A 30 second scan of Wowhead yielded the following:
http://www.wowhead.com/?spell=37764
It's the only spell named Earthquake that does 4000 damage, and it has a 50 yard range. Unfortunately I don't have any practical experience with Morogrim yet, so this may be inaccurate, but I also noticed some of the spell data for this ability changed in the 2.1.0 patch, too.
For what it's worth, I've also noticed that a lot of boss strategy sites misrepresent the radius on the AE abilities of large bosses because they measure distance from healer to tank, not healer to boss. Healer to tank very well may be 40 yards, and the tank may be up to 10 yards away from the boss's center of gravity (which in my experience may not correlate with their hit box).