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ELASTIC BEHAVIOUR OF ROCKS AT LOW FREQUENCIES
Author(s) -
USHER M. J.
Publication year - 1962
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1962.tb02002.x
Subject(s) - igneous rock , mineralogy , geology , sedimentary rock , carbonate rock , moisture , range (aeronautics) , magnitude (astronomy) , petrology , materials science , composite material , geochemistry , physics , astronomy
A bstract An apparatus is described for the measurement of Young's modulus, E , and the energy loss per cycle, Δ W/W, of small beam‐shaped rock samples, over the frequency range 2 to 40 c/s. Results are given for seven sedimentary and two igneous types of rock. An increase of between 1 % and 3 % in E, and of up to 100 % in Δ W/W, occurred over this range. Experiments on rocks containing moisture showed a decrease in the magnitude of E (at 2 c/s), an increased frequency variation of E, and a greater and almost linear increase of Δ W/W with frequency. The effect of oil was similar except that the magnitude of E at 2 c/s was unaffected. It is suggested that the moisture and oil results are due to viscous movements of fluid through the pores in the rock, and that the changes in E and Δ W/W with frequency, in dry rocks, are due to a small viscous mechanism operative at low frequencies.