Tech UPTechnologyThe asteroid that killed the dinosaurs caused a 'mega-earthquake'...

The asteroid that killed the dinosaurs caused a 'mega-earthquake' that lasted weeks or months

 

About 66 million years ago, a massive asteroid 10 kilometers in diameter slammed into Earth near the small town of Chicxulub in what is now Mexico. The impact caused a firestorm that engulfed most of the North American continent and was the trigger for the last mass extinction in Earth’s history, releasing energy equivalent to 1023 joules, enough to generate gigantic earthquakes, mega-tsunamis and form a 180-200 km diameter crater in the Yucatan Peninsula. Now, new research suggests the Chicxulub impact also triggered a mega-earthquake so massive it shook the planet for weeks or even months after the collision.

“This tsunami was strong enough to disturb and erode sediments in ocean basins on the other side of the world, leaving a gap in the sedimentary record or a jumble of older sediments,” said Molly Range , lead author of the study. AGU Advances magazine.

 

Analyzing tektites and microtektites

During the asteroid’s impact, layers of sediment, fragments known as tectictes, were ejected into the atmosphere. These spheres, under the influence of gravity, fell back to the Earth’s surface in the form of glass. In addition, about 3,000 kilometers southwest of the impact, layers of mud and sandstone up to 10 to 15 meters below the seafloor experienced soft sediment deformation that is still preserved today. These deformations would have been caused by a massive earthquake that lasted many weeks after the asteroid’s collision.

The team estimates that the initial energy of the Chicxulub impact 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 largest tsunamis in the modern record.

The researchers’ simulations show that the impact tsunami radiated primarily east and northeast toward the North Atlantic Ocean, and southwest through the Vía Marítima Centroamericana (which used to separate North and South America) into the Atlantic Ocean. South Pacific Ocean. In those basins and some adjoining areas, ocean current speeds probably exceeded 20 centimeters per second , a speed strong enough to erode fine-grained sediments on the seafloor.

Evidence of the deformation of the mega-earthquake in Mexico and the United States is also preserved. For example, at the ‘El Papalote’ exposure site in Mexico, researcher Hermann Bermúdez found evidence of liquefaction , a process caused by strong shaking, which causes water-saturated sediments to flow as a liquid. In Mississippi, Alabama, and Texas, the paleontologist also documented faults and crevasses most likely associated with the megaquake.

“Our data help explain the geological evidence that records the end of the Cretaceous and the beginning of the Cenozoic and characterizes one of the largest earthquakes experienced by our planet during the Phanerozoic ,” the authors said.

the simulation

To create the computer model of the mass extinction event, software simulated the chaotic first 10 minutes of the extinction event. According to the simulation, the ejected material formed a wave 4.5 km high two and a half minutes after impact, which then subsided as the material fell back to Earth. Ten minutes later, a tsunami wave 1.5 km high began to cross the ocean in all directions. Within 48 hours of impact , huge tsunami waves had reached most of the Earth’s coastlines.

“Any historically documented tsunami pales in comparison to such a global impact,” the experts conclude.

Referencia: “The Chicxulub Impact Produced a Powerful Global Tsunami” by Molly M. Range, Brian K. Arbic, Brandon C. Johnson, Theodore C. Moore, Vasily Titov, Alistair J. Adcroft, Joseph K. Ansong, Christopher J. Hollis, Jeroen Ritsema, Christopher R. Scotese and He Wang, 4 October 2022, AGU Advances.
DOI: 10.1029/2021AV000627

 

Hermann Bermudez et al. 2022. The Chicxulub Mega-Earthquake: Evidence from Colombia, Mexico, and the United States. Geological Society of America Abstracts with Programs 54 (5); doi: 10.1130/abs/2022AM-377578

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