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1. What is near-surface geophysics?
The following definitions of geophysics have been obtained from the Environmental and Enginnering Geophysical Society (EEGS) website:
A. Geophysics is: The subsurface site characterization of the geology, geological structure, groundwater, contamination, and human artifacts beneath the Earth’s surface, based on the lateral and vertical mapping of physical property variations that are remotely sensed using non-invasive technologies. Many of these technologies are traditionally used for exploration of economic materials such as groundwater, metals, and hydrocarbons.
B. Geophysics is: The non-invasive investigation of subsurface conditions in the Earth through measuring, analyzing and interpreting physical fields at the surface. Some studies are used to determine what is directly below the surface (the upper meter or so); other investigations extend to depths of 10’s of meters or more.
2. How can geophysics help me?
Geophysical surveys are rapidly becoming the standard method to characterize the subsurface at project sites due to their non-invasive and cost-effective characteristics. Need to know the geology at a project site prior to construction? A geophysical survey in conjunction with strategic drilling can provide a detailed assessment of the subsurface, while at the same time minimizing the higher cost of additional borings that would otherwise be required. Need to delineate a contaminant plume for an environmental assessment? Geophysical surveys can track changes in conductivity associated with plumes and minimize the installation of monitor wells. Whether your problem lies in the geotechnical, environmental, or geologic realm, Pyramid’s use of geophysical survey techniques will provide you with an accurate assessment of your site at significant cost and man-hour savings.
3.Which geophysical method is right for me?
There are a variety of geophysical methods, each with their own benefits and limitations. For example, electrical methods are an ideal way to perform groundwater studies, however, the presence of metal or other objects in the subsurface that conduct electricity can cause interference during the test, producing erroneous results. Each method provides specific information as it relates to the physical properties of the earth that are being measured. Many times, a combination of two or more methods is needed to reach a definitive interpretation regarding the subsurface. For more information on the best approach to solve your own problem, contact Pyramid Geophysical Services today and speak with one of our professionals.
4. Will a geophysical survey tell me everything I need to know about my site?
In short, no. While geophysical methods are extremely effective if used properly, they are only a tool that must be ground-truthed, using traditional sampling methods such as soil borings or groundwater sampling. However, once the geophysical data have been ground-truthed, the rapid survey techniques allow for a much more effective characterization of an entire project site with only minimal sampling, resulting in a more cost effective study.