admin Just off the west coast of Mexico’s Yucatán Peninsula lies the Chicxulub crater, 19 kilometers deep and 10 kilometers wide. The 66-million-year-old impact crater is where a giant asteroid struck Earth, wiping out the dinosaurs and about three-quarters of all life on Earth. But new evidence suggests it is even more destructive than previously thought.
A study published today in the journal AGU Advances shows that the asteroid also caused a massive tsunami with waves several kilometers high along the ocean floor miles from the impact site in Mexico. thousand kilometers.A team of researchers built the world’s first simulation of the Chicxulub impact tsunami for publication in a peer-reviewed journal and examined geological records from more than 100 locations around the world to determine the trajectory and strength of the tsunami. “This tsunami was powerful enough to break up and erode sediment from ocean basins on the other side of the globe, leaving a gap in the record,” said lead author Molly Range, who carried out the study. sediment or a jumble of old sediments”. modeling studies for a master’s degree. thesis at the University of Michigan, said in a press release.
The team estimates that the initial energy of the Chicxulub tsunami was up to 30,000 times greater than the tsunami energy of the 2004 Indian Ocean earthquake – a devastating disaster that killed more than 230,000 people and was one of the the largest tsunamis in modern history.
To determine the power of the tsunami, the team analyzed published records of 165 marine boundary sections or marine sediments in the geological record that were deposited around the time of the asteroid impact mainland, as well as sediment cores. The cores act as Earth’s timeline that scientists can use to analyze layers of rock, sand and ice to better understand what Earth looked like millions of years ago.
The K-Pg boundary (also called the K-T boundary) marks the point where the asteroid struck, thus ending the Cretaceous period. Using sediments contained in these boundary segments, they found that the tsunami impact propagated primarily east and northeast (into the North Atlantic), then southwest across the Central America’s maritime border once separated the North and South American continents. . America. Finally the tsunami spread into the South Pacific.
“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,” said Range.
The authors also used sediments from boundary profiles to determine underwater flow rates in these basins. In some nearby locations, the current was perhaps 0.4 miles per hour (20 centimeters per second), a speed strong enough to erode fine sediment from the seafloor. Meanwhile, the South Atlantic, North Pacific, Indian Ocean and what is now the Mediterranean appear to have been largely protected from the most violent effects of the tsunami.
Outcrops of the K-Pg boundary have been discovered on the east coast of the North and South Islands of New Zealand, more than 7,500 miles (12,000 km) from the crater impact site.”We believe these sediments record the impact of the tsunami and this is perhaps the clearest confirmation yet of the global significance of this event,” Range said.
To create a computer model of the mass extinction event, a large computer program called hydrocode simulated the chaotic first 10 minutes of the extinction event. The asteroid in the simulation was adapted from previous studies showing that the dinosaur-killing space rock was 8.7 miles in diameter and traveling at 27,000 mph. After impacting the Earth’s crust beneath shallow ocean waters, a crater 62 miles (100 km) wide was ejected. Thick clouds of dust and soot in the atmosphere.
According to the simulation, ejected material formed a 2.8 mile (4.5 km) high wave two and a half minutes after impact which then subsided when the material fell back to Earth. Ten minutes after the projectile hit the Yucatan, a 0.93 mile (1.5 km) high tsunami wave began rolling across the ocean in all directions.
This 10-minute simulation was entered into two tsunami-propagation models (called MOM6 and MOST) used by the National Oceanic and Atmospheric Administration (NOAA) to track and understand these enormous waves. “The big result here is that two global models with differing formulations gave almost identical results, and the geologic data on complete and incomplete sections are consistent with those results,” University of Michigan paleoceanographer and study co-author Ted Moore said in a press release. “The models and the verification data match nicely.”
The simulation mirrored geologic findings, showing that about one hour after impact, the wave had spread outside the Gulf of Mexico and into the North Atlantic. Four hours after impact, the tsunami passed through the Central American Seaway and into the Pacific, and by the end of day one, the waves had crossed most of the Pacific Ocean and entered the Indian Ocean from both sides. By 48 hours after impact, significant tsunami waves had reached most of the coastlines on Earth.
“Depending on the geometries of the coast and the advancing waves, most coastal regions would be inundated and eroded to some extent,” the authors said. “Any historically documented tsunamis pale in comparison with such global impact.”
