SEATTLE - Seismology experts and geology researchers are literally waiting for the earth under the Pacific Northwest to move at any moment. The earthquake will be strong but it's certainly not going to knock plates off the wall or homes off their foundations.  Experts say it will last a long time - about two weeks - and that's why you won't feel it.

The seismic event the scientists are waiting for is called a deep tremor or silent earthquake and the scientists have known about them for less than a decade.

Normally, the North American tectonic plate moves in a northeast direction, about 8 millimeters a year.  We don't even notice its movement.  But scientists have found that every 14 months or so, the plate seems to reverse course, sliding backwards for between 6 and 15 days. It happened in July 1998, August 1999, December 2000, February 2002 and September 2005.  It's now due.

In anticipation, researchers have set out an array of monitors and are watching them closely.

In November, those monitors began picking up movements in the Vancouver Island area but they stopped after a just a few days.  Scientists don't believe those shakes are linked to a silent earthquake.  They say once the deep tremors start they'll definitely know it.