Five-mile asteroid impact crater under Atlantic captured in ‘exquisite’ detail by seismic data

New images of an asteroid impact crater buried deep beneath the floor of the Atlantic Ocean have been released today by researchers at Heriot-Watt University.

The images confirm that the 9 km long Nadir crater, located 300 m below the floor of the Atlantic Ocean, was caused by an asteroid crashing into Earth at the end of the Cretaceous period, around 66 years ago. millions of years.

That’s the same age as the 200km-wide, dinosaur-killing Chicxulub impact crater in Mexico.

The images helped researchers determine what happened in the minutes after the impact: the first bowl-shaped crater formed, the rocks transformed into a fluid state and flowed toward the high to the crater floor, the creation of a damage zone covering thousands of square kilometers beyond the crater and a tsunami more than 800 meters high which would have crossed the Atlantic Ocean.

The results are reported in Earth and Environment Communications.

66 million year old underwater footprint

Dr Uisdean Nicholson of Heriot-Watt University discovered the Nadir crater in 2022 while studying seismic reflection data from the seafloor of the Atlantic Ocean, off the coast of Guinea, West Africa.

The data revealed a depression more than 8.5km wide, which Dr Nicholson said could be an asteroid impact crater.

He worked with planetary scientists and geologists in the UK and US to classify the crater: the data suggested it came from an asteroid several hundred meters wide that hit the planet about 66 million years ago, but they couldn’t say it definitively.

Now they can.

From a grainy ultrasound to a 3D image

High resolution 3D seismic data was captured by TGS, a global geophysical company and shared with Dr Nicholson, geologist. Data proves that an asteroid caused the Nadir crater.

Dr Nicholson said: “There are around 20 confirmed marine craters around the world, and none of them have been captured in this level of detail. It’s exquisite.

“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 obtain a complete three-dimensional image and peel back the layers of sedimentary rock to observe the crater at all levels.

“One way to understand this is to think of a pregnancy ultrasound. A few generations ago, the ultrasound showed a grainy spot. Now you can see the baby’s features in 3D, in incredible detail, including all organs internal.

“We went from blurry 2D imagery to stunning high-resolution imagery of Nadir Crater.”

Data reveals minute-by-minute chaos after collision

Dr Nicholson said: “The new images paint a picture of the catastrophic event.

“We initially thought the asteroid would be around 400m wide. We now think it was between 450m and 500m wide, due to the larger size of the crater, as shown in 3D data .

“We can tell that it came from about 20 to 40 degrees to the northeast, due to the spiral ridges generated by the thrust surrounding the central summit of the crater – these only formed as a result from a low angle oblique impact.

“And we think it would have hit Earth at a speed of about 20 km per second, or 72,000 km per hour, although we still need to confirm this with a new set of impact models.”

Using this data, scientists created a timeline of what happened in the seconds and minutes following impact.

Dr Nicholson said: “After the impact and the formation of the central uplift, the soft sediments surrounding the crater flowed inwards towards the evacuated crater floor, creating a visible ‘rim’.

“Earthquakes caused by the impact appear to have liquefied sediments beneath the seafloor across the entire shelf, causing faults to form beneath the seafloor.

“The impact was also associated with large landslides as the shelf margin collapsed beneath the ocean.

“Additionally, we see evidence of a train of tsunami waves moving away and then returning toward the crater, with large resurgence scars preserving evidence of this catastrophic event.”

A natural laboratory for asteroid impact research

Dr. Nicholson points out that humans have never seen an asteroid of this size crash into Earth.

“The closest human event has come to seeing something like this is the Tunguska event of 1908, when a 50-meter asteroid entered Earth’s atmosphere and exploded in the sky above the Siberia.”

“The new 3D seismic data across the entire Nadir Crater provides an unprecedented opportunity to test hypotheses about impact craters, develop new models of crater formation in the marine environment, and understand the consequences of such an event.

“We have applied to IODP3, which is a new international drilling program, to drill into the seafloor and recover cores from the crater. These will give us more information about the shock pressures experienced during the impact as well that about the precise age and sequence of events that occurred after this event.

Unlike the Moon, Earth’s craters erode

Collaborator Dr Sean Gulick of the University of Texas at Austin, USA, a geophysicist and impact process expert, noted: “3D seismic images of a fully preserved impact crater provide a fantastic opportunity to research that can allow us to examine how impact processes and craters scale with impactor size, both to understand the evolution of Earth and other worlds.

Collaborator Dr Veronica Bray of the University of Arizona, an expert on impact craters across the solar system, commented: “We see pristine impact craters on airless bodies like the moon, but we don’t have no subsurface structural information.

“On Earth, it’s the opposite: we have structural data from seismic, field mapping and drill cores, but craters are generally very eroded on the surface.

“New 3D seismic imaging from Nadir gives us both. It’s a surprisingly good look at an impact crater!”

Could an asteroid this size hit Earth soon?

The asteroid Bennu, a pile of rubble, is about 400 m in diameter. It is considered the most dangerous object in near-Earth orbit. According to NASA scientists, the total probability of impact until 2300 is approximately 1 in 1,750 (or 0.057%).

The researchers were also able to identify September 24, 2182 as the most significant date in terms of potential impact, with a probability of impact of 1 in 2,700 (or approximately 0.037%).