THE USE OF GEOPHYSICAL METHODS IN ENGINEERING GEOLOGY. PART 2: ELECTRICAL RESISTIVITY, MAGNETIC AND GRAVITY METHODS

Although electrical resistivity is more versatile than other shallow geophysical exploration methods in respect of the range of geophysical situations with which it can contend, its many practical and interpretative limitations restrict its success to comparatively simple cases on land. Magnetic and gravity methods, on the other hand can be used over water. The many variations of the electrical resistivity techniques are all based on passing a current through the ground between certain electrodes and measuring the potential difference resulting between other (potential) electrodes set up in the path of the current, from which a quantity termed "apparent resistivity" can be calculated. The detection of changes in resistivity is described, and the ascribing of geological meaning to the recorded variations is discussed. The detailed interpretation (carried out by curve-matching techniques) of a resistivity can be complicated and expensive, calling for the highest degree of experience and objective data. The advantages of the resistivity method over other methods are noted. The details are outlined of the magnetic method which depends on the measurement of local variations in the earth's total magnetic field strength. Mechanical magnometers and fluxgate magnetometers are described. Gravity methods are generally restricted to the location of faults and for the detection of large subsurface voids. The observation and reduction of gravity readings are discussed.

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  • Corporate Authors:

    Foundation Publications Limited

    7 Ongar Road
    Brentwood CM15 9AU, Essex,   England 

    Wells (Edward) and Sons, Limited

    143/145 Camberwell New Road
    London SE5,   England 
  • Authors:
    • HIGGINBOTTOM, I E
  • Publication Date: 1976-3

Media Info

  • Features: Figures; References;
  • Pagination: p. 34-38
  • Serial:
    • GROUND ENGINEERING
    • Volume: 9
    • Issue Number: 2
    • Publisher: EMAP CONSTRUCT LIMITED
    • ISSN: 0017-4653

Subject/Index Terms

Filing Info

  • Accession Number: 00135926
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 6 1976 12:00AM