  Observations from GPS receivers and the Very Large Array (VLA) radio
telescope recorded traveling ionospheric disturbances (TID) from underground
nuclear explosions (UNEs), detonated in September 1992. The slant TEC (STEC)
data derived from GPS observations were processed for all ray paths to isolate
TIDs. For the TIDs from the Hunters Trophy test on 18 September 1992 and the
Divider test on 23 September 1992, the propagated mean velocities of the TIDs
were about 573m/s and 740m/s with standard deviations of 85m/s and 135 m/s,
respectively. For the VLA observations, the spectral analysis produced
three-dimensional fluctuation spectral cubes for the Hunters Trophy event. The
arrival time of the TID at the VLA implied a propagation speed of 570-710 m/s.
This study suggests the global availability of GNSS tracking networks and new
low-frequency (VHF) radio telescopes may offer a method of UNE detection and
characterization, which could complement the International Monitoring System
(IMS).
