Magnetics and Electromagnetic Methods

Electromagnetic Surveys: Rapid Subsurface Conductivity Mapping

Electromagnetic (EM) surveys provide a fast, cost-effective method for mapping subsurface conductivity variations across large areas, making them invaluable for environmental site characterization and contamination assessment. The technique operates by inducing a primary electromagnetic field through an alternating current in a transmitter coil, which then penetrates the subsurface and interacts with conductive materials below. When this primary field encounters conductors such as metallic objects, saline groundwater, or zones of elevated soil conductivity, it generates secondary electromagnetic responses that are detected and measured by receiver coils. Our advanced EM systems capture these subtle variations in the electromagnetic field, which our geophysicists then process and interpret to reveal both the geometry and intensity of subsurface conductivity anomalies with remarkable efficiency.

The real power of EM surveys emerges in environmental investigations where human activities have altered natural ground conditions. Inorganic contaminants introduced into the subsurface—including dissolved salts, heavy metals, petroleum hydrocarbons, and industrial chemicals—can dramatically increase soil and groundwater conductivity, creating detectable electromagnetic signatures that stand out against background geology. This sensitivity makes EM surveying an excellent tool for rapidly mapping the lateral extent of contamination plumes, identifying impacted areas that require further investigation, and tracking the effectiveness of remediation efforts over time. Many oil and gas facilities, industrial sites, and contaminated properties utilize our EM services as a complement to regulatory Environmental Site Assessments, allowing them to determine the extent of environmental impacts in a completely non-intrusive manner while significantly reducing the number of expensive soil sampling points required.

Because EM surveys can be conducted quickly with minimal site disruption, they are ideally suited for baseline assessments, ongoing compliance monitoring, and time-lapse studies where periodic surveys track how subsurface conditions change over months or years. Whether you need to characterize a site for due diligence, delineate contamination for remediation planning, or monitor environmental conditions as part of regulatory compliance, our electromagnetic survey services deliver comprehensive subsurface information with speed and efficiency that drilling-based programs cannot match.

Magnetometry: Precision Detection of Buried Metallic Objects or Ore deposits

Magnetometry provides a highly effective method for detecting and mapping buried ferromagnetic materials through precise measurement of variations in Earth's total magnetic field. Our magnetometer instruments measure magnetic field intensity in nanoteslas (nT), capturing even subtle disturbances caused by subsurface metallic objects. When ferromagnetic materials such as steel drums, tanks, pipelines, utilities, or buried debris are present in the shallow subsurface, they create distinctive anomalies in the ambient magnetic field that stand out clearly against the natural geologic background. This sensitivity makes magnetometer surveys the method of choice for rapidly locating buried metal objects across large areas with minimal site disturbance and exceptional efficiency.

The magnetic anomalies we detect arise from two fundamental mechanisms. Induced magnetism occurs when ferromagnetic materials respond to Earth's ambient magnetic field by temporarily acting as magnets themselves, creating localized field enhancements proportional to both the strength of the background field and the material's magnetic susceptibility. Remnant magnetism, by contrast, represents a permanent magnetic signature acquired during an object's manufacturing or exposure to heat, which persists regardless of the ambient field. Our experienced geophysicists can distinguish between these signatures and interpret the size, depth, and orientation of buried objects based on anomaly characteristics.

Whether you need to clear a site for safe excavation, locate abandoned infrastructure, map historical fill materials, or identify potential environmental liabilities, our magnetometry services deliver fast, reliable results that support confident decision-making and risk management.