Ahrens, Thomas J. and Shen, Andy H. and Ni, Sidao (2004) Giant Impact Induced Atmospheric Blow-Off. In: Shock Compression of Condensed Matter -- 2003: Proceedings of the 13th Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter. American Institute of Physics Conference Proceedings. No.706. American Institute of Physics , Melville, NY, pp. 1419-1422. ISBN 0-7354-0181-0 http://resolver.caltech.edu/CaltechAUTHORS:AHRaipcp04
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Previous calculations indicate that the Earth suffered impacts from objects up to Mars size. Such a giant impact may have produced a temporary ejecta-based ring that accreted to form the Moon. To simulate the surface waves from such events we approximated the cratering source as a buried pressurized sphere. For a 10^27 J impactor we calculated the resulting surface wave using the mode summation method of Sato et al.. For such an impact, the solid Earth free-surface velocity above, and antipodal to, the source achieves 2.6 and 1.9 km/s. Such large ground motions pump the atmosphere and result in upward particle motions which cause the atmosphere to be accelerated to excess of the escape velocity (11.2 km/s) at high altitudes. For a 1.3 × 10^32 J Moon-forming impact we calculate that ~50% of the Earth's atmosphere is accelerated to escape.
|Item Type:||Book Section|
|Additional Information:||©2004 American Institute of Physics Research supported by NASA. Editorial suggestions proffered by M.D. Furnish are gratefully acknowledged. Contribution # 8975, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.|
|Subject Keywords:||planetary surfaces; collision processes; impact (mechanical); atmospheric movements; Mars; Earth|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Archive Administrator|
|Deposited On:||21 Mar 2006|
|Last Modified:||26 Dec 2012 08:48|
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