CNN is reporting an 8.9 earthquake has struck not long ago approximately 150 kilometers off the coast of Honshu island, Japan. (By comparison, the 2004 Boxing Day tsunami that struck off Banda Aceh, Indonesia was a 9.0.) Various types of tsunami watches, warnings and advisories are out for basically the entire western half of the Pacific Ocean, and considering that tsunamis can cross entire oceans, not just half of them, the eastern half of the Pacific Rim should be expecting problems as well in the coming hours.
If you're reading right now from the western Pacific coastline, get to higher ground. If you're reading from the eastern Pacific coastline, be ready to wake up real early just in case.