The study, published in early October in the journal AGU Advances, is the first simulation of a tsunami created by the impact of the asteroid that wiped out the dinosaurs.
The models showed that the water reached a height of about 1,000 meters immediately after impact, with offshore wave heights in the Gulf of Mexico exceeding 300 meters about an hour after impact, with heights wave maximums generally decreasing with time and distance from impact.
The authors calculated that the initial tsunami energy was up to 30,000 times greater than the energy of the tsunami caused by the December 2004 Indian Ocean earthquake, one of the largest waves ever recorded. The models also showed that the prehistoric “harbor wave” energy (like the Japanese word for tsunami sounds) was so great that it took about a week to fully dissipate.
“All historically documented events pale in comparison to such a global impact,” the authors wrote.
Evidence of prehistoric wool is hard to find
The model is one thing, but reality is another thing. Therefore, the authors tried to find field evidence that confirmed their modeling. They examined some 120 geological sites before and after the asteroid impact and found evidence of a global tsunami that reached the territory of present-day New Zealand.
“This tsunami was powerful enough to destroy and erode sediments in ocean basins halfway around the globe, leaving a gap in the sedimentary record or a medley of older sediments,” said lead author Molly Range, physical oceanographer at the ‘University of Michigan. “The distribution of erosion and gaps we observed in marine sediments from the Late Cretaceous is consistent with our model results, giving us more confidence in the model’s predictions.”
“The geological evidence definitely reinforces this work,” added oceanographer Brian Arbic of the University of Michigan, who collaborated on the research. According to him, the most precious are those of the east coast of the northern and southern islands of New Zealand, which are more than 12 thousand kilometers from the place where the asteroid hit the Yucatan.
These highly disturbed deposits were initially thought to be the result of local tectonic activity, but given the age of the deposits and their location directly in the modeled path of the impact tsunami of the Chicxulub asteroid, the team suspected a different origin. “These deposits are actually a record of the effects of an impact tsunami, which is perhaps the most significant confirmation of the global significance of this event,” said Range.
Although the study did not model the coastal flood, wave height could approach more than ten meters as the tsunami approached coastal areas of the North Atlantic and parts of the Pacific coast of South America.
Once the tsunami approached these shores and hit the shallow bottom, the height of the waves would increase dramatically due to a process called “shoaling”. Such wave heights may have caused significant flooding and further studies by some of the authors of this research will address this process.
