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Internal friction quality-factor Q under confining pressureIt has been found in previous studies that small amounts of adsorbed volatiles can have a profound effect on the internal friction quality-factor Q of rocks and other porous media. Pandit and Tozer (1970) have suggested that the laboratory-measured Q of volatile-free rocks should be similar to the in situ seismic Q values of near-surface lunar rocks which according to Latham et al. (1970) are in the range of 3000-5000. Observations of dramatic increases in Q with outgassing up to values approaching 2000 in the seismic frequency range confirm this supposition. Measurements under confining pressures with the sample encapsulated under hard vacuum are reported to aid in the interpretation of seismic data obtained below the lunar surface. It has been possible to achieve in the experiments Q values just under 2000 at about 1 kbar for a terrestrial analog of lunar basalt. It was found that a well-outgassed sample maintains a high Q whereas one exposed to moisture maintains a low Q as the confining pressure is raised to 2.5 kbar. This result suggests that volatiles can indeed affect Q when cracks are partially closed and the high lunar seismic Q values reported are concomitant with very dry rock down to depths of at least 50 km.
Document ID
19780057724
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Tittmann, B. R.
(Rockwell International Science Center Thousand Oaks, CA, United States)
Ahlberg, L.
(Rockwell International Science Center Thousand Oaks, CA, United States)
Nadler, H.
(Rockwell International Science Center Thousand Oaks, CA, United States)
Curnow, J.
(Rockwell International Science Center Thousand Oaks, CA, United States)
Smith, T.
(Rockwell International Science Center Thousand Oaks, CA, United States)
Cohen, E. R.
(Rockwell International Science Center Thousand Oaks, Calif., United States)
Date Acquired
August 9, 2013
Publication Date
January 1, 1977
Subject Category
Lunar And Planetary Exploration
Meeting Information
Meeting: Lunar Science Conference
Location: Houston, TX
Start Date: March 14, 1977
End Date: March 18, 1977
Accession Number
78A41633
Funding Number(s)
CONTRACT_GRANT: NAS9-13846
Distribution Limits
Public
Copyright
Other

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