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Relative Source Time Function Estimation, Applications to the Source Physics Experiments

Description: 

The Source Physics Experiment (SPE) are a series of chemical explosion experiments at the Nevada National Security Site (NNSS). SPE Phase-I (2011-2016) provided a wealth of dense, local- to regional-distance observations suitable for characterizing shallow chemical explosions located within the same borehole. SPE Phase-II (2018-2019) was emplaced in alluvium with a dense array network in both linear profiles, borehole emplaced accelerometers and a grid of geophones. We investigate the time-dependent source processes of each chemical explosion using relative source time function (RSTF) estimation. We characterize SPE Phase-I using data from five linear seismometer profiles located between 100 and 2000 meters from the shot location. For SPE Phase-II, we experiment with using surface and near-source borehole instrumentation within 100 meters to compute RSTF's, this is due to complexities of the source medium and propagation. We attempt to reconstruct the relative source time functions (RSTF) to improve the resolution of time-dependent source processes utilizing the lower yield events in the series as the green functions. The RSTF estimates do provide exceptional resolution to each explosion’s time-history for SPE Phase-I. Preliminary modeling efforts suggest these measurements may be useful for precise characterization of explosion processes and spallation. Using the relative source time functions allow us to expand our understanding of the SPE Phase-I and Phase-II explosion series. Application of these techniques contributes to our understanding of source physics and facilitates future efforts to additional seismic source experiments and phenomenology.

Session: Advancements in Forensic Seismology and Explosion Monitoring [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: James

Student Presenter: No

Invited Presentation: 

Authors