Tsunami warnings prompted gridlocked traffic as people tried to reach higher elevations in Hawaii, but the threat level was later downgraded.

"It's not one that's going to cause mass devastation. But it will cause coastal flooding and it will cause damage and it does put lives at risk if people don't move to high ground," an oceanography professor says.

Hawaii is under a tsunami warning after an 8.7 earthquake hit off the coast of Russia. Parts of Alaska are also under a tsunami warning and watch. The entire west coast of the United States is under a tsunami watch.