[Slick]

Interesting. Strange that they only addressed land hits and crater size and did not address that the earth's surface is ~70% water. If all parts of the earth are equally likely to be hit, then there is a ~70% chance that it will hit water. This would generate some form of tidal wave or tsunami. If the projectile has enough mass that we would "worry about it", the tidal wave could have much more life-threatening effects for humans since population is more concentrated near costal areas.

Slick.