Accession Number : AD0456359


Title :   THE SEPARATION OF REMANENT FROM INDUCED MAGNETISM OF NEAR-SURFACE ROCKS BY MEANS OF IN SITU MEASUREMENTS,


Corporate Author : CALIFORNIA UNIV BERKELEY SPACE SCIENCES LAB


Personal Author(s) : Goldstein,Norman


Report Date : 30 Dec 1964


Pagination or Media Count : 1


Abstract : A distinction between induced and remanent magnetism of near-surface rocks can be obtained by means of a careful analysis of geomagnetic fluctuations. Diagnostic information concerning the type of magnetization possessed by nearsurface rocks is revealed from a study of the magnetic time variations for the following reasons: (1) the intensity of remanent magnetization is independent of the strength of an external field, (2) the intensity of induced magnetization, on the other hand, is directly proportional to the strength of an external field (except for demagnetization effects), and (3) at the low frequencies of the geomagnetic oscillations secondary magnetic fields due to an eddy current response in earth materials do not arise. A measure of the intensity of induced magnetization can be obtained from the amplitude of time variations observed simultaneously at two or more sites in the vicinity of a static field anomaly. The spatial variation of induced alternating magnetic fields can then be used to estimate magnetic susceptibility of the buried rocks. (Author)


Descriptors :   *ROCK , INTENSITY , ELECTROMAGNETIC PULSES , GEOMAGNETISM , MAGNETOMETERS , CALIFORNIA , UTAH , NEVADA , IRON


Distribution Statement : APPROVED FOR PUBLIC RELEASE