KEGS January Talk
Details of the KEGS talk happening this month.
Title: A Conservative Approach to Inversion with AI
Speaker: Jim Craven - Geological Survey of Canada
Date: Tuesday, Jan 9th at 4:00 PM
Location: University of Toronto, Department of Earth Sciences, Room ES2093 (22 Ursula Franklin Street) and online. Register for the virtual session below:
Abstract:
AI offers many advantages for large data set analyses and is an attractive solution to many issues currently faced in geophysics. The physics underlying geophysical methods become increasingly complicated and time consuming to simulate as we model the Earth in ever more realistic approaches. Increasingly large or detailed models are matched by the increasingly large amounts of data we can collect in modern surveys. AI is well adapted to solve complex large data problems.
But there exist a few drawbacks to AI for physics-based analyses primarily due to the lack of direct incorporation of the underlying equations governing how the data should be analyzed. Working with geophysical data is predicated upon the concept of resolution. An inversion in a traditional sense can compute sensitivities based on the physics and creep or jump towards the best fit model to your data using guides from physics-based sensitivities whilst under some form of constraint such as model smoothness. This makes a lot of sense as it establishes a conservative framework that generates models that not only fit the data, but simultaneously supresses sporadic unresolved features not required by the data. However, similar physics-based guides and spurious feature constraints on AI models do not appear to be explicitly involved.
At the outset, it appears as if AI is both non physics based in its approach plus its lack of explicit constraint suggests results may be untrustworthy. To investigate the first drawback, we took an approach using the magnetotelluric method (MT) as it has the property of uniqueness meaning the data collected, theoretically, are representative of a singular earth model. Working initially in 1D to easily meet the uniqueness requirements allows one to attribute deviation from the true model as failure in the AI methodology. To address the second drawback, we work with a convolutional neural network (CNN) as the convolution operator offers a smoothing factor in the workflow serving to filter out spurious structure. A suitably trained CNN was validated with independent synthetic datasets, and the predicted resistivity distribution displayed an acceptable resolution and reliability, seemingly surpassing traditional smoothed inversion even when artificial noise was introduced. Based on these successes, the CNN was also used to analyze real MT data and early work in 3D demonstrates the ability of CNNs to quickly and accurately model synthetic and real world data.
Bio:
Mr. Jim Craven has been working at the Geological Survey of Canada as either a student, scientist or Section Head since 1987 after completing his Master’s degree looking at the effect of overburden on large loop UTEM responses across northern Ontario with Dick Bailey. His work at the GSC involves all aspects of magnetotelluric geophysics from data collection to analysis including co-supervising students working on Metal Earth and geothermal topics at Carleton and Laurentian Universities.
KEGS is currently looking for speakers for the Spring 2024 meetings. If you are interested to speak at a KEGS monthly talk, please contact any of the Executive.
Upcoming talks and events:
Find out about more geoscientific events in GTA Geoscience calendar here.
A warm welcome to Emily Data who will be the new KEGS Secretary for 2024.
Emily is a geophysicist in the mineral exploration industry with experience working for leading geophysical companies in several countries world-wide. Her career started in the field, collecting and processing ground geophysical data, then transitioning to data processing management in both ground and airborne geophysics. Currently, Emily is the Data Processing Manager at Expert Geophysics Limited.
The KEGS Ottawa group meets on the 3rd Monday of each month, usually at the GSC on Booth St. It is also possible to hold the presentations at other venues in Ottawa. We generally follow our presentation by adjourning socially to a nearby local establishment.
Please note: In order to enter Harrison Hall, you will have to show some Canadian id: a passport, permanent resident card, driver license, or health card. If you are a foreign student and have a residency visa, that should work too. Send me an email if you are not Canadian and have some questions about whether your id will work. The reason for this extra complication is that Harrison Hall is inside the controlled area. Checking everyone's id documents might take time - please try to get on site with some time to spare for the extra security procedure.
Upcoming KEGS Ottawa Presentations:
Please contact Luise Sander, SGL, luise@sgl.com, (613) 521 9626 for:
Mark your calendars - KEGS is excited to announce the return of the annual Symposium to be held the Saturday preceding the 2024 Prospectors and Developers Association of Canada (PDAC) Convention in Toronto, Canada. The event is planned to be held in person on March 2nd, 2024.
Further information on the KEGS website.
SEG MME ROUNDUP MEETING
The SEG Mining and Mineral Exploration Committee will host a hybrid meeting at the AME RoundUp on Thursday, January 25, 2024. 12:30-13:30 Pacific Time
Location: UK Building, 409 Granville St, Vancouver
Room: Boardroom on the 1st floor (same as BCGS meetings). Thank you to Mira Geoscience for use of this room again!
SEGMIN CHANGES
Earlier this fall, there were security concerns around the SEGMIN list server. Sadly, the list server is not an up-to-date modern way of communication and we have to make a change. We will be moving to an online community through Seequent that has been tested and behaves in a similar manner as the current list server, with some additional features. We will further discuss this change at the RoundUp meeting and tour the new platform. I know many like the emails that come in, and that feature will still be available (whether you like an email for each post, a weekly digest, etc). We expect the change to occur sometime early 2024.
IMAGE24
The call for abstracts will open in January for the IMAGE24 conference in August 2024 in Houston, TX. We have been working on pushing through special sessions and field trips to SEG. More to be shared at the RoundUp meeting.
NEW SEG MME KEY CONTACT
We are looking for a new key technical contact to start in August 2024 at the 2024 IMAGE meeting. Jiajia Sun will become the new SEG MME chair, with Dan Hollis moving into the vice-chair position. Please reach out to Sarah Devriese, Dan, or Jiajia if you are interested or have questions about the role.
AMBIENT SEISMIC WORKSHOP
SEG & AGU will be holding an Ambient Seismic Field Studies Workshop at Colorado School of Mines on July 31 to August 2, 2024. The general technical program will contain content relevant to mineral exploration and develop, including a session focused on case studies using ambient seismic tomography for mineral exploration. The Call for Abstracts opens in mid-January 2024. More information can be found here.
