>A 50km rock would more or less sterilize a planet. The impactor that took out the dinosaurs (and a lot more) had a diameter of roughly 10km. Your rock masses more than 100 times as much, and thus would deliver more than 100 times more impact energy. Life might survive deep underground or underwater, but it's hard to imagine anything on or near the surface surviving.

Especially since I missed out the note in the scenario that this rock is a 50km wide nickel-iron asteroid, I re-ran the calcluations with the same numbers and well, if you check the results below, well, it'll ruin your whole day.



		Calculated Results Multistory wall-bearing buildings will collapse. Wood frame buildings will almost completely collapse.

		View on impact.ese.ic.ac.uk	Preview by Yahoo

Still I'd like to know if there are any other published scenarios than 'Critical Vector' involving asteroid collisions?

...I have not spoken of the work Santha and I did in the South Pacific around the Tahitian islands of Taiatea and Huahine, or of the strange things we saw underwater off the Tongan island of Haapai. (Graham Hancock, Underworld 2002)