Simply put, Geophysics is a tool that helps us to see what’s in the ground without digging it.
A more formal definition (by EEGS*): Geophysics is the non-invasive investigation of subsurface conditions through measuring, analyzing, and interpreting physical fields at the surface.
There are two main branches of Geophysics that often overlap in terms of technologies and methods:
Exploration Geophysics focuses on exploration of mineral resources such as hydrocarbons, ore minerals, geothermal and groundwater reservoirs. Target depths are typically hundreds and thousands of feet.
Environmental and Engineering Geophysics is an applied branch with a focus on solving problems in environmental and engineering fields. The target depths are typically in the range of a few inches to a hundred feet.
Geophysical imaging is another tool in a geoscientist’s toolbox that can be used at any project stage.
At the beginning of a project subsurface utilities can be mapped before any excavation work, or a site can be evaluated by imaging the top of rock and mapping potential karst features or buried obstructions, such as old foundations or tanks, prior to development.
In the middle of a project an unexpected feature (e.g., a void or anomalous depth to rock) may be encountered during drilling. Geophysics can help to image the horizontal and vertical extents of that anomalous feature.
At the end of a project concrete thickness, rebar depth and placement can be evaluated with geophysical tools as a part of a quality control process.
Next week we will explore the Geophysical Applications in Engineering and Environmental Fields.
*EEGS – Environmental and Engineering Geophysical Society