Tsunami: Asteroid Impact - 66 Million Years Ago

The 6+ miles wide asteroid that hit Earth 66 million years ago, widely accepted to have wiped out nearly all the dinosaurs and roughly three-quarters of the planet’s plant and animal species, also triggered a megatsunami with mile-high waves. Recent historical tsunamis pale in comparison with this globally catastrophic event, thought to be 30,000 times more initial energy than any recorded events.

In this dataset, the black continents depict the land masses at the time of the impact, around 66 million years ago. The white country borders show where the land masses are today — moving at approximately 2.5 cm (1 inch) per year, the continents are constantly drifting. The animation shows tsunami wave amplitude 10 minutes after impact until 48 hours after impact, shown in hours below the scale. After the first 48 hours, the tsunami had mostly subsided except near the point of impact. The colors on the tsunami animation are associated with both positive (red) and negative (blue) wave amplitudes, highlighting how the ocean ripples with both higher and lower water levels in the ocean basins during a catastrophic tsunami.

Note that even though the color bar numerical values top out at +/- 5 meters, the wave amplitudes were much more extreme in some places. 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 4.5 kilometers high (2.8 miles) wave that subsided as the ejecta fell back to Earth. Ten minutes after the projectile hit the Yucatan, and 220 kilometers (137 miles) from the point of impact, a 1.5 kilometers high (0.93 miles) tsunami wave—ring-shaped and outward-propagating—began sweeping across the ocean in all directions, according to the U-M simulation.

An international group of researchers from academic institutions and government agencies, including NOAA’s Pacific Marine Environmental Lab and Geophysical Fluid Dynamics Lab, combined numerical modeling and analysis of geological records to recreate the global impact of the tsunami generated by the asteroid. This dataset presents the first global simulation of the Chicxulub asteroid impact tsunami.

Numerical analysis of the event used three different models to reproduce tsunami generation and propagation. A large computer program that models details of complex fluid flows, called a hydrocode, simulated the first 10 minutes of the tsunami generation, and two NOAA-developed models were then used to simulate the tsunami propagation around the global ocean. Additionally, the research team reviewed the geological record at more than 100 sites worldwide and found evidence that supports the models’ predictions of the tsunami’s path and power — a remarkable verification of the model for the megatsunami event of 66 million years ago.

This study helps to assess and quantify the risk of future large asteroid impacts. In addition, the ability to reproduce mega-events like this is an important validation that the models can help scientists forecast global impacts of more conventional tsunamis that humanity has to deal with. In a future study, PMEL’s Vasily Titov plans to model the extent of coastal flooding caused by this tsunami, which will further inform tsunami impact forecasts. For more information, see the original University of Michigan press release, NOAA release, or AGU Advances Research Article.

The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore near the community of Chicxulub, after which it is named. The crater is estimated to be 180 kilometers (110 miles) in diameter and 20 kilometers (12 miles) deep. Its position has shifted from its original impact location 66 million years ago due to the movement of the plates.

The date of the impact coincides with the Cretaceous–Paleogene boundary (commonly known as the K–Pg or K–T boundary). It is now widely accepted that the resulting devastation and climate disruption was the cause of the Cretaceous–Paleogene extinction event, a mass extinction of 75% of plant and animal species on Earth, including all non-avian dinosaurs.