Source-mechanism from spectra of long-period seismic surface waves.

1963 ◽  
Vol 53 (5) ◽  
pp. 905-919 ◽  
Author(s):  
Ari Ben-Menahem ◽  
M. Nafi Toksöz
Keyword(s):  
Step Function ◽  
Source Mechanism ◽  
Aftershock Distribution ◽  
The Press ◽  
Seismic Surface Waves ◽  
Double Couple ◽  
T Phase ◽  
Phase Spectra ◽  
Fault Length ◽  
Good Agreement

Abstract Source-mechanism is derived from amplitude and phase spectra of mantle Love and Rayleigh waves of the Alaska earthquake of July 10, 1958. The signals R2, R3, G2, G4, G5 recorded on the Gilman 80–90 and the Press-Ewing 30–90 seismograph systems at Pasadena, California, are separated, digitized, filtered and Fourier-analyzed. An agreement between theory and observations is obtained for a unilateral fault of 300–350 km, which ruptured with a speed of 3-3.5 km/sec in the direction N40°W. Fault length is in good agreement with the extent of aftershock distribution in the month of July, 1958, and the time of rupture checks with the duration of an impressive T-phase recorded at Hawaii. The phases of the signals are corrected for propagation, instrumental shift and the source finiteness. Initial phases thus obtained agree on a mechanism of a right double-couple with a unit step-function in time.

Radiation from supersonic faulting

1971 ◽  
Vol 61 (4) ◽  
pp. 1009-1012 ◽  
Author(s):  
J. C. Savage
Keyword(s):  
Initial Point ◽  
Step Function ◽  
Fault Model ◽  
Dislocation Segment ◽  
Far Field ◽  
Fault Propagation ◽  
Unit Step ◽  
Propagation Factor ◽  
Double Couple ◽  
Field Radiation

abstract The far-field radiation from a simple fault model is given by the radiation pattern associated with the appropriate strain nucleus (e.g., double couple) multiplied by a fault propagation factor. For a unilateral fault model the propagation factor is F ( c ; t ) = ζ bd [ H ( τ ) − H ( τ − ( L / ζ ) ( 1 − ( ζ / c ) cos ψ )) ] / ( 1 − ( ζ / c ) cos ψ ) where ξ is the velocity of fault propagation, b is the fault slip, d is the fault width, τ = t − r0/c, r0 is the distance of the observer from the initial point of faulting, c is the velocity of the seismic wave, H(τ) is the unit-step function, L is the length of the fault, and ψ the angle between r0 and the direction of fault propagation. This representation is valid for both subsonic and supersonic fault propagation. The latter case is important because Weertman (1969) has recently shown that spontaneous faulting may propagate at supersonic velocities. Because the propagation factor is always positive, the nodal planes for the radiation are the same as for the appropriate strain nucleus. Finally, it is shown by the application of this equation that the radiation from a screw dislocation segment is represented by the double-couple nucleus, not the compensated linear-vector dipole nucleus as recently suggested by Knopoff and Randall (1970).

scholarly journals Distribution of Maximal Luminosity of Galaxies in the Sloan Digital Sky Survey

2014 ◽  
Vol 10 (S306) ◽  
pp. 351-354
Author(s):  
E. Regős ◽  
A. Szalay ◽  
Z. Rácz ◽  
M. Taghizadeh ◽  
K. Ozogany
Keyword(s):  
Limit Distribution ◽  
Finite Size ◽  
Gumbel Distribution ◽  
Sloan Digital Sky Survey ◽  
Extreme Value Statistics ◽  
Independent Variables ◽  
Sky Survey ◽  
The Press ◽  
Galaxy Sample ◽  
Good Agreement

AbstractExtreme value statistics (EVS) is applied to the pixelized distribution of galaxy luminosities in the Sloan Digital Sky Survey (SDSS). We analyze the DR8 Main Galaxy Sample (MGS) as well as the Luminous Red Galaxy Sample (LRGS). A non-parametric comparison of the EVS of the luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for independent variables distributed by the Press-Schechter law) indicates a good agreement provided uncertainties arising both from the finite size of the samples and from the sample size distribution are accounted for. This effectively rules out the possibility of having a finite maximum cutoff luminosity.

Comparative study on the oily exudation of aluminized explosives containing EVA and F2603

2020 ◽  
Vol 19 (08) ◽  
pp. 2050035
Author(s):  
Jun Tao ◽  
Xiaofeng Wang ◽  
Kun Zhang
Keyword(s):  
Migration Rate ◽  
Polyvinyl Acetate ◽  
Vinylidene Fluoride ◽  
Great Influence ◽  
Binding Energies ◽  
The Other ◽  
Binding Strength ◽  
The Press ◽  
Exudation Rate ◽  
Good Agreement

In order to compare the influence of binders on the oily exudation of cyclotrimethylenetrinitramine (RDX) based aluminized explosives, polyvinyl acetate (EVA) and copolymer of vinylidene fluoride and perfluoropropylene (F2603) were selected as binders, which are most commonly used in the press-packed explosives. Herein, the binding energies of wax with the components of RDX-based aluminized explosives containing EVA and F2603 were predicted. Then, the migration models of wax in EVA and F2603 were constructed respectively, and the migration rate of wax in two binders was also calculated. Finally, experimental verification was carried out for wax migration in the two aluminized explosives. The results show that the binding energies of wax with other components of RDX-based composite explosive are all positive, which indicates that the physical compatibility of RDX-based aluminized explosives containing EVA and F2603 is excellent. In addition, wax interacts with the other components of RDX-based explosives mainly via Van der Waals force. However, the binding strength of wax with RDX crystals and binders decreases with the increase of temperature. The type of binders has a great influence on the migration rate of wax, and the oily exudation rate of wax in F2603 is about 4 times than that in EVA both at 298 K and 344 K. Meanwhile, the polymer configuration greatly changes the migration rate of wax. The calculated results are in good agreement with the experimental results.

REIGNITION OF FREELY RECOVERING SPARK CHANNELS IN HYDROGEN

1963 ◽  
Vol 41 (4) ◽  
pp. 610-624 ◽  
Author(s):  
R. J. Churchill
Keyword(s):  
Current Pulse ◽  
Recovery Period ◽  
Step Function ◽  
Electrode Size ◽  
Copper Electrodes ◽  
Spark Gap ◽  
Initial Discharge ◽  
Recovery Mechanisms ◽  
Spark Breakdown ◽  
Good Agreement

The paper describes an experimental technique and apparatus for the measurement of spark gap reignition in freely recovering spark channels in hydrogen. A unidirectional 235-ka current pulse produces the initial discharge while subsequent reignition is effected by a voltage generator whose output approximates a step-function over 50 μsec. Recovery characteristics are given for 16-mm-diameter tungsten rod electrodes in hydrogen at pressures ranging from 200 to 760 mm Hg, for 4-mm-diameter tungsten rods, and for 16- and 76-mm-diameter copper electrodes at 760 mm Hg. Gap length was varied from 1 to 5 mm. Study of the parameters shows that electrode size has the most pronounced effect on the recovery process.The deionization and recovery mechanisms are predicted theoretically and verified during the final recovery period where reignition by spark breakdown is observed. Gas temperatures derived from the recovery results are in good agreement with measured values.

scholarly journals Velocities of mantle Love and Rayleigh waves over multiple paths

1963 ◽  
Vol 53 (4) ◽  
pp. 741-764 ◽  
Author(s):  
M. Nafi Toksöz ◽  
Ari Ben-Menahem
Keyword(s):  
Rayleigh Waves ◽  
Great Circle ◽  
Love Waves ◽  
Period Range ◽  
Phase Velocities ◽  
Multiple Paths ◽  
Lateral Variations ◽  
Phase Spectra ◽  
Group Velocities ◽  
Good Agreement

Abstract Phase velocities of Love waves from five major earthquakes are measured over six great circle paths in the period range of 50 to 400 seconds. For two of the great circle paths the phase velocities of Rayleigh waves are also obtained. The digitized seismograph traces are Fourier analyzed, and the phase spectra are used in determining the phase velocities. Where the great circle paths are close, the phase velocities over these paths are found to be in very good agreement with each other indicating that the measured velocities are accurate and reliable. Phase velocities of Love waves over paths that lie far from each other are different, and this difference is consistent and much greater than the experimental error. From this it is concluded that there are lateral variations in the structure of the earth's mantle. One interpretation of this variation is that the mantle under the continents is different from that under the oceans, since the path with the highest phase velocities is almost completely oceanic. This interpretation, however, is not unique and variations under the oceans and continents are also possible. Group velocities are computed from the phase velocities and are also directly measured from the seismograms. The group-velocity curve of Love waves has a plateau between periods of 100 and 300 seconds with a shallow minimum at about 290 seconds. The sources of error in both Fourier analysis and direct time domain methods of phase velocity measurement are discussed.

The Meckering earthquake of 14 October 1968: A possible downward propagating rupture

1987 ◽  
Vol 77 (5) ◽  
pp. 1558-1578
Author(s):  
Kristín S. Vogfjörd ◽  
Charles A. Langston
Keyword(s):  
Moment Tensor ◽  
Source Parameters ◽  
Time History ◽  
Vertical Displacement ◽  
Body Waves ◽  
Finite Fault ◽  
Short Period ◽  
Double Couple ◽  
The Moment ◽  
Fault Length

Abstract Average source parameters of the 1968 Meckering, Australia earthquake are obtained by the inversion of body waves. The objectives of the inversion are the elements of the moment tensor and the source-time history. An optimum source depth of 3 km is determined, but because of source complexity the point source assumption fails and the moment tensor obtained at that depth has a large nondouble-couple term, compensated linear vector dipole = 34 per cent. The source parameters of the major double-couple are: strike = 341°; dip = 37°; rake = 61°; and seismic moment = 8.2 ×1025 dyne-cm. The source-time function is of approximately 4 sec duration, with a long rise time and a sharp fall-off. The fault length is constrained on the surface by the observed surface break, and results from vertical displacement modeling suggest a width of approximately 10 km in the middle, assuming a dip of 37°. That restricts the entire faulted area to lie above 6 km depth. Two finite fault models for the earthquake are presented, with rupture initiating at a point (1) near the top of the fault and (2) at the bottom of the fault. Both models produce similar long-period synthetics, but based on the short-period waveforms, model 1 is favored. It is argued that such a rupture process is the most reasonable in this cold shield region.

Dynamic Contact Between a Rigid Indenter and a Zener Half-Space

2004 ◽  
Author(s):  
Florina Carmen Ciornei ◽  
Emanuel N. Diaconescu
Keyword(s):  
Half Space ◽  
Glass Plate ◽  
Experimental Tests ◽  
Dynamic Contact ◽  
Step Function ◽  
Contact Radius ◽  
Low Frequencies ◽  
Receding Contact ◽  
Contact Pressures ◽  
Good Agreement

This paper investigates the dynamic contact between an axi-symmetric rigid paraboloid and a standard solid (Zener) viscoelastic half-space. The load consists of a pulse cosine applied over a step function. Following the theory developed by Ting, analytical expression of contact radius for an advancing contact is derived. For receding contact, contact radius is numerically obtained. Contact pressures for increasing and decreasing contacts are derived. The influence of load frequency is evidenced. At low frequencies, contact pressure has an initial Hertz shape and then, as the contact increases, a relaxed one. As the contact reaches its maximum, the pressure tends again to an elastic pattern. Experimental tests were carried out on a contact between a polymeric sphere and a glass plate. A good agreement is found with theoretical results by measuring contact radius.

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