Nuclear test illuminates US array data quality

The seismographic stations deployed as part of USArray are one component of the U.S. National Science Foundation‐funded major research equipment facility Earth‐Scope. When fully operational, USArray will include 400 broadband stations in a Transportable Array (TA) that will be deployed over a regular grid of sites with approximately 70 kilometer spacing. The TA will migrate across the United States over the next decade, ultimately occupying about 2000 sites in the conterminous United States and Alaska. While USArray's primary objective is to record seismic signals for research applications addressing the structure, evolution, and seismicity of North America, the high quality seismic recording capabilities of the TA installations allow data from small, distant events to be acquired and analyzed for other purposes, such as deep mantle studies, earthquake rupture investigations, and analysis of unusual seismic sources, such as underground nuclear explosions. The TA currently is undergoing its initial deployment in the western United States, and about 240 stations were operational at the time of the underground nuclear explosion detonated by North Korea on 9 October 2006 (Figure 1).