Multi-physics approach to damage quantification by SPE/DAG explosions.

Abstract:

The Source Physics Experiment (SPE) is a series of highly instrumented chemical explosions at the Nevada National Security Site. Two phases of SPE were performed: first, a series of 6 explosions in a borehole in a granite outcrop between 2010 and 2016, and, in 2018, a series of four explosions in a borehole in alluvium. These two explosion series offer the opportunity to study the role of damage for explosion monitoring, and this for a range of scaled depth of burials and for different geologic settings. Previous work has allowed quantification of damage for the first phase of SPE as a secondary source of high-frequency Rg waves (Larmat, Rougier, & Patton, 2017) and as a source of variable-magnitude surface deformation (Schultz-Fellenz, E. S. et al. 2018; 2020). In this work, we investigate whether and how seismic and surface deformation observations are linked. Surface topographic change data from individual SPE experiments will be presented. We perform analysis on the Rg amplitude spectrum on records along five lines of GS11D geophones for the first series. We use the fact that the propagation path of Rg waves is the same for the 6 explosions, in order to remove the path effect and derive source amplitude spectrum for the explosions. The amplitude spectrum can be transformed into apparent seismic moment, enabling a quantification of the deviation from a pure elastic response such as the Denny & Johnson (1991) model. We are also planning an analysis of the spallation on surface and near-field records. Hydrodynamic modeling with the Hybrid Optimization Software Suite (HOSS) developed at LANL is also planned to provide guidance of the extent of the damage, especially in depth. This work is the first step in investigating and quantifying differences between spallation and surface deformation in the SPE series.