ERI surveys offer a non-invasive, efficient way of gathering depth and volume information about subsurface structures through electrical measurements at the surface. With this method, it is possible to accurately analyze a wide variety of subsurface features. An array of electrodes are placed on the surface and current is then passed through; the transmitted current variations are then recorded. By altering the electrode separation and placement, it is possible to determine soil resistivity changes beneath the surface and track these changes in regards to depth and location.
This method has countless practical applications, from mineral prospecting and ground water flow monitoring to archaeology and assessing voids in clay-rich, conductive areas where GPR is ineffective. With the right equipment and survey design, this method can be utilized quickly and extensively, offering insights into shallow and deep soil conditions.