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Reviewing Seismoacoustic Coupling Mechanisms for Infrasound From Underground Explosions

Infrasound from underground explosions is a key component of explosion monitoring, and is useful for constraining the explosion depth-of-burial. Many chemical explosion experiments have been conducted to understand the seismoacoustic coupling mechanisms for infrasound. Previous experiments showed that gas release and spall generation at the epicenter can govern infrasound characteristics. However, those detonation depths were generally shallow and may not represent deeper events such as overburied explosions or earthquakes. Here, we report a rare infrasound observation from a large, overburied chemical explosion and describe possible seismoacoustic coupling mechanisms. A multi-physics experiment (PE1-A) for low-yield nuclear explosion monitoring was conducted at the Nevada National Security Site in 2023. The PE1-A experiment was a fully coupled, chemical detonation with a TNT-equivalent yield of 16.3 tons at a 254-m depth. This overburied explosion produced unusually long duration infrasound signatures recorded at a range of several kilometers. These signals may indicate complex seismoacoustic coupling mechanisms for overburied explosions, which differ from gas release or spall mechanisms invoked to explain signals from shallower explosions. Preliminary numerical modelings and analysis indicate the extent of seismoacoustic coupling area and local topography affect the duration and amplitudes of generated infrasonic waveforms. Seismoacoustic coupling at this depth may be fully governed by linear elastic-to-acoustic conversion along the surface without the gas venting and spall generation observed in shallow explosions. In this case, local topography and subsurface seismic structures are likely to play a critical role in infrasound generation. In this study, we review seismoacoustic coupling mechanisms for underground explosions depending on the depths of burial and local topography.

Session: Advancements in Forensic Seismology and Explosion Monitoring - III

Type: Oral

Room: Holiday Ballroom 4-6+Corridor

Date: 4/17/2025

Presentation Time: 02:45 PM (local time)

Presenting Author: Keehoon Kim

Student Presenter: No

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