A dinosaur-killing asteroid spouted mile-high tsunamis that swept the entire world

The asteroid that struck Earth off the coast of Mexico’s Yucatan Peninsula was simply devastating to all life on Earth, not just the dinosaurs. The cosmic impact unleashed the power of 10 billion Hiroshima-A bombs and ejected gigatons of sulfur and carbon dioxide into the atmosphere, which could have lowered surface air temperatures by a staggering 26 degrees Celsius (47 degrees Fahrenheit). This global winter lasted for years, enough to destroy plant life and everything else along the food chain. About 75% of all animal and plant species are extinct, including the legendary dinosaurs (excluding birds).

But it wasn’t just the explosion and subsequent famine that wreaked havoc. Immediately after the cosmic impact, a monstrous tsunami was unleashed. Its waves were up to a mile high and ravaged the seabed many thousands of miles from the point of impact. In a new study, scientists have now performed the first global simulation of the Chicxulub tsunami, revealing new insights into the path and power of these powerful waves.

“This tsunami was powerful enough to disrupt and erode sediments in ocean basins halfway around the world, leaving either a gap in the sediment record or a jumble of older sediments,” said lead author Molly Range of the University of Michigan, who led the research led as part of the master’s thesis.

The waves of an ancient giant tsunami

Range and colleagues, including physical oceanographer Brian Arbic and paleoceanographer Ted Moore, combed the geological record from more than 100 locations around the world. In particular, they looked at the K-Pg boundary, a thin layer of sediment deposited shortly after the asteroid impact that marks the end of the Cretaceous period and is around 66 million years old.

These sites revealed faults in the Upper Cretaceous marine sediments consistent with the results of the researchers’ simulation, giving confidence that the model is a good approximation of the chain of events that unfolded as a result of the asteroid impact. Based on previous studies, the researchers estimated that the killer asteroid was about 14 kilometers (8.7 miles) in diameter and impacted the granite crust of Yucatan at 43,500 km/h (27,000 mph) and had a massive 100-kilometer width ( 62-mile wide) crater.

Researchers estimated that the energy of the first tsunami was up to 30,000 times that of the 2004 Indian Ocean earthquake-tsunami, one of the deadliest disasters in modern history. The Indian Ocean tsunami struck the coasts of several countries in South and Southeast Asia, killing over 230,000 people and displacing millions. The 2004 magnitude 9.1 quake ruptured a 900-mile-long fault line where the tectonic plates of India and Australia meet and unleashed 100-foot waves. It’s totally devastating, but now imagine the devastation caused by the Chicxulub tsunami, with waves reaching up to 1,600 meters just ten minutes after the projectile hit and up to 4,500 meters two and a half minutes after impact.

From the Yucatan Peninsula, the tsunami radiated primarily east and northeast, causing most of the damage in the North Atlantic Ocean, as well as southwest through the Central American Sea Route, which formerly separated North America and South America, into the South Pacific Sea. The South Atlantic, the North Pacific, the Indian Ocean and what is now the Mediterranean Sea were largely spared by the tsunami’s strongest waves.

An hour after the impact, the tsunami was already spreading to the North Atlantic. In twenty-four hours the waves had crossed most of the Pacific from the east and most of the Atlantic from the west. After 48 hours, the tsunami had reached virtually all Late Cretaceous coasts. For example, researchers identified heavily disturbed marine sediments in New Zealand more than 12,000 kilometers (7,500 miles) from the Yucatan impact site. These disturbances in sedimentary deposits were previously thought to be caused by tectonic activity, but their age and location in the path of the modeled Chicxulub impact tsunami suggest a different origin.

“We believe these deposits are recording the effects of the impact tsunami, and this is perhaps the most telling confirmation of the global significance of this event,” Range said.

“Depending on the geometry of the coast and the waves, most coastal regions would be partially flooded and eroded,” the study authors said. “Any historically documented tsunami pales in comparison to such global impacts.”