A study of a crater recently discovered in southern Egypt concludes that the Earth may be more vulnerable to large meteorite impacts than previously thought.

Results of the study have been published in a paper co-authored by ICTP junior associate Mohamed El Gabry that appears in the 22 July online version of Science magazine. The paper, titled "The Kamil Crater in Egypt", analyzes the crater's well-preserved features and concludes that iron meteorites with a mass of tens of tons can indeed penetrate the Earth's atmosphere and remain in intact, contrary to geophysical model predictions.

"Current impact models state that iron meteors around this size and mass should break into smaller chunks before impact," explained El Gabry, adding, "Instead, the existence of the new-found crater implies that up to 35% of these iron giants may actually survive whole, and thus have greater destructive power."

Based on the average diameter of the impact crater—about 45 meters, with 16 meters depth—scientists estimate that the size of the meteorite was about 1.3 meters in diameter, weighing about 9,000 kg, and that its pre-atmospheric mass would have been between 20,000 to 40,000 kg. Geophysical models have held that meteorites with masses of less than 3x106  kg become fragmented when passing through the Earth's atmosphere.

El Gabry said that the Kamil Crater is the most conserved crater found yet. "While small meteorite impact craters are common surface structures on solid planetary bodies in the solar system, they are rare on Earth due to the relative ease with which smaller structures can be buried by post-impact sediments or destroyed by erosion. The few identified have lost many of their primary features. As a consequence, knowledge of their formation mechanism, their effect on the environment, and of the hazard small impactors pose to human populations is largely based on theoretical models and experimental analogs," he said.

El Gabry is a seismologist with the National Research Institute of Astronomy and Geophysics in Helwan, Egypt. He has been an ICTP junior associate since 2005.