Author: Brian P. CoheePublisher:
ISBN:
Category : Seismic waves
Languages : en
Pages : 44
Book Description
Modeling Teleseismic SV Waves from Underground Explosions with Tectonic Release
Author: Brian P. CoheePublisher:
ISBN:
Category : Seismic waves
Languages : en
Pages : 44
Book Description
Analysis of Teleseismic P Wave Amplitude and Coda Variations for Underground Explosions
Author: Thorne LayPublisher:
ISBN:
Category :
Languages : en
Pages : 127
Book Description
This report presents the results of four investigations which have as their common goal, the development and application of techniques for determining near-source contributions to the observed variations in short-period P wave amplitudes, travel times, waveforms and coda for underground explosions. A waveform modeling analysis of long-period teleseismic SH and SV waves from two large underground explosions at the Southern Novaya Zemlya test site indicates that the appropriate equivalent double couple orientation for the tectonic release is vertical strike slip. complete waveform modeling of the SV signals using the method of Baag and Langston allows us to distinguish between the strike slip and 45 deg. dipping thrust geometries. The resulting mechanism and associated F-factors indicate that teleseismic P waves from these events are probably not strongly affected by tectonic release radiation, consistent with the previous coda and P wave amplitude analysis we conducted under our previous contract. (rh).
Nonlinear Modeling of Tectonic Release from Underground Explosions
Author: Publisher:
ISBN:
Category : Blast effect
Languages : en
Pages : 84
Book Description
Reversal of teleseismic Rayleigh wave polarity has been observed for some underground explosions in eastern Kazakh, and in some cases the polarity is reversed at all azimuths of observation. We analyze two-dimensional, nonlinear numerical simulations of underground explosions to examine the hypothesis that these phase reversals result from the action of tectonic prestress on the explosion-created nonlinear volume. We conclude that the effect of tectonic prestress on surface wave excitation is potentially large. When a shear prestress of 7.5 MPa (75 bars) is introduced, with horizontal principal stresses more compressive than the vertical principal stress, the explosion Rayleigh wave amplitude is reduced by a factor of 4 (i.e., Ms is reduced by 0.6). The large surface wave reduction is accompanied by no significant perturbation of body wave magnitude (mb). The nonlinear model predictions imply that if tectonic release is modeled elastically as the relaxation of the deviatoric part of the prestress into a spherical cavity, the appropriate cavity radius is approximately 80 percent of the explosion elastic radius.
An Analysis of the Effects of Tectonic Release on Short-Period P Waves Observed from Shagan River Explosions
Author: Brian W. BarkerPublisher:
ISBN:
Category :
Languages : en
Pages : 65
Book Description
Large samples of teleseismic P wave amplitude and waveform data recorded from Shagan River underground explosions have been collected and systematically analyzed in an attempt to identify any effects which may correlate with the amount of tectonic release accompanying these explosions. Results of these analyses indicate that these teleseismic P wave data do not provide any unambiguous evidence of effects of tectonic release in the short-period range of interest in m sub b determination. However, the results of a preliminary theoretical analysis indicate that such negative evidence is not definitive in that there are plausible models of tectonic release for which no detectable variations in the observed teleseismic P waveforms are theoretically expected to result from the superposition of these two sources. At the same time, such models of tectonic release predict significant positive bias in the network-averaged m sub b values for explosions accompanied by the mode of tectonic release traditionally associated with the Shagan River test site. Thus, the currently available seismic data do not exclude the possibility that tectonic release may be introducing a positive bias of as much as several tenths of a magnitude unit into the network-averaged m sub b values computed for some Shagan River explositons. Keywords: Explosion seismology; Threshold Test Ban Treaty; Network; USSR; Global Digital Seismic; Seismic body waves; Nuclear explosion detection; Radiation patterns.
Energy Research Abstracts
Author: Energy Research Abstracts
Author: Induced Seismic Events
Author: Peter KnollPublisher: Birkhäuser
ISBN: 3034892047
Category : Science
Languages : en
Pages : 227
Book Description
Induced seismic events are of high scientific and economic significance. They are the result of human activities interacting with regional and local tectonics, changing the local crustal stress state by mining, extraction of rock masses, injection of fluids into the rock massif, and by changing the surface loading and pore pressure state near large reservoirs. Within Europe the study of induced seismic events has a long tradition and international scientific organizations have actively stimulated the co-operation in this field. During its General Assembly in September 1994, the European Seismological Society organized the symposium "Induced Seismic Events". The focus of this symposium was concentrated on induced events in central and eastern Europe, as well as in the former Soviet Union. The major contributions to the symposium, and also some Chinese, Canadian, and South African results are presented here. Case studies as well as data analyses and methodological studies are included. Seismologists and specialists working in the field of geohazard prevention will find much information in this volume that is pertinent to their work.
Simulation of Teleseismic Body Waves from Underground Explosions Beneath Sloping and Flat Surfaces Using Nonlinear Axisymmetric Finite Difference Calculations
Author: J. L. StevensPublisher:
ISBN:
Category : Detonation waves
Languages : en
Pages : 57
Book Description
Monitoring the Comprehensive Nuclear-Test-Ban Treaty: Source Processes and Explosion Yield Estimation
Author: Goran EkstromPublisher: Springer Science & Business Media
ISBN: 9783764365523
Category : Science
Languages : en
Pages : 444
Book Description
Pure appl. geophys., by 161 nations. Entry of the treaty into force, however, is still uncertain since it requires ratification by all 44 nations that have some nuclear capability and, as of 15 June 2001, only 31 of those nations have done so. Although entry of the CTBT into force is still uncertain, seismologists and scientists in related fields, such as radionuclides, have proceeded with new research on issues relevant to monitoring compliance with it. Results of much of that research may be used by the International Monitoring System, headquartered in Vienna, and by several national centers and individual institutions, to monitor compliance with the CTBT. New issues associated with CTBT monitoring in the 21st century have presented scientists with many new challenges. They must be able to effectively monitor com pliance by several countries that have not previously been nuclear powers. Effective monitoring requires that we be able to detect and locate much smaller nuclear events than ever before and to distinguish them from small earthquakes and other types of explosions. We must have those capabilities in regions that are seismically active and geologically complex, and where seismic waves might not propagate efficiently.
Body and Surface Wave Modeling of Observed Seismic Events
Author: D. G. HarkriderPublisher:
ISBN:
Category : Earthquake simulators
Languages : en
Pages : 113
Book Description
Contents: A Generalized Reflection - Transmission Coefficient Matrix and Discrete Wavenumber Method for Synthetic Seismograms; Body Wave Amplitude and Travel Time Correlations across North America; and Evidence of Tectonic Release from Underground Nuclear Explosions in Long-period P-waves.