Hypervelocity impact of asteroid/comet on the oceanic crust of the earth

The mass extinction at the K/P (Cretaceous–Paleogene) boundary was caused by an extraterrestrial impact and the following abrupt climate/environment change. In this study, numerical simulations of asteroid/comet impact on the oceanic crust of the earth are carried out by using the hydrocode AUTODYN-2D (ANSYS, Inc.). The objective of this work is to estimate how much impact debris is ejected into the atmosphere. Therefore the accumulations of ejected mass originating from different sources were calculated as functions of time at different altitudes. It is found that about 50 tera-tons of seawater and 35 tera-tons of crust are ejected when a 10 km diameter asteroid collides on the Earth with the speed of 20 km/s. The values increase to 240 and 175 tera-tons when the asteroid diameter is increased to 20 km. It is also demonstrated that a typical comet disintegrates and bounces back into the atmosphere due to small density, while much heavier asteroids do not recoil much.