Ten Trials at Lower Slobbovia: Searching for Repetitive Electromagnetic and Seismoacoustic Signatures in Explosions

Nemzek, Robert J and Arrowsmith, Stephen J and Layne, John P
Technical Report, Los Alamos National Lab.(LANL), Los Alamos, NM (United States), 2013

We performed a series of ten explosion tests, each test being a single 10-kg cylinder of Comp-B with a PBXN-9 booster. Eight of the tests were placed 2 m above ground level, one was at ground level, and one was 1 m below ground in a backfilled hole. The explosions were monitored by radio antennas to detect electromagnetic emissions and seismo-acoustic instrumentation. We found that certain aspects of the radiofrequency emission regimes repeated from test to test. Some features showed a systematic variation across tests, which we interpret as the effect of each detonation on the nearby ground. The radio emissions were probably from the high-temperature detonation shock, follow-on combustion, and frictional charging of dirt entrained by the blast. The below-ground test in particular generated an anomalously-high level of RF at both low and high frequencies, presumably due to the large amount of dirt and rock involved. The seismoacoustic observations clearly discriminate the buried shot from the table and surface shots, which appear as a single population. Seismoacoustic waveforms from repeating tests at local distances have highly self-similar waveforms but amplitudes are strongly dependent on atmospheric conditions. We show that we can correct for meteorological effects on amplitude for upward-refracting atmospheres, but that correction for downward-refracting atmospheric profiles requires a coupled correction for topography.