The Laboratory Study of Seismic Wave Attenuation
- B.E. Hobbs and
- H.C. Heard
Published Online: 18 MAR 2013
Copyright 1986 by the American Geophysical Union.
Mineral and Rock Deformation: Laboratory Studies: The Paterson Volume
How to Cite
Jackson, I. (1986) The Laboratory Study of Seismic Wave Attenuation, in Mineral and Rock Deformation: Laboratory Studies: The Paterson Volume (eds B.E. Hobbs and H.C. Heard), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM036p0011
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1986
Print ISBN: 9780875900629
Online ISBN: 9781118664353
- Rocks—Testing—Addresses, essays, lectures;
- Rock deformation—Addresses, essays, lectures
Recent progress in the experimental investigation of the anelasticity of rocks is reviewed with particular emphasis upon studies of nearly-dry rocks at relatively low frequencies and strain amplitudes. An introduction to the phenomenology of anelasticity, illustrated with simple mechanical models, is followed by a brief outline of experimental methods. A survey of the literature is presented in order to highlight the factors which most strongly influence the internal friction of nearly-dry rocks. Included among these are the concentration of adsorbed H2O, pressure, temperature and microstructure. For practical reasons these effects have generally been studied in isolation. It is argued that the future of laboratory study of seismic wave dispersion and attenuation lies in the simultaneous control of all these important variables. A recently developed apparatus is described which will ultimately facilitate the study of rock anelasticity under conditions which closely approach those of seismic wave propagation: simultaneous high pressure (to 700 MPa) and temperature (to 1400°C), low frequency (10−3 -1 HZ) and strain amplitude (< 10−6), and controlled pore pressure of volatiles. Its performance has been tested in a series of preliminary high pressure room temperature experiments in which the specimen pore space was vented to atmosphere. Measurements on a steel standard have demonstrated the sensitivity of the apparatus to very small departures (QG −1 < 10−3) from ideal elasticity. Experimental data for a fine-grained granitic rock show that both the shear modulus G and quality factor Q increase sharply with increasing pressure below ∼100 MPa, beyond which pressure both parameters become markedly less pressure sensitive. These observations are in accord with those of previous studies at higher frequencies and larger strains, and are consistent with the view that the anelasticity of rocks at ambient pressure is dominated by mechanisms operative at open cracks and grain boundaries.