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Seismic Observations and Aftershock Analysis from a Fully Coupled Chemical Explosion in Layered Tuff

Description: 

On October 18, 2023, as part of the Low-Yield Nuclear Monitoring Program (LYNM), a multi-organization research team executed a fully coupled underground chemical explosion in Aqueduct Mesa on the Nevada National Security Site (NNSS). Experiment objectives were to investigate both prompt and non-prompt source and signal propagation signatures of underground explosions. To this end, measurements were recorded using a variety of geophysical sensors including geophones, accelerometers, seismometers, and distributed acoustic sensing (DAS), among several other sensing modalities. Signatures of elastic deformation were recorded across spatial scales from 10s of meters out to greater than 100 kilometers.

Here, we focus on the data collected within the tunnel complex where the experiment was conducted and at surface ground zero (i.e., the mesa surface) restricting our analysis to radial distances of ~ 1.5 kilometers. Our work targets explosion source signature and the numerous aftershocks recorded by the multi-modal sensing network. Regarding the explosion source signature, we compare in-tunnel and surface recordings on both geophones and accelerometers, as well as comparison of co-located measurements across the different modalities (i.e., DAS and accelerometers). We compare our measurements to pre-experiment predictions of ground motion and strain rate. Additionally, we report on aftershock magnitudes, Omori decay rate, frequency content, and productivity to compare with pre-experiment predictions and aftershock sequences from previous underground explosions and natural earthquakes.

Session: Advancements in Forensic Seismology and Explosion Monitoring - II

Type: Oral

Date: 5/2/2024

Presentation Time: 10:45 AM (local time)

Presenting Author: D. Parker

Student Presenter: No

Invited Presentation: 

Authors