Amplitudes and energies of primary seismic waves near the hardhat, haymaker, and shoal nuclear explosions

1966 ◽  
Vol 56 (3) ◽  
pp. 643-653 ◽  
Author(s):  
Lynn D. Trembly ◽  
Joseph W. Berg
Keyword(s):  
Theoretical Model ◽  
Seismic Waves ◽  
Theoretical Data ◽  
Source Model ◽  
Similar Data ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Long Period ◽  
Radiation Fields ◽  
Amplitude Data

abstract Records of near-source (0.3 to 20 km) primary seismic waves generated by the Hardhat, Haymaker, and Shoal underground nuclear explosions were analyzed in terms of displacement amplitude and energy variations with distance. The observed data were compared to similar data from a theoretical source model to determine the adequacy of the theoretical model. There was evidence that a long-period displacement field existed near the explosions as predicted by the theoretical source. Scatter in the observed amplitude data made it difficult to distinguish between the long-period and the radiation fields. However, the variation of total energy of the observed primary seismic waves with distance showed the presence of the long-period field. The comparison of observed and theoretical data indicates that a theoretical elastic source model approximated the observed sources.

Evidence of tectonic release from underground nuclear explosions in long-period P waves

1983 ◽  
Vol 73 (2) ◽  
pp. 593-613
Author(s):  
Terry C. Wallace ◽  
Donald V. Helmberger ◽  
Gladys R. Engen
Keyword(s):  
Upper Mantle ◽  
High Stress ◽  
Test Site ◽  
Strike Slip ◽  
Body Waves ◽  
Release Time ◽  
P Waves ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Long Period

abstract In this paper, we study the long-period body waves at regional and upper mantle distances from large underground nuclear explosions at Pahute Mesa, Nevada Test Site. A comparison of the seismic records from neighboring explosions shows that the more recent events have much simpler waveforms than those of the earlier events. In fact, many of the early events produced waveforms which are very similar to those produced by shallow, moderate-size, strike-slip earthquakes; the phase sP is particularly obvious. The waveforms of these explosions can be modeled by assuming that the explosion is accompanied by tectonic release represented by a double couple. A clear example of this phenomenon is provided by a comparison of GREELEY (1966) and KASSERI (1975). These events are of similar yields and were detonated within 2 km of each other. The GREELEY records can be matched by simply adding synthetic waveforms appropriate for a shallow strike-slip earthquake to the KASSERI observations. The tectonic release for GREELEY has a moment of 5 ՠ1024 dyne-cm and is striking approximately 340°. The identification of the sP phase at upper mantle distances indicates that the source depth is 4 km or less. The tectonic release time function has a short duration (less than 1 sec). A comparison of these results with well-studied strike-slip earthquakes on the west coast and eastern Nevada indicate that, if tectonic release is triggered fault motion, then the tectonic release is relatively high stress drop, on the order of several hundred bars. It is possible to reduce these stress drops by a factor of 2 if the tectonic release is a driven fault; i.e., rupturing with the P velocity. The region in which the stress is released for a megaton event has a radius of about 4 km. Pahute Mesa events which are detonated within this radius of a previous explosion have a substantially reduced tectonic release.

Earthquakes and faults

1963 ◽  
Vol 53 (5) ◽  
pp. 873-891 ◽  
Author(s):  
F. F. Evison
Keyword(s):  
Seismic Waves ◽  
Surface Phenomenon ◽  
Local Phase ◽  
Fault Creep ◽  
Satisfactory Explanation ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Shallow Earthquakes ◽  
Deep Focus ◽  
Natural Earthquakes

Abstract The hypothesis that earthquakes are caused by faulting has been prominent in seismological theory for half a century, but continues to present many difficulties. Although the chief support comes from studies of large shallow earthquakes that have been accompanied by surface faulting, the evidence given by these infrequent events can be interpreted otherwise. No satisfactory explanation of deep-focus earthquakes has emerged; sudden faulting may be essentially a surface phenomenon. Nor does the hypothesis aid the understanding of such phenomena as sudden regional uplift, or slow fault creep. There is much to encourage the view that fracture of the ground is but a gross form of earthquake damage. On the other hand, the similarity between natural earthquakes and underground nuclear explosions, as radiators of seismic waves, suggests that sudden local phase transitions may provide a source mechanism for earthquakes at all depths.

P-wave coupling of underground nuclear explosions

1966 ◽  
Vol 56 (4) ◽  
pp. 861-876 ◽  
Author(s):  
Donald L. Springer
Keyword(s):  
P Wave ◽  
Propagation Path ◽  
Seismic Signals ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Scaling Relationships ◽  
Amplitude Data ◽  
Detonation Energy ◽  
Relationship Of ◽  
The Relationship

abstract P-wave amplitude data for underground nuclear explosions are correlated with detonation energy. Amplitudes are reproducible to 25 per cent when source media and propagation path differences are minimized. These data verify theoretical scaling relationships and establish relative coupling for various shot media. An empirical correlation of these amplitude data with dry porosity of the detonation medium indicates that a medium with 60 per cent dry porosity may couple explosive energy one-fourth or one-fifth as efficiently as does alluvium. The relationship of teleseismic magnitude to explosive yield for various types of low coupling shows that dry porous media give a significant reduction of seismic signals generated by underground nuclear explosions.

Long-Period Seismic Waves from Nuclear Explosions in Various Environments

Science ◽  
1960 ◽  
Vol 131 (3416) ◽  
pp. 1804-1805 ◽  
Author(s):  
Jack Oliver ◽  
Paul Pomeroy ◽  
Maurice Ewing
Keyword(s):  
Solid Earth ◽  
Seismic Waves ◽  
Upper Atmosphere ◽  
Nuclear Explosions ◽  
Long Period

Large nuclear explosions in the solid earth, the hydrosphere, and the lower and upper atmosphere have generated seismic waves of periods greater than about 5 seconds which have been detected at great distances from the source.

Synthesis of nonstationary seismic signals

1970 ◽  
Vol 60 (5) ◽  
pp. 1615-1624 ◽  
Author(s):  
Paul R. Beaudet
Keyword(s):  
Seismic Waves ◽  
Radial Component ◽  
Synthetic Seismograms ◽  
Time Varying ◽  
Analog Filter ◽  
Stationary Characteristic ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Wide Range ◽  
Noise Input

Abstract Synthetic seismograms are a powerful tool which can be used to approximate the complex signature which an inhomogeneous, anisotropic, and imperfectly elastic Earth imparts to seismic waves generated by underground nuclear detonations. The concept and design of a time-varying analog filter for generating synthetic seismograms which approximate real seismograms observed from underground nuclear explosions have been developed. The basic design of this filter exploits a non-stationary characteristic commonly observed on seismograms, the gradual increase of period with time. The parameters of the time-varying analog filter were determined on the basis of the characteristics of the radial component of 50 seismograms recorded from underground nuclear detonations encompassing a wide range of yields (80 to 1000 kt) and distances (50 to 550 km) from the detonation. These parameters determine the time-varying response of the analog filter to a white noise input. The comparison of the spectra of synthetic and real seismograms indicates that the synthetic seismograms generated with the time-varying analog filter are close approximations to real seismograms having equivalent yield and range parameters.

Review of seismic source models for underground nuclear explosions

1981 ◽  
Vol 71 (4) ◽  
pp. 1249-1268 ◽  
Author(s):  
Robert P. Massé
Keyword(s):  
Seismic Source ◽  
Source Model ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Thrust Faulting ◽  
Seismic Source Models ◽  
Regional Source ◽  
Source Models ◽  
Strain Release ◽  
Wave Conversion

abstract A number of seismic source models for underground nuclear explosions have been developed over the past 2 decades. These models include the spherically symmetric compressional source model, the wave conversion source model, the tectonic strain release source model, the spall slapdown source model, and the near-regional source model. These model are reviewed in this study and are shown to be inconsistent with various geophysical data associated with underground nuclear explosions. In particular, the Rayleigh and Love wave signals generated by underground nuclear explosions have not been explained satisfactorily by any of these source models. To explain the observed explosion data, it may be necessary to model the explosion seismic source as a sequence of mechanisms producing seismic signals. These mechanisms all act within the first few seconds following the explosion detonation. One of the most important of these mechanisms is probably explosion-induced thrust faulting.

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