Pressure dependence of Q in selected rocks.

K. W. Katahara, M. H. Manghnani, N. Devnani, B. R. Tittmann

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9 Scopus citations

Abstract

The dissipation factor (Q-1) for torsional vibration has been measured for several low-porosity crystalline rocks up to 0.5GPa confining pressure. Q was measured at frequencies of approx 10kHz by a resonant bar technique in which cylindrical samples are enclosed in a thin-walled copper sheath welded to copper end plugs, with piezoelectric transducers bonded to the ends. Some of the samples were encapsulated under laboratory conditions (30-40% humidity) whereas others were encapsulated in vacuum (approx 10-5torr). Q was found to increase by 103 or more between 0 and 0.5GPa for most of the samples. In some cases, values well over 2000 were found at 0.5GPa. For some of the rocks, including vacuum-dry as well as air-dry samples, Q was found to continue increasing pressure even after most of the cracks were closed. A significant time dependence was also observed. After any increase or decrease in confining pressure, Q was observed to increase slowly for several days at least. Possible attenuation mechanisms and implications for the earth's interior are discussed.-Authors

Original languageEnglish (US)
Pages (from-to)147-158
Number of pages12
JournalUnknown Journal
DOIs
StatePublished - 1982

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

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