PERMANENT DEFORMATION FROM UNDERGROUND EXPLOSIONS: INTEGRATING SUBSURFACE AND SURFACE OBSERVATIONS

A long-standing challenge in the geosciences is understanding the nature of the subsurface from surface-based observations. In underground nuclear explosion monitoring, the extent of surface and subsurface damage is a particularly important parameter for building predictive modeling capabilities. To help address this critical issue, we collected both surface and subsurface data that indicate the extent of permanent deformation from a series of controlled underground chemical explosion experiments. New advances in tools that provide high-resolution topography, such as photogrammetry and LiDAR, allowed us to collect cm-scale resolution of the test bed surface. Collections were made from terrestrial and UAS-based platforms prior to, and following, several explosive experiments, which allowed the development of digital elevation models for surface morphological change detection analyses. In addition, drilled core was collected prior to, and following, these same experiments. Microfracture densities were measured on ~15 thin sections collected from each core. We compare the extents of damage in both the horizontal (surface) direction and the vertical (depth) direction, and discuss implications for the control of local geology on the fracturing process.