Tsunami waves reached Hawaii and the West Coast after one of the strongest earthquakes in recorded history, a magnitude 8.8 temblor, struck off Russia's Kamchatka Peninsula on July 29 before most of the warnings were downgraded hours later.

"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.