Are asteroids a threat to Earth?
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(CNN) --
When a city-sized asteroid slammed into Earth 66 million years ago, it wiped out the dinosaurs and sent a monstrous tsunami that swept across the planet, according to new research.
The asteroid, about 14 kilometers wide, left a crater about 100 kilometers in diameter near the Yucatan peninsula in Mexico.
In addition to ending the reign of the dinosaurs, the direct impact caused a mass extinction of 75% of the animal and plant life on the planet.
This model shows the maximum amplitude of the tsunami wave after the asteroid impact 66 million years ago.
Credit:De Range et al
When the asteroid hit, it created a series of cataclysmic events.
Global temperatures fluctuated, plumes of aerosol, soot and dust filled the air, and wildfires ignited as bits of burning material ejected 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 better understand the tsunami and its extent through modeling and found evidence to support their conclusions about the tsunami's path and power by studying 120 ocean sediment cores from around the world.
A study detailing the results was published Tuesday in the journal American Geophysical Union Advances.
This 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.
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According to the study, the tsunami was powerful enough to create waves more than a mile high and devastate the ocean floor thousands of miles from where the asteroid hit.
In fact, it 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 halfway around the world, leaving either a gap in the sedimentary record or a jumble of older sediments," said lead author Molly Range, who started work in the study as an undergraduate student and completed it for her master's thesis at the University of Michigan.
The researchers estimate that the tsunami was up to 30,000 times more energetic than that of December 26, 2004 in the Indian Ocean, one of the largest recorded, which killed more than 230,000 people.
The energy of the asteroid's impact was at least 100,000 times greater than that of the Tonga volcanic eruption earlier this year.
Tracing the path of an ancient tsunami
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 moving at 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 up a wall of water from the impact, creating a wave 4.5 kilometers high, according to the simulation.
This wave subsided as the exploded material fell back to Earth.
But as the debris fell, it created even more chaotic waves.
Ten minutes after impact, a ring-shaped wave approximately one kilometer high began to travel across the ocean in all directions from a point 220 kilometers from impact.
This graph shows the sea surface height movement of the tsunami four hours after the asteroid impact.
Credit: De Range et al
This simulation was fed into two different global tsunami models, MOM6 and MOST.
While MOM6 is used to model deep ocean tsunamis, MOST is part of the National Oceanic and Atmospheric Administration (NOAA) Tsunami Warning Center tsunami forecast.
Both models gave almost the same results, creating a tsunami timeline for the research team.
Within an hour of impact, the tsunami had moved beyond the Gulf of Mexico into the North Atlantic Ocean.
Four hours after impact, the waves passed through the Central American Channel and reached the Pacific Ocean.
The Central America Canal once separated North America and South America.
This graph shows the sea surface height movement of the tsunami 24 hours after impact.
Credit: De Range et al
Within 24 hours, the waves entered the Indian Ocean from both sides after traveling through the Pacific and Atlantic oceans.
And within 48 hours of impact, large tsunami waves had reached most of the Earth's coastlines.
A changing ocean floor
The underwater current was strongest in the North Atlantic Ocean, the Central American Sea and the South Pacific Ocean, exceeding 643 meters per hour, which is strong enough to drag sediment from the ocean floor.
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, mostly from previous scientific ocean drilling projects.
There were more layers of intact sediment in the waters protected from the wrath of the tsunami.
But gaps were also found in the sediment record of the North Atlantic and South Pacific oceans.
The researchers were surprised to discover that the sediments on the eastern shores of New Zealand's North and South Islands had been heavily disturbed with multiple lagoons.
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 away.
The asteroid that killed the dinosaurs fell in the boreal spring
"We believe that these deposits are recording the effects of the tsunami impact, and this is perhaps the strongest confirmation of the global importance of this event," Range said.
Although the team did not estimate the impact of the tsunami on coastal flooding, the model shows that the coastal regions of the North Atlantic and the Pacific coast of South America were probably hit with waves of more than 20 meters in height.
The waves grew as they approached the shoreline, causing flooding and erosion.
According to study co-author, University of Michigan professor and physical oceanographer Brian Arbic, the extent of global flooding after the impact and how far inland the effects of the tsunami might have been felt will be studied in the future.
"Clearly the greatest flooding would have been near the impact site, but even far away the waves were probably very large," Arbic said.
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