Surface Ground Motion Prediction for Chemical Explosions in Alluvium

Date: 4/24/2019

Time: 11:30 AM

Room: Cascade I

The Dry Alluvium Geology (DAG) experiment is the second phase of the Source Physics Experiments (SPE) at the Nevada National Security Site (NNSS). The SPE program is examining the phenomenology of explosions in granite (Phase I) and dry alluvium (Phase II). The DAG experiment seismo-acoustic networks and support infrastructure locations were selected based on ground motion predictions from the Perret and Bass (1975) alluvium regressions (PB75), which are based on free-field recordings of nuclear explosions in that medium. The PB75 model predicts two regimes, the initial non-linear regime, which is dominated by extremely high attenuation to scaled ranges from 30 to 150 m/kt^1/3, followed by a linear region of less attenuation. For the DAG predictions we extrapolated the model to scaled ranges beyond those covered by the PB75 dataset, and then doubled those values to account for surface reflection. The data recorded from the DAG-1 (1 ton) and DAG-2 (50 tons) explosions indicate that this methodology does not correctly predict the observed surface ground motions for these chemical explosions. The observed ground motions at near-source distances (<1 km) are significantly stronger than predicted by PB75, while at farther ranges, the data were below predictions. We will provide new predictive relationships for three-component ground motion in alluvium for chemical explosions at near-source distances. This work was done by Mission Support and Test Services, LLC, under Contract No. DE-NA0003624 with the U.S. Department of Energy. DOE/NV/03624--0346

Presenting Author: Jessie L. Bonner

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