bluuebunny/crossref_metadata_2025 huggingface dataset:
Francisco GARCÍA JURADO, Ramiro GONZÁLEZ DELGADO y Marta GONZÁLEZ GONZÁLEZ (eds.), «La historia de la literatura grecolatina en España: de la Ilustración al Liberalismo (1778-1850)», Málaga, Analecta Malacitana, anejo 90, 2013. 467 págs.
Authors: Lorenzo Álvarez Elena de
Published: July 2021

SIN RESUMEN
Jesús MARTÍNEZ BARO, «La libertad de Morfeo. Patriotismo y política en los sueños literarios españoles (1808-1814)», Zaragoza, Universidad de Zaragoza, 2014 y Desvelos y pesadillas de una nación. Sueños literarios españoles entre 1808 y 1814, Cádiz, Ayuntamiento de Cádiz, 2014.
Authors: Lorenzo Álvarez Elena de
Published: July 2021

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Juan NAVARRO LOIDI, «Don Pedro Giannini o las matemáticas de los artilleros del siglo XVIII». Segovia, Asociación Cultural «Biblioteca de Ciencia y Artillería», 2013, 701 págs.
Authors: Valles Garrido José Manuel
Published: July 2021

SIN RESUMEN
Álvaro RUIZ DE LA PEÑA SOLAR, «La hora de Asturias en el siglo XVIII», Oviedo, Real Instituto de Estudios Asturianos-Instituto Feijoo de Estudios del Siglo XVIII, Oviedo, 2012.
Authors: Enciso Recio Luis Miguel
Published: July 2021

SIN RESUMEN
Benito Jerónimo FEIJOO, «Obras completas». Tomo II. «Cartas eruditas y curiosas»,I. Edición crítica de Inmaculada Urzainqui y Eduardo San José Vázquez. Estudio introductorio de Inmaculada Urzainqui. Oviedo, Instituto Feijoo de Estudios del Siglo XVIII-Ayuntamiento de Oviedo-KRK Ediciones, 2014. («Colección de Autores Españoles del Siglo XVIII», I-II).
Authors: Aguilar Piñal Francisco
Published: July 2021

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El problema del actor en Cervantes: una revisión desde la preceptiva neoclásica
Authors: Vellón Lahoz Javier
Published: July 2021

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Repertorio bibliográfico del Real Instituto Asturiano de Náutica y Mineralogía de Gijón (1794-1994)
Authors: Nieto Fernández Natividad
Published: July 2021

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La Real Sociedad Económica de Amigos del País de Alcázar de San Juan
Authors: Higueruela del Pino Leandro
Published: July 2021

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La decadencia de las Reales Sociedades de Amigos del País
Authors: Demerson Georges , Demerson Paula de
Published: July 2021

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Miguel Egual, poeta y traductor (II). Sonetos
Authors: Mas i Usó Pasqual , Vellón Lahoz Javier
Published: July 2021

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El último texto educativo de Sarmiento: «Sobre el método de estudios» de San Isidro de Madrid
Authors: Santos Puerto José
Published: July 2021

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Un alcalde de barrio en el Madrid de Carlos IV
Authors: Aguilar Piñal Francisco
Published: July 2021

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Una crítica de la imagen de España en la literatura de viajes: Giuseppe Baretti
Authors: Bacigalupo Mario Ford
Published: July 2021

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La historia interna de los «Orígenes de la poesía castellana» de Luis Joseph Velázquez
Authors: Deacon Philip
Published: July 2021

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La física de Feijoo: tradición y renovación
Authors: Lafuente Antonio , Sellés Manuel A.
Published: July 2021

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Notas para la biografía de una poetisa bable del siglo XVIII: Teresa Cónsul
Authors: Ruiz de la Peña Álvaro
Published: July 2021

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Un arabista del siglo XVIII: el franciscano Fr. José Banqueri, T. O. R. (1745-1818)
Authors: Soto Pérez José Luis
Published: July 2021

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En torno a unos manuscritos de Jovellanos referentes al dialecto asturiano
Authors: Patac de las Traviesas José María
Published: July 2021

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De etnomusicología española: notas de historia. Una aproximación al folklore musical del XVIII a través de la literatura
Authors: Gómez Rodríguez José Antonio
Published: July 2021

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André Pons
Authors: Murphy Martin
Published: July 2021

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La religiosidad popular en la España del siglo XVIII: cofradías, ermitas y romerías
Authors: Arias de Saavedra Alías Inmaculada
Published: July 2021

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Perfil psicológico del escritor J. F. de Isla (1703-81)
Authors: Olaechea Rafael
Published: July 2021

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On the mechanism of earthquakes
Authors: Randall M. J.
Published: July 2021

An earthquake may be regarded as resulting from a sudden change in the condition of elastic equilibrium in the Earth. A new form of the general solution of the elastic wave equation relates seismic radiation to displacement from equilibrium. Calculation of the radiation pattern for a proposed mechanism is thus reduced to an elastostatic problem.
The fine structure of the Earth's core
Authors: Adams R. D. , Randall M. J.
Published: July 2021

Detailed study of arrivals from accurately fixed earthquakes has revealed additional complexity in the travel-time curve for PKP. A notation is introduced in which observations are denoted by P′ with a two-letter suffix indicating the branch to which they belong, namely P′AB, P′IJ, P′GH and P′DF. A new velocity solution for the Earth's core has been derived from these observations. This velocity solution differs from those previously suggested in having three discontinuous increases in velocity between the outer and inner core, at levels corresponding to 0.570, 0.455 and 0.362 times the radius of the core. This implies two shells, each between 300 and 400 km thick, surrounding the inner core; in each shell there is a small negative velocity gradient. The outer discontinuity is sufficiently shallow to prevent rays in the outer core from forming a caustic.
Mode-ray duality
Authors: Ben-Menahem Ari
Published: July 2021

Earlier results in the theory of terrestrial radio waves are applied to seismology. A partial field of the complete eigen-value solution for a sphere can be interpreted as real rays. Watson's transformation and the WKBJ approximation are employed to establish links between the index trio (l, m, n) of a mode and the corresponding parameters of the ray trajectory associated with this mode. It is shown that Snell's law for rays and Jean's formula are complementary. The condition of constructive interference is expressed as an integral equation for the eigen-frequencies nωl.
Spectral response of an elastic sphere to dipolar point-sources
Authors: Ben-Menahem Ari
Published: July 2021

A stratified elastic sphere is excited by an harmonic dipolar source of arbitrary orientation and depth. The total field is expanded in series of vector spherical harmonics and then condensed into a convenient form of a displacement dyadic. The Haskell-Gilbert matrix method is employed to obtain the radial factor of the displacements for a multilayered sphere. The dependence of the field on the azimuth angle and the fault elements is obtained for the case of a double-couple at depth. Expressions are also developed for the radiation pattern of surface waves over a spherical stratified earth.
Excitation of free oscillations of the earth by the Kurile Islands earthquake of 13 October 1963
Authors: Alsop L. E.
Published: July 2021

Peaks corresponding to free oscillation of the earth have been observed in the spectrum of a seismogram written following the Kurile Islands earthquake of 13 October 1963 by a special long-period vertical seismograph, with a 60-second pendulum. The periods obtained for the free oscillations, which are all of the spheroidal type, and which lie in a range of 200 to 1000 seconds, are in good agreement with values previously obtained from the great Chilean earthquake of 22 May 1960. No spectral peaks are observed at periods shorter than 200 seconds. This same phenomenon was observed in the spectra of the Chilean earthquake, and it is probably associated with the properties of the vibrating medium, i.e., the upper mantle, rather than with the source.
On a possible explanation of the PF-phase
Authors: Ghosh M. L.
Published: July 2021

As an explanation for PF phase, the author has considered propagation of Stoneley waves along the inclined continental margin which constitutes the interface of liquid and solid media. An iterative process has been applied to find the displacement on the level surface. The results agree with observations of PF phase and it has been suggested that PF are probably Stoneley waves.
Note on Fourier analysis
Authors: Jeffreys Harold
Published: July 2021

In the search for empirical periodicities there is no advantage in carrying out computations except for periods that are submultiples of the length of the record. Coefficients for four such periods in the neighbourhood of a maximum amplitude will yield by least squares estimates of a true period and its harmonic coefficients with a valid estimate of uncertainty.
Application of communication network theory to the electromagnetic seismograph
Authors: Dopp S.
Published: July 2021

Communication network theory is applied to the equivalent circuit of the electromagnetic seismograph. The seismograph's transfer function is derived in the general case of an arbitrary linear passive coupling network between pendulum and galvanometer. Examples are given, one of which refers to the construction of a band-pass filter in the form of a lattice of filter galvanometers.
Propagation of Love waves in a fluid-saturated porous layer lying beteen two elastic half-spaces
Authors: Paul M. K.
Published: July 2021

abstract

Propagation of Love waves in a fluid saturated porous layer lying between two elastic half-spaces has been considered in this note. It has been found that in the case of small porosity factor, the wavelength of the Love wave propagated in a fluid saturated porous layer increases or decreases in comparison with the case of elastic intermediate layer according as the density of the solid is greater or less than that of the fluid filling the pores.
On the numerical inversion of the Laplace transform
Authors: Longman I. M.
Published: July 2021

abstract

Methods are demonstrated for the numerical calculation of the inverse Laplace transform g(t) of a function g(p) given on the positive real axis of the p-plane.
Attenuation of shear waves in the upper and lower mantle
Authors: Kovach Robert L. , Anderson Don L.
Published: July 2021

abstract

The attenuation of seismic waves is a direct measure of the absorption due to nonelastic processes in the earth. The well known difficulties in obtaining body wave amplitude decrement data have been avoided by studying the spectral ratios of multiple ScS and sScS phases from two deep focus earthquakes recorded at near normal incidence. The average Q, for shear, in the mantle is about 600 for the frequency range 0.015 to 0.07 cps. Assuming that equal radiation occurs upwards and downwards from the source the average Q for the upper 600 km of the mantle is determined to be about 200 and about 2200 for the rest of the mantle. The value for Q at the base of the mantle is at least 5000 for shear waves.
Seismic waves with frequencies from 1 to 100 cycles per second recorded in a deep mine in Northern New Jersey
Authors: Isacks Bryan , Oliver Jack
Published: July 2021

abstract

A vertical component seismograph with a magnification of about 8 million at 20 cps was operated cps was operated 1780 feet below the surface at the Sterling mine of the New Jersey Zinc Company in Ogdensburg, New Jersey. Background noise, local earthquakes and teleseismic body phases were recorded. For frequencies greater than 2 cps, the continuous part of the background noise was fairly stationary during nighttime recording intervals and at a level lower than that at all but 9 of the 54 sites surveyed by Frantti (1963).

During 730 hours of recording at quiet background noise levels, 8 local earthquakes were detected. Six local shocks were recorded during an additional 2160 hours by conventional short period instrumentation located at Ogdensburg and Sterling Forest, New York. These data, combined with historical data on the occurrence of 22 larger shocks local to the area, are consistent with a linear relation between the logarithm of earthquake number and magnitude. This relation is given by log N = 2.6−0.9M, where N is the annual number of earthquakes which occur within 300 km of Ogdensburg and which have magnitudes greater than or equal to M. On this basis the seismicity of the area, which lies within a region of Paleozoic and early Mesozoic diastrophism, is about 2 orders of magnitude less than that of Southern California, 3 orders of magnitude less than that of the Garm region in Central Asia, and 4 orders of magnitude less than that of the Kwanto region in Japan.

Phases from 18 distant earthquakes were recorded by the high gain instrument. Only P and S phases from West Indies shocks, 20 degrees distant, exhibited motion with frequencies greater than 3 cps.
A note on the Alaska earthquake of July 10, 1958
Authors: Gupta Indra N.
Published: July 2021

abstract

A second phase arriving about 10 seconds later than the first P wave is seen on many seismograms used by Stauder (1960) in his study of the Alaska earthquake of July 10, 1958. Treating this event as an independent occurrence, it is proposed that this second event was caused by a “jerk” during the course of the propagation of the fault. Agreement with the fault mechanisms proposed by Stauder (1960) and Ben-Menahem and Toksoz (1963) is satisfactory.
Partition of energy in the focal region of earthquakes
Authors: Niazi Mansour
Published: July 2021

A spherical focal model is considered in which the release of the shear energy at the time of rupture sets up a laminar displacement field. Based on some geodetic observations, the field is assumed to decrease gradually as the distance from the focal point increases. This assumption allows the fault plane to be of finite extent.

The concept of static elasticity is applied to evaluate the fraction of stored shear energy which is released with the occurrence of an earthquake. Comparison of the distribution of the strain energy density in the focal region before and after rupture leads to some explanation about the partition of energy in that region.

The application of the model to three shallow earthquakes in the western United States yields energies comparable to those given previously.
Wave propagation phenomena at an irregular infinite interface: Part II: The free surface
Authors: Adams W. M. , Schubel E. K. , Schlesinger E.
Published: July 2021

In this paper the problem of scattering of a plane, simple harmonic acoustic wave from a free surface is treated. The boundary is rough as defined in Part I. Numerical results obtained by means of an IBM 7094 computer are given.
Comparison of theoretical and observational expressions for elastic strains of the earth
Authors: Takeuchi H. , Alsop L. E.
Published: July 2021

Transitional equations are provided between the quantities obtained in theoretical studies of tidal deformation, loading, and free oscillations of the earth and the empirical quantities obtained from observations of these phenomena. Tables of theoretical quantities are provided so that estimates may be made of the values to be expected observationally. Several examples are discussed.
Vibration of multistory buildings considering floor and wall deformations
Authors: Goldberg John E. , Herness Ervin D.
Published: July 2021

The vibration problem of multistory buildings, considering both shear and bending deformations in floors and in stiffening walls, is formulated and methods for calculating the normal modes and associated natural frequencies are described and illustrated.

A generalized slope deflection equation is used which takes into account shear deformation in addition to the flexural deformation conventionally included. This generalization permits the inclusion of shear deformation effects with no increase in the number of equations. Using this equation to represent the action of walls, a method for calcuating the modes and frequencies of stiffened multistory buildings is described. Going further and using the generalized equation to represent the action of floor slabs, a method for determining the two-dimensional modes and frequencies of stiffened and unstiffened multistory buildings with relatively long and narrow floors is presented. These modes and frequencies, which are not obtainable through the use of the usual analytical model, may be quite important in seismic design of this type of building.

As illustrative examples, the theory and method are applied to the calculation of several modes and frequencies of a 10-story building and a 20-story stiffened building.
A procedure for source studies from spectrums of long-period seismic body waves
Authors: Ben-Menahem Ari , Smith Stewart W. , Teng Ta-Liang
Published: July 2021

The well-known first motion method of Nakano and Byerly is extended, generalized and combined with recent new ideas in body wave theory in order to set up a routine procedure for extracting source parameters from spectral analysis of isolated P and S pulses recorded at a net of standardized stations around a non-shallow source.

The method consists of compensating the observed spectrums for instrumental and propagational effects. A combined study of the resulting radiation patterns, initial phases, and the initial amplitudes will render information regarding the spatial and temporal nature of deep and intermediate earthquake sources as seen through the spectral window of 10-100 seconds. The shorter periods can be used for source studies only if an accurate station correction is available.
Comments on a paper by Papadopoulos on the use of singular integrals in wave propagation problems
Authors: Longman I. M.
Published: July 2021

In a recent paper Papadopoulos [1]1 claims to have obtained solutions to the problem of sound propagation from an impulsive point source in a semi-infinite elastic solid which differ in certain respects from solutions previously obtained by Pekeris [2], [3], and by Pekeris and Lifson [4]. The results of Papadopoulos are based on a singular integral source representation developed by him [5]. By tests based on simple special cases we show that, in a number of cases where Papadopoulos claims a result different from that of Pekeris, the results of Papadopoulos are unacceptable whereas the results of Pekeris are acceptable. Reasons for these errors in Papadopoulos's work are suggested. A number of other errors in the paper of Papadopoulos are also noted.

1 Numbers in brackets refer to references at rear.
Investigations on surface-waves generated by explosion
Authors: Bisztricsány E. , Kiss Z. , Molnár K.
Published: July 2021

Surface-waves generated by explosion were investigated at distances between 1 and 20 km. On the basis of seismograms and particle motions two principal surface-wave groups can be separated. In the first group of surface waves the rotation of particles is progressive, while in hat of the second retrograde.
Local travel-time curves and their geologic implications for the Pacific Northwest states
Authors: Dehlinger Peter , Chiburis E. F. , Collver M. M.
Published: July 2021

Travel-time curves were constructed for the Pacific Northwest states based on recordings of recent local earthquakes. Average velocities of Pn and S waves were found to be 4 per cent lower in the region west of the Cascade Mountains than they are to the east of the Cascades, while velocities of P* and P¯ waves are essentially the same in the two provinces. West of the Cascades the velocities obtained are 7.67 km/sec for Pn, 4.37 for Sn, 6.61 for P*, and 5.48 for P¯. East of the Cascades they are 7.96 km/sec for Pn, 4.56 for Sn, 6.60 for P*, and 5.53 for P¯. Intercept times indicate that the crust (above the Mohorovicic discontinuity) is 5 to 10 km thinner to the west than east of the Cascades. Pn velocities are found to be independent of epicentral distance to distances of 1000 km, implying that the corresponding mantle materials and densities are uniform down to the low-velocity layer in each province. In both provinces Poisson's ratio in the mantle is 0.26. From the travel-time curves and gravity data, it appears that the section above the low-velocity layer east of the Cascades is approximately typical or “normal,” while the corresponding mantle west of the Cascades consists of a different or anomalous material. The likelihood of crystal alignment, temperature anomalies, and normal velocity-density relations in the upper mantle sections are discussed.
Seismicity of the Galápagos Islands and vicinity
Authors: Acharya H. K.
Published: July 2021

A study has been made of seismographically recorded submarine earthquakes between 1935 and 1961 in the region between 10°S and 20°N and 75°W and 110°W. Observational material on travel times was taken from the I.S.S., B.C.I.S. and U.S.C.G.S. catalogues for 191 earthquakes. New hypocentral solutions were found in each case by a uniform method of least-square adjustment. The earthquakes occur in the following belts: (a) the crest of the East Pacific Rise, (b) the Tehuantepec Ridge, (c) the Central American Trench, (d) the trench south of Panama and (e) around the Galápagos Islands. Focal depths and magnitudes of earthquakes are discussed. Escarpments appear to be aseismic.
Correction analysis of Jeffreys-Bullen travel time tables
Authors: Husebye Eystein S.
Published: July 2021

By dividing deviations between observed travel times and those of the Jeffreys-Bullen travel time tables into a station and an epicenter correction, it is possible to calculate corrections to these tables. A significant dependence of station and epicenter corrections upon locality is demonstrated. For the epicenter correction this is especially pronounced in the region of Japan. The correlation between calculated corrections and structures is discussed and the conclusion is that the corrections can be explained by velocity anomalies in the crust and upper part of the mantle. However, systematic errors in the calculated values are possible, especially for the epicenter corrections. No systematic correlation between the observed deviations of P and S waves can be detected, although such a relation should be expected from their respective velocity distributions. An appropriate way to improve the epicenter determinations is proposed, by incorporating the station and epicenter corrections in the solution procedure.
Tsunamis and seismic seiches reported from regions adjacent to the Indian Ocean
Authors: Berninghausen Wm. H.
Published: July 2021

abstract

References have been made in the past to the absence of tsunamis and seismic seiches in the Indian Ocean. However, a survey of available literature indicates that at least 27 such waves have been reported. Most of these were reported from the coastal regions of the seismically active Indonesian Arc, whereas progressively fewer such waves were reported from the coastal regions adjacent to the Bay of Bengal, Arabian Sea, and the southeastern coast of Africa and the western coast of Australia.
The transfer function for P-waves for a system consisting of a point source in a layered medium
Authors: Fuchs Karl
Published: July 2021

abstract

This paper investigates in what manner the spectrum of body waves radiating from point sources in a multilayered medium over a homogeneous half-space is different from the spectrum of body waves from the same source in an infinite medium. The effect of the system consisting of a point source in a layered crust on the spectrum of P-waves observed at large distances in the half space is studied. Analytical expressions for the transfer function of this system are derived for three types of point sources: an explosive source, a single couple, and a double couple of arbitrary orientation within the crust.

Preliminary numerical computations for the explosive source at various depths in a realistic model of the earth's crust permit the study of the effect of: a) the angle of incidence into the homogeneous half-space, b) the source depth, c) minor variations of the crustal model. In the case of an explosive source the most influential parameter of the transfer function is the source depth. In shallow explosions the low frequency part of the spectrum of body waves is comparatively rejected.
Reflection and refraction of elastic waves at a corrugated interface
Authors: Asano Shuzo
Published: July 2021

abstract

The effect of a corrugated interface on wave propagation is considered by using the method that was first applied to acoustical gratings by Rayleigh. The problem is what happens when a plane P wave is incident on a corrugated interface that separates two semi-infinite media. As is well known, there are irregular (scattered) waves as well as regular waves. By assuming both the amplitude and the slope of a corrugated interface to be small, quantities of the order of the square of corrugation amplitude are taken into account. In the case of normal incidence for three models considered, the effect of corrugation on reflection is larger than the effect of corrugation on refraction; the amplitude of the regularly reflected waves decreases, and that of the regularly refracted waves and of the irregular waves increases, as the corrugation amplitude becomes larger. Generally, the larger the velocity contrast, the larger the variation of wave amplitude with the wavelength and the amplitude of corrugation. The S wave component generally becomes larger as the wavelength of corrugation becomes smaller. Boundary waves exist, depending upon the ratio of wavelength of corrugation to that of the incident wave. For a specified interface, it is possible that there is a significant difference in wave amplitude as a function of the elastic constants. In the case of oblique incidence, computation was carried out for angles of incidence smaller than 15° for one model. For these small angles of incidence, almost all results for the case of normal incidence still hold. Furthermore, it can be concluded that the effect of the angle of incidence on reflected S waves is larger than for the other waves and that large differences in the amplitudes of waves at different angles of incidence may be expected for the irregular waves.
Use of a high speed computer for the preliminary determination of earthquake hypocenters
Authors: Engdahl Eric R. , Gunst Robert H.
Published: July 2021

abstract

At the U. S. Coast and Geodetic Survey, where preliminary earthquake locations must be computed from as many as 30,000 initially unrelated P arrivals and associated phases per month, considerable effort has been devoted toward making this process more fully automatic. A single pass program, COAST, has now been developed for use on the IBM 7030 (STRETCH) computer. This program discriminates compatible time groups from an uncorrelated chronological data file, computes a first approximation to the hypocenter using only five stations, and determines the refined hypocenter and earthquake magnitude using all relevant data without any intervention by a seismologist.
Transmission of Rayleigh waves at a corner
Authors: Mal A. K. , Knopoff L.
Published: July 2021

abstract

Using a Green's function method of approximation, transmission and reflection coefficients are computed for the problem of Rayleigh waves normally incident upon the corner of a homogeneous elastic wedge formed by two stress-free planes. The Rayleigh waves are incident from infinity and travel along one surface of the wedge. The transmitted waves on the second surface and the reflected waves on the first surface are calculated by the application of Huygens' principle. A pair of coupled integral equations for the displacements are obtained by means of a representation theorem. Neglecting the diffracted body waves near the corner, the coupled integral equations are reduced to a pair of algebraic equations. A new feature of the calculation involves consideration of diffracted surface waves travelling toward the vertex. Numberical values of the phase shifts and attenuation factors in the transmitted and reflected waves are computed as functions of the wedge angle. Comparison with experimental results show considerably better agreement than has been obtained previously.
Reflection of elastic waves from a linear transition layer
Authors: Gupta Ravindra N.
Published: July 2021

abstract

A separation of P- and S-wave potentials is achieved for an inhomogeneous medium in which density is constant and Lame's parameters, λ and μ, are assumed to vary as λ/λ1 = μ/μ1 = (1 + bz)2 where λ1, μ1 and b are constants. The resulting equations are solved for an arbitrary angle of incidence. Plane wave reflection coefficients are obtained for the situation when the material mentioned above forms a transition layer between two homogeneous, elastic half-spaces. First and/or second-order discontinuities in material properties are permitted at the boundaries of the transition layer. Some numerical results are given.
Reflection of plane elastic waves from transition layers with arbitrary varration of velocity and density
Authors: Gupta Ravindra N.
Published: July 2021

abstract

The problem of reflection of plane elastic waves is generalized numerically to an arbitrary variation, with depth, of the elastic parameters inside a transition layer between two homogeneous half-spaces. Numerical results are given for some cases of interest.
Response of a vertical strain seismometer to body waves
Authors: Gupta Indra N.
Published: July 2021

abstract

Expressions have been derived for vertical strain due to P and SV type waves arriving at an arbitrary angle of incidence within a semi-infinite medium. The amplitude and phase relationships between vertical strain and vertical displacement have been investigated for both wave types, assuming a Poisson's ratio of 0.25. The effect of finite depth and finite length of the vertical strain instrument has been examined and found to be significant especially for small angles of incidence.
Wind-induced vibrations and building modes
Authors: Ward H. S. , Crawford R.
Published: July 2021

abstract

This paper outlines the methods that have been used to determine the frequencies and modes of vibration of multistory buildings from their wind-induced vibrations. Three buildings of ten, thirty-eight and forty-seven stories were investigated. A simple theoretical model was used to calculate the frequencies of vibration of the buildings; the model was based on the assumption that there was no joint rotation in the building frames. A comparison of the theoretical and measured values of the frequencies showed that this simple model was a realistic representation of only the smaller building. It is concluded that a model that includes joint rotation would be more realistic for the taller buildings. Auto-correlation and power spectrum analysis of the vibration records were used to obtain an estimate of the damping characteristics of the buildings. The values obtained were 1 to 3 per cent of the critical amount of damping.
Teleseismic response of a uniform dipping crust (part I of a series on crustal equalization of seismic arrays)
Authors: Kane Julius
Published: July 2021

abstract

Most seismic theory is confined to a consideration of crustal structures that can be abstracted as plane parallel elastic layers. For such configurations, the response of each element of a seismic array will be similar to any other except for a time delay. Signal enhancement of an array located on such an idealized structure can be accomplished by suitable time delays of the individual traces followed by superposition.

On the other hand, if the crustal structure is anything but a plane parallel configuration, the signals received by the individual elements will not be identical to one another, but will include distortion effects characteristic of the local geometry. As a result, the records of seismic arrays located on realistic crustal configurations will have to be equalized to some standard reference if optimum signal processing is to be achieved.

In this paper we introduce a ray procedure for the calculation of theoretical seismograms for the teleseismic response of an array of stations located above a uniform dipping crust (wedge-shaped). In terms of this mathematical model, we demonstrate the signal distortion effects of the geometry and discuss equalization techniques that will permit a superior recovery of the desired signal.
Parkfield earthquakes of June 27-29, 1966, Monterey and San Luis Obispo Counties, California—Preliminary report
Authors: Oakeshott Gordon B. , Allen Clarence R. , Smith Stewart W. , Pakiser L. C. , McEvilly T. V. , Cloud William K. , Steinbrugge Karl V.
Published: July 2021

abstract

Two earthquakes, M = 5.3 and 5.5, shook the Parkfield area in southern Monterey County, California, at 0409:56.5 and 0426:13.8 GMT, 28 June 1966. They were preceded by foreshocks on the same day at 0100 and 0115. A third shock, M = 5.0, occurred in the same area at 1953:26.2 on 29 June. The earthquakes were followed by a heavy sequence of aftershocks with epicenters along the San Andreas fault zone extending for about 15 miles southward beyond Cholame in San Luis Obispo County. A P-wave first-motion fault plane solution shows strike of vertical fault plane is N 33°W, coinciding with a surface zone of en echelon fault fractures in the pattern characteristic of right-lateral, strike-slip movement. The motion appears to have an upward component on the west side, at about 20° from pure strike slip. Extensive instrumentation within a few miles of the epicentral district gave unusually complete records from foreshock to aftershock sequence. A strong-motion instrument in the fault zone near Cholame recorded the unusually high horizontal acceleration of 0.5 g.

The epicentral region of the earthquakes is on a known active segment of the San Andreas fault. Earthquakes in 1901, 1922, and 1934 in this region were also accompanied by surface faulting. On the published State geologic map, scale 1:250,000, the San Andreas fault zone shows a braided pattern of several branching en echelon major faults. Topographic forms, typical of the features of rift valleys, testify to the recency of fault movements. Small right-lateral surficial displacements had been recognized prior to the late June earthquakes in at least three places on the Parkfield-Cholame trace of the fault. Similar creep, or slippage, has continued since the earthquakes. Extensive nets of survey markers installed by 30 June across the active fault trace had recorded slippage as great as 0.1 inch per day by 12 July. The fault trace associated with the earthquakes is principally in alluvium of unknown depth in Cholame Valley, apparently a faulted graben within the San Andreas fault zone. Under a blanket of Tertiary and Quaternary sedimentary rocks in this part of the southern Coast Ranges, the great fault separates Jurassic-Cretaceous granitic and metamorphic rocks in the western block from Late Jurassic eugeosynclinal sedimentary and volcanic rocks of the Franciscan Formation in the eastern block.

In spite of the large horizontal acceleration recorded near the fault, very little building damage occurred in this sparsely populated region. Small concrete and steel bridges in, and adjacent to the fault trace, did not have their structural strength impaired.
Higher modes of seismic surface waves: Propagation in Eurasia
Authors: Crampin Stuart
Published: July 2021

Second Love and second Rayleigh modes are found to propagate in Eurasia across many different structures; the continent is divided into regions where these higher modes have the same dispersion characteristics. The condition for constructive interference breaks down only when the second modes cross areas of rapid change at oceanic-continental boundaries and under some mountain ranges. There are many paths in Eurasia where the second Love and Rayleigh modes have the same dispersion, and along these paths the two wave trains have a constant phase relationship, suggesting that the modes have some form of elastic linkage.
The S-wave project for focal mechanism studies, earthquakes of 1963
Authors: Stauder William , Bollinger G. A.
Published: July 2021

P- and S-wave data for thirty-five earthquakes selected from among the larger earthquakes of 1963 have been investigated. Focal mechanism determinations for twenty-six of these shocks are here presented. The solutions are based upon a combination of a graphical and a computer method for determining the poles of the nodal planes. In all cases it has been found that the mechanism may be adequately represented by a double couple as an equivalent point source of the focus, although in some few instances a single couple cannot be excluded as a possible alternate interpretation. The solution of a mid-Atlantic earthquake of November 17, 1963 is presented as an example of a focus which clearly conforms to the double couple model.

Special attention is called to the solutions for a series of earthquakes in the Kurile Islands, and to three earthquakes of the mid-Atlantic.
Signal-generated noise recorded at the Eskdalemuir seismometer array station
Authors: Key F. A.
Published: July 2021

abstract

An investigation of the signal-generated noise at the UKAEA seismometer array station at Eskdalemuir, Scotland, has shown a close correlation between apparent noise sources and topographic features. A particularly strong local source, in the region of a deep river valley, was found and has been studied in some detail.
A wide range seismogram digitizer
Authors: Wickens A. J. , Kollar F.
Published: July 2021

abstract

A visual seismogram drum-digitizer has been developed with precision adequate for the seismograms generated in standard networks. The variable speed, sampling interval and optical magnification permit convenient and efficient digital conversion of a wide range of record traces for different seismological research purposes.

An analysis of the precision has been made: over a dynamic range of 150 mm errors are less than 50 μ, and time intervals accurate to ±.05 sec for short-period seismograms or ±0.2 sec for long-period records.
The earthquake sequence of September, 1965 near Antioch, California
Authors: McEvilly T. V. , Casaday K. B.
Published: July 2021

abstract

A foreshock-aftershock sequence associated with an earthquake of magnitude 4.9 on September 10, 1965, in the San Francisco Bay Region is analyzed. The sequence was monitored by nearby Berkeley network stations and by one temporary station in the epicentral region. Precise hypocenters were determined for 29 of the shocks and these clustered in a small focal region with dimensions on the order of a few kilometers and at an average depth of 12 km. Within this focal region a N-S trend was observed with shocks apparently migrating down and then back up the trend.

(First motion radiation patterns were uniform throughout the sequence, and a P-wave fault plane solution for the main shock yielded as one possible source, consistent with observed S-wave polarization, a N-S trending fault with right-lateral motion. The log cumulative frequency of shocks versus magnitude plot yields a slope of b = −0.78. The similarities between this sequence and the 1964 Corralitos sequence are discussed and are shown to be at variance with the 1963 Salinas-Watsonville sequence and, from preliminary indications, from the 1966 Parkfield sequence. As a result, two characteristically different types of earthquake sequences in the magnitude 5.0-5.5 range are defined for the Central California region.
Crustal structure of the Mediterranean sea by surface waves. Part I: Group velocity
Authors: Payo Gonzalo
Published: July 2021

abstract

The purpose of this paper is to obtain an approximation to the crust-mantle structure of the Mediterranean Region, using only group-velocity data.

Earthquakes whose seismic paths cross totally or partially the Mediterranean Sea have been used. Forty-eight earthquakes have been selected and their corresponding Rayleigh and Love group-velocity dispersion curves were calculated. Most of the records belong to the standard seismological stations installed in the borders of the Mediterranean Sea.

The Rayleigh and Love wave dispersion curves obtained have been classified in five different groups which show the same dispersive character. There is a correlation of such classification with the oceanic percentage and geographic region crossed by the paths, i.e., with the corresponding type of crustal structure.

Crust-mantle theoretical models have been computed for both Rayleigh and Love waves. The dispersion curves of these models fit acceptably into an average of the data of each group. They show a remarkable difference between the eastern and western Mediterranean crust, which is considered as one of the main results of this investigation. The crust to the south of the Ionian and Aegean Seas shows somewhat smaller velocities and larger thicknesses, for the uppermost crustal layers, than that of the western Mediterranean, which seems to be of a more oceanic character.
Attenuation of earthquake generated P waves along the western flank of the Andes
Authors: Sumner Roger D.
Published: July 2021

abstract

The attenuation of longitudinal body waves generated by local shocks in southern Peru was investigated. Thirty-four shocks, with focal depths between 20 and 180 km, were used in the study of attenuation as a function of depth and as a function of frequency (1-30 cps). Shocks were recorded on magnetic tape at three stations along the western flank of the Andes. The dimensionless specific attenuation factor Q was computed from measurements of the relative change in shape of P-particle velocity spectra with distance from the source. Near surface effects on amplitudes were taken into account. It was found that: Qp(1.5-15 cps) > 1 × 103; the attenuation of P waves increases markedly above 15 cps, probably due to scattering losses; and although absolute Qp values as a function of depth could not be resolved, an increase in P wave attenuation at a depth of about 80 km is suggested. Vp/Vs, determined from S-P and P readings at seven stations for 150 shocks, is significantly higher for oceanic shocks than inland shocks.
Near-surface dispersion studies at Tonto Forest Seismological Observatory
Authors: Linville A. Frank , Laster Stanley J.
Published: July 2021

abstract

Four local seismic events digitally recorded on a crossed-linear array have been analyzed to evaluate the representation of wave propagation in inhomogeneous earth models in terms of “local” dispersion. The analysis techniques studied are based primarily on the correlation properties of the signals at various receivers. Frequency-wave-number spectra are computed for the events by various methods, and a comparison of the results indicates that the best method is a combination using averaged correlations computed from prewhitened data. The utility of computing dispersion curves from an estimation of the “transfer function” has been evaluated. The studies show the necessity of recording data directly “inline” in areas of rough topography between source and array if “local” dispersion is to be measured. Multichannel prediction studies indicate that the signals are highly nonstationary in space.
Forced vibration of an eight-story reinforced concrete building
Authors: Englekirk R. E. , Matthiesen R. B.
Published: July 2021

abstract

The 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

abstract

Explosions 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.