The mystery of the concrete bunker

An abandoned reinforced-concrete bunker, built partially underground, sits atop an isolated granite mountain knob approximately a mile south of the Grand Coulee Dam; approximately 330 feet above the western shoreline of Lake Roosevelt. From September 1941 to August 1942 the United States Coast and Geodetic Survey would construct a recording seismographic station. The bunker would house a seismograph and associated instruments installed to detect possible earthquakes caused or initiated by the filling of the Columbia Reservoir (now called Lake Roosevelt).  On Sept. 11, 1942 the seismograph became operational and would operate six years, ceasing operations on Dec.14, 1948. The seismographic data revealed that there was little to no seismic activity associated with the filling of Lake Roosevelt. The study concluded that the geology beneath Lake Roosevelt was largely un-faulted granite, and pre-existing faults needed to be present to produce loading-induced earthquakes. It was later rumored that the seismic station was considered as a monitoring site to detect nuclear weapons tests conducted by Russia, China, and others during the Cold-War era. However, information suggests that spillage of water over the top of the dam and impacting the river below created too much seismic noise for that use. 

Bert Smith 2018. Picture: The Seismic Bunker