An Explosion Aftershock Model with Application to On-Site Inspection

Ford, S. R.; Labak, Peter

doi:10.1007/s00024-015-1041-x

Cited by 6 publications

(3 citation statements)

References 17 publications

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“…The p decay exponent for DAG‐2 and DAG‐4 aftershocks of 1.49 and 1.48, respectively is considered high compared to the earthquake range between 0.9 and 1.5 (Utsu et al., 1995) and in the lower population of nuclear explosions between 0.9 and 3 (Gross, 1996). A similar decay rate of p ∼ 1.5 was estimated for the 1992 Non‐proliferation Experiment and several Yucca Valley nuclear tests (Ford & Labak, 2016; Jarpe et al., 1994) suggesting no differences due to emplacement geology (alluvium or volcanic tuff) or differences between nuclear and chemical explosion. Using these aftershock model parameter values, we can hindcast the lack of aftershocks from the smaller (1 ton) DAG‐1 and DAG‐3.…”

Section: Resultssupporting

confidence: 72%

“…The K productivity parameter is related to other seismicity parameters by

\log_{10} (K) = a + b (M - M_{min})

, where a is related to the seismicity rate, b is the Gutenberg‐Richter b‐value and M – M min is magnitude difference between the mainshock of a sequence and the smallest detectable aftershock (Gutenberg and Richter, 1956). If we take the a and b values from the soft‐rock model by Ford and Labak (2016), which are −3.40 and 1.10, respectively, and the K values from the Omori fits to the DAG‐2 and DAG‐4 data, then M min is about −3. We can then estimate the cumulative number of aftershocks assuming a Poissonian aftershock rate.…”

Section: Resultsmentioning

confidence: 99%

“…Ford (2020) used recorded waveforms from the smallest SPE chemical explosion (SPE-4 Prime) as templates to detect ∼108 aftershocks triggered by the SPE-5 (5 ton) chemical explosion within the first 10 days. The hard-rock explosion aftershock model from Ford and Labak (2016) predicted the SPE-5 observations well despite the model being trained on data from a 1.2 Megaton underground nuclear explosion.…”

Section: Aftershocks Triggered From Nuclear and Chemical Explosionsmentioning

confidence: 99%

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Preliminary Analysis of Source Physics Experiment Explosion‐Triggered Microseismicity Using the Back‐Projection Method

et al. 2021

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The first campaign of the SPE included a series of six chemical explosions, with yields between 1 and 5 tons TNT equivalent yield, conducted at borehole U-15N in Climax Stock granite of northern Yucca Flat (e.g., Snelson et al., 2013). The second campaign was designated Dry Alluvium Geology (DAG) experiment and consisted of a series of four chemical explosions with yields Abstract A series of four chemical explosions were detonated in a deep borehole within the Yucca Flat Dry Alluvium Geology (DAG) at the Nevada National Security Site between 2018 and 2019. The two larger chemical explosions of 50 tons (DAG-2) and 10 tons (DAG-4) TNT equivalent yield triggered energetic aftershock sequences numbering 1392 and 347 microearthquakes, respectively, within the first 10 days. No significant aftershock activity was observed for the two smaller 1-ton explosions (DAG-1 and DAG-3). We used a back-projection method based on travel-time migration and stacking of signal-to-noise ratio traces to detect, associate and locate aftershocks from a subset of 22-geophones within a larger 2  2 km seismic array surrounding the borehole. The aftershocks located within 300 m of the borehole and the depths were above the working points of 300 and 50 m depths of DAG-2 and DAG-4, respectively, ruling out triggering slip on geologic faults or disturbances beneath neighboring collapse craters. DAG-2 and DAG-4 aftershocks decayed at similar rates, with power-law exponents of p = 1.48 and p = 1.49, respectively. These decay rates are comparable to aftershocks sequences triggered by earthquakes and historical nuclear explosions at Yucca Flat. A smooth power-law aftershock decay within the first 10 days suggests a triggering mechanism from explosion generated stress relaxation due to the diffusion of high gas pressures in the cavity and radial fractures. A more random and episodic aftershock rate would be expected due to cavity collapse or falling rubble in chimney formation.Plain Language Summary Large earthquakes trigger sequences of smaller earthquakes which are clustered in space and time and are known as aftershocks. Explosions also trigger aftershocks that behave similar to earthquake-triggered aftershocks. However, not all explosions trigger aftershocks and if they do, the aftershocks are fewer, smaller in size, and limited to a few kilometers from the point of the explosion. Detection of explosion-triggered aftershocks after a suspected nuclear test helps international inspectors locate an area for on-site-inspection and differentiate explosions from earthquakes which reduces false alarms. Four chemical explosions were conducted at the Nevada National Security Site as an experiment to study the physics of underground explosions for improving nuclear nonproliferation verification and monitoring capabilities. We detected 1392 explosion-triggered aftershocks from the largest test explosion and another explosion one-fifth the size triggered only 347 aftershocks within the first 10 days. These aftershocks have very small magnitudes and went u...

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Section: Resultssupporting

confidence: 72%

“…The K productivity parameter is related to other seismicity parameters by