bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forced vibration of an eight-story reinforced concrete building
Authors: Englekirk R. E. , Matthiesen R. B. 
Published: July 2021

abstractThe determination of the dynamic characteristics of an eight-story reinforced concrete building was undertaken. Lateral stability of the structure was provided by shear walls in one direction and by a space frame in the other direction, an unsymmetrical location of rigid elements providing a natural coupling of lateral and torsional vibration.A pair of synchronized vibration generators were used to generate the desired steady state vibrations. Measurements were made of one translational mode in the direction parallel to the shear walls, two translational modes in the direction parallel to the space frame, and two torsional modes.A definite nonlinearity in the response of the space frame was observed. Values of damping were 3.5 per cent of critical damping in each direction. The value of dynamic modulus of elasticity that gave the best analytical results compared favorably with standard laboratory determined values for dynamic modulus of elasticity. A simple method for obtaining approximations to the natural frequencies and mode shapes of multistory space frames is discussed.
Scale-model study of refraction arrivals in a three-layered structure
Authors: Siskind D. E. , Howell B. F. 
Published: July 2021

abstract
The effects of an intermediate velocity layer on the frequency spectra of waves refracted along its upper and lower boundaries are compared to the effects of a layer of constant velocity gradient. The same relationship was found in both cases: there being a cutoff frequency at 1.7 times the velocity gradient. These two types of structures could not be distinguished from one another by their effects on the frequency spectra. This should also hold in full-scale field experiments.
A low-stress-drop, low-magnitude earthquake with surface faulting: The Imperial, California, earthquake of March 4, 1966
Authors: Brune James N. , Allen Clarence R. 
Published: July 2021

abstract
Right-lateral surface displacement reaching 1 1/2 centimeters occurred over a ten-kilometer section of the Imperial fault in association with a magnitude 3.6 earthquake on March 4, 1966, the smallest known earthquake yet associated with surface displacement. The displacement is documented by field observations of en-echelon cracking in pavement and the offset of the white center line of Highway 80. The association of the observed displacement with the March 4 earthquake is supported by the shallow depth of the earthquake source, the high excitation of waves in the top layer of sediments, the high excitation of Love waves of period 8-15 seconds, the distribution of aftershocks, and the agreement between the source moment as calculated from the observed faulting and from the amplitudes of Love waves. Calculations based on faulting theory indicate a fault depth of 1.1 km, a net moment of 2 × 1022 dyne-cm, a stress drop of 1.1 bar and an energy release of 1017 ergs. The remarkable internal consistency of the various calculations provides strong support for the faulting mechanism. It is suggested that low stress drops and relatively large fault lengths may be associated with many other small earthquakes and that allowance must be made for a wide range in the stress drops and fault lengths for any given magnitude range.
A statistical discussion ofPresiduals from explosions
Authors: Freedman Helen W. 
Published: July 2021

abstractExplosions at large distances from the Berkeley seismic array of the University of California have been studied in an attempt to obtain an estimate of a P travel time “adjustment” function for each station in the array relative to a standard P table. The probability distribution of residuals is discussed and some error estimates for station adjustments given.A method is suggested for relocating groups of events occurring in small regions. This problem was suggested by the existence of groups of explosions in small regions which gave rise to widely varying sets of residuals.The probable presence of azimuthally varying source, as well as station, terms makes it advisable to obtain times from world-wide stations for each source area in order to attempt to separate the two terms. In fact, the presence of these terms makes it questionable whether a meaningful adjustment function for a single station can be obtained at all.
Seismicity in Utah, 1850 through June 1965
Authors: Cook Kenneth L. , Smith Robert B. 
Published: July 2021

abstractDuring 1850 through June 1965, at least 609 earthquakes occurred in Utah, of which at least 38 were damaging. Pertinent data of these earthquakes are listed, and an earthquake epicenter map of Utah is presented. The epicenter determinations of about 344 earthquakes (all felt) in Utah during 1850 through 1949 (Williams and Tapper, 1953) were non-instrumental. The epicenters and magnitudes and depths of focus (when determined) of the earthquakes during 1950 through June 1962 (77) were generally instrumental determinations taken from the Coast and Geodetic Survey, U. S. Department of Commerce (CGS). The epicenters of the earthquakes during July 1962 through June 1965 (188) were all instrumental and were obtained as follows: 23 were obtained from already-published CGS data; 165 were obtained by the University of Utah, of which 68 epicentral determinations were also made by the CGS. The comparisons of epicenter locations were generally good. Our epicenters were determined using a slightly modified Geiger's method programmed on an IBM 7044 digital computer at the University of Utah. The computer program used unpublished travel-time curves (B. H. Atwell, 1967) computed from the earth crustal model of Berg and others (1960) for the Utah region and included depths-of-focus data at 10-km-depth intervals from 0 to 60 km. The data show recent earthquake activity in the Ephraim (1961), Cache Valley (1962), and Levan (1963) areas, and swarm activity in the lehman Caves (1963) area. During 1962-1964 Utah averaged about 60 earthquakes per year for which instrumental epicenter determinations were made.
Foundation—Structure interaction in the analysis of wave motions
Authors: Scavuzzo R. J. 
Published: July 2021

abstract
During shock motion, inertia forces of large structures will influence the foundation motion locally. In the present study, the structure-foundation problem is analyzed by coupling an N-mass structure with a one dimensional wave; the resulting solution is formulated as a Volterra integral equation. By using an input wave similar to those encountered in earthquake motions, the significance of this interaction was investigated. Results show that the reduction in spectrum acceleration is significant and depends both on structure frequency and weight for a given foundation input.
An analysis of the travel times of S waves to North American stations in the distance range 28° to 82°
Authors: Doyle H. A. , Hales A. L. 
Published: July 2021

abstract
The travel times of S waves from 20 earthquakes to stations in North America in the distance range 28° to 82° have been studied. The deviations from J-B times were analyzed into station, source and distance components using the least-squares time-term approach of Cleary and Hales. Station anomalies had a range of about eight seconds, as compared to three seconds for the P anomalies, and are believed to be caused largely by variations in the upper mantle velocity distribution. S residuals, like the P residuals, were generally positive in the western United States, and negative in the central and eastern United States. P and S residuals at the same station correlated with a coefficient of 0.75, the slope of the regression of S anomaly on P anomaly being 3.72. Corrections to J-B times for S were of the order of the standard errors of the determinations. Within the distance range of 28° to 82° large changes of the S travel times, such as were required by the lower mantle velocities proposed by MacDonald and Ness (1961), are not permitted by the present data. The analysis was checked by carrying out a univariate analysis of variance of the same data.
Dissipation in the earth's mantle and rigidity and viscosity in the earth's core determined from waves multiply reflected from the mantle-core boundary
Authors: Sato R. , Espinosa A. F. 
Published: July 2021

abstract
Spectral amplitude ratios of 33 shear waves multiply reflected from the core (from a deep-focus earthquake recorded in the epicentral distance range from 7° to 80°) are used to determine statistically the following quantities: (a) the quality factor, Q, of shear waves in the mantle, (b) the rigidity of the earth's core, and (c) the viscosity of the earth's core.
The determined mean value of Q for the whole mantle, using eight stations in the epicentral range of 7° to 80°, is much lower than any mean Q value obtained previously. This Q value is called the mean apparent quality factor of shear waves in the earth's mantle. The mean lower bound value of Q determined from 13 observations when two close stations are used is 581 ± 33. In this case, when Q is assumed to depend upon period, its value decreases with increasing period, from 720 at 34 sec to 232 at 90 sec. When the recording stations are grouped according to epicentral distances, the mean apparent values of Q obtained from the combined series for each group show a tendency to decrease as the epicentral distance increases.
An upper bound of the mean core rigidity is determined to be 5.45 × 1010 dynes/cm2, shear velocity in the core = 0.73 km/sec, when the mantle is assumed to be a perfect elastic body (Q = ∞). When the core is assumed to be a viscous-liquid medium and the mantle is assumed to have an infinite Q, an upper bound for the viscosity of the upper part of the outer core is found to be 8.61 × 1011 dynes-sec/cm2. The computed values of the rigidity and viscosity of the earth's core are affected by the assumed Q distribution in the earth's mantle. Since there is insufficient data available on Q as a function of depth, various μc and vc for 13 assumed Q distributions as a function of depth have been computed and tabulated.
Spatial distribution and source mechanism of microearthquakes in Central Nevada
Authors: Stauder William , Ryall Alan 
Published: July 2021

AbstractDuring the summer of 1966 a small tripartite array was established at the southern extremity of the surface faulting of the Fairview Peak earthquake of 1954. Over a period of six weeks an average 31 earthquakes per day were detected. Of these approximately 400 were selected for detailed study. Site corrections were made to reduce arrival times for all elements of the array to a common base, and the properties of the array and S-P time intervals were used to determine direction of approach, apparent surface velocity across the array, and hypocentral coordinates.Foci were found to concentrate at a depth of 10 to 15 kilometers and to cluster toward the end of the surface faulting of the 1954 earthquake. The foci were also found to lie along two planar zones. The first is parallel to the fault plane solution (strike N 11° W, dip 62° E) of the Fairview Peak earthquake and terminates at the southern extremity of the surface fracture. The second begins at this point and extends to the southwest, with foci distributed about a plane striking N 50° E and dipping 50° to the southeast. The latter zone apparently marks the southern terminus of the 1954 faulting. The polarity of the first motion of P at the array indicates predominantly dip-slip motion along the faults of both zones. The character of the seismic signatures from foci occurring closely together in space and time indicates that the complexity of the signature arises chiefly from propagation effects rather than from complexity of the time history at the source.
Propagation of waves in a multilayered elastic medium and their dependence on source mechanisms
Authors: Chakrabarty S. K. 
Published: July 2021

Abstract
The stress equations of motion for a multilayered elastic medium subjected to body forces of general type have been solved in terms of three new variables which are functions of the displacement components and their space derivatives. The contributions of the different layers appear as separate 2 × 2 and 4 × 4 matrices whose elements are functions of the material constants and thickness of the particular layer. Some simple applications of the analysis have been discussed.
A two-dimensional ultrasonic model study of compressional and shear-wave diffraction patterns produced by a circular cavity
Authors: Teng T. L. , Wu F. T. 
Published: July 2021

abstract
Diffraction patterns of compressional (P) and shear (SV) waves produced by a circular hole were experimentally obtained on a two-dimensional ultrasonic model. The shapes of the Fresnel patterns were found to depend on, 1) α/λ, the ratio of the radius of the cylinder to the wavelength; and, 2) the wave type. The transitional zone between the illuminated and the shadow regions broadens, and the half-amplitude point shifts away from the geometrical shadow as α/λ decreases. For comparable α/λ, the shadow boundary of the SV wave appears to start much earlier than that of the P wave.
The focus of the 1906 California earthquake
Authors: Bolt Bruce A. 
Published: July 2021

abstract
The location of the 1906 California earthquake is reexamined using both the P and S recordings at teleseismic distances and the local observations. Analysis of the observed travel times using modern empirical tables rules out a focus of the principal shock south of the Santa Cruz Mountains or north of Point Arena. By inter-comparison with the measurements from the 1957 San Francisco earthquake, it is demonstrated that the lines of evidence are slightly more favorable to a principal focus near that of the 1957 California shock (37°40′N, 122°29′W) with t0 = 13h12m21s than to Reid's focus near Olema, although the latter is not precluded.
There is no evidence from the travel times against the hypothesis that the first rupture was associated with the San Andreas fault and occurred within the crust. The analysis confirms that the rupture was of the (perhaps unusual) bilateral type. Calculations which confirm the contentious magnitude of 814 are set down.
Correlation function of teleseismic noise
Authors: Johnson K. R. 
Published: July 2021

Abstract
A theoretical calculation is made of the correlation function for the vertical component of Earth motion caused by teleseismic microseismic noise. The calculation pertains to an idealized case in which the Earth is assumed to be spherically symmetric and to transmit seismic waves as a non-dispersive linear system, and in which all noise is assumed to originate at the Earth's surface. Diffraction effects are neglected. Only phases that originate and terminate as longitudinal waves are considered, although the method of analysis is readily applicable to other phases. The correlation function for teleseismic noise is calculated and plotted for the case of isotropic noise having a specific noise spectrum. The theoretical noise reduction is calculated and plotted versus average seismometer spacing for a set of seven-seismometer seismic arrays for the cases of teleseismic noise alone, surface noise alone, and a combination of teleseismic and surface noise.
Three-dimensional fields due to a Volterra dislocation imbedded in a layered half-space: Analytical representation of a seismic mechanism
Authors: Braslau David , Lieber Paul 
Published: July 2021

Abstract
Strike-slip faulting in the crust and its mechanical interaction with the underlying mantle is presented as the basis for an earthquake and aftershock mechanism. The usual problem of a fault in a homogeneous half space is a special case of the present model, where both layering and time-dependence play an important role. The system is characterized by a three-dimensional problem in static linear elasticity and viscoelasticity, where the fault is represented by a vertical Volterra disclocation in the layer with slip parallel to the surface. Both materials are assumed to be incompressible. The problem is solved by means of a modified form of the Galerkin vector and use of double Fourier transforms, and solutions are obtained in quadrature for the surface displacements and some of the stresses at the interface. Time-dependent properties are introduced formally into the quadrature by use of the correspondence principle of linear viscoelasticity.
Geologic and related effects of the Taltal earthquake, Chile, of December 28, 1966
Authors: Lemke Richard W. , Dobrovolny Ernest , Alvarez S. Leonardo , Ortiz O. Francisco 
Published: July 2021

abstract
Surface effects of the Taltal earthquake were comparatively small, probably because of the deep focus, although the magnitude was 7 ¾. Small fractures broke the ground surface along fault zones in the vicinity of Taltal. Minor slumping occurred on a few steep natural slopes and in some cuts and fills along highways. There was minor damage at a few open pit mines. At Taltal, the town most affected by the earthquake, 250 buildings out of a total of 1,100 were heavily damaged.
The agreement of proposed earth models with observed body-wave travel times
Authors: Walker Daniel A. , Sutton George H. 
Published: July 2021

abstract
A computer program was used to evolve a model of compressional and shearwave velocity for the earth's mantle which would be consistent with the travel times given in the Jeffreys-Bullen (J-B) tables. The sensitivity shown by our computed travel times to changes in layer velocities suggests that models containing low-velocity channels would produce travel times different from those given in the tables. Travel times associated with velocity models proposed by others were also computed. The significance of travel-time residuals depends primarily on the reliability of observed travel times for those epicentral distances at which the model fails.
Velocity and displacement of explosion-induced earth tremors derived from acceleration
Authors: Poppitz J. V. 
Published: July 2021

Abstract
Velocity and displacement time histories which are derived by integrating acceleration time histories of nuclear-explosion-induced earth tremors usually end in values that are obviously too large. It can be demonstrated that small errors, which are within the range of error one would expect from field-recorded data, could cause such unacceptable velocities and displacements. Assuming that such errors do exist but realizing that they cannot be determined exactly, two “correction” procedures are presented which adjust the acceleration data so that it is more rational. The two procedures are the least-mean-square-velocity technique (by G. V. Berg and G. W. Housner and used extensively with seismic data), which is based on the criterion of minimizing the mean of the velocity squared, and the end-time-zero technique, which depends on boundary conditions at the beginning and end of the tremor. The end-time-zero technique is recommended for use with nuclear-explosion-induced data.
Maximum response ranges of nonlinear multi-story structures subjected to earthquakes
Authors: Giberson Melbourne F. 
Published: July 2021

Abstract
The earthquake responses of a twenty-story nonlinear structural frame representative of a modern high-rise building were calculated. The structure was modeled by a two-dimensional frame with girders and columns having bilinear bending moment-end rotation hysteretic characteristics. In addition to hysteretic damping, viscous damping mechanisms were assumed. The earthquakes used were the El Centro (N-S) earthquake of May 18, 1940 and several pseudo-earthquakes having statistics similar to those of previously recorded earthquakes. Time history plots for displacements, bending moments, joint rotations, etc., at several stations in the structure are presented. A displacement envelope and a plot of the ductility factors, which measure the amount of yielding incurred, are also given. It was possible to identify certain behavior characteristics of the structural responses which appeared to be determined more by the properties of the structure than by the earthquake. For the series of pseudo-earthquakes used, a large range was found in the maximum values of the responses of the yielding structure. For example, the spread between extremum values of the maximum absolute displacements was 50 per cent of the arithmetic mean value. Statistics of the magnitudes of the displacements and ductility factors were compared with three common measurements of the strength of earthquake accelerograms. It was found that none of these three measurements correlated well with the trend of the maximum responses.
Amplitude spectra of PcP and P phases
Authors: Buchbinder Goetz G.R. 
Published: July 2021

ABSTRACT
Amplitude spectra were obtained from short-period PcP and P phases from seven explosions and six earthquakes. Long-period PcP and P amplitude spectra were obtained from two earthquakes.
PcP and P amplitude spectra for both explosions and earthquakes are similar for any one event; therefore, station and core-mantle boundary effects are small and the general shape of the spectra is related to the source. All of the explosions studied have characteristic spectra with a pronounced minimum in the spectrum near one second. The period of this minimum increases with magnitude of the event. Short-period amplitude spectra from some intermediate- and deep-focus earthquakes resemble those from explosions. Spectra from the other earthquakes studied differ markedly from those of explosion; they have either no minimum in the spectrum near one second or very little energy for periods less than one second. The characteristics of the spectra may be of help in the classification of sources. On a plot of magnitude mb versus period of the minimum Td in the spectrum of explosions, the data form a straight line. Earthquakes with an amplitude spectrum similar to that of an explosion are randomly distributed on the plot of mb versus Td.
Systematic effects of focal depth were not observed. Layering at the coremantle boundary was not detected.
A crust-mantle profile from Mould Bay, Canada, to Tucson, Arizona
Authors: Wickens A. J. , Pec K. 
Published: July 2021

ABSTRACT
Love-wave phase velocities were determined for five adjacent segments of a 5000 kilometer great circle path from Mould Bay, Canada, to Tucson, Arizona. Mean-phase velocity curves were obtained from curves based on reciprocal data, thus minimizing the detrimental effects of non-parallel layering. By careful selection and precise treatment of the data over relatively short distances (800 km), detail hitherto suppressed has been retained. Finally, by using reciprocal seismograms, the effect of sloping interfaces was observed.
The crustal and upper mantle models obtained indicate significant differences in structure between different provinces of the Precambrian Shield.