SPOKANE VALLEY, Wash. – The Eastern Washington University Regional Geology and Field Methods classes studied rock formations from an old Saltese Uplands Conservation Area fault zone.
There are multiple fault zones, both active and inactive, in the greater Spokane region, and students like Marilyn Smith explained how these zones can show how our region came to be.
“Looking at the rocks and trying to figure out how to describe them, and how to map them and how to measure them. So I can see what angles they are dipping at and that can help us piece together the history and how it all got here,” Smith said.
The Saltese uplands area is an inactive fault zone, and in the Spokane area, the Latah fault zone is the main active fault area. In 2013, geologists were able to use satellites to discover the Spokane fault zone, a very small fault line running through the heart of the city. The fault runs roughly from the Spokane airport to the north-south freeway.
“The Latah fault we know has been more active in recent years, with about 60 meters of offset, along the Latah area,” Geology professor Chad Pritchard said.
Pritchard also said a significant earthquake in Spokane is possible, but not likely.
“In Spokane we’re fairly quiet, our biggest earthquake is a 4.0 which is fairly small. We are on really old rocks that are super thick, we don’t have many plate boundaries around us. So it’s a fairly seismically inactive zone,” Pritchard said.
Pritchard said another advantage of Spokane is its deposits of gravel and other soft sediments, which can mitigate the distance energy from an earthquake travels.
“If an earthquake goes through the sand and gravel of the Spokane Valley, the energy will actually dissipate in the sand and gravel. You’ll get a little bit more shaking, but it doesn’t go quite as far,” Pritchard said.
