Analysis of Ground Motion from An Underground Chemical Explosion

Journal Article · Tue Sep 08 00:00:00 EDT 2015 · Bulletin of the Seismological Society of America

DOI:https://doi.org/10.1785/0120150066· OSTI ID:1423856

Pitarka, Arben ^[1]; Mellors, Robert J. ^[1]; Walter, William R. ^[1]; Ezzedine, Souheil ^[1]; Vorobiev, Oleg ^[1]; Antoun, Tarabay ^[1]; Wagoner, Jeffery L. ^[1]; Matzel, Eric M. ^[1]; Ford, Sean R. ^[1]; Rodgers, Arthur J. ^[1]; Glenn, Lewis ^[1]; Pasyanos, Mike ^[1]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Atmospheric, Earth and Energy Division

Here in this paper we investigate the excitation and propagation of far-field seismic waves from the 905 kg trinitrotoluene equivalent underground chemical explosion SPE-3 recorded during the Source Physics Experiment (SPE) at the Nevada National Security Site. The recorded far-field ground motion at short and long distances is characterized by substantial shear-wave energy, and large azimuthal variations in P-and S-wave amplitudes. The shear waves observed on the transverse component of sensors at epicentral distances <50 m suggests they were generated at or very near the source. The relative amplitude of the shear waves grows as the waves propagate away from the source. We analyze and model the shear-wave excitation during the explosion in the 0.01–10 Hz frequency range, at epicentral distances of up to 1 km. We used two simulation techniques. One is based on the empirical isotropic Mueller–Murphy (MM) (Mueller and Murphy, 1971) nuclear explosion source model, and 3D anelastic wave propagation modeling. The second uses a physics-based approach that couples hydrodynamic modeling of the chemical explosion source with anelastic wave propagation modeling. Comparisons with recorded data show the MM source model overestimates the SPE-3 far-field ground motion by an average factor of 4. The observations show that shear waves with substantial high-frequency energy were generated at the source. However, to match the observations additional shear waves from scattering, including surface topography, and heterogeneous shallow structure contributed to the amplification of far-field shear motion. Comparisons between empirically based isotropic and physics-based anisotropic source models suggest that both wave-scattering effects and near-field nonlinear effects are needed to explain the amplitude and irregular radiation pattern of shear motion observed during the SPE-3 explosion.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-06NA25946; AC52-07NA27344
• OSTI ID: 1423856
• Alternate ID(s): OSTI ID: 1834499
• Report Number(s): LLNL-JRNL--743967; LLNL-JRNL--745680
• Journal Information: Bulletin of the Seismological Society of America, Journal Name: Bulletin of the Seismological Society of America Journal Issue: 5 Vol. 105; ISSN 0037-1106
• Publisher: Seismological Society of America
• Country of Publication: United States
• Language: English

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