Geologists discover new quake fault line in Spokane

SPOKANE, Wash. - EQ Fault Line vo

Spokane has a recently discovered earthquake fault that runs from north to south through the heart of the city practically paralleling Division Street.

Since 2001 this thrust fault has only raised northwest Spokane over the top of northeast Spokane about 15 millimeters, roughly equal to about the height of your thumbnail.

But there is some compression of two big pieces of real estate going on out here which could mean more earthquakes in our future.

In early 2001, Spokane was rocked by a series of small earthquakes, the largest a 4.0 magnitude tremor that knocked bricks off of chimneys but did little damage.

"It scared many, many people at that time however there was not a lot of damage thankfully that occurred," Geologist Dr. Chad Pritchard from Eastern Washington University said.

Twelve years ago geologists blamed the quake on the Latah Fault, which created Latah Creek west of the city. But now it appears there's another fault running straight through the north side of the city parallel to Division Street.

"If we think about this line right between the yellow and the gray as being Division Street, it looks like just a little bit west of that, the ground is being shoved up just a little bit," Prtichard said. "It's about 15 millimeters of off-set where the west block's been pushed up over the east block."

The U.S. Geological Survey mapped the newly discovered fault earlier this spring when it flew over Spokane. By towing a magnetometer behind an airplane, geologists found underground rocks that didn't match the neighboring strata, a sign of moving earth.

"They fly over with a magnetometer and they also take gravity measurements and they found a very nice lineation that seems to correlate with what they feel is the Spokane Fault around Division Street," Pritchard said.

The fault appears to be driven by the west to east compression of Washington state as two continental plates collide off the coast so the likelihood of a killer quake in Spokane continues to be rather remote.

"I would not be too concerned about it in this point and time, you might hear some booms if an earthquake was to happen however I don't think earthquakes seem to happen very often in our area," Pritchard said.

The USGS is holding a news conference Friday in Spokane to discuss their preliminary findings.