Talk About Geophysics!  TAG Webinar Series

EEGS’ Monthly Educational Webinar Series

EEGS has developed a new educational webinar series exploring topics ranging from scientific presentations to a deeper dive into noted authors’ published articles. The webinar series is intended to offer an informal setting and an interactive opportunity to address diverse geophysical topics. Students will be pleased to see that some scheduled topics will focus on career paths, working with your advisor, etc. and small business owners will benefit from sessions ranging from business technical tools to client management.

If you have questions, email [email protected].  If you'd like to suggest a future TAG Topic or offer to host a webinar, please click here (a short, online feedback form for EEGS' TAG Webinar organizers).  

NEW:  If you find EEGS' TAG Webinar series valuable or you just want to support the program, please consider donating to the development of the webinars.  Just use the feedback/donation form to donate online.  Any amount is appreciated. 

December TAG Webinar 
Best of the Proximal/Remote Sensing Soil Investigation Symposium
December 8, 2021

TopicBest of the Proximal/Remote Sensing Soil Investigation Symposium 
Date:  Wednesday, Dec. 8, 2021
Panelists:   Harrison Smith (University of Arkansas), Felippe Hoffmann Silva Karp (McGill University), and Steven van der Veeke (University of Groningen)
Time3:00 p.m. MT (2:00 pm PT; 4:00 pm CT; 5:00 pm ET)  PLEASE NOTE THE START TIME FOR THIS TAG WEBINAR!

Registration Required!
Register in advance for the webinar by clicking on the Zoom registration link:

The December TAG Webinar is a content rich, impressive line up of topics covered by our three presenters.  The “Application of Proximal and Remote Sensing Technologies for Soil Investigations” virtual symposium was held August 16-19, 2021.  This virtual symposium was a collaborative effort between the International Union of Soil Sciences – Proximal Soil Sensing Working Group, the Society of Exploration Geophysicists, and EEGS.  The symposium provided a unique opportunity for bringing together scientists and engineers across a range of disciplines to explore the combined potential of proximal and remote sensing technologies as related to soil science applications.  Approximately half of the 45 research presentations given at this symposium were provided by students.  The quality of the student presentations was outstanding.  The symposium’s Technical Committee reviewed all the student presentations and bestowed three best presentation awards.  EEGS is honored that the three students that received these awards, Harrison Smith (University of Arkansas), Felippe Hoffmann Silva Karp (McGill University), and Steven van der Veeke (University of Groningen), have all agreed to give presentations on their exiting research at our December TAG webinar.

Harrison Smith Felippe Hoffmann Silva Karp  Steven van der Veeke 

"Ground Penetrating Radar for Soil Characterization in an Experimental Agroforestry Site Using Qualitative and Quantitative Techniques"
Presenter:  Harrison Smith

Abstract:  The use of ground penetrating radar (GPR) has grown rapidly in recent years due to increases in computer processing power and advances in GPR. With this growth, interest in GPR agricultural applications has also increased. In this study, we explore applications of some common qualitative (visual estimates and interpretations) and quantitative methods (correlation, Random Forest regression) for GPR analysis and characterization of soil conditions in a 20-year silvopasture system. We collected GPR data from six transects at our 4.25 ha study site. Following GPR data collection, we collected validation data from soil pit excavations and screw auger sampling along transect lines. A qualitative analysis of the radargram data revealed a strong response from important geomorphic and hydrologic features, including channel and furrow bedrock features, bulges in clay content, and subsurface flow pathways. Time-to-depth conversion showed our GPR scans penetrated to a depth of around 2.11 meters. Visual estimates of depth to bedrock based on radargram data correlated well with observations from field sampling (rs=0.61, p<0.01), but estimates of depth to argillic horizons based on GPR data were not well correlated with observations from soil pits and screw auger sampling (rs=0.47 ,p=0.09). In order to train our machine learning algorithms, we extracted features such as amplitude, instantaneous attributes, and texture features generated from a Grey-Level Co-occurrence Matrix (GLCM) from the GPR data. These features, along with the soil pit validation data, were used to train a random forest regression model to predict rock fragment percentages. The GPR features extracted were found to be moderately good predictors of coarse fragments in soils (R2=0.81, RMSE=18.82). Our results demonstrate that features extracted from GPR data can provide information on soil characteristics that may be relevant for soil management decisions.  Features extracted from GPR data could also be combined with existing digital soil maps to contribute to a better understanding of soil conditions, inform agricultural management decisions, and promote more sustainable agricultural systems.

"Validation of Soil Survey Maps Using Different Proximal Soil Sensing Methods"
Presenter:  Felippe Hoffmann Silva Karp 

Abstract: High resolution soil characterization is relevant information to understand and manage spatial variability present in agricultural fields. However, high resolution soil surveys are usually scarce and nation-wide surveys tend to have small scales while also do not provide much insight on field soil characterization. Therefore, the use of sensors, especially proximal soil sensors (PSS) and geophysics, has become an important tool for soil characterization and delineation of different zones within a field. Thus, data collection from a specific field, which had a high-resolution soil survey (1:5000) took place using apparent electrical conductivity (direct/galvanic contact and electromagnetic induction), passive gamma-ray spectroscopy and ground-penetrating radar sensors. Comparing the sensors’ readings among the delineated zones obtained from the soil survey confirmed that those regions presented different characteristics. In addition, by using a machine learning system (random forest) the capabilities of the sensors and their fusion on the delineation of the soil types took place. It was observed that none of the sensors when used alone could capture all the variability within the studied field. However, when combined/fused they were able to delineate with a high accuracy the different soil zones. Consequently, there is a potential of using PSS and their fusion during soil classification surveys in order to reduce costs (due to reduction of sampling points), as well as generate a more precise and accurate delineation of the soil spatial variability.

"Using Drones with Large Gamma-Ray Spectrometers for Radiological Characterization of Geophysical Scenarios"
Presenter: Steven van der Veeke 

Abstract:  The introduction of affordable heavy-duty unmanned aerial vehicles (UAVs) has led to the possibility to do UAV-borne gamma-ray spectrometry (GRS) surveys. Many geophysical airborne GRS studies aim to map the tiny concentrations of naturally occurring 40K, 238U and 232Th in the environment. These surveys can be extended to track down and identify artificial radioactive contamination. Historically, GRS studies have been used to characterize the geological composition of an area and aid in the search for mineral resources. The technique has also been applied as a proxy for the soil texture, which is valuable input for agricultural applications.  The possibility to use GRS on UAVs have led to new applications and interpretations of spectral data. UAVs combine the high spatial resolution of walking surveys with the ease of access associated with airborne surveys, thereby allowing the efficient mapping of dangerous or difficult to access areas.  A model for the footprint and a height correction algorithm for UAV-borne GRS measurements are published. This model is shown to be significantly different from the well-known methods currently used to process airborne collected data. Moreover, the optimal detector size in UAV-borne GRS measurements has been studied and published as well.  This presentation will give an overview of the technological and analytical developments done in the past years that have resulted in the possibility to use a gamma-ray spectrometer under a UAV for geophysical surveys.


Harrison Smith is a data scientist who specializes in the use of Geographic Information Systems (GIS) and remote and proximal sensing to study issues in sustainable food systems and agroecology. Broadly, Harrison is interested in issues at the intersection of climate change, sustainable agriculture, conservation ecology, and environmental justice. He earned a Bachelor’s degree in Biological Sciences from the University of Arkansas in 2016, with a focus on ecology and biodiversity conservation. In 2019, he graduated with a Master of Science from the University of Michigan School for Environment and Sustainability, where he completed a thesis using satellite sensors to map cropped area in the Eastern Indo-Gangetic Plains of India. After that, he worked various on projects related to sustainable agriculture as a research associate at the University of Michigan, a Program Specialist at the University of Arkansas, and a research scientist with USDA-ARS. In the fall of 2021, Harrison started a doctoral program in Environmental Dynamics at the University of Arkansas, where he is currently working researching crop suitability modeling on Tribal Lands, applications of ground penetrating radar for soil characterization, and post-mining land reclamation efforts at the Tar Creek superfund site.

Felippe Hoffmann Silva Karp is a PhD candidate at the Bioresource Engineering Department at McGill University in Canada. Felippe's main research focus is on Precision Agriculture, most specifically on data fusion and spatial data analysis. His background is in Agronomy with a Bachelor's in Agronomic Engineering from University of Sao Paulo campus “Luiz de Queiroz” College of Agriculture (ESALQ), Brazil and MSc in Plant, Environment and Soil Sciences from Louisiana State University, USA. Felippe has worked extensively with remote and proximal sensing technologies as tools to improve the understanding and management of the spatial variability existent in agricultural fields. Since 2019 Felippe has also focused on applying machine learning as a tool for spatial data analysis and prediction.

Steven van der Veeke is an R&D engineer at Medusa Radiometrics, a company that develops the next generation of gamma-ray spectrometers used in geophysics. This next generation of spectrometers allows the possibility to use them when mounted under a drone. Using drones for geophysical gamma-ray spectrometry work is an emerging field and opens up new opportunities for data collecting and results in potentially new interpretations of existing scenarios. Steven combines this engineering position at Medusa with a PhD position at the University of Groningen, Netherlands. In this doctoral research, Steven investigates the scientific questions that come up when using a drone as the platform for gamma-ray measurements. His thesis will answer questions related to drone-borne gamma-ray measurements, among which height corrections, the footprint, spectral analysis optimization and radon correction methods. This work will result in a first draft for the “guidelines for drone-borne radioelement."

 All TAG Webinars begin at times based on US Mountain Time Zone. 

January TAG Webinar - Scheduled Soon

Geophysical Exploration of a Historical Stamp Mill Dump for the Volume Estimation of Valuable Residues

The Journal of Environmental and Engineering Geophysics (JEEG) offers an opportunity for published authors to earn a yearly Best Paper Award in
honor of Alan Witten. The Best Paper Award is decided by the EEGS board of directors after a recommendation from the current JEEG editor. The award is presented yearly at SAGEEP. The 2020 award was bestowed on Tina Martin for her paper "Geophysical Exploration of a Historical Stamp Mill Dump for the Volume Estimation of Valuable Residues." The TAG Webinars series is pleased to feature Ms. Martin for its January presentation. Be sure to check back for date and time in January!

Presentation Title: Geophysical Exploration of a Historical Stamp Mill Dump for the Volume Estimation of Valuable Residues
Presenter: Tina Martin, Lund University, Lund, Sweden

Presentation Summary
Historical mining dumps are of increasing interest due to economic, environmental or archaeological reasons. Geophysical investigations can help accessing the potential reuse of the remaining material to recover metallic raw material or it can be used for the estimation of the hazard potential from the buried material due to dissolution occurrence. In our study, we present an approach for the estimation of ore processing residue volumes in a historical mine waste dump by combining electrical resistivity tomography (ERT), ground penetrating radar (GPR) and spectral induced polarization (SIP) flanked by mineralogical studies. That enabled us to distinguish between valuable and non-valuable waste material and to calculate the volume of the ore processing residues, which can be used further for the determination of the economic potential from the remaining metal content.

Tina Martin is a senior researcher at the Division of Engineering Geology at Lund University in Sweden. In her research, she focusses on geoelectrical and electromagnetics methods and is specialized in the induced polarization technique. Her range of applications reaches from mineral exploration, dam and dyke monitoring, to hydrogeological research questions. Furthermore, she adapts and applies geophysical methods for the investigation of wood and trees as well as for bacterial remediation processes.

Return to this page for details and registration information for January's TAG Webinar!

TAG Webinar Presentations History

November TAG Webinar:  Careers in Near-surface Geophysics

A panel of six professional geophysicists led a discussion on their careers and trends in geophysics on Nov. 10.  Bart Hoekstra, Dan Glaser, Esther Babcock, Evgeniy Torgashov, Katherine Grote, and Craig Murray represented a wide range of positions and roles in geophysics and shared their experience, education and professional development path with participants.  Great questions, as one panelist termed them, were posed by participants, adding to the value of the experience.     

October TAG Webinar: GeoLatinas presenters and members

On October 13, EEGS welcomed Adriana Crisóstomo Figueroa and Alma Vázquez-Lule of GeoLatinas to TAG Webinars.  GeoLatinas is a grassroots organization building bridges towards equity, diversity, inclusion and accessibility in the geosciences.  EEGS' Task Force DEI (Diversity, Equity and Inclusion) Chair, Moira Poje, hosted the event, presided over the question and answer session and thanked the presenters for their informative overview of GeoLatinas, its work to inspire and support those currently engaged or working in earth and planetary sciences, and impressive list of initiatives and accomplishments.     

September TAG Webinar - Magnetic Surveying for Man Made Objects – Theory 

On September 8, Gretchen Schumauder and Bart Hoekstra hosted a pre-recorded presentation by Becky Bodger, Seequent Limited, and Stefan Burns, Bart Hoekstra and Gretchen Schumauder from Geometrics Inc. This was the first in a series about magnetic surveying for anthropogenic objects and focused on the practical implications of magnetic theory for conducting surveys.  Following the pre-recorded presentation was a question and answer session hosted by Gretchen and Bart.  

August TAG Webinar - G2HE - Transforming Geophysical Parameters into Hydrogeological and Engineering Parameters and the Relevance of the Factors of Empiricism, Scalability, Resolution, Uncertainty, Clay and Experience

On August 11, attendees participated in EEGS' August TAG Webinar and an extended question and answer period.  Organizers thanked Mr. Pettifer for his interesting title and informative presentation.  

July TAG Webinar - Characterizing a Physical Model of a Collapsing Void Using a Trapdoor and Time-Lapse Surface-Wave Analysis

On July 14, Sarah Morton Rupert presented findings from a laboratory text box using a physical model designed to simulate void roof failure and migration to the ground surface to support the conceptual model that Vs variations can be an indicator of stress-field variations in the roof structure above a void and used to map the progression of a collapsing structure.  Questions and Ms. Morton Rupert's responses rounded out the well attended webinar.  Organizers and attendees thanked Ms. Morton Rupert for presenting her award-winning presentation with EEGS TAG Webinar participants.   

May TAG Webinar - New Frontiers in Near Surface Geophysics: Muons, Cosmic Ray Neutron Probes, and Hyperspectral Imagery

On May 12, Leon DuPlessis, formerly with Freeport-McMoRan Inc., Trenton Franz, Univ. of Nebraska, and Isabel Barton, Univ. of Arizona presented three very interesting and informative talks and answered participants' questions.  Dr. DuPlessis spoke about Subsurface Density Mapping Using Muon Technology; Dr. Barton presented Mineral Mapping Using Drone-Based Hyperspectral Imaging;  and Dr. Franz summarized the Opportunities and Challenges Towards Integration of Hydrogeophysical Sensors in Agriculture.  TAG Webinar organizers expressed their appreciation to all three presenters for a very well received event.

April TAG Webinar -  Proximal Soil Sensing: State of the Science

Dr. Craig Lobsey, senior lecturer in mechatronic engineering at the University of Southern Queensland, University of Southern Queensland presented his perspective on some of the key challenges in the application of sensor technology for soil management, recent developments and what may be on the horizon for proximal soil sensing technology.  Organizers extended many thanks to Dr. Lobsey for his talk as well as a robust question and answer session which followed.  

In March, EEGS held SAGEEP 2021 - held virtually March 14-19, 2021.

February TAG Webinar - Meet Me Halfway

The EEGS Task Force Diversity, Equity and Inclusion (DEI) takes advantage of every opportunity to raise awareness and take a lead role in setting and achieving the highest standards of integrity, fairness, dignity and respect. Therefore, February's TAG webinar series featured a Task Force DEI webinar:  Meet Me Halfway, an interactive webinar exploring intergenerational communication in a geophysics workplace.  EEGS President Barry Allred commented: "Thanks to all the Task Force members for your efforts putting together the TAG webinar. It was excellent, well organized, and the discussions in the breakout rooms were very interesting and insightful.  I think everyone really enjoyed the interactive webinar format."

The webinar slide presentation is available for viewing by clicking here.

Inaugural January TAG Webinar a Success!

TAG's first webinar was held on January 13 and welcomed guest speaker, G. Didem Beskardes, the JEEG's 2019 Alan Witten Best Paper Award recipient.  By all measures - audience participation, attendee feedback and content quality - the TAG Webinar was successful and well received.  Dr. Beskardes discussed her findings from the study published in the JEEG paper "Power Density Distribution in Subsurface Fractures Due to an Energized Steel Well-casing Source" and conducted a lengthy and insightful Q&A session.