When the Pacific Plate continues its move underneath the Rocky Mountains with a sudden shift then the Rocky Mountains Plate will go upward at the Pacific Coast and correspondingly will go down in the Mississippi Valley from down south way up north to the Great Lakes. The NA continent torn apart.
It's said that a big move along the Andreas Line is overdue. The friction between the two plates is increased by the growing pressure of the Rocky Plate. The tension is rising. When our solar system fully enters the Milky Way Plane in 2012 this may cause the Pacific Plate to overcome this lockdown and make a sudden move eastward.
Not all people at FEMA and DHS are mean or stupid. You can assume that they have better knowledge and try to prepare for a worst case scenario.
They can't afford risky fearmongering and pre-emptive hysteria.
I think they know very well what they are doing and why they do it.
The 'Psychology of the Masses' is difficult to handle in times of disaster.