The discovery of what appears to be a second meteorite impact crater, off the coast of Guinea, has opened up new questions about how the dinosaurs became extinct. The finding is very similar in age to the Chicxulub crater in Mexico, where until now it was thought that the asteroid that caused the mass disappearance of this species from Earth had fallen. Baptized with the name of Nadir, the new grave is located more than 300 meters below the seabedabout 400 kilometers off the coast of Guinea, in West Africa, just across the Atlantic Ocean from the one studied so far.
With a diameter of 8.5 kilometers, it is likely that the asteroid that created it had just under half a kilometer in diameter, explained to the BBC Uisdean Nicholson, a professor at Heriot-Watt University in Edinburgh, and one of the authors of the discovery. Nicholson was analyzing seismic survey data, looking for a place to drill, to better understand climate change when he stumbled upon the large underwater hole.
“I have spent 20 years conducting ultrasound studies on the seabed, but never seen anything like this“, the professor of the Scottish university told BBC News. “The shape of Nadir is a clear effect of the impact of an asteroid. It has a raised rim that surrounds a central uplift area and then layers of debris that extend outward,” he added.
a minor impact
The asteroid that created the Chicxulub crater in the Gulf of Mexico is estimated to have been about 12 kilometers in diameter and opened a depression 200 kilometers wide, causing strong Earthquakes, Tsunamis, and a Global Firestorm. The impact hurled so much material into the sky that Earth sank into a deep freeze phase. The dinosaurs could not survive the climate shock.
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By comparison, the effects of the asteroid that caused Nadir’s crater would have been much smaller. “Our simulations suggest that this crater was caused by the collision of a 400 meter wide asteroid in an area of between 500 and 800 square meters of water”, explained Veronica Bray of the University of Arizona, USA. “This would have generated a tsunami of more than a kilometer high, as well as an earthquake of magnitude 6.5 more or less”, adds the researcher.
“The energy released would have been about 1,000 times greater than that of the January 2022 Tonga eruption and tsunami,” he adds. In the case of Chicxulub it would have been 10 million times greater.