Paper No. 132-0
DEPTH OF CRACKING BENEATH IMPACT CRATERS: NEW CONSTRAINT FOR IMPACT VELOCITY
AHRENS, Thomas J., Lindhurst Laboratory of Experimental Geophysics 252-21, California Institute Technology, 1200 E California Blvd, MC 252-21, Pasadena, CA 91125-0001, tja@caltech.edu, XIA, Kaiwen, Seismological Laboratory 252-21, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, and COKER, Demirkan, Aeronautics 105-50, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125

Both small-scale impact craters in the laboratory and less than 5 km in diameter bowl-shaped craters on the Earth are strength (of rock) controlled. In the strength regime, crater volumes are nearly proportional to impactor kinetic energy. The depth of the cracked rock zone depth beneath such craters depends on both impactor energy and velocity. Thus determination of the maximum zone of cracking constrains impact velocity. We show this dependency for small scale laboratory craters where the cracked zone is delineated via ultrasonic methods. The 1 km deep cracked zone beneath Meteor Crater is found to be consistent with the crater scaling of Schmidt et al. (1980) and previous shock attenuation calculations.

GSA Annual Meeting, November 5-8, 2001
General Information for this Meeting
Session No. 132
Planetary Geology (Posters)
Hynes Convention Center: Hall D
1:30 PM-5:30 PM, Wednesday, November 7, 2001
 

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