Source comparisons between nuclear and chemical explosions detonated at Rainier Mesa, Nevada Test Site

1999 ◽  
Vol 89 (2) ◽  
pp. 409-422 ◽  
Author(s):  
Brian W. Stump ◽  
D. Craig Pearson ◽  
Robert E. Reinke
Keyword(s):  
Source Region ◽  
Spectral Ratio ◽  
Test Site ◽  
Source Model ◽  
Transverse Component ◽  
Propagation Path ◽  
Cube Root ◽  
Nevada Test Site ◽  
Spectral Difference ◽  
Receiver Array

Abstract A series of nuclear [MINERAL QUARRY (MQ), HUNTERS TROPHY (HT)] and chemical [NON-PROLIFERATION EXPERIMENT (NPE) and NPECAL] explosions were detonated in the same geological material at Rainier Mesa, Nevada Test Site. These sources were extensively instrumented with the same near-source, free-surface instrumentation array. The data from these explosions allow the establishment of empirical source scaling relations as well as investigation of possible chemical and nuclear source differences. Even in the near-source region at common receivers, the data display propagation path effects resulting from slight differences in source locations. These effects are effectively taken into account by smoothing the source comparisons across the different stations in the receiver array. As many as 30 individual waveforms from each source are used in this smoothing process. Comparison of HT and NPE at near-source distances indicates that within the bandwidth of the data (0.36 to 100 Hz), there is no apparent spectral difference between the nuclear and single-fired chemical source. The smoothed spectral ratio between the NPE and NPE CAL is consistent with the long-period source spectral difference (104), corner frequencies (2 to 3 Hz/NPE and 40 to 60 Hz/NPE CAL), and high-frequency decay (ƒ−2) similar to the Mueller-Murphy source model for wet tuff after modifying the cavity radius to scale as the cube root of yield. Comparison of the two nuclear sources, HT and MQ, indicates that at long periods, the HT/MQ ratio is 0.4 to 0.6 with the spectra from the two explosions merging above 5 Hz, which is consistent with the 0.3 magnitude difference observed for the two sources. In all the source comparisons, the spectral ratios of the transverse components of motion are indistinguishable from those produced by either the vertical or radial components. This fact argues that the transverse component of motion from an explosion is generated at very close-in distances, in this case on the order of 1 to 2 km. These observations are in agreement with some type of linear scattering mechanism.

A multipole representation of earthquake source mechanisms

1973 ◽  
Vol 63 (1) ◽  
pp. 211-225
Author(s):  
F. Richard Yeatts
Keyword(s):  
Test Site ◽  
Multipole Expansion ◽  
Source Model ◽  
Elastic Half Space ◽  
Nevada Test Site ◽  
Fault Movement ◽  
Source Mechanisms ◽  
The Relationship ◽  
Multipole Source ◽  
Finite Disturbance

abstract The static displacement field in an elastic half-space caused by a general, finite disturbance is derived in the form of an infinite series (multipole) expansion. The relationship between this theory and dislocation theory is discussed with the aid of examples. A multipole source model is derived for the strain-step field associated with the nuclear blast HANDLEY set off at the Nevada Test Site on March 26, 1970. The results suggest that there was significant fault movement associated with the detonation.

Application of Nuttli's method to estimate yield of Nevada Test Site explosions recorded on Lawrence Livermore National Laboratory's Digital Seismic System

1988 ◽  
Vol 78 (5) ◽  
pp. 1759-1772
Author(s):  
H. J. Patton
Keyword(s):  
Source Region ◽  
Test Site ◽  
Nevada Test Site ◽  
Underground Nuclear Explosions ◽  
Threshold Test ◽  
Gas Porosity ◽  
Sigma Level ◽  
Source Regions ◽  
Test Ban ◽  
Seismic System

Abstract Methods utilizing Lg waves for estimating yields of underground nuclear explosions have attracted considerable attention for their accuracy, claims of portability, and suitability for low yield test ban verification. In this study, the method developed by Nuttli is applied to a large dataset of Nevada Test Site explosions recorded on Livermore's Digital Seismic System. The purpose was to check the reproducibility of Nuttli's results and to verify the accuracy of mb(Lg) to estimate yield at high and low yield levels. Portability of the method is examined from the perspective of variability of the magnitude-yield relations as a function of station site and source geology. The results of this study show accuracies of about a factor of 1.6 in yield at the two sigma level for shots below the water table in source regions exhibiting more or less uniform coupling. At Nevada Test Site, there are three such source regions: Pahute Mesa (areas 19 and 20), northern Yucca including areas 2 and 9, and southern Yucca including areas 3, 4, and 7. There is no apparent degradation in accuracies at low yields (1 to 10 kt). Variations in source coupling were observed as a function of shot location and as a function of the medium's gas porosity for shots in tuff. The effect of gas porosity was not observed for shots in alluvium, which have uniformly low coupling compared to shots in tuff. Variations in magnitude-yield relations were observed from station to station, while the four-station network-average magnitudes are more robust and agreed well with Nuttli's magnitude-yield relations. Thus, portability to other test sites should be considered guardedly optimistic, requiring geologic and seismic data related to coupling in each source region and sufficient numbers of stations (four or five) to estimate a robust network magnitude. Taken all together, the findings of this study lend support to this method as a viable means of monitoring a threshold test ban or low yield threshold test ban.

mb(LgCoda): A stable single station estimator of magnitude

1993 ◽  
Vol 83 (3) ◽  
pp. 851-861 ◽  
Author(s):  
Kevin Mayeda
Keyword(s):  
Water Table ◽  
Source Region ◽  
Test Site ◽  
Strongly Correlated ◽  
Nevada Test Site ◽  
Nuclear Explosions ◽  
Empirical Relations ◽  
Single Station ◽  
Lg Coda ◽  
Lateral Variations

Abstract Stable single-station estimates of magnitude have been made using the 1-Hz Lg coda envelope of regionally recorded nuclear explosions from the Nevada Test Site (NTS). After empirical relations describing the Lg coda envelope were found for each NTS-station path, single station magnitudes based on the Lg coda envelope were made with precision in the range of 0.03 to 0.04 magnitude units, whereas magnitudes based on third peak Lg amplitude, rms Lg amplitude, and Pn amplitude had scatter on the order of 0.15 to 0.2 magnitude units, generally five times larger than the coda scatter. Despite the high station correlations, the magnitude-yield residuals for events above the water table using the network average mb(LgCoda) were only marginally better than the other magnitude estimates, roughly 10% smaller. Magnitude-yield residual for events above the water table between mb(LgCoda) and mb(Lg) are strongly correlated suggesting that the source region properties, such as gas porosity, affect both magnitudes. Using only a single station, the standard deviation for magnitude-yield residuals using mb(LgCoda) were roughly 25% smaller than those derived from mb(Lg) or mb(Pn). These results show that the method is ideally suited to monitoring efforts in sparsely instrumented regions where little is known about the lateral variations of medium properties.

Spectral discrimination between NTS explosions and Western United States earthquakes at regional distances

1988 ◽  
Vol 78 (4) ◽  
pp. 1563-1579
Author(s):  
Steven R. Taylor ◽  
Nevin W. Sherman ◽  
Marvin D. Denny
Keyword(s):  
United States ◽  
High Frequency ◽  
Source Region ◽  
Spectral Ratio ◽  
Source Model ◽  
Pressure Effects ◽  
Western United States ◽  
Dislocation Source ◽  
Overburden Pressure ◽  
Single Station

Abstract Spectral ratio disciminants are applied to 72 Western United States earthquakes and 64 NTS explosions recorded at four broadband seismic stations surrounding NTS. The ratio of the energy in the 1- to 2- and 6- to 8-Hz bands for Pn, Pg, and Lg is calculated and a simple distance correction applied to the data. The spectral ratio appears to have potential as a disciminant at relatively small magnitudes (3.0 < mb < 4.5) and single station misclassification probabilities for detected phases range from 4 to 33 per cent, with Lg showing the best performance followed by Pg and Pn. Below mb 4.5 to 5.0, the earthquakes are observed to have more high-frequency energy than the explosions for all three phases. This observation may be due to actual source differences or to depth-dependent effects of attenuation on the shallow explosions and deeper earthquakes. At higher magnitudes, the two populations merge and discrimination is poor. Overburied explosions are characterized by the existence of more high-frequency energy than those at standard containment depths and are often misclassified. The Brune dislocation source model is shown to satisfactorily fit the earthquake spectral ratios plotted as a function of mb for reasonable stress drops. However, the Mueller-Murphy explosion source model has problems predicting the decrease in the explosion spectral ratio observed at higher magnitudes (mb > 4.5 to 5.0). This may be due to uncertainties in the apparent source-time function for explosions. These complications may be due to changes in the dynamic response of the material in the near-source region as a function of overburden pressure, effects of secondary sources, or to variations in regional phase excitation with depth.

Teleseismic spectral and temporal M0 and Ψ∞ estimates for four French explosions in southern Sahara

1988 ◽  
Vol 78 (4) ◽  
pp. 1580-1596
Author(s):  
K. L. McLaughlin ◽  
A. C. Lees ◽  
Z. A. Der ◽  
M. E. Marshall
Keyword(s):  
Hot Spot ◽  
Spectral Estimation ◽  
Source Region ◽  
Test Site ◽  
Estimation Methods ◽  
Nevada Test Site ◽  
Displacement Potential ◽  
Show Evidence ◽  
Using Data ◽  
T Values

Abstract Estimates for explosion moment M0, and reduced displacement potential, Ψ∞, are made for four French explosions at Taourirt Tan Afella Massif in southern French Sahara using data from the long-range seismic measurement network and the EKA and YKA arrays. Preparatory to determining moments, attenuation, t⋆, estimates are made for each station, and the source region t⋆ values of 0.30 to 0.35 sec are found for the southern Sahara test site. This source region attenuation level is consistent with the “hot spot” hypothesis for the Ahaggar plateau in northern Africa. Consequently, the attenuation bias between Ahaggar and the Nevada Test Site should be small. Both spectral estimation and broadband temporal deconvolution methods are used for estimation of the explosion moments. The deconvolution estimates of static moment are found to be consistent with the spectral estimation methods. Deconvolved seismograms for the explosions EMERAUDE, RUBIS, SAPHIR, and GRENAT show evidence of strong anisotropic free surface interaction that may be due to scattering or spall from the steep topography of the Taourirt Tan Affela Massif test site.

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