BAGS Seminar

Imaging the critical zone using near-surface geophysics: applications in peatlands, karst environments and fractured bedrock
Dr. Xavier Comas
June 24, 2021, 5 PM
Webinar (see member email for details)

Abstract:Near-surface geophysics is the study of the critical zone using geophysical methods, and while most of these methods were originally developed more than a century ago for oil and mineral exploration, they now involve a very wide spectrum of environmental applications, with new applications constantly emerging. One of the unique capabilities of near-surface geophysical methods is their ability to non-invasively capture the spatial and temporal variability in materials and processes of the subsurface as inferred from changes in a wide variety of physical properties, including dielectric permittivity, electrical resistivity, or acoustic impedance. While resolution and depth of penetration is directly dependent on the particularities of each method, a wide range of scales of measurement are possible given their versatility, particularly in terms of deployment, i.e. from ground-based (sub-meter) to airborne (1000s of meters) scales, even recently allowing deployment of near-surface methods in other planets. The current rise in popularity of unmanned aircraft systems (UAS) also presents unique opportunities (when paired with near-surface methods) for bridging the gap between ground-based and aerial scales. In this presentation, the versatility of near-surface geophysical methods is demonstrated through a series of examples and specific applications including the exploration of hydrogeological dynamics in karst and organic sediments, or characterization of fractured bedrock. The examples presented here also stress the importance of interdisciplinary approaches to properly constrain geophysical results, and the wide applicability range and potential of near-surface geophysical methods to promote national and international collaborative research.

Speaker Bio:

Dr. Xavier Comas is a Professor in the Department of Geosciences at Florida Atlantic University (FAU). He has been conducting research in peatland and karst systems around the globe for nearly two decades, from the tropics to the Arctic, including sites in the US (such as Puerto Rico, Florida, Maine or Oregon) as well as abroad (such as in Indonesia, Ecuador, Spain or the UK). His work has focused on the use of hydrogeophysical methods for better understanding carbon cycling in peat soils, imaging dissolution features like sinkholes in karst environments, or characterizing fractures in bedrock. Comas has over 50 peer-reviewed journal articles and book chapters including edited monographs and special journals. Comas is the current Past President of the Near-Surface Geophysics Section of the American Geophysical Union (AGU).