Devastating global tsunami
The asteroid that hit Earth and led to the Cretaceous-Paleogene mass extinction (K-Pg) 66 million years ago also triggered a global tsunami that began as a wave of more than a mile / 1,600 m high, according to a new study. The tsunami was large enough to travel across the ocean floor thousands of kilometers from the impact site in Mexico’s Yucatan Peninsula.
The study, published in AGU Advancespresents the first global simulation of the Chicxulub impact tsunami to be published in a peer-reviewed scientific journal, corroborated by a comprehensive new compilation of geological sites containing evidence of a massive global tsunami.
Their models indicated that open ocean wave heights in the Gulf of Mexico would have exceeded 300 meters (984 ft) about an hour after impact.
With maximum wave heights generally decreasing with time and distance from impact. The authors calculated that the initial energy of the tsunami was up to 30,000 times greater than the tsunami energy of the December 2004 Indian Ocean earthquake., which is one of the largest tsunamis in modern history. According to models, the tsunami would have dissipated in less than a week.
“Any historically documented tsunami pales in comparison to such a global impact,” the authors wrote.
To check their models against geological evidence, the authors examined 120 geological sites from before and after the asteroid impact and found evidence of a global tsunami, reaching as far as what is now New Zealand. They compared those sediments to the waves and erosion predicted by their models.
“This tsunami was strong enough to disturb and erode sediments in ocean basins on the other side of the world, leaving a gap in the sedimentary record or a jumble of older sediments.said lead author Molly Range, a physical oceanographer at the University of Michigan. “The distribution of erosion and hiatus that we observed in the Late Cretaceous marine sediments are consistent with our model results, giving us more confidence in the model predictions.“.
“Geological evidence definitely strengthens the document“, said Brian Arbica physical oceanographer at the University of Michigan and a co-author of the study.
Of particular importance, according to the authors, are the K-Pg boundary outcrops on the eastern coasts of New Zealand’s North and South Islands, which are more than 12,000 kilometers (7,500 miles) from the Yucatan impact site.
The heavily disturbed New Zealand sediments were originally thought to be the result of local tectonic activity. But given the age of the deposits and their location directly on the modeled path of the Chicxulub impact tsunami, the team suspected a different origin.
“We believe that these deposits are recording the effects of the impact tsunami, and this is perhaps the strongest confirmation of the global importance of this event.Range said.
While the study did not explicitly model coastal flooding, wave heights could have approached more than 10 meters (32.8 feet) as the tsunami approached coastal regions of the North Atlantic and parts of the Atlantic coast. Pacific of South America. Coastal regions of the North Atlantic and parts of the Pacific coast of South America.
As the tsunami approached those shorelines and encountered shallow bottom water, the height of the waves would have increased dramatically through a process called banking. Such heights could well have caused substantial flooding, and a future study by some authors on the study will explore that process.
Press release related to the study, here.
The Chicxulub Impact Produced a Powerful Global Tsunami. Molly M. Range, Brian K. Arbic, Brandon C. Johnson, Theodore C. Moore, Vasily Titov, Alistair J. Adcroft, Joseph K. Ansong, Christopher J. Hollis, Jeroen Ritsema, Christopher R. Scotese, He Wang. AGU Advances. 04 October 2022 https://doi.org/10.1029/2021AV000627