EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Ai & Ahrens 2007
Ai, H.A. and Ahrens, T.J. (2007). Effects of shock-induced cracks on the ultrasonic velocity and attenuation in granite. Journal of Geophysical Research 112: doi: 10.1029/2006JB004353. issn: 0148-0227.

Measurements of the compressional wave velocity and the attenuation coefficients of 1-cm cubes were conducted. Samples were taken at various radii and depths beneath a 20 ¿ 20 ¿ 15 cm San Marcos granite block, impacted by a lead bullet at a velocity of 1200 m/s. The damage parameters of the cubes are calculated from the measured preimpact and postimpact P wave velocities, V p0 and V p , and the crack density is inverted from the measured P wave velocities. The anisotropic orientation of cracks is more obvious from the attenuation than crack density and damage parameters calculated from the ultrasonic velocity. P wave velocity and the normalized distance from the impact point follow an exponential decay relation. Other properties, such as the damage parameter, crack density, and attenuation coefficient, are expressed by a power law decay with distance. The damage parameter and attenuation coefficients are approximately linearly related. The slope of the linear fitting results in directions normal to the crack orientation is about twice the value in direction along the crack orientation. The attenuation coefficient is found to be a more useful parameter than elastic velocity in describing the anisotropic orientation of cracks.

BACKGROUND DATA FILES

Abstract

Keywords
Physical Properties of Rocks, Fracture and flow, Physical Properties of Rocks, Acoustic properties, Physical Properties of Rocks, Wave attenuation, Planetary Sciences, Solid Surface Planets, Impact phenomena, cratering (6022, 8136)
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit