The West Coast and Alaska Tsunami Warning Center says a watch is in effect for Alaska, Washington, Oregon, California and British Columbia.
The center says people in coastal communities should be on alert and prepare for possible evacuation.
The first waves are expected to hit San Francisco at 8:16 a.m., Santa Barbara at 8:24 a.m., Santa Monica at 8:39 a.m. and La Jolla at 8:48 a.m.
A watch can be upgraded to a warning if there are destructive waves or canceled if there's no further threat to the area.
The Pacific Tsunami Warning Center issued a separate tsunami warning for Hawaii. The estimated earliest arrival of the first tsunami wave for Hawaii is 2:59 a.m. HST Friday.