The US government's official campaign to prepare people for natural disasters - features online advise for those in the vicinity of a tsunami to stay away from the beach and head inland with only their family and pets in tow. People should move to higher ground if possible.
But the campaign website was not providing any live advice or updates due to the US government shutdown.
Only four earthquakes with a greater magnitude have ever been recorded in the US, all of which were in Alaska and caused a tsunami.
The most powerful came on 27 March 1964, when a 9.2 magnitude quake caused ground fissures, collapsed buildings and killed 139 people.