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.

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.

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.

S waves generated by small seismic sources

1966 ◽  
Vol 290 (1422) ◽  
pp. 448-460
Keyword(s):  
Wave Motion ◽  
Wave Generation ◽  
Good Resolution ◽  
University Of Michigan ◽  
Period Range ◽  
S Waves ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Wide Range ◽  
The University

Observations of S waves from small earthquakes recorded at near distances indicate that the relative S wave generation extends over a wide range. Similar measurements from underground nuclear explosions indicate a ratio of S to P wave generation to be below the observed values for 70 % of the earthquakes studied. The observation of S waves from small events at teleseismic distances is made difficult by interference of microseisms in the period range where S waves may be expected. The observation is also made difficult by the physical requirement that two horizontal component seismographs are required to obtain good resolution of S wave motion. Some measurements have been made at the University of Michigan by means of three-component seismometers in arrays to obtain better resolution of S wave motion. The results of these measurements suggest that improvements in S wave signal/noise ratios similar to those obtained for P waves are possible. The use of S waves from small events at teleseismic distances should not be considered of value as a method of detection. It does, however, offer promise as an added method of identification for small seismic events.

Understanding Distressed Residential Transaction Discounts Across Price Segments and Market Conditions

2020 ◽  
Vol 42 (1) ◽  
pp. 151-182
Author(s):  
Ramya Rajajagadeesan Aroul ◽  
J. Andrew Hansz ◽  
Mauricio Rodriguez
Keyword(s):  
Transaction Costs ◽  
Time Varying ◽  
Market Segment ◽  
Market Conditions ◽  
Large Market ◽  
Space And Time ◽  
Wide Range ◽  
Time Periods ◽  
Market Areas

In the literature, there is a wide range of discounts associated with foreclosures. Comparisons across studies are difficult as they use different methodologies across large areas over different time periods. We employ a consistent methodology across space and time. We find modest discounts, within the range of typical transaction costs, in all but the highest priced market segment. Higher priced segments could explain prior findings of substantial discounts. We find that discounts are time-varying, with discounts increasing with market distress. A one-size-fits-all approach is not appropriate when estimating distressed transaction discounts across large market areas or under changing market conditions.

scholarly journals Discriminating underground nuclear explosions leading to late-time radionuclide gas seeps

2020 ◽  
Author(s):  
Dylan Robert Harp ◽  
Suzanne Michelle Bourret ◽  
Philip H. Stauffer ◽  
Ed Michael Kwicklis
Keyword(s):  
Late Time ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Gas Seeps
Sign in / Sign up

Export Citation Format

Share Document