Seismologists eager to research slow slip events after recent quake rattles Western Washington

SEATTLE -- After a magnitude 4.6 earthquake rattled the greater Seattle area earlier this month, seismologists say we're due for a major event that, strangely, no one will feel.

It's called a slow slip event. It’s a relatively recent discovery in geophysics and not fully understood.

It’s essentially an earthquake in slow motion as tectonic plates move more than normal. However, these events last for days, if not weeks - not as a sudden burst which lasts from seconds to minutes.

"It is fundamentally the same thing,” Steve Mallone with the PNW Seismic Network explained. “It’s a fracture in the ground that slowly moves instead of jerking around in a real earthquake.”

The slip moves the ground as much as a magnitude 6.0 quake, and the Pacific Northwest actually just had one about 13 months ago.

The USGS says slow slip events play a critical role in relieving stress on the plate interface but have not fully understood its relationship with larger, destructive earthquakes.