UM-led study simulates impact of global tsunami after dinosaur-killing asteroid

When a miles-wide asteroid hit Earth 66 million years ago, killing nearly all the dinosaurs as well as most plant and other animals, it also triggered a massive tsunami that altered the globe, according to a new study led by researchers at the University of Michigan.

The findings published online Tuesday in the journal AGU Advances are believed to be the first global simulation of the Chicxulub impact tsunami published in a peer-reviewed scientific journal, UM officials said in a statement. It also covered how powerful the tsunami was.

Reviewing marine sediments deposited shortly before or after the asteroid impact and the subsequent mass extinction that ended the Cretaceous Period, the study authors determined “the initial energy in the impact tsunami was up to 30,000 times larger than the energy in the December 2004 Indian Ocean earthquake tsunami, which killed more than 230,000 people and is one of the largest tsunamis in the modern record,” the university said Tuesday.

"This tsunami was strong enough to disturb and erode sediments in ocean basins halfway around the globe, leaving either a gap in the sedimentary records or a jumble of older sediments,” said Molly Range, the lead author who started the project as an undergraduate, in the release.

She conducted the modeling study for a master’s thesis under Brian Arbic, a UM physical oceanographer, and Ted Moore, a UM paleoceanographer, officials said. Both co-authored the study.

The team’s simulations found that in some areas, “underwater current speeds likely exceeded 20 centimeters per second (0.4 mph), a velocity that is strong enough to erode fine-grained sediments on the seafloor,” according to UM.

The study also found the event scoured the ocean floor near what is now New Zealand, thousands of miles from the impact site on Mexico’s Yucatan Peninsula.

The authors noted the giant waves following the arrival of the asteroid believed to be nearly 8.7 miles in diameter that eventually left a nearly 62-mile-wide crater.

“Two and a half minutes after the asteroid struck, a curtain of ejected material pushed a wall of water outward from the impact site, briefly forming a 4.5-kilometer-high (2.8-mile-high) wave that subsided as the ejecta fell back to Earth,” UM officials said.

The UM simulation estimated a ring-shaped, 0.93-mile high tsunami wave started sweeping across the ocean 10 minutes later.

“Any historically documented tsunamis pale in comparison with such global impact,” the authors wrote in the study. “Depending on the geometries of the coast and the advancing waves, most coastal regions would be inundated and eroded to some extent.”

A follow-up study on the coastal inundation worldwide is planned and will be led by Vasily Titov of the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Lab, a co-author of the AGU Advances paper, UM said.