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D K Smith - One of the best experts on this subject based on the ideXlab platform.
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seismic source summary for all u s below surface nuclear Explosions
Bulletin of the Seismological Society of America, 2002Co-Authors: Donald L. Springer, Gayle A Pawloski, Janet L Ricca, Robert F Rohrer, D K SmithAbstract:A summary of information is presented for all U.S. nuclear tests detonated below the Earth's surface. The data include explosion times, locations, yields, and depths of burial, as well as geophysical information about working-point media, and, for the Underground Explosions, data about surface collapse (subsidence) phenomena. This summary is intended to furnish available and up-to-date data useful for studies of seismic and hydroacoustic sources, as well as for studies of the seismic and hydroacoustic transmission characteristics of the Earth. Manuscript received 2 July 2001.
Jessie L Bonner - One of the best experts on this subject based on the ideXlab platform.
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modeling surface waves from aboveground and Underground Explosions in alluvium and limestone
Bulletin of the Seismological Society of America, 2013Co-Authors: Jessie L Bonner, David R Russell, Robert E ReinkeAbstract:The May 2012 HUMBLE REDWOOD III (HRIII) experiment series in New Mexico provides a unique dataset to study surface‐wave generation from Explosions conducted above and Underground for different rock types. Four 90.6 kg trinitrotoluene‐equivalent Explosions were detonated either at 2 m height‐of‐burst (HOB) or 7 m depth‐of‐burial (DOB) at separate alluvium and limestone test sites. For the alluvium site, data from a temporary seismoacoustic network show that fundamental‐mode surface waves (![Graphic][1] ) from the 7 m DOB in‐alluvium shot were four to five times larger than the above‐alluvium shot. The ![Graphic][2] amplitudes from the 7 m DOB limestone shot were 15 times larger than ![Graphic][3] recorded from the collocated 2 m HOB shot. To model these differences in ![Graphic][4] , we generated 1D velocity models for both test sites using observed surface‐wave dispersion. We considered two different methods for synthetic seismogram generation. For the aboveground shots, we have coupled near‐field blast wave pressures and shapes with source medium properties to model seismic data at distance. For the Underground shots, we use explosion source theory to estimate a moment for scaling explosion synthetics. For both above and Underground shots, the synthetics provide excellent fits to the observed 1–5 Hz ![Graphic][5] data. This modeling provides a viable technique to predict peak particle velocities for surface and aboveground Explosions in different rock types that can be used to estimate combined seismoacoustic yields. Online Material: Movies of four Explosions studied in this paper. [1]: /embed/inline-graphic-1.gif [2]: /embed/inline-graphic-2.gif [3]: /embed/inline-graphic-3.gif [4]: /embed/inline-graphic-4.gif [5]: /embed/inline-graphic-5.gif
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rg excitation by Underground Explosions insights from source modelling the 1997 kazakhstan depth of burial experiment
Geophysical Journal International, 2005Co-Authors: Howard J Patton, Jessie L Bonner, Indra N GuptaAbstract:SUMMARY Near-field seismograms of chemical Explosions detonated as part of the 1997 depth-of-burial (DOB) experiment at the former Semipalatinsk nuclear test site provide an excellent opportunity to study the excitation of Rg waves for source effects. Rg wave sw ere identified with particle-motion analysis and isolated from other arrivals using group velocity filtering. Amplitude and phase spectra of Rg wave sw ere corrected for path effects based on observed attenuation in the near-field and path-specific phase velocity models. The path-corrected spectra were inputs to a grid-search method for finding source parameters of an axisymmetric source consisting of a monopole plus a compensated linear vector dipole (CLVD) or a horizontal tensile crack. The suite of observations, including ground-zero accelerograms and geophysical data from borehole logs, are best satisfied by models involving a CLVD with static (zero-frequency) seismic moment Mo. The CLVD source is related to tensile failure occurring at depths above the shotpoint. A static Mo distinguishes this source from classical models of spall, which are usually characterized by horizontal cracks that dynamically open and close with no permanent displacement (i.e. no static Mo). The CLVD source in this study appears to be more closely related to a driven block motion model envisaged by Masse. Rg source amplitudes are consistent with mb(Lg) measurements at station MAK, as would be expected if near-field Rg-to-S scattering plays a role in generating S waves observed at regional distances.
Howard J Patton - One of the best experts on this subject based on the ideXlab platform.
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a digital seismogram archive of nuclear explosion signals recorded at the borovoye geophysical observatory kazakhstan from 1966 to 1996
GeoResJ, 2015Co-Authors: Vadim A An, Howard J Patton, V M Ovtchinnikov, Pyotr B Kaazik, Vitaly V Adushkin, Inna N Sokolova, Iraida B Aleschenko, Natalya Mikhailova, Paul G Richards, Scott W PhillipsAbstract:Abstract Seismologists from Kazakhstan, Russia, and the United States have rescued the Soviet-era archive of nuclear explosion seismograms recorded at Borovoye in northern Kazakhstan during the period 1966–1996. The signals had been stored on about 8000 magnetic tapes, which were held at the recording observatory. After hundreds of man-years of work, these digital waveforms together with significant metadata are now available via the project URL, namely http://www.ldeo.columbia.edu/res/pi/Monitoring/Data/ as a modern open database, of use to diverse communities. Three different sets of recording systems were operated at Borovoye, each using several different seismometers and different gain levels. For some Explosions, more than twenty different channels of data are available. A first data release, in 2001, contained numerous glitches and lacked many instrument responses, but could still be used for measuring accurate arrival times and for comparison of the strengths of different types of seismic waves. The project URL also links to our second major data release, for nuclear Explosions in Eurasia recorded in Borovoye, in which the data have been deglitched, all instrument responses have been included, and recording systems are described in detail. This second dataset consists of more than 3700 waveforms (digital seismograms) from almost 500 nuclear Explosions in Eurasia, many of them recorded at regional distances. It is important as a training set for the development and evaluation of seismological methods of discriminating between earthquakes and Underground Explosions, and can be used for assessment of three-dimensional models of the Earth’s interior structure.
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rg excitation by Underground Explosions insights from source modelling the 1997 kazakhstan depth of burial experiment
Geophysical Journal International, 2005Co-Authors: Howard J Patton, Jessie L Bonner, Indra N GuptaAbstract:SUMMARY Near-field seismograms of chemical Explosions detonated as part of the 1997 depth-of-burial (DOB) experiment at the former Semipalatinsk nuclear test site provide an excellent opportunity to study the excitation of Rg waves for source effects. Rg wave sw ere identified with particle-motion analysis and isolated from other arrivals using group velocity filtering. Amplitude and phase spectra of Rg wave sw ere corrected for path effects based on observed attenuation in the near-field and path-specific phase velocity models. The path-corrected spectra were inputs to a grid-search method for finding source parameters of an axisymmetric source consisting of a monopole plus a compensated linear vector dipole (CLVD) or a horizontal tensile crack. The suite of observations, including ground-zero accelerograms and geophysical data from borehole logs, are best satisfied by models involving a CLVD with static (zero-frequency) seismic moment Mo. The CLVD source is related to tensile failure occurring at depths above the shotpoint. A static Mo distinguishes this source from classical models of spall, which are usually characterized by horizontal cracks that dynamically open and close with no permanent displacement (i.e. no static Mo). The CLVD source in this study appears to be more closely related to a driven block motion model envisaged by Masse. Rg source amplitudes are consistent with mb(Lg) measurements at station MAK, as would be expected if near-field Rg-to-S scattering plays a role in generating S waves observed at regional distances.
O Vorobiev - One of the best experts on this subject based on the ideXlab platform.
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cavity radius scaling for Underground Explosions in hard rock
Bulletin of the Seismological Society of America, 2016Co-Authors: Anastasia Stroujkova, Mario Carnevale, O VorobievAbstract:The main objective of this study was to examine the relationship between the explosive yield and the cavity sizes for chemical Explosions in granite. We performed borehole studies in the two cavities produced by chemical Explosions in Vermont, including the caliper, acoustic, and optical televiewer logs. The two irregularly shaped explosive cavities imaged during this study have the equivalent scaled radii of 8.26 and 8.34 m/kt1/3. Comparison of the cavity radii, determined in this study, with historical data from other chemical and nuclear Explosions in hard rock (e.g., granite) demonstrates that the cavity radius as a function of yield obeys cube root scaling law. The empirical linear fit calculated for the nuclear cavity radii as a function of yield also provides a good approximation for the chemical cavity radii, even though the mechanisms responsible for the creation of cavities during chemical and nuclear shots are different. The depth dependence of the cavity size in hard rock appears to be weaker than proposed by the classical source theory, although there is not enough data to unambiguously resolve the depth dependence. The experimental field measurements of the cavity sizes (determined from geophysical log measurements) agree with the numerical simulations using the hydrodynamic code GEODYN (Antoun et al. , 2000; Lomov et al. , 2005), which confirm approximate cube root scaling with yield assuming that the quality of the rock mass is similar for all events. Online Material: Composite logs for the boreholes S1‐3, S2‐2, and S2‐4.
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Simulation of Seismic Waves from Underground Explosions in Geologic Media: FY2009 Progress Report
2009Co-Authors: A Rodgers, Bjorn Sjogreen, O Vorobiev, N A PeterssonAbstract:This report summarizes work done after one year on project LL09-Sim-NDD-02 entitled 'Exploratory Research: Advanced Simulation of Low Yield Underground Nuclear Explosions To Improve Seismic Yield Estimation and Source Identification'. Work on this effort proceeded in two thrusts: (1) parametric studies of Underground explosion generated motions with GEODYN; and (2) coupling of GEODYN to WPP. GEODYN is a code for modeling hydrodynamic (shock-wave) motions in a wide variety of materials, including earth materials. WPP is an anelastic finite difference code for modeling seismic motions. The sensitivity of seismic motions to emplacement conditions was investigated with a series of parametric studies of low-yield (0.2-4 kiloton) chemical high-explosive shots at a range of burial depths in four canonical geologic media (granite, limestone, tuff and alluvium). Results indicate that the material has a strong impact on the seismic motions consistent with previous reports. Motions computed with GEODYN in realistically complex material models are very consistent with reported motions from nuclear tests by Perret and Bass (1975). The amplitude, frequency content and cavity size resulting from Explosions are all strongly sensitive to the material strength. Explosions in high-strength (granite) resulted in the highest amplitude, shortest duration pulse and smallest cavities, whereas Explosions in low-strength more » material (alluvium) resulted in the lowest amplitudes, longest duration pulse and larger cavities. The corner frequencies of P-wave motions at take-off angles corresponding to propagation to teleseismic distances show corresponding behavior, with high-strength materials having the highest corner frequency and low-strength materials having low corner frequency. Gravity has an important effect on the cavity size and outgoing motions due work done against lithostatic stress. In fact without gravity the cavity radius and elastic motions are largely insensitive to depth of burial. We investigated the effects of depth of burial for a given yield and material model in the presence of gravity and found that the cavity radius is slightly smaller for deeper shots and the resulting motions have shorter duration and higher corner frequency compared to shallower shots. On the second thrust, progress has been made on one-way coupling of GEODYN to WPP. Early in the project we demonstrated this capability from one-dimensional (1D) GEODYN calculations. We have now completed the capability to pass motions computed in 2D or 3D with GEODYN to WPP and propagated (in 3D) to large distances. « less
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Simulation of Seismic Waves from Underground Explosions in Geologic Media: FY2009 Progress Report
Lawrence Livermore Report, 2009Co-Authors: Arthur J. Rodgers, Bjorn Sjogreen, O Vorobiev, N A PeterssonAbstract:This report summarizes work done after one year on project LL09-Sim-NDD-02 entitled “Exploratory Research: Advanced Simulation of Low Yield Underground Nuclear Explosions To Improve Seismic Yield Estimation and Source Identification”. Work on this effort proceeded in two thrusts: 1) parametric studies of Underground explosion generated motions with GEODYN; and 2) coupling of GEODYN to WPP. GEODYN is a code for modeling hydrodynamic (shock-wave) motions in a wide variety of materials, including earth materials. WPP is an anelastic finite difference code for modeling seismic motions. The sensitivity of seismic motions to emplacement conditions was investigated with a series of parametric studies of low-yield (0.2-4 kiloton) chemical high-explosive shots at a range of burial depths in four canonical geologic media (granite, limestone, tuff and alluvium). Results indicate that the material has a strong impact on the seismic motions consistent with previous reports. Motions computed with GEODYN in realistically complex material models are very consistent with reported motions from nuclear tests by Perret and Bass (1975). The amplitude, frequency content and cavity size resulting from Explosions are all strongly sensitive to the material strength. Explosions in high-strength (granite) resulted in the highest amplitude, shortest duration pulse and smallest cavities, whereas Explosions in low-strength material (alluvium) resulted in the lowest amplitudes, longest duration pulse and larger cavities. The corner frequencies of P-wave motions at take-off angles corresponding to propagation to teleseismic distances show corresponding behavior, with high-strength materials having the highest corner frequency and low-strength materials having low corner frequency. Gravity has an important effect on the cavity size and outgoing motions due work done against lithostatic stress. In fact without gravity the cavity radius and elastic motions are largely insensitive to depth of burial. We investigated the effects of depth of burial for a given yield and material model in the presence of gravity and found that the cavity radius is slightly smaller for deeper shots and the resulting motions have shorter duration and higher corner frequency compared to shallower shots. On the second thrust, progress has been made on one-way coupling of GEODYN to WPP. Early in the project we demonstrated this capability from one-dimensional (1D) GEODYN calculations. We have now completed the capability to pass motions computed in 2D or 3D with GEODYN to WPP and propagated (in 3D) to large distances.
Yu O Vorobiev - One of the best experts on this subject based on the ideXlab platform.
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two sources of nonisotropic radiation from Underground Explosions in granite
Journal of Geophysical Research, 2017Co-Authors: Yu O VorobievAbstract:Significant tangential ground motion observed during Underground Explosions makes it difficult to distinguish them from natural earthquakes. Such motion can be generated by the source geometry and emplacement conditions, by the heterogeneous nature of the rock mass (mechanical properties may vary in space due to the presence of cracks, joints, faults, and various geologic layers) and also by the nonuniform in situ stress state. The last mechanism is increasingly important with depth when the difference in main principal stresses becomes significant. This paper is focused on the role of material strength of the rock mass in generation of nonradial motion during Explosions in prestressed media. Numerical modeling of Underground chemical Explosions in granite at various depths has been conducted to compare two possible mechanisms of shear wave generation. The first, caused by rock mass anisotropy, is important at shallow depth. The second is related to elastic-plastic relaxation around the cavity created by the explosion. As a result, tangential motions for these two mechanisms have different signatures.
