![]() The North Atlantic and South Pacific had the fewest locations with complete, uninterrupted K-Pg boundary sediments. Most of the sediments came from cores collected during scientific ocean-drilling projects. ![]() He was able to obtain usable information from 120 of them. U-M’s Moore analyzed published records of 165 marine boundary sections for the review of the geological record. In those places, the modeled current speeds were likely less than the 20 cm/sec threshold. In contrast, the South Atlantic, the North Pacific, the Indian Ocean, and the region that is today the Mediterranean were largely shielded from the strongest effects of the tsunami, according to the team’s simulation. This velocity is powerful enough to erode fine-grained sediments on the seafloor. In those basins and in some adjacent areas, underwater current speeds likely exceeded 20 centimeters per second (0.4 mph). 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). This image shows results from the MOM6 model, one of two tsunami-propagation models used in the University of Michigan-led study. Modeled tsunami sea-surface height perturbation, in meters, four hours after the asteroid impact. That one is one of the largest tsunamis in the modern record and killed more than 230,000 people. “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, who started the project as an undergraduate in Arbic’s lab in the Department of Earth and Environmental Sciences.Īccording 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. The analysis of the geological record focused on “boundary sections.” These are marine sediments deposited just before or just after the asteroid impact and the subsequent Cretaceous–Paleogene (K-Pg) mass extinction, which closed the Cretaceous Period. She conducted the modeling study for a master’s thesis under U-M physical oceanographer and study co-author Brian Arbic and U-M paleoceanographer and study co-author Ted Moore. “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.
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