I know you meant this as a joke but there is evidence gases rise to the surface after a long period of time and after a large impact like this.
http://en.wikipedia.org/wiki/Large_igneous_province
The earth seen a number of events we call them mass extinction.
The greatest extinction in world history coincide with what seems to be a belching of the earth.
the great extinction of 250 million years ago is very likely one of those ‘burps’
Terrible article.
More mass!= smaller core. Same principle behind white dwarfs and neutron stars.