66 million years ago, an asteroid hit Earth in what we know today as the Gulf of Mexico. The impact was so enormous that the dinosaurs were wiped out. But there may have been a second impact that day, across the Atlantic.
A crater similar to the one in Chicxulub, Mexico, has been discovered off the coast of Guinea. The new crater is about the same age and was named Nadir crater. It is more than 300 meters below the seabed and about 400 km off the coast of Guinea in West Africa. The Nadir crater is smaller than the Mexican one, but also seems to indicate a catastrophic event. Based on the diameter of the Nadir crater of 8.5 km, the responsible asteroid probably had a diameter of more than 400 meters.
It was Uisdean Nicholson of Heriot-Watt University in Edinburgh who discovered the hidden West African crater. The scientist examined seismic data, looking for a place to drill to gain more insight into past climate changes on Earth. In such analyses, the various layers of the subsoil are mapped to a depth of often several kilometres.
“These studies are like an ultrasound of the Earth,” Nicholson told BBC News. He spent just about the last 20 years interpreting it. “But I’ve never seen anything like this,” he claims. “Nadir’s shape is characteristic of an asteroid impact. It has a ridge around a central uphill area, and then layers of rubble extending outwards.”
By comparison, the asteroid that created Chicxulub Crater in the Gulf of Mexico was an estimated 12 km across. The crater is no less than 200 km wide. The impact caused severe earthquakes, tsunamis and a worldwide firestorm. So much dust was thrown into the air that the earth ended up in a deep freeze. The dinosaurs did not survive the climate shock.
In the case of the Nadir asteroid, the impact would not have been as great, but still “generated a tsunami more than a kilometer high, and an earthquake of magnitude 6.5 or so,” according to Veronica Bray of the University. from Arizona. “The energy released would have been about 1,000 times that of the Tonga eruption and tsunami in January 2022,” she suspects.
Further investigation of Nadir Crater is needed – based on rocks from the crater itself, not from a nearby borehole – to more accurately determine its age and confirm that it is indeed an asteroid impact.
Scientists are cautious about linking this event to the Chicxulub impact, even though speculation about a possible cluster of past large space rock impacts is not new. For example, it cannot be ruled out that the Boltish crater in Ukraine is also somehow related to the Chicxulub event.
According to Professor Sean Gulick of the University of Texas at Austin, the West African crater may have formed on the same day as Chicxulub crater, but it won’t directly teach us anything about the fate of the dinosaurs. “A much smaller cousin doesn’t necessarily add to what we know about the extinction of the dinosaurs, but it does add to our understanding of the astronomical event that was Chicxulub.” For example, the expert asks the question, which has yet to be investigated: “Was Chicxulub a double asteroid with a smaller object orbiting a larger object?”
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