Electrical Conductivity Measurements of the Earth at Audio Frequencies,
Abstract
Ground conductivity measurements from 20 to 16,000 c were made with electrical sounding techniques to a maximum depth of 8 km. Soundings were taken at 2 locations - Boulder, Colorado and Pole Mountain District of the Medicine Bow National Forest, Wyoming. The very deep soundings at Pole Mountain indicated a very low conductivity (10-5 mhos/m or less) for the basement of the earth's crust. Frequencies above 200 c yielded conflicting results at depths large compared to a skin depth. At relatively shallow depths, however, results appear to be valid at all frequencies used and indicate the displacement currents may be neglected. The electrical conductivity of earthen materials in situ were also obtained from intrinsic impedance measurements. These were in effect audio MagnetoTelluric measurements with lightning providing the source of energy. Results were obtained at frequencies from 12 to 330 c and are compared with electrical sounding data. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 28, 1961
- Accession Number
- AD0267997
Entities
People
- A.j. Farstad
- E.l. Maxwell