Asteroid which killed dinosaurs ‘caused 2.8-mile-high tsunami’
A Mount Everest-sized rock smashed into our planet 66 million years ago, sending up clouds which blotted out the sun and killed most creatures on Earth.
But the impact also triggered a vast, terrifying tsunami up to 2.8 miles high, which left traces on the ocean floor thousands of miles from the impact site on Mexico’s Yucatan Peninsula, according to a new University of Michigan-led study.
The study authors calculated that 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.
The 2004 tsunami killed more than 230,000 people and is one of the largest tsunamis in modern times.
The tsunami sparked by the dinosaur asteroid would have briefly been 2.8 miles wide before collapsing to lower levels as it surged around the world.
Read more: Were the dinosaurs killed off by the asteroid or volcanoes?
The study is the first global simulation of the Chicxulub impact tsunami in a peer-reviewed scientific journal.
The University of Michigan researchers reviewed the geological record at more than 100 sites worldwide and found evidence that supports their predictions.
Lead author Molly Range, who conducted the study for a masters thesis, said, “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.”
“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,”
The review of the geological record focused on “boundary sections”, marine sediments deposited just before or just after the asteroid impact.
The team’s simulations show that the impact tsunami radiated mainly to the east and northeast into the North Atlantic Ocean, and to the southwest through the Central American Seaway (which used to separate North America and South America) into the South Pacific Ocean.
Read more: Asteroid ‘wouldn’t have killed the dinosaurs if it hit somewhere else’
In those basins and in some adjacent areas, underwater current speeds likely exceeded 20 centimetres per second (0.4 mph), a velocity that is strong enough to erode fine-grained sediments on the seafloor.
In contrast, the South Atlantic, the North Pacific, the Indian Ocean and the region that is today the Mediterranean were largely shielded from the strongest effects of the tsunami, according to the team’s simulation.
In those places, the modelled current speeds were likely less than the 20 cm/sec threshold.
“We found corroboration in the geological record for the predicted areas of maximal impact in the open ocean,” said Brian Arbic, professor of earth and environmental sciences who oversaw the project. “The geological evidence definitely strengthens the paper.”
Watch: Animation shows impact as dinosaur asteroid tsunami hits
