"This paper reviews and summarizes prior work related to low frequency (< 100 Hz) EMP (ElectroMagnetic Pulse) observed from explosions. It focuses on how EMP signals might, or might not, be useful in monitoring underground nuclear tests, based on the limits of detection, and physical understanding of these signals."
U.S. Dept. of Energy, Lawrence Livermore National Laboratory: LLNL-TR-471856
U.S. Dept. of Energy, Office of Scientific and Technical Information: http://www.osti.gov/