Offshore, maybe not a big impact, but this is one of those times where a lot of little earthquakes meant a big one was coming. Happens 1 in 10. Could have even a bigger one: 1 in 10.
Update: Major impact, now upgraded to M8.2
Major Tom Update:
This earthquake is most likely at the max for this area.
We can see the subduction zone is extremely curved at this point. I really can't see the physics of rounding this curve with a 9.
We have a classic reverse fault at the exact orientation of the fault. Lest I forget how these beachballs work, I can always look at this.