How Many Large Craters Exist on Earth?

posted: 06/29/15
by: Danny Clemens
crater impact site

As part of a new study from Germany's University of Freiburg, researchers scoured the Earth in search of every single large impact crater on the planet's surface.

The research follows a study last year that sought to identify all impact craters measuring 85 km (53 miles) in diameter and larger. Study lead author Brandon Johnson, of the Massachusetts Institute of Technology, and his team confirmed the existence of seven such craters, which, unlike smaller craters, are large enough to survive erosion (although not immune to the impacts of plate tectonics).

Now Stefan Hergarten and Thomas Kenkmann, two geophysicists from Freidburg, are taking Johnson's research a step further: the pair was also able to identify all craters as small as 6 km (4 miles) in diameter. By cross-referencing asteroid impact and erosion rates with visual evidence of craters, they identified an additional 70 craters between 6 and 85 km.

"It's the first time anyone has done this kind of thing--taking into account the effects of erosion," Johnson told Science Magazine in an interview.

Between work done by Hergarten and Kenkmann, Johnson and others, the geologic record now identifies 128 craters scattered around our planet's surface.

The hunt for craters, however, is nowhere near complete: an additional 350 craters smaller than 6 km in diameter could still be unidentified, in addition to the 60 subterranean craters that have already been documented.

Hergarten and Kenkmann's research is slated to appear in the September issue of the journal Earth and Planetary Science Letters.

Click here for more information from Science Magazine

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