Worldwide tsunami accompanied the asteroid that wiped out the dinosaurs
(CN) — The asteroid that took out the tyrannosaurus and the triceratops didn’t just unleash a billion tons of explosive energy and disrupt the Cretaceous climate for years afterward, but it also triggered a tsunami so enormous that it reached all the way across the world, according to a new University of Michigan study.
Published Tuesday in the journal AGU Advances, the study presents the first modelled simulation of the tsunami impact of the asteroid that is recognized as the cause of a mass extinction event that would come to end the age of the dinosaurs.
Simulations show a tsunami with towering, far-reaching waves on a scale far exceeding some of the largest tsunamis in recent recorded history. The study also compares the simulations to marine core data from 66 million years ago to confirm disturbances in the ancient seafloor.
“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, University of Michigan researcher and lead author of the study, in a press release.
The model for the asteroid was based on prior research that has estimated a satellite with a diameter nearly nine miles around, hurtling toward Earth at 27,000 miles per hour, creating a crater over 12 times its size. The Chicxulub crater, first discovered in the 1970s under Mexico’s Yucatan Peninsula, has been studied for decades as the presumed impact location for the world-changing asteroid.
The initial impact was marked by an enormous blast that would have created the crater and ejected dust and debris high into the atmosphere, enough to produce a dust cloud that blocked the sunlight and lowered temperatures worldwide. Researchers have debated the possibility of an aftermath of firestorms, an impact winter or acid rains killing a majority of land and water-based dinosaurs and plants.
One simulation, showing the first 10 minutes after the asteroid hits, models how that blast, combined with debris falling back into the ocean, would have created an initial mile high wall of water that would begin to gather strength and spread across the globe.
The asteroid’s impact, simulations indicated, produced waves over 300 miles tall in the Gulf of Mexico that would radiate outward toward the North Atlantic Ocean and the Pacific Ocean near South America. Although the waves would lose some steam as they approached the other side of the world at the Indian Ocean around 24 hours after the asteroid first struck, substantial tsunami activity would have eventually reached nearly every coast in the world.
“The big result here is that two global models with differing formulations gave almost identical results, and the geologic data on complete and incomplete sections are consistent with those results,” said Ted Moore, co-author and University of Michigan professor emeritus of earth and environmental sciences.
As the tsunami swept across the oceans, it would have produced, according to simulations, underwater current speeds over 0.4 miles per hour, which would have eroded the layer of rock and clay on the seafloor. This disturbance to what is known as the Cretaceous-Paleogene (K-Pg) boundary can be studied today from marine cores collected for geologic record.
Complete samples of the K-Pg boundary from the North Atlantic and South Pacific were few and far between, indicating that these areas had experienced significant disturbances from high-speed currents. In contrast, researchers found a larger number of uninterrupted boundary data from other locations, like the Indian Ocean on the opposite end of the world from the Chicxulub impact, where current speeds would have been tempered by distance.
“The distribution of the erosion and hiatuses that we observed in the uppermost Cretaceous marine sediments are consistent with our model results, which gives us more confidence in the model predictions,” Range said.
The study’s simulations certainly showed the massive scale of the asteroid’s resultant tsunami, but study authors say more work needs to be done on the impact on the Cretaceous-era shorelines.
Shoaling, a phenomenon where wave heights would have increased as the wave approached shallower waters, would have generated extensive coastal flooding and erosion not covered by the simulation’s estimates. Planned further study of these effects will be led by the National Oceanic and Atmospheric Administration’s Vasily Titov, one of the paper’s co-authors.