Discovery of a second giant asteroid impact dating from the extinction of the dinosaurs

The impact of a previously unknown asteroid from the past has left an impressive mark beneath the ocean. Thanks to modern technologies, researchers were able to make this discovery.

This crater, named Nadir, is located beneath the sea near Guinea. It dates back to a pivotal period in Earth's history: 66 million years ago.


Buried under 300 meters (~984 feet) of sediment, this crater is nearly undetectable by traditional means. Seismic imaging allowed researchers to reveal its shape and to detail the events that followed the asteroid's impact.

Discovered in 2022, the crater measures around 8.5 kilometers (~5.3 miles) in diameter. The seismic detection technique, used to analyze the seafloor, provided a 2D and then a 3D image of this depression. This revealed a clear disturbance in the stratification of the sediments.

The impact responsible for the formation of Nadir would have triggered a huge tsunami. A wave of 800 meters (~2,600 feet) is thought to have crossed the Atlantic Ocean, drastically altering the surrounding landscape.

What intrigues scientists is the age of the crater: it coincides with that of Chicxulub, the asteroid linked to the extinction of the dinosaurs. Some estimate it could be a fragment of a larger asteroid. However, despite these hypotheses, uncertainty remains about the connection between the two events. Scientists are not yet able to precisely date the impact or determine if these collisions are related.


The 3D modeling of the Nadir crater represents a major breakthrough in understanding asteroid impacts on Earth. This first step could pave the way for new discoveries. Upcoming studies, such as planned drilling campaigns, will likely explore the crater's composition in more detail and provide new insights into this cataclysmic event.

Through these future analyses, researchers hope to better understand the global consequences of the impact on the marine and terrestrial environments of the time.

What is seismic imaging and how does it help discover underwater craters?

Seismic imaging is a geophysical technique used to explore the subsurface by sending acoustic waves. These waves, similar to those from earthquakes, pass through various geological layers before being reflected back to the surface. By analyzing the reflected waves, scientists can reconstruct an image of the subsurface, much like an ultrasound.

In the case of the Nadir crater, this method revealed a disruption in sediment layers, evidence of a massive impact. Instruments called geophones capture the waves after their journey, allowing the creation of highly detailed 2D and 3D images of the seafloor. This is how the structure of the crater, hidden beneath the sediment, was identified.

Seismic imaging is particularly useful in marine environments, where erosion is less significant than on land. This allows the discovery of well-preserved craters that have remained intact for millions of years, providing valuable information on asteroid impacts.

How is a tsunami generated by an asteroid impact?

A tsunami caused by an asteroid impact occurs when the object strikes a body of water, such as an ocean. The enormous energy released by the collision abruptly displaces a large volume of water, generating a series of massive waves.


These waves, initially formed near the impact site, then spread at high speeds over thousands of miles. The Nadir crater, for example, is thought to have generated a tsunami 800 meters (~2,600 feet) high after the asteroid struck the ocean floor. This shockwave would have traveled across the Atlantic, creating destructive waves along the coasts.