Listening in on the Nuclear Underground

A global network of seismic and infrasound monitoring stations listens constantly for underground clues that a nuclear test has taken place. Set up by the Comprehensive Test Ban Treaty Organization (CTBTO) Preparatory Commission, the stations will be part of the verification system for a comprehensive test ban treaty, should it come into force. The United States signed the treaty in 1996, but in 1999, the US Congress declined to ratify it.