Laboratory measurements of p-wave seismic Q on lunar and analog rocksThe longitudinal-wave, internal friction quality factor (Qp) of out-gassed rock subjected to hydrostatic confining pressure was measured by a technique of aerodynamically shaping the sample ends to remove most of the air drag. Q values of about 1000 and 100 were obtained at 100 MPa and in laboratory air, respectively. The temperature dependence of Q in lunar rock 70215.85 and an analog of lunar basalt was investigated over the range -100 to 450 deg C. A systematic increase in Q was observed at 50 Hz, 5 kHz and 50 kHz. When the temperature was lowered to -100 deg C moderate decreases in Q were observed from 100 to 250 deg C, and high Q values were obtained at 450 deg C. The temperature and pressure dependences of Q suggest that high lunar seismic Q values imply a very dry crust to depths of at least 50 km. These results further indicate that elastic waves are damped in volatile-rich rock by an absorption mechanism which involves changes in the bonding, structure and coverage of the molecular, physisorbed and chemisorbed H2O at crack and grain boundaries.
Document ID
19790055290
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)
Richardson, J. M. (Rockwell International Science Center Thousand Oaks, CA, United States)
Ahlberg, L. (Rockwell International Science Center Thousand Oaks, Calif., United States)