ELECTROMAGETIC SURVEYS
EM-31
The Geonics EM31 is a type of electromagnetic (EM) induction instrument that is commonly used in geophysical surveys to measure soil conductivity. It consists of two horizontal coils that transmit a low-frequency EM signal into the ground and two receiver coils that detect the signal that is induced by the presence of conductive materials in the soil.
The EM31 is designed to locate and map variations in subsurface conductivity, which can be indicative of changes in soil composition, moisture content, and the presence of subsurface features such as buried metal objects or contaminants. Specifically, the EM31 is typically used to locate and map the following features:
Buried metal objects, such as pipes, tanks, or drums.
Soil moisture variations, which can indicate variations in soil type, depth to water table, or the presence of subsurface water bodies.
Contaminant plumes, which can be detected by mapping variations in soil conductivity caused by the presence of the contaminant.
The EM31 is particularly useful in environmental investigations, where it can be used to detect and map subsurface contamination plumes from sources such as leaking underground storage tanks or industrial spills. It can also be used in archaeological surveys to locate buried artifacts or structures, or in engineering projects to identify buried infrastructure such as pipelines or cables.
Overall, the Geonics EM31 is a powerful and versatile tool for locating and mapping subsurface features and variations in soil conductivity, and it is widely used in a variety of geophysical survey applications.
EM-61
The EM61 consists of transmitter and receiver coils that emit and detect EM signals. However, the EM61 has multiple receiver coils and can be configured in different orientations to optimize its sensitivity to specific subsurface targets. The EM61 can operate in both time-domain and frequency-domain modes, allowing it to detect and measure variations in subsurface conductivity over a range of frequencies and depths.
The EM61 is typically used to locate and map the following subsurface features:
Buried metal objects, such as pipes, tanks, or drums, at greater depths than the EM31 can detect.
Subsurface geology variations, such as bedrock or clay layers, which can be detected by changes in conductivity.
Mineral deposits, such as ore bodies or mineralized zones, which can also be detected by variations in conductivity.
UXO (unexploded ordnance), which is a common target in military and UXO clearance applications.
The EM61 is widely used in a variety of geophysical survey applications, including environmental investigations, archaeological surveys, and UXO detection. It is particularly useful in areas where subsurface targets are buried deep or have low conductivity, as it can detect these targets with high sensitivity and resolution.
Overall, the Geonics EM61 is a powerful and versatile tool for detecting and mapping subsurface targets and variations in conductivity, and it is widely used in a variety of geophysical survey applications.
