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When a city-sized asteroid collided with Earth 66 million years ago, it wiped out the dinosaurs and sent monstrous tsunami waves circling the planet, according to new research.
The asteroid, which is about 8.7 miles (14 kilometers) wide, left its impact crater about 62 miles (100 kilometers) near Mexico’s Yucatan Peninsula. In addition to ending the reign of the dinosaurs, the direct blow caused a mass extinction of 75% of animal and plant life on the planet.
When the asteroid collided, it caused a chain of catastrophic events. global temperature fluctuations; Columns of aerosols, soot and dust fill the air; The bushfires started when flaming pieces of material exploded from the impact and re-entered the atmosphere and rained down. Within 48 hours, tsunamis circled the globe – and were thousands of times more active than modern tsunamis caused by earthquakes.
Researchers set out to gain a better understanding of the tsunami and its prevalence through modeling. They found evidence to support their findings about the course and strength of the tsunami by studying 120 ocean sediment cores from around the world. A detailed study of the results was published Tuesday in the journal American Geophysical Union advances.
It’s the first global simulation of a Chicxulub-induced tsunami to be published in a peer-reviewed scientific journal, according to the authors.
According to the study, the tsunami was powerful enough to create towering waves more than a mile high and clean the ocean floor thousands of miles from where the asteroid impacted. It effectively removed the sediment record of what happened before the event, as well as during it.
said lead author Molly Ring, who began work on the study as a freshman and completed her master’s thesis at the University of Michigan.
Researchers estimate that the tsunami was up to 30,000 times more active than the Indian Ocean tsunami on December 26, 2004, one of the largest recorded tsunamis that killed more than 230,000 people. The energy of the asteroid impact was at least 100,000 times greater than the eruption of the Tonga volcano earlier this year.
Brandon Johnson, co-author of the study and assistant professor at Purdue University, used a large computer program called hydraulic code to simulate the first 10 minutes of the Chicxulub effect, including crater formation and the onset of the tsunami.
He included the size and speed of the asteroid, which was estimated to be moving at 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, sending it up 2.8 miles (4.5 kilometers), according to the simulation. This wave subsided as the explosive material fell back to the ground.
But as the debris fell, it made even more chaotic waves.
Ten minutes after the collision, a ring-shaped wave nearly a mile high began across the ocean in all directions from a point located 137 miles (220 kilometers) from the collision.
These simulations were then entered into two different global tsunami models, MOM6 and MOST. While MOM6 is used to model tsunamis in the deep ocean, MOST is part of tsunami forecasting at the National Oceanic and Atmospheric Administration’s Tsunami Warning Centers.
Both models provided roughly the same results, creating a tsunami timeline for the research team.
An hour after the collision, the tsunami traveled out of the Gulf of Mexico into the North Atlantic. Four hours after the collision, the waves passed through the Central American sea lane into the Pacific Ocean. The Central American Route separated North and South America.
Within 24 hours, waves entered the Indian Ocean from both sides after traveling across the Pacific and Atlantic. By 48 hours after the impact, the large tsunami waves had reached most of the Earth’s coasts.
The underwater current was strongest in the North Atlantic, Central American and South Pacific sea lanes, exceeding 0.4 mph (643 meters per hour), strong enough to blow sediments to the ocean floor.
Meanwhile, the Indian Ocean, the North Pacific, the South Atlantic, and the Mediterranean were sheltered from the worst of the tsunami, with fewer underwater currents.
The team analyzed information from 120 sediments that came largely 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 discover that the sediments on the eastern shores of New Zealand’s northern and southern islands were deeply disturbed with multiple cavities. At first, scientists believed that this was due to the activity of tectonic plates.
But the new model shows that the sediment was directly in the path of the Chicxulub tsunami, despite being 7,500 miles (12,000 km) away.
“We feel that these deposits record the effects of a tsunami impact, and this is perhaps the most telling confirmation of the global significance of this event,” Ring said.
While the team did not estimate the tsunami’s impact on coastal flooding, the model shows that coastal regions in the North Atlantic and Pacific coasts of South America were likely exposed to waves greater than 32.8 feet (20 meters) in height. The waves grew as they approached the shore, causing flooding and erosion.
Future research will model the extent of global flooding after an impact and to what extent the effects of a tsunami can be felt, according to study co-author and University of Michigan physics professor Brian Arbeck.
“Obviously, the greatest floods were closest to the impact site, but even further away the waves are likely to be very large,” Arbeck said.