'Spokane Fault' Found in Geo Survey

By Steve Jackson

Scientists who have been studying a swarm of small earthquakes that occurred in Spokane back in 2001 now say they may have evidence of a new fault in the Spokane area. On Friday, scientists from the US Geological Survey announced that an airborne survey of the Spokane area has found clues that look to be connected to a so called “swarm’ of small earthquakes that took place back in 2001.

The swarm was actually several small quakes, the largest that registered a four on the Richter scale, that took place November 11th of that year. Richard Blakely of USGS says images from a satellite indicate an unusual ground deformation in north central Spokane.

Blakely: “The ground bulged up, the bulge is about 1 to 2 miles across, and about half an inch high. Now that sounds trivial unless you are a geologist, than it’s pretty significant, and unusual. The fact it corresponded with the earthquakes tells us the quakes and ground deformation were caused by the same thing, namely a fault.”

Follow-up studies done this summer by an aircraft flying over Spokane using magnetic sensors was able to detect magnetic anomalies, one of which could be a fault. The anomaly seems to run parallel to the 2001 earthquakes.

Blakely says follow up studies on the ground will be undertaken to see if the evidence really does indicate a fault. He says new guidelines for public safety may have to be put in to place if the evidence indicates a true fault.
 
Blakely: “Well if we could prove that the fault was capable of producing magnitude size 6 earthquake, which I don’t think is out of the question, my recommendation would be of a campaign  strap down there water heaters, bolt their house to the foundation , have an evacuation plan, that sort of thing.”

Future studies will likely include excavating an area near the magnetic anomaly to determine if there is physical evidence of a fault line. Newspaper records indicate there was a series of small earthquakes in the 1920’s in Spokane.
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