The massive asteroid that brought about the end of the dinosaurs’ reign when it crashed into Earth 66m years ago was not a one-off, researchers say.
Detailed scans of an underwater crater off the coast of Guinea in West Africa suggest it was created when another large asteroid slammed into the planet around the same time at the end of the Cretaceous period.
The violent impact between 65m and 67m years ago left a crater more than five miles across, the scans show, with scientists estimating that the asteroid measured a quarter of a mile wide and hit Earth at nearly 45,000mph.
Although smaller than the asteroid that caused the mass extinction, it was still large enough to leave scars on the face of the planet. “The new images paint a picture of the catastrophic event,” said Dr Uisdean Nicholson, a marine geologist at Heriot-Watt University in Edinburgh. discovered the Nadir Crater in 2022. At the time, the details of the impact were unclear.
To understand more about the impact, the scientists used 3D seismic imaging to map the crater rim and geological scars that lie 300 meters below the sea floor. “There are about 20 confirmed marine craters worldwide, and none of them have been captured in anything close to this level of detail,” Nicholson said. “It’s beautiful.”
The collision appeared to have caused intense shaking that liquefied sediments beneath the ocean floor, causing faults to form beneath the ocean floor, the researchers found. The impact caused landslides with traces of damage visible thousands of square miles beyond the crater rim, and triggered a huge tsunami more than 800 meters high that would have traveled across the Atlantic Ocean. Details are published in Nature Communication Earth and Environment.
The researchers cannot determine when the asteroid hit Earth, but the discovery of the crater and its approximate age have led to speculation that it may have belonged to a group of impacts at the end of the Cretaceous period. The asteroid linked to the extinction of the dinosaurs was much larger than the rock that produced the Nadir Crater. It left a crater 100 miles wide in what is now Chicxulub on the Yucatan Peninsula in Mexico.
“The closest people have come to seeing something like this is the Tunguska event in 1908, when a 50-meter-long asteroid entered the Earth’s atmosphere and exploded in the sky over Siberia,” Nicholson said. “The new 3D seismic data over the entire Nadir crater is an unprecedented opportunity to test impact cratering hypotheses, develop new models of cratering in the marine environment and understand the consequences of such an event.”
