A long-running dispute about the origin of a North Sea crater has finally been settled, as new research finds a massive asteroid hit the water and triggered a towering tsunami millions of years ago.
Scientists have found that the Silverpit Crater – which lies around 700 meters beneath the southern North Sea seabed, roughly 80 miles off the coast of Yorkshire – was formed when an asteroid or comet struck the region roughly 43 to 46 million years ago, sparking a 330 feet tsunami.
Since geologists first identified the formation in 2002, the 3km-wide crater and its surrounding ring of circular faults spanning about 20 km have sparked intense debate, according to The Independent.
But researchers say their new study marks the clearest evidence yet that the structure is one of Earth’s rare impact craters.
This confirmation places it in the same category as well-known structures such as the Chicxulub Crater in Mexico, which is linked to the dinosaur mass extinction.
The team used computer modelling and analyzed newly available seismic imaging and microscopic geological samples taken from beneath the seabed.
Dr. Uisdean Nicholson, a sedimentologist in Heriot-Watt University’s School of Energy, Geoscience, Infrastructure and Society, who led the investigation, said: “New seismic imaging has given us an unprecedented look at the crater.”
He said samples from an oil well in the area also revealed rare ‘shocked’ quartz and feldspar crystals at the same depth as the crater floor.
“We were exceptionally lucky to find these – a real ‘needle-in-a-haystack’ effort. These prove the impact crater hypothesis beyond doubt, because they have a fabric that can only be created by extreme shock pressures,” said Nicholson.
The scientists say these microscopic minerals form only under the extreme pressures generated during asteroid impacts, providing strong confirmation of the event.
Early research proposed that the feature was created by a high-speed asteroid impact. Supporters of that idea pointed to its round shape, central peak, and surrounding concentric faults, which are often seen in known impact craters.
But other scientists suggested different explanations. Some proposed that underground salt movement distorted the rock layers and created the structure.
Others argued that volcanic activity may have caused the seabed to collapse.
In 2009, geologists even voted on the issue. According to a report in the December 2009 issue of Geoscientist magazine, most participants rejected the asteroid impact explanation at the time.
The latest findings, published in the journal Nature Communications and funded by the Natural Environment Research Council (NERC), now appear to overturn that conclusion.
Dr. Nicholson said: “Our evidence shows that a 160-meter-wide asteroid hit the seabed at a low angle from the west.”
“Within minutes, it created a 1.5 km high curtain of rock and water that then collapsed into the sea, creating a tsunami over 100 meters high.”
The impact would have produced a violent explosion at the seafloor and sent enormous waves spreading across the region.
Professor Gareth Collins, of Imperial College London, who attended the 2009 debate about the crater’s origin and contributed to the new research, said the researchers have “finally found the silver bullet” to end the debate.
He said: “I always thought that the impact hypothesis was the simplest explanation and most consistent with the observations.”
“It is very rewarding to have finally found the silver bullet. We can now get on with the exciting job of using the amazing new data to learn more about how impacts shape planets below the surface, which is really hard to do on other planets,” Collins added.
Dr. Nicholson also expressed his excitement about using the new findings for further research into asteroids.
“Silverpit is a rare and exceptionally preserved hypervelocity impact crater,” he said.
“These are rare because the Earth is such a dynamic planet – plate tectonics and erosion destroy almost all traces of most of these events.”
