Generation and propagation of a tsunami from the Cretaceous-Tertiary impact event

We have studied the mechanism of tsunami generation by meteorite impact on a shallow ocean at 65 Ma and modeled the propagation of that tsunami in the Gulf of Mexico. We found that the water flow into and out of the crater cavity causes most of the tsunami. The height of the wave coming out of the crater is controlled by the depth of the shallow-water region surrounding the crater. We show that the lower the flow velocity in the shallow-water region, the lower the wave height, and the longer the oscillation period. If the depth of the sea above the Yucatan platform was 200 m at the end of the Maastrichtian, the maximum tsunami wave height and period at the rim of the crater are estimated to be ∼50 m and 10 h, respectively. Using these results, we simulated the propagation of the K-T impact-generated tsunami in the Gulf of Mexico. There are two types of tsunami; the receding wave and the rushing wave. The receding wave traveled across the entire gulf within 10 h of the impact. Tsunamis attacked the coast as a leading negative wave. The rushing wave flowed with a height of more than 200 m and reached the coastal area of North America. It ran up over the land and crossed the Mississippi embayment, a distance of more than 300 km. The averaged runup was more than 150 m, but it reached a height of 300 m near the Rio Grande embayment.