Apparently it was a significant quake, but located way out west in the Aleutians, and very deep (~62 miles deep). The National Tsunami Warning Center initially issued a "Warning" for the Western Aleutians, but this was later downgraged to an "Advisory" with significant wave heights less than one foot.

EDIT: A bit more info in this story: Tsunami warning reduced to advisory after 8.0 quake in Western Aleutians