Seismic Q and velocity at depthMeasurements of the p-wave and s-wave internal friction quality factors (Q) and velocities of samples of a moderately outgassed terrestrial analog of lunar basalt exposed simultaneously to temperatures and hydrostatic confining pressures in accordance with the best available estimates of the lunar selenotherm are presented. Q values and velocities are found to increase with simulated depth, and an extrapolation of the Q value to a thoroughly outgassed states provides a Q value in reasonable agreement with those derived from lunar seismic data, suggesting a very dry lunar crust. Results also imply that similar seismic determinations for Mars would be able to distinguish between a dry crust and a crust containing water trapped beneath a layer of ice. Results of thermal cracking tests which demonstrate that high degrees of cracking associated with thermal cycling, as during the lunar day, are not inconsistent with high Q in a dry environment are presented, and it is shown that volatiles with diple moments comparable to H2O can greatly affect Q. Possible attenuation mechanisms are then considered, and velocity measurements on a synthetic anorthosite are presented.
Document ID
19800039508
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Tittmann, B. R. (Rockwell International Science Center Thousand Oaks, CA, United States)
Nadler, H. (Rockwell International Science Center Thousand Oaks, CA, United States)
Clark, V. (Rockwell International Science Center Thousand Oaks, CA, United States)
Coombe, L. (Rockwell International Science Center Thousand Oaks, Calif., United States)