In November last year, scientists, including researchers from NASA, discovered a 19-mile-wide crater beneath Hiawatha Glacier in Greenland. 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. Just 114 miles away from the original crater, NASA scientists have found one which has a width of more than 22 miles.
But at 22 miles wide, when the meteorite hit, which was approximately 79,000 years ago, it would have been big enough to alter the global climate.
The researchers used images from NASA’s Terra and Aqua satellites to notice strange anomalies on the ground.
Following this, the experts coincided the satellite information with topographic maps to discover the new crater.
Joe MacGregor, a glaciologist with NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who participated in both findings, said: “I began asking myself ‘Is this another impact crater? Do the underlying data support that idea?
“Helping identify one large impact crater beneath the ice was already very exciting, but now it looked like there could be two of them.”
“We’ve surveyed the Earth in many different ways, from land, air and space – it’s exciting that discoveries like these are still possible.”
Researchers had considered the possibility that the craters were caused by imploding volcanos, but they were quickly able to rule that out.
Mr MacGregor said: “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.
“Also, a volcano should have a clear positive magnetic anomaly, and we don’t see that at all.”
Despite their relatively close proximity, the researchers say that the meteorite impacts likely occurred at different times.
Mr MacGregor said: ”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.”
According to the research published in the journal Geophysical Research Letters, it is the 22nd largest crater impact in the world.