Low And High Frequency Electromagnetics In Landfill Investigations

Low frequency induced electromagnetic (EM) fields (< 1 megahertz (MHz)) primarily respond to<br>the earth’s conductivity, whereas high frequency EM fields (propagated as in ground penetrating<br>radar (GPR)) are a complex function of the earth’s dielectric permittivity, conductivity and<br>magnetic permeability.<br>Low frequency (c 40 kilohertz &Hz)) EM data can be utilized to approximate a shallow (< 6<br>meters (m)) multi-layered earth model provided different instruments and intercoil spacings are<br>used. The constructed model can be used as a starting model for higher frequency EM<br>techniques such as GPR, which operate at radio frequencies and provide increased resolution of<br>the geologic system.