Abstract
Efficient detection and high-fidelity quantification of surface changes resulting from underground activities are important national and global security efforts. In this investigation, a team performed field-based topographic characterization by gathering high-quality photographs at very low altitudes from an unmanned aerial system (UAS)-borne camera platform. The data collection occurred shortly before and after a controlled underground chemical explosion as part of the United States Department of Energy’s Source Physics Experiments (SPE-5) series. The high-resolution overlapping photographs were used to create 3D photogrammetric models of the site, which then served to map changes in the landscape down to 1-cm-scale. Separate models were created for two areas, herein referred to as the test table grid region and the nearfield grid region. The test table grid includes the region within ~40 m from surface ground zero, with photographs collected at a flight altitude of 8.5 m above ground level (AGL). The near-field grid area covered a broader area, 90–130 m from surface ground zero, and collected at a flight altitude of 22 m AGL. The photographs, processed using Agisoft Photoscan® in conjunction with 125 surveyed ground control point targets, yielded a 6-mm pixel-size digital elevation model (DEM) for the test table grid region. This provided the ≤3 cm resolution in the topographic data to map in fine detail a suite of features related to the underground explosion: uplift, subsidence, surface fractures, and morphological change detection. The near-field grid region data collection resulted in a 2-cm pixel-size DEM, enabling mapping of a broader range of features related to the explosion, including: uplift and subsidence, rock fall, and slope sloughing. This study represents one of the first works to constrain, both temporally and spatially, explosion-related surface damage using a UAS photogrammetric platform; these data will help to advance the science of underground explosion detection.
| Original language | English |
|---|---|
| Pages (from-to) | 3159-3177 |
| Number of pages | 19 |
| Journal | Pure and Applied Geophysics |
| Volume | 175 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 1 2018 |
| Externally published | Yes |
Funding
The Source Physics Experiments (SPE) would not have been possible without the support of many people from several organizations. The authors thank NNSA, the Office of Defense Nuclear Nonproliferation Research and Development, and the SPE working group, a multi-institutional, interdisciplinary group of scientists and engineers. This work relied on the skill, dedication, and focus of our UAS pilot, Michael Grimler of Los Alamos National Laboratory’s Security Division, for safe and successful airborne operations. Katherine Norskog and Steven Clement of Los Alamos National Laboratory, Leon Berzins and Beth Dzenitis of Lawrence Livermore National Laboratory, TJ Williams of Sandia National Laboratories, and Jesse Bonner and Robert Ziehm of National Security Technologies, LLC provided essential field and logistics support. Los Alamos National Laboratory performs work for the US Department of Energy under contract DE-AC52-06NA25396. This document is unclassified and has been approved for unlimited release (LA-UR-16-29246).