Before Christmas the US Government elevated the national security level to 'orange' or 'high risk'
Tanker loading at the Valdez terminal, the southern terminus of the trans-Alaska pipeline, was shut off on Tuesday night and remains closed for the time being.
The 1,280km pipeline carries 17% of the nation's oil supply from the Prudoe Bay oil fields off Alaska's northern slope.
Valdez is located on Prince William Sound and is one of the largest crude oil terminals, with fixed and floating berths designed to withstand earthquakes and six-metre tsunami waves.
