National

Title: Learning to learn about the earth, using Bayesian inference

Presenter: Anandaroop Ray (Geoscience Australia)

Abstract: To understand earth processes, geoscientists infer subsurface earth properties such as electromagnetic resistivity or seismic velocity from surface observations such as magnetotelluric data or seismograms. These properties are used to populate an earth model vector, and the spatial variation of properties sheds light on the underlying earth structure and phenomena, from groundwater aquifers to plate tectonics. I will show that in order to make accurate inferences about earth properties, inferences can first be made about the underlying length scales of these properties. From a mathematical point of view, the length scales can be conveniently thought of as “properties” of earth properties. This can be treated in an “infer to infer” paradigm analogous to the “learning to learn” paradigm which is now commonplace in the machine learning literature. A non-stationary trans-dimensional Gaussian Process (TDGP) is used to parameterise earth properties, and a multi-channel stationary TDGP is used to parameterise the length scales. Using non-stationary kernels, i.e., kernels with spatially variable length scales, earth models with sharp discontinuities can also be represented within this framework. As GPs are multi-dimensional interpolators, the same theory and computer code can be used to solve geophysical problems in 1D, 2D and 3D. This is demonstrated through a combination of 1D and 2D non-linear regression examples and a controlled source electromagnetic field example.

Biography: Anandaroop Ray (“Anand”) started his career as a non-seismic geophysicist with Shell Exploration and Production in 2007. In 2010 he joined the PhD programme in marine electromagnetics at the Scripps Institution of Oceanography in San Diego, California. In 2014 he completed his thesis focusing on uncertainty estimation in electromagnetic inversion for marine hydrocarbon exploration. From 2012-19, he worked for Chevron R&D on various problems – controlled source electromagnetics (CSEM), seismic full waveform inversion (FWI), reservoir properties from seismic (RPFS), airborne electromagnetics (AEM), statistical hydrocarbon exploration lookback analyses, and the role of machine learning in geophysics. The question most asked through his work is “how credibly can we interpret our inversion model(s),” the answering of which often requires the use of high-performance computing (HPC) techniques. He currently co-advises a PhD student at Columbia University on Bayesian geophysical inversion and has been active in convening and organizing the Uncertainty in Geophysical Inversion session at the American Geophysical Union’s Fall Meeting. In March 2019 he joined the Minerals, Energy and Groundwater Division at Geoscience Australia, where he continues to work on inverse uncertainty, model representation and geostatistics.

Register: https://us02web.zoom.us/webinar/register/WN_j_B7TWtMQvOSxy9zTLj5Iw

You are invited to join online with GSA  -- 31 March 2021 – 6.30pm

Speaker: Brad Pillans, Chair of the National Rock Garden Steering Committee

Topic: The thrill of the chase: Finding (and funding) 100 iconic rocks for the National Rock Garden

Zoom link:  click here to watch

Abstract: When the National Rock Garden was officially launched in 2010 at the Australian Earth Sciences Convention in Canberra, it seemed a straightforward task to bring in a bunch of rocks from all around the country and tell the story of Australian geology. Are we there yet? Not quite, but the thrill of the chase remains as we build our national collection of 100 or more iconic rocks. In this presentation, Brad will reveal some of the great rocks we already have and some that we don’t have (but would like to have).

Survey Design and Seismic Acquisition for Land, Marine, and In-between in Light of New Technology and Techniques

Registration: SEG DISC registration

ASEG members get the member price of $250US, and registration comes with free copy of the e-book.

Day 1 – August 10th

Start time: 8:00am – 12:00pm PERTH time

Day 2 – August 11th

Start time: 8:00am – 12:00pm PERTH time

Description

Seismic surveys are subject to many different design criteria, but often the parameters are established based on an outdated view of how data can be acquired, and how it will be processed. This course is designed to highlight what is possible using modern methods, and how they impact seismic survey design.

Survey designs are subject to a limited set of operational and geophysical considerations. What frequencies do we require (in the source), and what will or can we detect? What geometry will be utilized, and what record length will be recorded?

However, new techniques and processing methods require that we understand and answer a new and different set of questions:

• Are classic survey geometries outdated? What geometry is optimum given almost limitless availability of channels, and how are these best deployed if they are not constrained to be connected together?
• How do you QC data from a system that doesn’t permit real time views of data?
• How do compressive sensing methodologies fit into classical geometry requirements, and can these significantly impact how data is acquired and processed? Is random “optimum” and is optimum unique?
• Do offset and sampling requirements change if processing will utilize FWI and/or least squares migration?
• Can very low frequencies be generated, detected and used for improved inversion?
• How should simultaneous sources be utilized, and can subsequent data be separated from the continuous records that will be required if this technique is used? If two sources are better than one, are four better than two?
• What should we expect of seismic data five or ten years from now?

This course is designed to cover some of the fundamentals of survey design, but will highlight the changes in technology that we have seen in the past five years, and those that are likely to develop in the next five years with a view to allowing seismic surveys to be designed and acquired to optimize technology efficiencies and interpretation requirements in light of new technology.

Goals

This course will not describe specific survey designs for particular geologic objectives, but after attending this course, the participant should:

• Understand the basic geophysical requirements of a seismic survey, based on geologic objectives
• Have a much-improved knowledge of the differences between classic survey design, and what is required for modern high-end processing techniques including FWI 
• Understand the concepts of simultaneous sources, compressive sensing, node acquisition, and broadband data, and see how these fit into survey design techniques
• Understand that there is a relationship between acquisition parameters and seismic image quality
• Understand how the basic requirements tied to modern acquisition and processing ideas can fundamentally change the data that is presented to an interpreter, and why final data volumes can look significantly different from legacy data

Who should attend?

All those interested in seismic surveys should attend. Geophysicists involved in acquisition may discover new techniques and concepts which with they are unfamiliar. Geophysicists involved in processing seismic data will better understand the shortcomings of the data that they are given to process, and better understand what techniques will, and will not, work for a particular survey. The interpreter may better understand the difference between modern seismic volumes presented for interpretation, and the legacy data that he is accustomed to interpreting. For those directly involved in survey design, the concepts will open up the potential for acquiring better images of the subsurface more efficiently, and at less cost.

The course does not require extensive mathematical knowledge or background. Concepts will be explained in a way that the layman or manager can understand. Students will be able to follow and understand the course from the basics to the level of asking knowledgeable questions of those actually involved in seismic acquisition and processing.

Survey Design and Seismic Acquisition for Land, Marine, and In-between in Light of New Technology and Techniques

Registration: SEG DISC registration

ASEG members get the member price of $250US, and registration comes with free copy of the e-book.

Day 1 – August 10^th

Start time: 8:00am – 12:00pm PERTH time

Day 2 – August 11^th

Start time: 8:00am – 12:00pm PERTH time

Description

Seismic surveys are subject to many different design criteria, but often the parameters are established based on an outdated view of how data can be acquired, and how it will be processed. This course is designed to highlight what is possible using modern methods, and how they impact seismic survey design.

Survey designs are subject to a limited set of operational and geophysical considerations. What frequencies do we require (in the source), and what will or can we detect? What geometry will be utilized, and what record length will be recorded?

However, new techniques and processing methods require that we understand and answer a new and different set of questions:

• Are classic survey geometries outdated? What geometry is optimum given almost limitless availability of channels, and how are these best deployed if they are not constrained to be connected together?
• How do you QC data from a system that doesn’t permit real time views of data?
• How do compressive sensing methodologies fit into classical geometry requirements, and can these significantly impact how data is acquired and processed? Is random “optimum” and is optimum unique?
• Do offset and sampling requirements change if processing will utilize FWI and/or least squares migration?
• Can very low frequencies be generated, detected and used for improved inversion?
• How should simultaneous sources be utilized, and can subsequent data be separated from the continuous records that will be required if this technique is used? If two sources are better than one, are four better than two?
• What should we expect of seismic data five or ten years from now?

This course is designed to cover some of the fundamentals of survey design, but will highlight the changes in technology that we have seen in the past five years, and those that are likely to develop in the next five years with a view to allowing seismic surveys to be designed and acquired to optimize technology efficiencies and interpretation requirements in light of new technology.

Goals

This course will not describe specific survey designs for particular geologic objectives, but after attending this course, the participant should:

• Understand the basic geophysical requirements of a seismic survey, based on geologic objectives
• Have a much-improved knowledge of the differences between classic survey design, and what is required for modern high-end processing techniques including FWI 
• Understand the concepts of simultaneous sources, compressive sensing, node acquisition, and broadband data, and see how these fit into survey design techniques
• Understand that there is a relationship between acquisition parameters and seismic image quality
• Understand how the basic requirements tied to modern acquisition and processing ideas can fundamentally change the data that is presented to an interpreter, and why final data volumes can look significantly different from legacy data

Who should attend?

All those interested in seismic surveys should attend. Geophysicists involved in acquisition may discover new techniques and concepts which with they are unfamiliar. Geophysicists involved in processing seismic data will better understand the shortcomings of the data that they are given to process, and better understand what techniques will, and will not, work for a particular survey. The interpreter may better understand the difference between modern seismic volumes presented for interpretation, and the legacy data that he is accustomed to interpreting. For those directly involved in survey design, the concepts will open up the potential for acquiring better images of the subsurface more efficiently, and at less cost.

The course does not require extensive mathematical knowledge or background. Concepts will be explained in a way that the layman or manager can understand. Students will be able to follow and understand the course from the basics to the level of asking knowledgeable questions of those actually involved in seismic acquisition and processing.

Date: 30th March 2021

Time: 5:30 - 6:30pm AEDT

Register: https://us02web.zoom.us/webinar/register/WN_J6zK4TXCTbCI1PxCI4uF9g

Richard retired from Geoscience Australia after more than a 30 year career of developing new geological understanding to open up provinces for exploration investment. Applied geophysics played a key component throughout his career, and this seminar will be a personal reflection on the key ‘geophysical-aha’ moments that have changed his understanding of a region’s geology and, through this new knowledge, Australia’s mineral potential.

The 30-year story begins in the field as a young geologist using geophysics to map Cape York, Pilbara and Yilgarn and seismic transects across a number of Proterozoic orogens, through the UNCOVER formulation to the lead designer of the Exploring for the Future programme.
 

Title:    An explanation for the distribution of Broken Hill style mineralization invoking dense rift-related igneous intrusions.

Presenter: Peter Gunn (MSc, PhD)
Day and Date of Event:    Wednesday 17th March 2021
Start and finish times:6:00 pm to 7:00 pm AEST

ABSTRACT
This talk is a revised version of an invited keynote presentation made at a Broken Hill Symposium in 2015.
 
The talk will suggest explanations for:
 
-                      the gravity field of the Broken Hill area
-                      the distribution and origin of the Ag-Pb-Zn mineralisation
-                      the distribution and origin of the Cu mineralisation
-                      the magnetic field of the Broken Hill area
-                      the original structure of the Broken Hill area
-                      the present structure of the Broken Hill area
-                      the topography of the Broken Hill area
-                      and - gives guidelines for exploring for Broken Hill type deposits.
 
Various workers have suggested that the Broken Hill area originated as a rift that was subsequently metamorphosed and intensively deformed. The presenter agrees with this idea and, based on his experiences with many well studied rifts elsewhere in the world, largely in the context of hydrocarbon exploration, identifies subtleties that do not appear to have been appreciated as applying to the Broken Hill rift.

Registration link: https://tas.currinda.com/register/event/2198

NExUS-Professional Development (NExUS-PD) workshops are very proud to to be able to present this highly regarded workshop online for the very first time.

The specially designed two-day online workshop will introduce the fundamentals of geological interpretation of aeromagnetic data.

The workshop will feature lectures, practical activities and case studies all using integrated data sets.

Each day will feature 3 x 2hr sessions with exercises to be completed between the sessions and time allocated for extended discussions. 

The format aims for open, transparent communication, with input from participants highly encouraged to share knowledge and experiences.

Note: This is a level-4 course (honours level) and is designed to be suitable for early career geoscientists, honours students and HDR students. The workshop is not assessed.

Day 1 (Tue, 30th Mar): Methodology of Aeromagnetic Interpretation – Presented by David Isles 

Day 2 (Wed, 31st Mar): Geological Interpretation and Structure – Presented by Leigh Rankin 

Cancellation and Refund T&C: Refunds will be given if notice of non-attendance is received prior to 3 days of the course start date or in the event the course is cancelled.

For further information view the flyer here or contact Richard Lilly: richard.lilly@adelaide.edu.au 

Register here.

We would like to remind members that the ASEG are offering full fee paid scholarships to attend the NExUS Course, Geological Interpretation of Aeromagnetic Data. The ASEG will fund registrations for two full and one student registration. Preference will be given to members earlier in their career. 

To apply for the scholarship, ensure your ASEG membership is current, and send an email to secretary@aseg.org.au outlining in 100 words or less how this would benefit you. Applications close 10 March, successful scholarship recipients will be announced Friday 19 March.

ASEG Fed AGM (Tues 6th April, Prof Graham Heinson, 5:30 pm ACDT). 

Zoom link for: https://us02web.zoom.us/meeting/register/tZ0qcOGtrjIoGt0sZtdmtSvXyAg-S7S6uIjn

More details to come.

Using Airborne Gravimetry Data To Improve The Australian Model Of Zero Heights

Presenter name & affiliations / institution: Dr Jack McCubbine, Geoscience Australia.

Abstract: In 2017, a new Australian quasigeoid model (AGQG2017) was released, with an accompanying map of uncertainty values. The model was determined from the national terrestrial gravity database and satellite altimetry derived gravity anomalies. The coverage and reliability of these data limit the accuracy of the quasigeoid model to 5 - 8 cm. However, users of the model require a reference surface which is accurate to 4 cm, or better. Geoscience Australia has partnered with, The South Australian Department of Planning, Transport and Infrastructure, The Surveyor-General Victoria within the Department of Land Water and Planning and The Geological Survey of Victoria within the Department of Jobs, Precincts and Regions to capture airborne gravity data over Greater Adelaide, Greater Melbourne and Eastern Victoria Highlands, to improve the quasigeoid model and to advance geophysical modelling.

Bio: In 2016, Jack was awarded a PhD in Geophysics from Victoria University of Wellington for his work on the collection of a national wide airborne gravity dataset, producing a new series of national gravity grids, and a new quasigeoid model for New Zealand. Following this, he came to work at Curtin University, as a post doc, working on the development of a new Australian quasigeoid model with uncertainty estimates. Jack later moved to work at GA in the National Geodesy section, to assist with the geodetic absolute gravity program and to continue to refine the national quasigeoid model.

More information can be found here: https://www.land.vic.gov.au/surveying/geodesy/airborne-gravity-survey

To register, use the following link: https://us02web.zoom.us/webinar/register/WN_gyOaiZS-RwWMQh2DJBD2aQ

Helping explorers find the nuggets in precompetitive

Join us for David Upton from Precompetitive Review speaking on March 16, 2021 at 12:00 PM (AEDT).

Abstract: Australian precompetitive data and research is having a big impact on mineral discovery in Australia, but it could be doing so much more. We can’t blame this on governments —funding support at federal and state levels is strong. And we can’t blame it in our public geoscientists and academics, who keep on delivering innovative, clever and industry-relevant work. The biggest barrier is a failure by more explorers to seize the opportunities in precompetitive data and research. They can’t be blamed for that either because keeping on top of precompetitive data and research is not easy. Precompetitive Review was launched last year to help the public sector share its work and translate precompetitive data and research into ideas industry can act upon.

Biography: David completed a BSc in Geology at Flinders University in 1985, but chose to write about resources rather than look for them. After several years as a business journalist, including a stint at the SMH/Age in Sydney, he veered off into the murky world of public relations, working for banks, accounting firms and management consultants. David came to his senses in 2007 when he started writing again about mineral exploration. A self-published book released in 2010, The Olympic Dam Story, sparked a fascination with big exploration concepts and the unappreciated value of precompetitive data and research. A decade later, David began publishing Precompetitive Review.

To register, please click here.