beecee Posted February 11, 2019 Posted February 11, 2019 https://phys.org/news/2019-02-nasa-impact-crater-greenland-ice.html NASA finds possible second impact crater under Greenland ice February 11, 2019 by Maria-José Viñas, NASA's Goddard Space Flight Center A NASA glaciologist has discovered a possible second impact crater buried under more than a mile of ice in northwest Greenland. Credit: NASA Goddard A NASA glaciologist has discovered a possible second impact crater buried under more than a mile of ice in northwest Greenland. his follows the finding, announced in November 2018, of a 19-mile-wide crater beneath Hiawatha Glacier—the first meteorite impact crater ever discovered under Earth's ice sheets. Though the newly found impact sites in northwest Greenland are only 114 miles apart, at present they do not appear to have formed at the same time. If the second crater, which has a width of over 22 miles, is ultimately confirmed as the result of a meteorite impact, it will be the 22nd largest impact crater found on Earth. Read more at: https://phys.org/news/2019-02-nasa-impact-crater-greenland-ice.html#jCp the paper: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL078126] A Possible Second Large Subglacial Impact Crater in Northwest Greenland: Abstract Following the discovery of the Hiawatha impact crater beneath the northwest margin of the Greenland Ice Sheet, we explored satellite and aerogeophysical data in search of additional such craters. Here we report the discovery of a possible second subglacial impact crater that is 36.5‐km wide and 183 km southeast of the Hiawatha impact crater. Although buried by 2 km of ice, the structure's rim induces a conspicuously circular surface expression, it possesses a central uplift, and it causes a negative gravity anomaly. The existence of two closely spaced and similarly sized complex craters raises the possibility that they formed during related impact events. However, the second structure's morphology is shallower, its overlying ice is conformal and older, and such an event can be explained by chance. We conclude that the identified structure is very likely an impact crater, but it is unlikely to be a twin of the Hiawatha impact crater. Plain Language Summary: It is increasingly rare to find new large impact craters on Earth, let alone such craters buried beneath ice. We describe a possible impact crater buried beneath 2 kilometers of ice in northwest Greenland. The circular structure is more than 36 kilometers wide, and both its shape and other geophysical properties are consistent with an impact origin. If eventually confirmed as an impact crater, it would be only the second found beneath either of Earth's ice sheets. The first was the Hiawatha impact crater, which is also in northwest Greenland and only 183 kilometers away from this new structure, so we also evaluated whether these two craters could be related. They are similarly sized, but the candidate second crater appears more eroded and ice above it is much less disturbed than above the Hiawatha impact crater. Statistical analysis of the frequency of two unrelated but nearby large impacts indicates that it is improbable but not impossible that this pair is unrelated. Our study expands knowledge of the impact history of the Earth and raises the question as to how many other impact craters buried beneath ice have yet to be found.
Recommended Posts