The rapid increase in the volume of remote sensing data obtained from different platforms has encouraged scientists to develop advanced, innovative, and robust data processing methodologies. Machine learning methods can help process a wide range of remote sensing datasets and determine the relationship between components such as the reflectance continuum and features of interest. These methods are robust in processing spectral and ground truth measurements against noise and uncertainties. In this presentation, I will provide a brief introduction to remote sensing data types and review the implementation and adaptation of some popular and recently established machine learning methods for processing different types of remote sensing data aiming at detecting various ore deposit types. I will also review our recent studies on combining remote sensing data and machine learning methods for mapping different geological features that are critical for providing mineral potential maps.

Bio:

Dr. Ehsan Farahbakhsh is a Research Associate in the EarthByte Group, School of Geosciences, University of Sydney. He holds a PhD degree in Mining Engineering - Mineral Exploration from Tehran Polytechnic. He has been involved in several projects as an exploration geologist or spatial data analyst for the exploration industry, primarily for providing prospectivity maps of various ore deposit types from regional to deposit scale. His research interests are multidimensional mineral prospectivity modeling, geological remote sensing, geostatistics, and the application of data science and UAVs in mineral exploration.

Asia Pacific Meeting on Near Surface Geoscience & Engineering returns for its 5th edition and the flagship conference on Near Surface APAC is set to be held from 6-9 March 2023 in Taipei, Taiwan. As we concluded the last edition, we  are pleased to welcome all of you to a yet another successful conference in Taipei, Taiwan next year. 

This year's conference is Co-Organized with Taiwan Geotechnical Society (TGS) and National Yang Ming Chiao Tung University, Taiwan under the overarching theme of: Global Challenges and Regional Experiences. The theme is set as it is important to welcome submissions that focus on the challenges faced by the Near-surface industry; regional centric as well as globally. 

If you are interested to share your work and be part of the speakers' line-up, submit your extended abstract  before 15 November 2022.

Submit abstracts here.

Title: Multi-parameter FWI imaging: high-resolution imaging directly from raw field data

Presenter: Tom Rayment, Chief Geophysicist, DUG Technology

Date: Tuesday 10th May 2022

Time: 7pm AEST

Registration: https://us02web.zoom.us/webinar/register/WN_CN-_WOEpTemeHTx7FF_gtA

Abstract:

Traditional seismic processing workflows can be extremely time-consuming since subsequent stages are only begun after extensive testing and QC of the current process. This linear approach takes the raw field data and passes it through a plethora of conditioning tools (such as designature, deghosting, demultiple and regularisation) to transform the data into a form that can be imaged by legacy migration algorithms, such as Kirchhoff 3D preSDM.

Full waveform inversion (FWI) imaging is a multi-scattering least-squares approach uses the raw field data to estimate many subsurface parameters, including reflectivity, simultaneously ahead of a conventional processing workflow. Since it is using the primaries, multiples and ghosts during imaging, the result is a set of higher resolution subsurface models but in a fraction of the time of a conventional processing workflow due to the fact that little to no pre-processing is required.

In this presentation we demonstrate an 85 Hz comparison between a conventional processing workflow and a novel FWI imaging technique that utilises an augmented wave equation and an advanced optimisation scheme. The FWI imaging approach is simultaneously inverting for velocity and an intercept-reflectivity vector which is fit for structural and amplitude analysis.