Effects of a catastrophic coronal m ejection?

Hi. This is something I've often pondered. Suppose Earth is struck by a mive CME like it's never felt before (like a density of 1000 p/cm^3 with a velocity of 2800 km/sec) <---- correct me if I'm wrong, but that would be hazardous to life on Earth, right? Anyhow... I'm interested in the effects its has on the auroral ovals. From space, what shape would the auroral ovals take as they merge together at the equator? Could the magnetosphere become so stretched and distorted that auroras might not even happen?