Seismic Source Characteristics of Nuclear and Chemical Explosions in Granite from Hydrodynamic Simulations
 Heming Xu,
 Arthur J. Rodgers,
 Ilya N. Lomov,
 Oleg Y. Vorobiev
 … show all 4 hide
Rent the article at a discount
Rent now* Final gross prices may vary according to local VAT.
Get AccessAbstract
Seismic source characteristics of lowyield (0.5–5 kt) underground explosions are inferred from hydrodynamic simulations using a granite material model on highperformance (parallel) computers. We use a nonlinear rheological model for granite calibrated to historical nearfield nuclear test data. Equivalent elastic Pwave source spectra are derived from the simulated hydrodynamic response using reduced velocity potentials. Source spectra and parameters are compared with the models of Mueller and Murphy (Bull Seism Soc Am 61:1675–1692, 1971, hereafter MM71) and Denny and Johnson (Explosion source phenomenology, pp 1–24, 1991, hereafter DJ91). The source spectra inferred from the simulations of different yields at normal scaled depthofburial (SDOB) match the MM71 spectra reasonably well. For normally buried nuclear explosions, seismic moments are larger for the hydrodynamic simulations than MM71 (by 25 %) and for DJ91 (by over a factor of 2), however, the scaling of moment with yield across this lowyield range is consistent for our calculations and the two models. Spectra from our simulations show higher corner frequencies at the lower end of the 0.5–5.0 kt yield range and stronger variation with yield than the MM71 and DJ91 models predict. The spectra from our simulations have additional energy above the corner frequency, probably related to nonlinear nearsource effects, but at high frequencies the spectral slopes agree with the f ^{−2} predictions of MM71. Simulations of nuclear explosions for a range of SDOB from 0.5 to 3.9 show stronger variations in the seismic moment than predicted by the MM71 and DJ91 models. Chemical explosions are found to generate higher moments by a factor of about two compared to nuclear explosions of the same yield in granite and at normal depthofburial, broadly consistent with comparisons of nuclear and chemical shots at the US Nevada Test Site (Denny, Proceeding of symposium on the nonproliferation experiment, Rockville, Maryland, 1994). For all buried explosions, the region of permanent deformation and material damage is not spherical but extends along the free surface above and away from the source. The effect of damage induced by a normally buried nuclear explosion on seismic radiation is explored by comparing the motions from hydrodynamic simulations with those for pointsource elastic Green’s functions. Results show that radiation emerging at downward takeoff angles appears to be dominated by the expected isotropic source contribution, while at shallower angles the motions are complicated by nearsurface damage and cannot be represented with the addition of a simple secondary compensated linear vector dipole point source above the shot point. The agreement and differences of simulated source spectra with the MM71 and DJ91 models motivates the use of numerical simulations to understand observed motions and investigate seismic source features for underground explosions in various emplacement media and conditions, including nonlinear rheological effects such as material strength and porosity.
 Title
 Seismic Source Characteristics of Nuclear and Chemical Explosions in Granite from Hydrodynamic Simulations
 Journal

Pure and Applied Geophysics
Volume 171, Issue 35 , pp 507521
 Cover Date
 201403
 DOI
 10.1007/s0002401206230
 Print ISSN
 00334553
 Online ISSN
 14209136
 Publisher
 Springer Basel
 Additional Links
 Topics
 Industry Sectors
 Authors

 Heming Xu ^{(1)}
 Arthur J. Rodgers ^{(1)}
 Ilya N. Lomov ^{(1)}
 Oleg Y. Vorobiev ^{(1)}
 Author Affiliations

 1. Lawrence Livermore National Laboratory, Livermore, CA, 94551, USA