NASA has discovered another massive crater beneath the ice in Greenland

Federico Mansilla
Febrero 12, 2019

The two sites are just 114 miles apart - and NASA glacologist Joe McGregor found the new crater by checking topographic maps of hte land beneath the ice.

Exactly how and when it formed still remain a mystery, though the researchers suspect it may be more than 80,000 years old. Using imagery of the ice surface from the Moderate Resolution Imaging Spectroradiometer instruments aboard NASA's Terra and Aqua satellites, he soon noticed a circular pattern some 114 miles to the southeast of Hiawatha Glacier. That was the first meteorite impact to be discovered beneath Earth's ice sheets, and now just a few months on, scientists have discovered an even bigger crater.

Experts previously thought that most evidence of ancient impacts would have been erased by erosion of the overlying ice over many years.

"I began asking myself 'Is this another impact crater?"

Although the holes are close to one another, they probably weren't formed at the same time as the icy deposits sitting above the Hiawatha impact crater are younger. Though the structure isn't as clearly circular as the Hiawatha crater, MacGregor estimated the second crater's diameter at 22.7 miles.

To calculate the statistical likelihood that the two craters were created by unrelated impact events, MacGregor's team used recently published estimates that leverage lunar impact rates to better understand Earth's harder-to-detect impact record.

"The only other circular structure that might approach this size would be a collapsed volcanic caldera". "But the areas of known volcanic activity in Greenland are several hundred miles away".

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The newly-discovered object is located only 114 miles away from a similar one discovered in November.

"The ice layers above this second crater are unambiguously older than those above Hiawatha, and the second crater is about twice as eroded. If the two did form at the same time, then likely thicker ice above the second crater would have equilibrated with the crater much faster than for Hiawatha", Dr. MacGregor said. There are many more crater-shaped features on Earth than there are actual craters formed by meteorites slamming into the planet.

Scientists recently identified what's said to be the first known impact crater found beneath one of Earth's ice sheets. The layers of ice were smooth, suggesting the ice hadn't been strongly disturbed during that time.

A topological map showing the location of the two potential impact craters hidden under Greenland's ice sheet.

A 19-mile-wide (30 km) impact crater left by the event remained hidden for at least 12,000 years beneath the Hiawatha Glacier in remote north-west Greenland, although scientists have not categorically dated the event. By employing computer models that can track the production of large craters on Earth, they found that the abundance of said craters that should naturally form close to one another, without the need for a twin impact, was consistent with Earth's cratering record.

Researchers had considered the possibility that the craters were caused by imploding volcanos, but they were quickly able to rule that out.

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