More than 100 small earthquakes have been recorded since Saturday about 30 miles northwest of the Tri-Cities on the edge of the Hanford Reach National Monument , according to the Pacific Northwest Seismic Network.
The quakes were at the western edge of the McGee Ranch of the monument, which is Hanford site land used as a security perimeter around the production portion of the nuclear reservation during the years it produced plutonium for the nation’s nuclear weapons program.
“This is a completely natural phenomenon; although this swarm happens just outside the Hanford site, is has nothing to do with the radioactive waste stored there,” said the seismic network, a University of Washington and University of Oregon program to monitor earthquake and volcanic activity across the Pacific Northwest, in a blog post.
As of Tuesday, the seismic network put the number of earthquakes in recent days at about 100, but with some of the smallest likely missed and others not analyzed yet. On Wednesday, Doug Gibbons, a research engineer for the network, put the number at 115.