Yield and Depth of Burial Hydrodynamic Calculations in Granodiorite: Implications for the North Korean Test Site.

摘要

This paper reports on continued research toward establishing a consistent modeling framework for calculating nuclear explosions in earth materials. The model must be consistent with observed phenomena in the near- field by correctly 1) calculating the resulting explosive cavity radius for a given yield and depth of burial, 2) accounting for the correct energy deposition by partitioning it into internal (heat and plastic strain) and kinetic (e.g. radiated seismic) energy, 3) predicting the free-field displacement/velocities waveforms and 4) predicting the measured attenuation of the free-field peak velocity with distance. The model developed in the last year satisfies all of these criteria and has been exercised in the investigation of the 2009 North Korean nuclear test. The main findings reported in this paper are: a) the extension of the developed model to the analysis of scaled depth of burial and free surface effects in 2D Earth structure, and b) the improvement of the computational equation of state (EOS) for granite/granodiorite and some examples of the models self-consistency. Our study focuses on the North Korean test site and the May 2009 test. When compared to the Denny and Johnson (1991) and to the Heard and Ackerman (1967) cavity radius scaling models, the results presented in this paper show a clear preference to the statistical model developed by Denny and Johnson. In addition, comparative work between Patton (2011) and the model developed under this project provides a lower limit to the yield and depth of burial for the 2009 North Korean test. A series of sensitivity analysis comprising the variation of key material properties and the incorporation of topography is being produced at the time of writing this paper and will be presented at the conference.