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When a city-sized asteroid slammed into Earth 66 million years ago, it wiped out the dinosaurs and sent a monstrous tsunami across the planet, according to new research.
The asteroid, about 14 kilometers (8.7 miles) wide, left an impact crater about 100 kilometers (62 miles) wide near Mexico’s Yucatan Peninsula. In addition to ending the reign of the dinosaurs, the direct hit triggered a mass extinction of 75% of plant and animal life on the planet.
When the asteroid hit, it created a series of catastrophic events. global temperatures fluctuated; plumes of aerosol, soot and dust filled the air; and wildfires started when bits of burning material thrown up by the impact re-entered the atmosphere and rained down. Within 48 hours, a tsunami had circled the globe, and was thousands of times more energetic than modern tsunamis caused by earthquakes.
The researchers set out to gain a better understanding of the tsunami and its extent through modeling. They found evidence to support their findings about the tsunami’s path and power by studying 120 ocean sediment cores from around the world. A study detailing the findings published Tuesday in the journal American Geophysical Union Advances.
It is the first global simulation of the tsunami caused by the Chicxulub impact to be published in a peer-reviewed scientific journal, according to the authors.
The tsunami was powerful enough to create towering waves more than a mile high and sweep across the ocean floor thousands of miles away from where the asteroid struck, according to the study. It effectively erased the sediment record of what happened before the event, as well as during it.
“This tsunami was strong enough to disturb and erode sediments in ocean basins on the other side of the world, leaving either a gap in the sedimentary record or a jumble of older sediments,” said lead author Molly Range, who began work in the studio as a student. she was a student and completed it for her master’s thesis at the University of Michigan.
Researchers estimate that the tsunami was up to 30,000 times more energetic than the Indian Ocean tsunami of December 26, 2004, one of the largest on record, which killed more than 230,000 people. The energy of the asteroid’s impact was at least 100,000 times greater than the Tonga volcanic eruption earlier this year.
Brandon Johnson, a co-author of the study and an associate professor at Purdue University, used a large computer program called hydrocode to simulate the first 10 minutes of Chicxulub’s impact, including the formation of the crater and the start of the tsunami.
It included the size of the asteroid and its speed, which was estimated to be 26,843 miles per hour (43,200 kilometers per hour) when it hit the granite crust and shallow waters of the Yucatan Peninsula.
Less than three minutes later, rocks, sediment and other debris pushed a wall of water away from the impact, creating a wave 2.8 miles (4.5 kilometers) high, according to the simulation. This wave subsided when the material that exploded fell back to Earth.
But as the debris fell, even more chaotic waves were created.
Ten minutes after impact, a ring-shaped wave about a mile high began to travel across the ocean in all directions from a point 137 miles (220 kilometers) from impact.
This simulation was then input into two different global tsunami models, MOM6 and MOST. While MOM6 is used to model deep-sea tsunamis, MOST is part of tsunami forecasting at the National Oceanic and Atmospheric Administration’s Tsunami Warning Centers.
Both models returned almost exactly the same results, creating a tsunami timeline for the research team.
Within an hour of impact, the tsunami had traveled beyond the Gulf of Mexico into the North Atlantic Ocean. Four hours after the impact, the waves crossed the Via Marítima Centroamericana and reached the Pacific Ocean. The Central American Seaway once separated North America and South America.
Within 24 hours, the waves entered the Indian Ocean from both sides after traveling through the Pacific and Atlantic oceans. And 48 hours after the impact, large tsunami waves had reached most of the Earth’s coastlines.
The underwater current was strongest in the North Atlantic Ocean, the Central American Seaway and the South Pacific Ocean, exceeding 0.4 miles per hour (643 meters per hour), which is strong enough to remove sediment from the bottom of the ocean.
Meanwhile, the Indian Ocean, North Pacific, South Atlantic and Mediterranean were protected from the worst of the tsunami, with minor undersea currents.
The team analyzed information from 120 sediments that largely came from previous scientific ocean drilling projects. There were more layers of intact sediment in the waters protected from the wrath of the tsunami. Meanwhile, there were gaps in the sediment record for the North Atlantic and South Pacific oceans.
The researchers were surprised to find that sediments on the eastern shores of New Zealand’s North and South Islands had been highly disturbed with multiple breccias. Initially, scientists thought this was due to plate tectonic activity.
But the new model shows that the sediments are directly in the path of the Chicxulub tsunami, despite being 12,000 kilometers (7,500 miles) away.
“We think these deposits are recording the effects of the impact tsunami, and this is perhaps the strongest confirmation of the global significance of this event,” Range said.
While the team did not estimate the impact of the tsunami on coastal flooding, the model shows that the North Atlantic and Pacific coastal regions of South America are likely to be hit with waves greater than 32.8 feet (20 meters). ). The waves only grew as they approached the shore, causing flooding and erosion.
Future research will model the extent of global flooding after the impact and how far inland the effects of the tsunami might be felt, according to study co-author and University of Michigan physical oceanographer and professor Brian Arbic.
“Obviously the largest floods would have been closest to the impact site, but even far away the waves were likely to be very large,” Arbic said.
