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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.
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.
Author: Goran Ekstrom Publisher: Birkhäuser ISBN: 3034883102 Category : Science Languages : en Pages : 426
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.
Author: Anatoli L. Levshin Publisher: Springer Science & Business Media ISBN: 9783764365516 Category : Science Languages : en Pages : 260
Book Description
On September 1996, the United Nations General Assembly adopted the Comprehensive Nuclear-Test-Ban Treaty (CTBT), prohibiting nuclear explosions worldwide, in all environments. The treaty calls for a global verification system, including a network of 321 monitoring stations distributed around the globe, a data communications network, an international data center (IDC), and on-site inspections to verify compliance. Seismic methods play the lead role in monitoring the CTBT. This volume concentrates on the measurement and use of surface waves in monitoring the CTBT. Surface waves have three principal applications in CTBT monitoring: to help discriminate nuclear explosions from other sources of seismic energy, to provide mathematical characterizations of the seismic energy that emanates from seismic sources, and to be used as data in inversion for the seismic velocity structure of the crust and uppermost mantle for locating small seismic events regionally. The papers in this volume fall into two general categories: the development and/or application of methods to summarize information in surface waves, and the use of these summaries to advance the art of surface-wave identification, measurement, and source characterization. These papers cut across essentially all of the major applications of surface waves to monitoring the CTBT. This volume therefore provides a general introduction to the state of research in this area and should be useful as a guide for further exploration.
Author: Eystein S. Husebye Publisher: Springer Science & Business Media ISBN: 9400985312 Category : Science Languages : en Pages : 867
Book Description
The subject of this NATO Advanced Study Institute was seismic monitoring under a nuclear test ban - an application of scienti fic knowledge and modern technology for a political purpose. The international political objective of a comprehensive nuclear test ban provided in turn the motivation for our technical and scientific discussions. In order to obtain a historical perspec tive on the progress of the work towards a comprehensive test-ban treaty (CTB), it is necessary to go back to 1958, when a confer ence of scientific experts in Geneva made the first steps toward an international seismic monitoring system. However, agreement on actual capabilities of a monitoring system for verifying compliance with such a treaty was not achieved, and thus the conference did not lead to immediate political results. After the Partial Test Ban Treaty of 1963, which banned nuclear explosions in the atmosphere, outer space and under the seas, renewed interest in the seismological verification of a CTB took place. A number of countries initiated large-scale research efforts toward detecting and identifying underground nuclear explosions, and it was in this context that the large aperture seismic arrays NORSAR and LASA were established. This type of development resulted in excellent seismic data in digital form and was thus of great irnprotance to the seismological com munity.
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Author: P. G. Richards
Author: Goran Ekstrom
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Author: Anatoli L. Levshin
Author: Eystein S. Husebye
Author: Joseph M. Harrer
Author: United States. Arms Control and Disarmament Agency
Author: United States. Arms Control and Disarmament Agency