People in Honolulu coastal areas have started to evacuate after authorities sounded tsunami warning sirens.
Hundreds of residents in Oahu flocked to the supermarket to buy water and supplies.
The estimated earliest arrival of the first tsunami wave for Hawaii is 4:59 a.m. PT (2:59 a.m. HST).
The magnitude-8.8 earthquake struck at 2:46 p.m. about 80 miles off the eastern coast of Japan.
The Hawaii-based Pacific Tsunami Warning Center widened its tsunami warning beyond East Asia late Thursday to include Hawaii, Australia, New Zealand, Mexico and Central and South America and the rest of the Pacific Ocean. A tsunami warning later was expanded to include the entire western U.S. coast.
The Associated Press contributed to this report.