Analysis of Ground Motion from An Underground Chemical Explosion

Pitarka, Arben; Mellors, R. J.; Walter, William R.; Ezzedine, S. M.; Vorobiev, O.; Antoun, T.; Wagoner, J. L.; Matzel, E.; Ford, S. R.; Rodgers, Arthur R.; Glenn, L. A.; Pasyanos, Michael E.

doi:10.1785/0120150066

Cited by 33 publications

(14 citation statements)

References 38 publications

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“…They found that a large part of the S-wave energy present in the simulations were generated by the source, whereas some scattering off of topography and shallow crustal heterogeneity was required to match the observations. Reasons for the different findings by Pitarka et al (2015) on the importance of very near-source scattering may include the different bandwidths studies (0-10 vs. 0-4 Hz here) and details of the near-source crustal model (grid spacing of 4 m with a minimum V S of 550 m=s vs. 100 m and 2500 m=s, respectively, in our study). Moreover, it should be noted that our fit between the synthetics and data, such as on the transverse component, has ample room for improvements, with delayed arrival of the largest phase at ∼140 s and overprediction of the later-arriving energy at ∼140-180 s. Although we show that the contribution from crustal and mantle scattering to the transverse-component energy arriving at regional distance can be significant, further simulations, including effects such as topographic scattering, nonisotropic sources, and nonlinearity, are clearly needed to illuminate the generation of near-source S-wave generation.…”

Section: Discussionmentioning

confidence: 60%

“…For example, Takemura et al (2015) simulated wave propagation out to distances of about 70 km from explosive and earthquake sources for frequencies up to 4.2 Hz in Japan. Rodgers et al (2010) investigated topographic scattering effects, and Pitarka et al (2015) simulated the seismic signature of a chemical explosion in 3D crustal models using finite-difference (FD) methods. Wang et al (2016) showed that including topographic scattering can improve the accuracy of source location.…”

Section: Introductionmentioning

confidence: 99%

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Constraints of Crustal Heterogeneity and Q(f) from Regional (<4 Hz) Wave Propagation for the 2009 North Korea Nuclear Test

Olsen

Begnaud

Phillips

et al. 2018

Bulletin of the Seismological Society of America

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We carried out 3D finite‐difference (FD) simulations (<4 Hz) of regional wave propagation for the 2009 North Korea nuclear explosion and compared the synthetics with instrument‐corrected records at stations INCN and TJN in South Korea. The source is an isotropic explosion with a moment magnitude of 4.1. Synthetics computed in the relatively smooth Sandia/Los Alamos National Laboratory SALSA3D (SAndia LoS Alamos 3D) velocity model significantly overpredict Rayleigh‐wave amplitudes by more than an order of magnitude while underpredicting coda amplitudes. The addition to SALSA3D of a von Karman distribution of small‐scale heterogeneities with correlation lengths of ∼1000 m, a Hurst number of 0.1, and a horizontal‐to‐vertical anisotropy of ∼5 produces synthetics in general agreement with the data. The best fits are obtained from models with a gradient in the strength of the velocity and density perturbations and strong scattering (10%) limited to the top 7.5–10 km of the crust. Deeper scattering tends to decrease the initial P‐wave amplitudes to levels much below those for the data, a critical result for methods discriminating between explosive and earthquake sources. In particular, the amplitude at the onset of Pn can be affected by as little as 2% small‐scale heterogeneity in the lower crust and upper mantle. Simulations including a constant Q of 200 (INCN) to 350 (TJN) below 1 Hz and a power‐law Q(f) formulation at higher frequencies, with an exponent of 0.3, generate synthetics in best agreement with the data. In our simulations, very limited scattering contribution from the near‐source area accumulates along the regional path.

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Section: Discussionmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Constraints of Crustal Heterogeneity and Q(f) from Regional (<4 Hz) Wave Propagation for the 2009 North Korea Nuclear Test

Olsen

Begnaud

Phillips

et al. 2018

Bulletin of the Seismological Society of America

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“…The primary scientific objective of SPE experiments is to understand the generation of S waves from a subsurface explosion. The DAG chemical explosions were recorded by an extensive suite of subsurface and surface seismic sensors (Larotonda & Townsend, 2021) in a location with extremely well‐characterized subsurface geology (Wagoner & Prothro, 2020) and seismic velocity structure (Pitarka & Mellors, 2021; Pitarka et al., 2015; Toney et al., 2019). The DAG events were the first subsurface explosions recorded by a nearby borehole fiber, although earlier explosions at the NNSS were measured using surface fiber at greater distances.…”

Section: Introductionmentioning

confidence: 99%

Modeling Subsurface Explosions Recorded on a Distributed Fiber Optic Sensor

Mellors

Abbott²,

Steedman

et al. 2021

JGR Solid Earth

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The potential is exciting, as spatially dense (∼1-10 m) but extensive (km length) datasets can be collected using only low-cost fiber optic cables as a sensor. The sensitivity of these fiber sensors approaches that of standard seismic sensors (Correa et al., 2017) but with a large dynamic range (Parker et al., 2014) and a wide frequency bandwidth (Lindsey et al., 2020). Moreover, the performance of the fiber recording systems has been steadily improving. The fiber sensors are especially well suited for boreholes, seafloor, or other challenging environments. In some cases, existing fibers already in place for telecommunications can be adapted for use as seismic sensors, which allows access to thousands of km of fiber onshore or on the sea floor at low cost (Lindsey et al., 2020).

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“…SW4 and its second-order predecessor WPP (Nilsson et al, 2007;Petersson and Sjogreen, 2010) have been used for earthquake (Aagaard et al, 2008(Aagaard et al, , 2010Rodgers et al, 2008;Dreger et al, 2015;Johansen et al, 2017; and explosion ground-motion simulations (Rodgers et al, 2010;Pitarka et al, 2015;Hirakawa et al, 2016). Under a recent Volume XX, Number XX -2019 3 Department of Energy Exascale Computing Project, SW4 has been modified to improve efficiency on computers with many cores (central processing units [CPUs]) per node with a hybrid OpenMP-message passing interface (MPI) parallelization scheme.…”

Section: Sw4 Simulationsmentioning

confidence: 99%

Broadband (0–5 Hz) Fully Deterministic 3D Ground‐Motion Simulations of a Magnitude 7.0 Hayward Fault Earthquake: Comparison with Empirical Ground‐Motion Models and 3D Path and Site Effects from Source Normalized Intensities

Rodgers

Petersson

Pitarka

et al. 2019

Seismological Research Letters

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We report on high-performance computing (HPC) fully deterministic simulation of ground motions for a moment magnitude (M w ) 7.0 scenario earthquake on the Hayward fault resolved to 5 Hz using the SW4 finite-difference code. We computed motions obeying physics-based 3D wave propagation at a regional scale with an M w 7.0 kinematic rupture model generated following Graves and Pitarka (2016). Both plane-layered (1D) and 3D Earth models were considered, with 3D subsurface material properties and topography interpolated from a model of the U.S. Geological Survey (USGS). The resulting ground-motion intensities cover a broader frequency range than typically considered in regional-scale simulations, including higher frequencies relevant for engineering analysis of structures. Median intensities for sites across the domain are within the reported between-event uncertainties (τ) of groundmotion models (GMMs) across spectral periods 0.2-10 s (frequencies 0.1-5 Hz). The within-event standard deviation ϕ of ground-motion intensity measurement residuals range 0.2-0.5 natural log units with values consistently larger for the 3D model. Source-normalized ratios of intensities (3D/ 1D) reveal patterns of path and site effects that are correlated with known geologic structure. These results demonstrate that earthquake simulations with fully deterministic wave propagation in 3D Earth models on HPC platforms produce broadband ground motions with median and within-event aleatory variability consistent with empirical models. Systematic intensity variations for the 3D model caused by path and site effects suggest that these epistemic effects can be estimated and removed to reduce variation in site-specific hazard estimates.This study motivates future work to evaluate the validity of the USGS 3D model and investigate the development of path and site corrections by running more scenarios.

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Analysis of Ground Motion from An Underground Chemical Explosion

Cited by 33 publications

References 38 publications

Constraints of Crustal Heterogeneity and Q(f) from Regional (<4 Hz) Wave Propagation for the 2009 North Korea Nuclear Test

Constraints of Crustal Heterogeneity and Q(f) from Regional (<4 Hz) Wave Propagation for the 2009 North Korea Nuclear Test

Modeling Subsurface Explosions Recorded on a Distributed Fiber Optic Sensor

Broadband (0–5 Hz) Fully Deterministic 3D Ground‐Motion Simulations of a Magnitude 7.0 Hayward Fault Earthquake: Comparison with Empirical Ground‐Motion Models and 3D Path and Site Effects from Source Normalized Intensities

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