Evidence of Ionospheric Perturbations from a Buried Chemical Explosion Captured Using High-Rate GNSS Measurements

Abstract:

We report potential ionospheric signatures created by acoustic waves radiating from a buried chemical explosion in Nevada. The event consisted of a of 10-ton TNT equivalent yield nitromethane explosion at a depth of 50 m in alluvium. It was part of the Dry Alluvium Geology (DAG) campaign as part of the Source Physics Experiment (SPE), a series of buried chemical explosions conducted in order to better understand signals generated by subsurface explosions. While the primary diagnostics of the DAG test series were seismic and ground-based infrasound, JPL and Sandia National Labs collaborated on secondary diagnostics that included balloon-borne and Global Navigation Satellite System-based (GNSS) infrasound detection and characterization. As part of the GNSS detection framework, JPL deployed a high-rate (20 Hz) survey quality GNSS receiver near ground zero. In this presentation, we share analysis that establishes the presence of an ionospheric signature approximately 12 minutes after the DAG-4 shot, which was detected through the measurement of ionospheric total electron content (TEC) using GNSS satellites. We also performed simulations using a software tool based on the SPECFEM simulation tool to better understand signal propagation from the DAG-4 shot to the ionosphere and disambiguate the signal from other possible anthropogenic and natural sources. This is the first time such a low-yield signal has been captured using a high frequency GNSS receiver with a high sampling rate and demonstrates the promise of such measurements for improving the robustness of the nuclear monitoring regime. In addition, this technique has applications to planetary science, where similar high-rate radio links between in-situ and orbital elements may help capture and characterize the ionospheric footprint of geophysical acoustic waves on Earth and beyond.