Preliminary interpretations of a recent geophysical survey confirm there are previously undiscovered earthquake faults in the greater Spokane area.
During the spring of 2013, a U.S. Geological Survey team conducted airborne magnetic testing over the Spokane area in order to understand the geological reasons for a series of earthquakes and ground uplifts that occurred in 2001.
The results, according to scientists, point to the discovery of a new fault line in the Spokane area that has been dubbed the Spokane Fault.
A series of 105 small earthquakes – all less than a magnitude 4 – shook Spokane in 2001, accompanied by a half-inch ground elevation. The evidence pointed to a northeast-trending fault beneath Spokane, but no known mapped faults had occurred in this area for 1.6 million years, the U.S. geophysicists noted.
Spokane Sheriff Ozzie Knezovich also became involved.
“As the director of Spokane Emergency Management, we work diligently on preparing our community for disasters, which includes identifying hazards in our area,” Knezovich said. “The USGS has performed studies, and their preliminary findings will help us develop effective mitigation strategies.”
During an “aeromagnetic survey,” a magnetic sensor is towed behind an airplane along closely spaced parallel lines in order to detect minute changes in the magnetic field. The differences, called anomalies, can help point to where fault lines exist.
The newly discovered fault is smaller and may produce no more tremors. However, further study needs to be done to see if a larger fault line – with the potential for more damage in the event of an earthquake – exists.