Download or read book Effects of Depth of Burial and Tectonic Strain Release on Regional and Teleseismic Explosion Waveforms written by and published by . This book was released on 1988 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: The seismic motions from nonlinear two dimensional (2D) axisymmetric finite difference calculations of underground explosions are propagated to regional and teleseismic distances. Synthetic seismograms are computed and examined to study the effects of depth of burial, medium structure, and prestress on seismic waveforms. The elastodynamic representation theorem is used to couple the results of finite difference source calculations to regional Green's functions computed using a wavenumber integration algorithm. The 2D finite difference source calculations include the nonlinear effects of gravity, spall, bulking, and cracking as well as the finite extent and divergence from spherical symmetry. The results are broadband full wave regional synthetics for explosion sources with cylindrical symmetry. These theoretical seismograms are studied with regard to proposed regional discriminants between explosions and earthquakes. Explosions, Tectonic release, Depth, Burial, Finite differences, Seismic waveforms.
Download or read book Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1989-06 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cities and Their Vital Systems written by Advisory Committee on Technology and Society and published by National Academies Press. This book was released on 1989 with total page 1298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cities and Their Vital Systems asks basic questions about the longevity, utility, and nature of urban infrastructures; analyzes how they grow, interact, and change; and asks how, when, and at what cost they should be replaced. Among the topics discussed are problems arising from increasing air travel and airport congestion; the adequacy of water supplies and waste treatment; the impact of new technologies on construction; urban real estate values; and the field of "telematics," the combination of computers and telecommunications that makes money machines and national newspapers possible.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Time Domain Study of Tectonic Strain Release Effects on Seismic Waves from Underground Nuclear Explosions written by K. K. Nakanishi and published by . This book was released on 1982 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Near Source Contributions to Teleseismic P Wave Coda and Regional Phases written by and published by . This book was released on 1991 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents the results of an investigation of near-source effects on teleseismic P-wave and early P-wave coda spectra for underground explosions. The underlying objective of this research has been to determine whether the differential behavior of P and P coda can be exploited to remotely determine near-source properties such as overburden velocity, burial depth, and degree of saturation. The report also contains a review paper on the pP phase, focussed on assessing the various methodologies that have been used to determine pP parameters and trying to reconcile the existing discrepancies in various estimates. The final section of the report is an encyclopedia article on the role of seismological monitoring of nuclear testing treaties. Energy radiated upward from underground nuclear explosions has a complex interaction with the free surface that strongly influences the seismic wavefields recorded at teleseismic and regional distances. This interaction, differing from that for earthquakes primarily due to the much higher strains and strain rates involved, is essential to understand for both explosion yield estimation and event discrimination. Reflection of explosion P wave energy from the free surface, which produces the pP phase, involves frequency-dependent, non-linear processes that are intimately linked to surface spallation.
Download or read book Nonlinear Modeling of Tectonic Release from Underground Explosions written by and published by . This book was released on 1982 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Explosion Source Phenomenology written by Steven R. Taylor and published by American Geophysical Union. This book was released on 1991-01-08 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 65. In March 1989, the Department of Energy (DOE) and the Lawrence Livermore National Laboratory (LLNL) sponsored a symposium on Explosion Source Phenomenology at Lake Tahoe, California. The purpose was to summarize the state of knowledge of the underground explosion source, based on U.S. experience at the Nevada Test Site (NTS). Specifically, the goals were to summarize knowledge of the explosion source, to identify limits of that knowledge and existing problems, and to propose directions of future research and data?]collection efforts.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1989 with total page 944 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Analysis of the Effects of Tectonic Release on Short Period P Waves Observed from Shagan River Explosions written by Brian W. Barker and published by . This book was released on 1987 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book U S National Report to International Union of Geodesy and Geophysics 1987 1990 written by and published by . This book was released on 1991 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface wave Generation by Underground Nuclear Explosions Releasing Tectonic Strain written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic surface-wave generation by underground nuclear explosions releasing tectonic strain is studied through a series of synthetic radiation-pattern calculations based on the earthquake-trigger model. From amplitude and phase radiation patterns for 20-s Rayleigh waves, inferences are made about effects on surface-wave magnitude, M/sub s/, and waveform character. The focus of this study is a comparison between two mechanisms of tectonic strain release: strike-slip motion on vertical faults and thrust motion on 45° dipping faults. The results of our calculations show that Rayleigh-wave amplitudes of the dip-slip model at F values between 0.75 and 1.5 are significantly lower than amplitudes of the strike-slip model or of the explosion source alone. This effect translates into M/sub s/ values about 0.5 units lower than M/sub s/ of the explosion alone. Waveform polarity reversals occur in two of four azimuthal quadrants for the strike-slip model and in all azimuths of the dip-slip-thrust model for F values above about 3. A cursory examination of waveforms from presumed explosions in eastern Kazakhstan suggests that releases of tectonic strain are accompanying the detonation of many of these explosions. Qualitatively, the observations seem to favor the dip-slip-thrust model, which, in the case of a few explosions, must have F values above 3.
Download or read book Government Reports Annual Index written by and published by . This book was released on 1989 with total page 1672 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Tectonic Release on Broadband Regional Distance Bodywaves written by Terry C. Wallace and published by . This book was released on 1987 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the distortion of explosion long-period waves is documented at upper mantle distances, the signature is much more subtle at regional and near-field distances. We document the robustness of the observation of sP in underground nuclear explosions waveforms of events which have large F factors. Although 'slapdown' has not been added to the synthetic, seismograms, the strong azimuthal variation can be explained by the simple addition of a double couple (tectonic release). We also calibrate the size of tectonic release for 18 Pahute Mesa events by comparing their SH waves with those of two western United States earthquakes. In general, the signature of tectonic release appears to be strongly frequency-dependent. We performed a moment tensor inversion at three Pahute Mesa events (CHESIRE, FARM and POOL) in different frequency bands in an attempt to isolate the 'dispersion' of the deviatoric component of the moment tensor. Although the apparent size of tectonic release source decreases, the orientation appears to be constant. The moments of the tectonic release at regional distance also are inconsistent with near-field estimates. We developed a model for near-field tectonic release, which requires a distributed source (shear dislocation takes place at the elastic radius). Using BOXCAR and HALFBREAK waveforms, we performed a constrained moment tensor inversion to obtain the tectonic release orientation. This near-field orientation is in excellent agreement with the far-field results.
Download or read book Modeling Teleseismic SV Waves from Underground Explosions with Tectonic Release written by Brian P. Cohee and published by . This book was released on 1987 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book U S National Report 1987 1990 written by and published by . This book was released on 1991 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993-02 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
