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Giant Impact Induced Atmospheric Blow-Off

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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Abstract

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
Record Number:CaltechAUTHORS:AHRaipcp04
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:AHRaipcp04
Alternative URL:http://dx.doi.org/10.1063/1.1780504
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2284
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:21 Mar 2006
Last Modified:26 Dec 2012 08:48

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