The only thing worse than getting punched in the face is getting punched twice. That’s almost exactly what happened to the dinosaurs, scientists now say—only on a much, much larger scale. The asteroid that hit Chicxulub, Mexico, is still credited with killing the dinosaurs, but a second asteroid struck during the same era at Nadir Crater off the coast of Guinea in West Africa, proving once and for all that nature really had it in for it. . the poor dinos.
A new study published in Nature shows the Nadir Crater in ways science hadn’t seen before. Led by Uisdean Nicholson, a geologist at Heriot-Watt University in Scotland, the scientists used 3D seismic data to measure the impact and were able to vary the size of the asteroid, its angle of impact, how fast it was going and its impact . had on the seabed and bedrock.
The asteroid was likely 450 to 500 meters in size, traveling at 20 kilometers per second and struck Earth at an angle of 20 to 40 degrees from the northeast, the study says.
“There are about 20 confirmed sea craters worldwide, and none of them have been captured in anything close to this level of detail. It’s brilliant,” Nicholson told Phys.org. “Craters on the surface are usually heavily eroded and we can only see what is exposed, whereas craters on other planetary bodies usually only show surface expression. This data allows us to image this fully in three dimensions and remove layers of sedimentary rock.” .to see the crater at all levels”.
Among other things, the study proved that the crater was, in fact, the result of an asteroid impact and that it happened at the same time as the asteroid that killed the dinosaurs, which was 66 million years ago at the end of the Cretaceous. period. So while the Chicxulub asteroid was the one that killed the dinosaurs, it looks like it may have had a little help from the asteroid that hit Nadir Crater.
Anatomy of an Asteroid Impact
The asteroid would have struck with incredible violence, displacing water in the area for up to a minute.
Perhaps most frightening is the blow-by-blow result of the impact, which scientists were also able to reconstruct. According to the study, the asteroid would have displaced all of the water in the area, which was about 800 meters deep at the time, firing a “massive tsunami train” into the Atlantic Ocean.
Sediment would have rushed in to fill the new hole made by the impact, causing a rim to form. Some of the sediment would have been vaporized during the impact. The tsunami was measured to have touched the sea floor up to 20 kilometers away.
From there, a massive earthquake would have caused damage beneath the seabed, liquefying bedrock throughout the area near the crater. The tsunami train would eventually reverse and roll back as water filled the area once more.
In addition to all this, scientists say the impact would have caused ionospheric disturbances and thermal radiation. The massive landslides would have occurred as parts of the sea plateau crashed further into the ocean.
Fortunately for humans, these types of impacts are extremely rare. The largest meteor impact in living memory is the “super bolide” asteroid that exploded over Russia in 2013. There is a very small chance that Bennu, an asteroid of similar size, could hit Earth sometime around 2300. The chances that this happens are about one in 1750.