Magnetics

---

The magnetic method measures variations in the Earth's magnetic field. Surveys are typically conducted by measuring the magnetic field strength along survey transects, or on closely spaced lines forming a grid over the area of interest. Variations in the Earth’s magnetic field occur for a variety of reasons, and may be strongly influenced by the underlying geology. In addition daily (diurnal) variations occur in the field strength, due to interaction of the solar wind with the ionosphere. 

Compared with other geophysical methods, magnetics can offer an advantage in ease of deployment in rough terrain, and in areas where vegetation may obstruct larger instruments, such as electromagnetic coils. Depending on the specific application, sophisticated magnetic modeling programs can be employed to characterize the source of the magnetic anomaly as to size, mass, depth, and possibly orientation.

Some applications of Magnetics include:

• Identifying unexploded ordnance (UXO)
• Locating underground storage tanks (UST)
• Locating buried drums
• Delineating landfill perimeters
• Identifying locations of historic structures
• Identifying geologic bedrock features such as mafic dikes or geologic contacts
• Delineating areas of ferromagnetic debris