Abstract
To explain an attenuation proportional to the frequency (internal friction Q−1 independent of the frequency) present for waves in the earth's crust, a nonlinear mechanism connected with the motion of dislocations is proposed. With the kink model for dislocation motion, it is shown that an energy loss occurs when the kink goes over the kink barrier and becomes unstable. This loss is proportional to the number of kink displacements, and for a given strain level the number of kink displacements per cycle, i.e. the Q−1 value, will be independent of the frequency. The energy loss measured is consistent with theoretical calculations of the dissipation stress, and the loop length lA and the number of dislocations found are consistent with the results for polycrystalline metals and rocks.
Published Version
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