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Environmental Perturbations Caused by the Impacts of Comets and Asteroids on EarthThe extinction mechanisms proposed at the Cretaceous-Tertiary geological boundary are reviewed and related to the impact of asteroids or comets in general. For impact energies below 10(exp 4) Megatons (less than 6 x 10(exp 4) years; asteroid diameter less than 650 m), blast, earthquake, and fire may destroy local areas up to 10(exp 5) square m. Tidal waves could flood a kilometer inland over entire ocean basins. The energy range from 105 to 106 Megatons (less than 2 x 10(exp 6) years; asteroid diameter less than 3 km) is transitional. Dust lifted, sulfur released from within impacting asteroids, and soot from fires started by comets can produce climatologically significant optical depths of 10. At energies beyond 10(exp 7) Megatons, blast and earthquake damage is regional (10(exp 6) square cm). Tsunami cresting to 100 m and flooding 20 km inland will sweep the coastal zones of the world's oceans. Fires will be set globally. Light levels may drop so low from the smoke, dust and sulfate that vision is not possible. At energies approaching 10(exp 9) Megatons the ocean surface waters may be acidified by sulfur. The combination of these effects would be devastating.
Document ID
20020010911
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Toon, Owen B.
(NASA Ames Research Center Moffett Field, CA United States)
Lawless, James G.
Date Acquired
August 20, 2013
Publication Date
January 1, 1994
Subject Category
Environment Pollution
Meeting Information
Meeting: 1994 Fall Meeting of the American Geophysical Union
Location: San Francisco, CA
Country: United States
Start Date: December 5, 1994
End Date: December 9, 1994
Sponsors: American Geophysical Union
Funding Number(s)
PROJECT: RTOP 154-30-80-16
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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