This area will cover relevant news of the threat to the planet from Near Earth Objects (NEOs) including concepts and designs for mitigation. All opinions are those of the author.

28 November 2008

Using LIDAR to find meteor craters

From a recent paper on using LIDAR to find meteor impacts on the Earth...

Anatomy of a young impact event in central Alberta, Canada: Prospects for the missing Holocene impact record
Volume 36, Issue 12 (December 2008)
Article: pp. 955–958
C.D.K. Herd, D.G. Froese, E.L. Walton, R.S. Kofman, E.P.K. Herd, and M.J.M. Duke

Small impact events recorded on the surface of Earth are significantly underrepresented based on expected magnitude-frequency relations. We report the discovery of a 36-m-diameter late Holocene impact crater located in a forested area near the town of Whitecourt, Alberta, Canada. Although undetectable using visible imagery, the presence of the crater is revealed using a bare-Earth digital elevation model obtained through airborne light detection and ranging (LiDAR). The target material comprises deglacial Quaternary sediments, with impact ejecta burying a late Holocene soil dated to ca. 1100 14C yr B.P. Most of the 74 iron meteorites (0.1–1196 g) recovered have an angular exterior morphology. These meteorites were buried at depths <25 cm and are interpreted to result from fragmentation of the original projectile mass, either at low altitude or during the impact event. Impact of the main mass formed the simple bowl-shaped impact structure associated with an ejecta blanket and crater fill. The increasing availability of LiDAR data for many terrestrial surfaces will serve as a useful tool in the discovery of additional small impact features.

Link: Geology Reference

Link: ars technia Article

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