SEATTLE - The Cascadia Subduction Zone stretches from Northern Vancouver Island to Northern California. Right now along the Cascadia fault line, there have been tremors deep beneath Puget Sound. It is pretty common and actually part of a routine event. Even so, seismologists are eager to learn from it.

Tuesday afternoon, geophysicist David Schmidt pointed to a color-coded map that he has been using to track the activity.

"Blue indicates where events occurred back on Feb. 18th which was at the start of this event," said Schmidt. "All of these dots represent a very small tremor source down on the megathrust, down there at 30 kilometers depth."

It's called a slow slip event. You don't feel any shaking, according to Schmidt. But he says the clusters of dots on the map add up.

"The onset event probably doesn't signal that a magnitude 9 or a bigger earthquake is about to happen. What it does signal is that we are giving the megathrust a little nudge," said Schmidt.

State Seismologist John Vidale described it as just a little more pressure pushing at the fault.

"It is loading up the fault that will eventually have the magnitude 9 up here, but it is just loading it a little bit," said Vidale.

The slow slip events usually happen every 14 months or so, according to Schmidt.

"People should not be worried about it," said Schmidt. "I think it is an exciting event that occurs regularly in our region."

Schmidt said at Pacific Northwest Seismic Network, they are paying close attention to the small tremors, hoping to learn from the activity happening right now.

Related links:

Pacific Northwest Seismic Network - ETS Event of Winter 2017