Geophysical Survey Services
Geophysical survey provides a rapid, non-invasive and cost-effective methods to determine characteristics of Earth’s subsurface. SDI specializes in conducting extensive and multidiscipline geophysical surveys on land and marine environment to identify subsurface features associated with man-made and natural phenomena. SDI survey team brings latest geophysical survey techniques to your project and provides cost-effective solutions to customer needs.
In the past 30 years, SDI has earned a reputation associated with quality products and services. SDI’s client list includes USDA, USACE, US Navy, US Army, USAF, USGS, NOAA, EPA, DOE, Bureau of Reclamation, Minerals Management Service, universities, utilities, private corporations, foreign governments and state agencies.
SDI provides a variety of geophysical survey services including:
Electrical Resistivity Tomography
Electrical resistivity tomography is a geophysical technique for imaging sub-surface variation of resistivity value from 2D/3D electrical resistivity survey made at surface or borehole. Depending on the client's need, SDI uses state of the art multi-channel resistivity equipment to acquire data from depths as great as 300 feet in order to define bedrock depth, map subsurface contaminant sources, delineate voids and fracture zones, and localize seepage through dams etc.
Seismic Refraction Survey
SDI has applied Seismic refraction survey in the fields of engineering geology, geotechnical engineering, and exploration geophysics. The seismic refraction method utilizes the refraction of seismic waves at the interface between subsurface/geological layers in order to characterize the subsurface geological structure and rock properties. Applications include mapping bedrock tomography, defining overburden thickness, locating buried channels, investigating landfill, and estimating depth to water table, etc.
Electromagnetic (EM) Survey
Electromagnetic (EM) survey uses the response of the ground to the propagation of electromagnetic field. EM methods are sensitive to variations in conductivity values of subsurface materials and can identify anomalous areas due to the presence of void, fluids, metals and other variations. Unlike electrical resistivity method, no ground contact is required for EM survey. Therefore, it eliminates direct electrode coupling problems and allows a rapid data acquisition. Applications include mapping saline intrusions, locating buried tanks and drums, mapping groundwater pollution, and groundwater exploration, etc.