Asteroid impact Earth's habitability

At SciTech Daily: Dinosaur-Killing Asteroid Triggered Monstrous Global Tsunami With Mile-High Waves

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Sixty-six million years ago a miles-wide asteroid struck Earth, wiping out nearly all the dinosaurs and around three-quarters of the planet’s plant and animal species.

It also triggered a monstrous tsunami with mile-high waves that scoured the ocean floor thousands of miles from the impact site on Mexico’s Yucatan Peninsula, according to a new University of Michigan-led study that was published online on October 4 in the journal AGU Advances.

The research study presents the first global simulation of the Chicxulub impact tsunami to be published in a peer-reviewed scientific journal. Additionally, U-M scientists reviewed the geological record at more than 100 sites worldwide and discovered evidence that supports their models’ predictions about the tsunami’s path and power.

“This tsunami was strong enough to disturb and erode sediments in ocean basins halfway around the globe, leaving either a gap in the sedimentary records or a jumble of older sediments,” said lead author Molly Range.

Maximum Tsunami Wave Amplitude Crop
Maximum tsunami wave amplitude following the asteroid impact 66 million years ago. Credit: From Range et al. in AGU Advances, 2022

Energy impact

According to the study’s calculations, the initial energy in the impact tsunami was up to 30,000 times larger than the energy in the December 2004 Indian Ocean earthquake tsunami. That one is one of the largest tsunamis in the modern record and killed more than 230,000 people.

The researcher’s simulations show that the impact tsunami radiated mainly to the east and northeast into the North Atlantic Ocean, and to the southwest into the South Pacific Ocean through the Central American Seaway (which used to separate North America and South America).

Geological corroboration

U-M’s Moore analyzed published records of 165 marine boundary sections for the review of the geological record. He was able to obtain usable information from 120 of them. Most of the sediments came from cores collected during scientific ocean-drilling projects.

“We found corroboration in the geological record for the predicted areas of maximal impact in the open ocean,” said Arbic. He is a professor of earth and environmental sciences and oversaw the project. “The geological evidence definitely strengthens the paper.”

Comparing models

The modeling portion of the study used a two-stage strategy. First, a large computer program called a hydrocode simulated the chaotic first 10 minutes of the event. This included the asteroid impact, crater formation, and initiation of the tsunami. That work was conducted by co-author Brandon Johnson of Purdue University.

Based on the findings of previous studies, the scientists modeled an asteroid that was 8.7 miles (14 kilometers) in diameter, moving at 27,000 mph (12 kilometers per second). It struck granitic crust overlain by thick sediments and shallow ocean waters, blasting an approximately 62-mile-wide (100-kilometer-wide) crater and ejecting dense clouds of soot and dust into the atmosphere.

Two and a half minutes after the asteroid struck, a curtain of ejected material pushed a wall of water outward from the impact site, briefly forming a 2.8-mile-high (4.5-kilometer-high) wave that subsided as the ejecta fell back to Earth.

According to the U-M simulation, 10 minutes after the projectile hit the Yucatan, and 137 miles (220 kilometers) from the point of impact, a 0.93-mile-high (1.5-kilometer-high) tsunami wave—ring-shaped and outward-propagating—began sweeping across the ocean in all directions.

According to the team’s simulation:

  • One hour after impact, the tsunami had spread outside the Gulf of Mexico and into the North Atlantic.
  • Four hours after impact, the waves had passed through the Central American Seaway and into the Pacific.
  • Twenty-four hours after impact, the waves had crossed most of the Pacific from the east and most of the Atlantic from the west and entered the Indian Ocean from both sides.
  • By 48 hours after impact, significant tsunami waves had reached most of the world’s coastlines.

Dramatic wave heights

For the current study, the research team did not attempt to estimate the extent of coastal flooding caused by the tsunami.

However, their models indicate that open-ocean wave heights in the Gulf of Mexico would have exceeded 328 feet (100 meters), with wave heights of more than 32.8 feet (10 meters) as the tsunami approached North Atlantic coastal regions and parts of South America’s Pacific coast.

As the tsunami neared those shorelines and encountered shallow bottom waters, wave heights would have increased dramatically through a process called shoaling. Current speeds would have exceeded the 0.4 mph (20 centimeters per second) threshold for most coastal areas worldwide.

“Depending on the geometries of the coast and the advancing waves, most coastal regions would be inundated and eroded to some extent,” according to the researchers. “Any historically documented tsunamis pale in comparison with such global impact.”

Full article at SciTech Daily.

We can be thankful that no such large impacts (extinction events) have occurred in human history.

5 Replies to “At SciTech Daily: Dinosaur-Killing Asteroid Triggered Monstrous Global Tsunami With Mile-High Waves

  1. 1
    chuckdarwin says:

    What about Noah’s flood, the biggest mass extinction event ever, every man, woman and child on the planet, except for Noah and his kin? And it only happened like five or six thousand years ago….

  2. 2
    relatd says:

    CD at 1,

    What about it? Most world cultures have stories about such a global flood.

  3. 3
    Sir Giles says:

    CD: And it only happened like five or six thousand years ago….

    And it only took 40 days and 40 nights. Where did all this water come from, and where has it gone? Even if all the ice on earth melted, ocean levels would only rise about 70 meters. Hardly enough to flood the entire earth.

  4. 4
  5. 5
    Sir Giles says:

    Relatd, from the first explanation in your link:

    Some 80-90% of the Earth’s surface is covered with sediment or sedimentary rock, as opposed to igneous or metamorphic rocks.

    Well, it only goes down hill from there. In reality, about 65% of the continents are covered by sedimentary rock. And they did not all originate at the same time.

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