Damaging Distant Airblast from Minor Scale

摘要

An unexpected change in winds at 4 to 5 km MSL caused airblast ducting and focusing on Carrizozo, NM, 60 km east from MINOR SCALE. Consequently, this 4.8 kt ANFO (ammonium nitrate-fuel oil) explosion test, sponsored by the Defense Nuclear Agency, and fired at 1220 MDT, 6/27/85, rattled the town with 300 Pa (0.0435 psi) overpressure, according to the microbarograph records. Four large (8 x 10 ft) store windows were broken. Weather data which were collected during this event show that conditions changed near shot time, as needed to explain this result, but we have no clues for predicting such localized wind patterns. In spite of reliance on series of upper air weather balloon observations to predict distant airblast propagations from WSMR explosion tests, there have already been two incidents of wide misses. It appears that the variability of winds over the mountainous region around WSMR is appreciably larger than over flatter terrain, so that airblast propagation predictions are subject to significant error. Microbarographs are essential in surrounding communities, to document the explosion airblast strength when unexpectedly enhanced blasts occur. The provided empirical model for estimating window damage from expected overpressure appeared to work well. As expected, large windows were the first to fail from the blast. Large plates are indeed hazardous when they break, so that such window damage should be avoided, in spite of their relatively low replacement cost in comparison with test delays. 8 refs., 9 figs. (ERA citation 11:051878)