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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Experimental investigation on the energy deposition and expansion rate under the electrical explosion of aluminum wire in vacuum

Experimental investigations on the electrical explosion of aluminum wire using negative polarity current in vacuum are presented. Current pulses with rise rates of 40 A/ns, 80 A/ns, and 120 A/ns are generated for investigating the influence of current rise rate on energy deposition. Experimental results show a significant increase of energy deposition into the wire before the voltage breakdown with the increase of current rise rate. The influence of wire dimension on energy deposition is investigated as well. Decreasing the wire length allows more energy to be deposited into the wire. The energy deposition of a 0.5 cm-long wire explosion is ∼2.5 times higher than the energy deposition of a 2 cm-long wire explosion. The dependence of the energy deposition on wire diameter demonstrates a maximum energy deposition of 2.7 eV/atom with a diameter of ∼18 μm. Substantial increase in energy deposition is observed in the electrical explosion of aluminum wire with polyimide coating. A laser probe is applied to construct the shadowgraphy, schlieren, and interferometry diagnostics. The morphology and expansion trajectory of exploding products are analyzed based on the shadowgram. The interference phase shift is reconstructed from the interferogram. Parallel dual wires are exploded to estimate the expansion velocity of the plasma shell.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

X-ray radiography of the overheating instability in underwater electrical explosions of wires

We introduce the measurements of the development of striation like instabilities during the electrical driven explosions of wires in a water bath. In vacuum based wire explosion experiments, such instabilities have long been known. Yet, in spite of intense research into the explosion of wires in liquids, the development of these instabilities has either not been observed or has been assumed to play a minor role in the parameters of the exploding wire due to the tamping of the wire's explosion. Using synchrotron based multiframe radiography, we have seen the development of platelike density structures along an exploding copper wire. Our measurements were compared to a 2D magnetohydrodynamics simulation, showing similar striation formation. These observed instabilities could affect the measurements of the conductivity of the wire material in the gas-plasma state—an important parameter in the warm dense matter community. The striations could also act as a seed for other instabilities later in time if the wire is in a dense flow of material or experiences a shock from an adjacent wire—as it would do in experiments with arrays of wires.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Scaled experiments on cavity confined explosions in limestone and poly(methyl methacrylate)

A scaled experiment comprising a laser-driven explosion in a cavity is used to characterize the coupling of mechanical energy into the surrounding solid material. Experiments are performed using poly(methyl methacrylate) and dry Salem limestone as the explosion containment blocks materials, in which are milled scaled spherical cavities of various dimensions. Measurements of the coupled shock, taken with fiber optic probes at the cavity wall, show the critical radius where wall deformation transitions from plastic to elastic deformation. These measurements also provide a diagnostic of the air blast, which is validated against GEODYN simulation code. The measurement of the coupled shock amplitude taken farther from the wall in the linear region indicates increased coupling efficiency in small cavities over the range of scaled cavity radii from 6 to 20 m/kt 1/3 , a phenomenon not previously observed in experiments. A comparison of results taken in this experiment with a parallel experiment using high explosive (HE) as the source shows that coupled shocks generated with HE are characteristically different with much larger amplitude than those produced by a high energy density laser-driven source with the same yield. This experimental technique potentially provides a rapid and cost-effective method to analyze the consequences of a full-scale, low yield, buried explosion.

58 GEOSCIENCES↗
DOE OSTI2012

A NEW MULTI-DIMENSIONAL GENERAL RELATIVISTIC NEUTRINO HYDRODYNAMICS CODE FOR CORE-COLLAPSE SUPERNOVAE. II. RELATIVISTIC EXPLOSION MODELS OF CORE-COLLAPSE SUPERNOVAE

We present the first two-dimensional general relativistic (GR) simulations of stellar core collapse and explosion with the COCONUT hydrodynamics code in combination with the VERTEX solver for energy-dependent, three-flavor neutrino transport, using the extended conformal flatness condition for approximating the space-time metric and a ray-by-ray-plus ansatz to tackle the multi-dimensionality of the transport. For both of the investigated 11.2 and 15 M{sub Sun} progenitors we obtain successful, though seemingly marginal, neutrino-driven supernova explosions. This outcome and the time evolution of the models basically agree with results previously obtained with the PROMETHEUS hydro solver including an approximative treatment of relativistic effects by a modified Newtonian potential. However, GR models exhibit subtle differences in the neutrinospheric conditions compared with Newtonian and pseudo-Newtonian simulations. These differences lead to significantly higher luminosities and mean energies of the radiated electron neutrinos and antineutrinos and therefore to larger energy-deposition rates and heating efficiencies in the gain layer with favorable consequences for strong nonradial mass motions and ultimately for an explosion. Moreover, energy transfer to the stellar medium around the neutrinospheres through nucleon recoil in scattering reactions of heavy-lepton neutrinos also enhances the mentioned effects. Together with previous pseudo-Newtonian models, the presented relativistic calculations suggest that the treatment of gravity and energy-exchanging neutrino interactions can make differences of even 50%-100% in some quantities and is likely to contribute to a finally successful explosion mechanism on no minor level than hydrodynamical differences between different dimensions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

AN INVESTIGATION INTO THE CHARACTER OF PRE-EXPLOSION CORE-COLLAPSE SUPERNOVA SHOCK MOTION

We investigate the structure of the stalled supernova shock in both two and three dimensions (2D and 3D, respectively) and explore the differences in the effects of neutrino heating and the standing accretion shock instability (SASI). We find that early on the amplitude of the dipolar mode of the shock is factors of {approx}2-3 smaller in 3D than in 2D. However, later in both 3D and 2D, the monopole and dipole modes start to grow until explosion. Whereas in 2D, the (l, m) = (1, 0) mode changes sign quasi-periodically, producing the 'up-and-down' motion always seen in modern 2D simulations, in 3D this almost never happens. Rather, in 3D when the dipolar mode starts to grow, it grows in magnitude and wanders stochastically in direction until settling before explosion to a particular patch of solid angle. Furthermore, in 2D, we find that the amplitude of the dipolar shock deformation separates into two classes. For the first, identified with the SASI and for a wide range of 'low' neutrino luminosities, this amplitude remains small and roughly constant. For the other, identified with higher luminosities and neutrino-driven convection, the dipolar amplitude grows sharply. Importantly, it is only for this higher luminosity class that we see neutrino-driven explosions within {approx}1 s of bounce. Moreover, for the 'low' luminosity runs (including zero), the power spectra of these dipolar oscillations peak in the 30-50 Hz range associated with advection timescales, while for the high-luminosity runs the power spectra at lower frequencies are significantly more prominent. We associate this enhanced power at lower frequencies with slower convective effects and the secular growth of the dipolar shock amplitude. Though our study involves a simplified, parameterized approach, on the basis of it we hypothesize that neutrino-driven buoyant convection should almost always dominate the SASI when the supernova explosion is neutrino-driven.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

NEW TWO-DIMENSIONAL MODELS OF SUPERNOVA EXPLOSIONS BY THE NEUTRINO-HEATING MECHANISM: EVIDENCE FOR DIFFERENT INSTABILITY REGIMES IN COLLAPSING STELLAR CORES

The neutrino-driven explosion mechanism for core-collapse supernovae in its modern flavor relies on the additional support of hydrodynamical instabilities in achieving shock revival. Two possible candidates, convection and the so-called standing accretion shock instability (SASI), have been proposed for this role. In this paper, we discuss new successful simulations of supernova explosions that shed light on the relative importance of these two instabilities. While convection has so far been observed to grow first in self-consistent hydrodynamical models with multi-group neutrino transport, we here present the first such simulation in which the SASI grows faster while the development of convection is initially inhibited. We illustrate the features of this SASI-dominated regime using an explosion model of a 27 M{sub Sun} progenitor, which is contrasted with a convectively dominated model of an 8.1 M{sub Sun} progenitor with subsolar metallicity, whose early post-bounce behavior is more in line with previous 11.2 M{sub Sun} and 15 M{sub Sun} explosion models. We analyze the conditions discriminating between the two different regimes, showing that a high mass-accretion rate and a short advection timescale are conducive for strong SASI activity. We also briefly discuss some important factors for capturing the SASI-driven regime, such as general relativity, the progenitor structure, a nuclear equation of state leading to a compact proto-neutron star, and the neutrino treatment. Finally, we evaluate possible implications of our findings for two-dimensional and three-dimensional supernova simulations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Constraints on explosive silicon burning in core-collapse supernovae from measured Ni/Fe ratios

Measurements of explosive nucleosynthesis yields in core-collapse supernovae provide tests for explosion models. We investigate constraints on explosive conditions derivable from measured amounts of nickel and iron after radioactive decays using nucleosynthesis networks with parameterized thermodynamic trajectories. The Ni/Fe ratio is for most regimes dominated by the production ratio of {sup 58}Ni/({sup 54}Fe + {sup 56}Ni), which tends to grow with higher neutron excess and with higher entropy. For SN 2012ec, a supernova (SN) that produced a Ni/Fe ratio of 3.4 ± 1.2 times solar, we find that burning of a fuel with neutron excess η≈6×10{sup −3} is required. Unless the progenitor metallicity is over five times solar, the only layer in the progenitor with such a neutron excess is the silicon shell. SNe producing large amounts of stable nickel thus suggest that this deep-lying layer can be, at least partially, ejected in the explosion. We find that common spherically symmetric models of M{sub ZAMS}≲13 M{sub ⊙} stars exploding with a delay time of less than one second (M{sub cut}<1.5 M{sub ⊙}) are able to achieve such silicon-shell ejection. SNe that produce solar or subsolar Ni/Fe ratios, such as SN 1987A, must instead have burnt and ejected only oxygen-shell material, which allows a lower limit to the mass cut to be set. Finally, we find that the extreme Ni/Fe value of 60–75 times solar derived for the Crab cannot be reproduced by any realistic entropy burning outside the iron core, and neutrino-neutronization obtained in electron capture models remains the only viable explanation.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

CONSTRAINING EXPLOSION TYPE OF YOUNG SUPERNOVA REMNANTS USING 24 {mu}m EMISSION MORPHOLOGY

Determination of the explosion type of supernova remnants (SNRs) can be challenging, as SNRs are hundreds to thousands of years old and supernovae are classified based on spectral properties days after explosion. Previous studies of thermal X-ray emission from Milky Way and Large Magellanic Cloud SNRs have shown that Type Ia and core-collapse (CC) SNRs have statistically different symmetries, and thus these sources can be typed based on their X-ray morphologies. In this Letter, we extend the same technique, a multipole expansion technique using power ratios, to infrared (IR) images of SNRs to test whether they can be typed using the symmetry of their warm dust emission as well. We analyzed archival Spitzer Space Telescope Multiband Imaging Photometer 24 {mu}m observations of the previously used X-ray sample, and we find that the two classes of SNRs separate according to their IR morphologies. The Type Ia SNRs are statistically more circular and mirror symmetric than the CC SNRs, likely due to the different circumstellar environments and explosion geometries of the progenitors. Broadly, our work indicates that the IR emission retains information of the explosive origins of the SNR and offers a new method to type SNRs based on IR morphology.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

On various mechanisms of shear wave generation from underground chemical explosions in hard rocks

Significant shear waves observed during underground explosions can make them look similar to natural earthquakes. In the near field, they can be caused by the source geometry and emplacement conditions, heterogeneous and anisotropic properties of the rock mass, relaxation of a non-uniform in situ stress around the source after the departure of the shock wave as well as by activation of nearby faults. Here, the stress relaxation mechanism is important at depth when the difference in main principal stresses becomes significant. Another mechanism of shear motion generation is due to explosive gas flow from the source cavity into the cracks initiated by the shock wave and joints connected to the cavity. Also, the shock wave from the explosion can cause weakening of the rock either due to permanent damage or shock-induced liquefaction at saturated joints. Numerical modelling of underground chemical explosions in hard rock at various confinement stresses has been conducted to compare various mechanisms of shear wave generation and their seismic characteristics with that of a simple fault rupture process observed during an earthquake.

58 GEOSCIENCES↗
DOE OSTI2018

Characteristics of infrasound signals from North Korean underground nuclear explosions on 2016 January 6 and September 9

This study investigates infrasound signals from North Korean underground nuclear explosions on 2016 January 6 at 01:30:01 UTC (UNEJ16) and on 2016 September 9 at 00:30:01 UTC (UNES16). Infrasound observations from eight, seismo-acoustic arrays at distances of 300–600 km from the explosions and aligned approximately east–west across South Korea are used in the analysis. Progressive multichannel correlation was used followed by analyst review to identify the infrasound arrivals with estimates of azimuth, phase velocity, celerity, F-statistic, signal-to-noise ratio, correlation and signal duration. These observations are compared with model predictions of travel path, ray turning height and relative amplitudes, using Ground-to-Space atmospheric specifications at the time of each explosion. Stratospheric conditions at the time of the UNEJ16 are favourable to the Korean arrays when all arrays detected infrasound signals, while the few detections for UNES16 are consistent with unfavourable stratospheric winds and reduced amplitude thermospheric arrivals. Infrasound locations of the explosions were estimated using the Bayesian Infrasonic Source Location method (BISL), with wind-corrected backazimuth estimates based on the ray tracing calculations. Adding wind corrections to BISL resulted in infrasound locations up to 50 per cent closer to the seismic epicentre over uncorrected locations. The UNES16 infrasound location estimate using atmospheric corrections had larger differences (~67 km difference from seismic location) than the UNEJ16 location (~11 km difference from seismic location) as a result of the reduced number of observations and poor azimuth coverage for UNES16. Based on stratospheric phases recorded at six arrays and the empirical yield-scaling relations, wind corrected amplitudes from UNEJ16 lead to equivalent infrasound source energy estimates between 0.9 and 16.1 tons of TNT detonated in the atmosphere with an average of 6.4 tons and a standard deviation of 4.6 tons.

58 GEOSCIENCES↗
DOE OSTI2022

Constraining Type Ia supernova explosions and early flux excesses with the Zwicky Transient Factory

In the new era of time-domain surveys, Type Ia supernovae are being caught sooner after explosion, which has exposed significant variation in their early light curves. Two driving factors for early-time evolution are the distribution of 56 Ni in the ejecta and the presence of flux excesses of various causes. We perform an analysis of the largest young SN Ia sample to date. We compare 115 SN Ia light curves from the Zwicky Transient Facility to the turtls model grid containing light curves of Chandrasekhar mass explosions with a range of 56 Ni masses, 56 Ni distributions, and explosion energies. We find that the majority of our observed light curves are well reproduced by Chandrasekhar mass explosion models with a preference for highly extended 56 Ni distributions. We identify six SNe Ia with an early-time flux excess in our gr-band data (four ‘blue’ and two ‘red’ flux excesses). We find an intrinsic rate of 18 ± 11 percent of early flux excesses in SNe Ia at z < 0.07, based on three detected flux excesses out of 30 (10 percent) observed SNe Ia with a simulated efficiency of 57 percent. This is comparable to rates of flux excesses in the literature but also accounts for detection efficiencies. Two of these events are mostly consistent with circumstellar material interaction, while the other four have longer lifetimes in agreement with companion interaction and 56 Ni-clump models. We find a higher frequency of flux excesses in 91T/99aa-like events (44 ± 13 percent).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Three-dimensional supernova explosion simulations of 9-, 10-, 11-, 12-, and 13-M⊙ stars

Abstract Using the new state-of-the-art core-collapse supernova (CCSN) code fornax, we have simulated the three-dimensional dynamical evolution of the cores of 9-, 10-, 11-, 12-, and 13-M⊙ stars from the onset of collapse. Stars from 8 to 13 M⊙ constitute roughly 50 per cent of all massive stars, so the explosive potential for this mass range is important to the overall theory of CCSNe. We find that the 9-, 10-, 11-, and 12-M⊙ models explode in 3D easily, but that the 13-M⊙ model does not. From these findings, and the fact that slightly more massive progenitors seem to explode, we suggest that there is a gap in explodability near 12 to 14 M⊙ for non-rotating progenitor stars. Factors conducive to explosion are turbulence behind the stalled shock, energy transfer due to neutrino–matter absorption and neutrino–matter scattering, many-body corrections to the neutrino–nucleon scattering rate, and the presence of a sharp silicon–oxygen interface in the progenitor. Our 3D exploding models frequently have a dipolar structure, with the two asymmetrical exploding lobes separated by a pinched waist where matter temporarily continues to accrete. This process maintains the driving neutrino luminosity, while partially shunting matter out of the way of the expanding lobes, thereby modestly facilitating explosion. The morphology of all 3D explosions is characterized by multiple bubble structures with a range of low-order harmonic modes. Though much remains to be done in CCSN theory, these and other results in the literature suggest that, at least for these lower mass progenitors, supernova theory is converging on a credible solution.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Monitoring Surface Phenomena Created by an Underground Chemical Explosion Using Fully Polarimetric VideoSAR

Sandia National Laboratories flew its Facility for Advanced RF and Algorithm Development X-Band (9.6-GHz center frequency), fully polarimetric synthetic aperture radar (PolSAR) in VideoSAR mode to collect complex-valued SAR imagery before, during, and after the sixth Source Physics Experiment's (SPE-6) underground explosion. The VideoSAR products generated from the data sets include "movies'' of single- and quad-polarization coherence maps, magnitude imagery, and polarimetric decompositions. Residual defocus, due to platform motion during data acquisition, was corrected with a digital elevation model-based autofocus algorithm. We generated and exploited the VideoSAR image products to characterize the surface movement effects caused by the underground explosion. Unlike seismic sensors, which measure local area seismic waves using sparse spacing and subterranean positioning, these VideoSAR products captured high-spatial resolution, 2-D, time-varying surface movement. The results from the fifth SPE (SPE-5) used single-polarimetric VideoSAR data. In this paper, we present single-polarimetric and fully polarimetric VideoSAR results while monitoring the SPE-6 underground chemical explosion. We show that fully polarimetric VideoSAR imaging provides a unique, coherent, time-varying measure of the surface expression of the SPE-6 underground chemical explosion. As a result, we include new surface characterization results from the measured PolSAR SPE-6 data via H/A/α polarimetric decomposition.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

The Study on the Shock Wave Propagation Rule of a Gas Explosion in a Gas Compartment

Combined with the k-ε turbulence model of general application, a refined finite element model of a utility tunnel’s gas compartment filled with the methane/air mixture is developed. A series of analyses are made by using the powerful industry-leading computational fluid dynamics (CFD) software flame acceleration simulator (FLACS) to study the shock wave propagation rule in the gas compartment. The longitudinal and transversal distribution laws of the explosion shock wave are gained taking into consideration the spatial characteristics of the gas compartment. The influences of a few parameters, such as initial conditions and section size of the gas compartment, on the shock wave propagation rule are further discussed. The basic procedure for predicting the peak pressure of the blast wave is provided by considering the initial conditions and the gas compartment, and the corresponding injury effect of the explosion wave on the living beings is assessed. The investigation demonstrates that the peak pressure by the coupled effect between the initial conditions is significantly influenced, especially at the upper and lower gas explosion limits. The peak pressure increases gradually as the width or height increases, and both basically meet the linear relation. The proposed method can forecast the peak pressure of the explosion shock wave in the gas compartment accurately. According to the peak pressure longitudinal and transversal distributions of the blast wave, the peak pressure is far greater than the killing pressure threshold in the underground and closed space; consequently, it is not safe for the living beings in the gas compartment.

Lin, Shu-Chao↗
DOE OSTI2014

Source Characterization of Underground Explosions from Combined Regional Moment Tensor and First-Motion Analysis

Here in this study, we investigate the 14 September 1988 U.S.–Soviet Joint Verification Experiment nuclear test at the Semipalatinsk test site in eastern Kazakhstan and two nuclear explosions conducted less than 10 years later at the Chinese Lop Nor test site. These events were very sparsely recorded by stations located within 1600 km, and in each case only three or four stations were available in the regional distance range. We have utilized a regional distance seismic waveform method fitting long-period, complete, three-component waveforms jointly with first-motion observations from regional stations and teleseismic arrays. The combination of long-period waveforms and first-motion observations provides a unique discrimination of these sparsely recorded events in the context of the Hudson et al. (1989) source-type diagram. We demonstrate through a series of jackknife tests and sensitivity analyses that the source type of the explosions is well constrained. One event, a 1996 Lop Nor shaft explosion, displays large Love waves and possibly reversed Rayleigh waves at one station, indicative of a large F-factor. We show the combination of long-period waveforms and P-wave first motions are able to discriminate this event as explosion-like and distinct from earthquakes and collapses. We further demonstrate the behavior of network sensitivity solutions for models of tectonic release and spall-based tensile damage over a range of F-factors and K-factors.

58 GEOSCIENCES↗
DOE OSTI2020

The Effects of Assumed Source Depth and Shear-Wave Velocity on Moment Tensors Estimated for Small, Contained Chemical Explosions in Granite

ABSTRACT The Source Phenomenology Experiment (SPE-Arizona) included of a series of chemical explosions detonated within a copper mine in Arizona. This study focuses on ground motions from detonations in the copper mine, which are analyzed to assess the uniqueness of the resulting source representation when the source region propagation characteristics have a range of possible models. P-wave velocities are well constrained by refraction data with less constraint of the S-wave velocities. The effects of explosion source depth and VS are assessed with Green’s functions for a range of models in which VP is held constant. Propagation models with a Poisson’s value of 0.25 and a source depth 30–60 m most accurately replicate the data. The explosion was detonated at a centroid depth of 30 m, so trade-offs in depth are demonstrated. The compensated linear vector dipole and explosion components of the Green’s functions convolved with a Mueller–Murphy source function are compared. Both produce significant energy in the 2–12 Hz band, due to surface-wave contributions with no clear depth dependencies above 20 Hz. The range of propagation models is used with the observational data to invert for the frequency-domain moment tensor. Fits to the data from these inversions have cross-correlation values of 0.64, demonstrating effectiveness in replicating the observations with the assumed propagation path effects and resulting source function. Inversions produce horizontal dipoles (Mxx and Myy), roughly half the maximum amplitude of Mzz, consistent with a compensated linear vector dipole source, which is frequency dependent. Denny and Johnson, Mueller–Murphy, Walter and Ford, and the revised Mueller–Murphy source models, parameterized for granite, are compared to the moment tensors. Despite a nonisotropic moment tensor source, the revised Mueller–Murphy isotropic source model best replicates the long-period moments, overshoot, and corner frequency.

Geochemistry & Geophysics↗
DOE OSTI2023

Explosive Yield Estimation Using Regional Seismic Moment Tensors

Here, we use the Pasyanos and Chiang (2022) data set to calculate the seismic moment M 0 for each explosion and use the measured explosive yield W to validate the W~M 0 relationship in Denny and Johnson (1991; hereafter, DJ91). The M 0 is corrected by transforming to a potency tensor and applying more appropriate near-source geophysical parameter values in the moment estimate. The mean residual between observed and predicted yield is near zero; however, the standard deviation of the residuals results in an F-value (a 95% confidence factor) of about 5. We re-estimate the coefficients in the DJ91 model and find similar values and only a slight improvement in the F-value. Next, we embark on a similar model selection process as DJ91, allowing for non-cube-root yield scaling and other plausible near-source elastic moduli. As was found by DJ91, the yield dependence is not significantly different from unity, and a cube root assumption is valid. Therefore, we yield scale the seismic moment and test the significance of all plausible explanatory variables. Isotropic moment performs better in the response variable than total moment. The preference for isotropic moment could be due to its relationship to volume change, which would be more directly affected by explosive yield. Surprisingly, we find that the overburden pressure, which is a function of depth, is not a significant parameter in the model. We hypothesize that this is due to the competing depth effects on source asymmetry and the incorporation of depth in the Green’s functions used to calculate the seismic moment tensors. Importantly, this emphasizes that only seismic moment tensor-derived moments should be used in these models. After removing insignificant model parameters, we are left with a simple model to predict explosive yield $\widehat{W}$ in kt from isotropic moment M I in N·m, $\widehat{W}$=κ –1.4132 10 0.035626GP M I , in which κ and GP are the near-source bulk modulus and gas porosity in Pa and %, respectively. The F-value for this model is approximately 3.

58 GEOSCIENCES↗
DOE OSTI2023

On Magnitudes and Inferred Yields of the 39 Underground Nuclear Test Explosions at the Novaya Zemlya Test Site

ABSTRACT We review the previously compiled seismic magnitudes for underground nuclear explosions at the Union of the Soviet Socialist Republics Novaya Zemlya Test Site, and analyze these data in the context of published details about individual tests and official Russian reports of annual cumulative explosive energy release at the test site. We derive relationships between teleseismic body wave magnitude mb and explosive yield Y by predicting the yield of each test using mb and minimizing the difference between predicted and reported annual cumulative yield. A linear relationship between mb and logY with a slope of 0.82 provides a good fit to the annual total yield, with a root mean square (rms) misfit of 0.095 logY units. A spectral magnitude relationship based on the explosion source model of Mueller and Murphy (1971) with a single-free-parameter provides a slightly better fit. For the 10 tests for which individual yields can be directly deduced from the official reports, the rms misfit of reported yields is less than 0.1 logY units or about 25%. More complex relationships that differentiate between the northern and southern test areas, or take account of variations in the scaled depth of burial, do not provide substantially better fits to the reported yields.

Geochemistry & Geophysics↗