bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of ScS-wave data in focal mechanism determinations
Authors: Furumoto Augustine S. 
Published: July 2021

abstract
In this paper the S wave method of focal mechanism determination is extended to include the ScS wave. By the establishment of the quantitative relationship between the directions of vibration of the S and the ScS, ScS wave data can be reduced to a form of S wave data usable for focal mechanism determinations.
The new extension has been checked by reobtaining focal mechanism solutions for four heartquakes using ScS wave data. Results were consistent with previous solutions by the S wave method or P wave method.
Signal-to-noise ratio and spectra of explosion-generated Rayleigh waves
Authors: Sherwood J. W. C. , Spencer T. W. 
Published: July 2021

abstract
This preliminary theoretical study is basically concerned with the estimation of the depth of an explosive source from a knowledge of the radiated Rayleigh wave. Details are given of the dependence of the amplitude spectrum on the explosive yield, depth of burial, horizontal range, and the elastic parameters of the medium. It is assumed that the medium is a homogeneous and isotropic half space which, as far as the Rayleigh wave is concerned, possesses a mechanical quality factor, or Q, which is independent of frequency. Furthermore, it is assumed that the explosive shot has been effectively decoupled from the medium by locating it within a cavity of appropriate size. It is shown that changes in either shot depth or Q can produce an identical change in the Rayleigh wave spectrum. Hence a lack of knowledge of Q limits the accuracy with which source depth may be estimated. An additional inaccuracy may result from the ambient ground motion preventing the recovery of the Rayleigh wave spectrum. For this reason estimates are given of the theoretically anticipated Rayleigh signal-to-noise ratio per kiloton of explosive in a seismically quiet location. It is emphasized that the study is preliminary in nature. To be of significant practical use it is believed that the theory must be extended to take into account the effect of surface layering of the medium.
The effect of boundaries on wave propagation in a liquid-filled porous solid: III. Reflection of plane waves at a free plane boundary (general case)
Authors: Deresiewicz H. , Rice J. T. 
Published: July 2021

abstract
A general solution is derived of Biot's field equations governing small motions of a porous solid saturated with a viscous liquid. The solution is then employed to study some of the phenomena attendant upon the reflection from a plane, traction-free boundary of each of the three body waves predicted by the equations. The problem, though more complex, bears some similarity to that of electromagnetic waves in a conducting medium, in that some of the reflected waves are inhomogeneous, planes of constant amplitude not coinciding with planes of constant phase.
Analytical expressions are displayed for the phase velocities, attenuation coefficients, angles of reflection and the amplitude ratios, and explicit formulas are given for the limiting cases of low and high frequencies, representing first-order corrections for porosity of the solid and viscosity of the liquid, respectively. The paper concludes with a presentation of results of numerical calculations pertinent to a kerosene-saturated sandstone.
Note on use of a Sofar geophone to determine seismicity of regional oceanic areas
Authors: Shurbet D. H. 
Published: July 2021

abstract
Daily Bermuda short period seismograms are compared with Sofar geophone records for a period of three years. Many short-period seismic signals were recorded on the geophone record that are not on the seismograms. Therefore, it is suggested that a geophone array could be most useful in determining regional seismicity in oceanic areas. The large number of geophone signals recorded gives some indication that the advantages of the expected quiet of the ocean bottom may be somewhat offset.
The San Agustin fault system of southern Peru
Authors: Rodriguez B. A. , Steinhart J. S. , Asada T. 
Published: July 2021

abstract
A study of the hypocentral location of 133 small earthquakes in southern Peru reveals the existence of a vertical fault zone parallel to, and west of, the axis of the Andes chain. This zone is named the San Agustin fault zone in honor of the University where the work was done.
Period equation for Rayleigh waves in a layer overlying a half space with a sinusoidal interface
Authors: Kuo John T. , Nafe John E. 
Published: July 2021

abstract
The problem of the Rayleigh wave propagation in a solid layer overlying a solid half space separated by a sinusoidal interface is investigated. The amplitude of the interface is assumed to be small in comparison to the average thickness of the layer or the wave length of the interface. Either by applying Rayleigh's approximate method or by perturbating the boundary conditions at the sinusoidal interface, plane wave solutions for the equations which satisfy the given boundary conditions are found to form a system of linear equations. These equations may be expressed in a determinant form. The period (or characteristic) equations for the first and second approximation of the wave number k are obtained.
The phase and group velocities of Rayleigh waves in the present case depend upon both frequency and distance. At a given point on the surface, there is a local phase and local group velocity of Rayleigh waves that is independent of the direction of wave propagation.
Generally applicable solutions of Zoeppritz' amplitude equations
Authors: McCamy Keith , Meyer Robert P. , Smith Thomas J. 
Published: July 2021

abstract
A crustal model, in addition to satisfying travel-time data, should agree with the observed distribution of amplitude in time and range. The study of observed amplitudes in seismic crustal work depends directly on the partition of the amplitude of an incident wave front at an interface. The Zoeppritz equations describe this partition for a plane wave and while they are simple simultaneous linear equations, their solution by hand methods is tedious and receptive to errors. Solutions of these equations have been obtained by numerical methods for both the incident P and SV cases and are presented in the form of curves showing the ratio of the amplitude of the resultant ray to that of the incident ray plotted against the angle of incidence. By solving the equations for velocity ratios ranging from 0.25 to 4.0, families of curves covering most realistic situations were obtained.
That generally applicable solutions of these equations can be presented in curve families ranging over velocity contrast alone, is demonstrable from the studies of the velocity vs. density relation made by Nafe and Drake and independently by Woollard.
The curves presented permit rapid, quantitative solution of the amplitude partition at an interface, thereby, greatly facilitating the study of wave train modifications.
A note on the effect of ripple firing on the spectra of quarry shots
Authors: Willis D. E. 
Published: July 2021

Abstract
A series of controlled quarry shots were recorded at a distance of approximately 900 feet to ascertain the effect of ripple firing on amplitude and spectra of the seismic waves. A measurable reduction in the amplitude of compressional and shear wave was observed at some frequencies. This effect was not so pronounced for the surface waves.
The Chilean earthquakes of May, 1960: A structural engineering viewpoint
Authors: Steinbrugge Karl V. , Flores A. Rodrigo 
Published: July 2021

abstract
The series of major earthquakes which occurred in south-central Chile during May of 1960 were of large Richter magnitude and were accompanied by major geologic changes. Epicenters were distributed throughout populated regions; the earthquakes violently shook many substantial buildings which had been specifically designed to resist earthquake forces.
In general, damage to earthquake resistive structures of reinforced concrete, structural steel, and wood frame was slight and the overall performance was quite satisfactory. When major damage did occur to structures with earthquake bracing, construction practices were almost always recognizably poor. The minor damage to earthquake resistive structures was instructive and a number of case histories are discussed. Of particular interest are the instances of shear wall rotation on compressible soils, construction and design errors, relative rigidity problems, and the performance of inverted pendulum structures.
The measurement of ground motion of destructive earthquakes
Authors: Hudson D. E. 
Published: July 2021

abstract
The need for a greatly expanded network of strong-motion accelerographs throughout the seismic regions of the world is stressed. A summary of the characteristics of currently available strong-motion accelerographs is presented, and the design details are given for an instrument suitable for acquiring the basic data needed by structural engineers for earthquake resistant design. It is shown that for such an instrument, the natural period must be less than 0.1 seconds, and that the recording speed must be at least 1 cm/sec. The critical nature of the inertia starting device is discussed, and some information is given on the transient response of the standard pendulum starter used in the United States Coast and Geodetic Survey Strong-Motion Accelerograph. The use of simpler, non-time-recording instruments such as the U.S.C.G.S. Seismoscope to supplement the accelerograph network is described.
Rayleigh waves in a two-layer heterogeneous medium
Authors: Dutta Subhas 
Published: July 2021

Abstract
The possibility of propagation of Rayleigh waves in an incompressible crust of constant density and rigidity varying exponentially with depth lying on (i) a semi-infinite incompressible homogeneous medium and (ii) a semi-infinite compressible homogeneous medium is studied in this paper. The variation of rigidity is assumed as μρ=beβZ, where b and β are constants. To fix ideas we suppose that the crust has the thickness 37.5 km. in which the rigidity increases exponentially from 2.747 × 1011 to 4.53 × 1011 dynes/cm2 over the ultrabasic material of infinite depth in which the rigidity is constant and equal to 6.47 × 1011 dynes/cm2. Frequency equations and their numerical solutions are obtained in both the cases. The results thus obtained are compared with the results derived from those given by Newlands.
Radiation pattern of Rayleigh waves from a fault of arbitrary dip and direction of motion in a homogeneous medium
Authors: Haskell N. A. 
Published: July 2021

Abstract
Expressions for the displacements in the body waves radiated in an unbounded, homogeneous elastic medium by dipolar point sources of arbitrary orientation may be readily derived in Cartesian coordinates from formulae given by Love. The free-surface boundary conditions are, however, most conveniently expressed in terms of Sezawa's cylindrical wave functions. The necessary transformation between the two representations is provided by the Sommerfeld integral and others that may be derived from it by differentiations with respect to the radial and axial (vertical) coordinates. By this means the total radiation field (direct plus surface reflected) is expressed in terms of integrals of cylindrical wave functions. The Rayleigh wave component may then be separated out by calculating the residue at the Rayleigh pole of the integrand. The azimuthal dependence of the Rayleigh wave displacements appears as the sum of three terms, one independent of the azimuth angle, φ, another depending upon sin φ and cos φ, and a third depending upon sin 2φ and cos 2φ. The coefficients of these terms are functions of the direction cosines of the normal to the fault plane and the direction of the relative displacement vector in the fault plane. Equations are presented for sources of both single and double couple types. The effect of fault propagation with finite velocity over a finite distance may be included by multiplying these expressions by the finite source factor previously derived by Ben-Menahem.
Polar plots of the amplitude and initial phase are presented for single and double-couple representations of a number of different types of faults. It is noted that for one certain orientation a shallow double-couple source generates no Rayleigh waves.
Three forgotten earthquakes
Authors: MacCarthy Gerald R. 
Published: July 2021

Abstract
For a given maximum intensity, most earthquakes of the Eastern United States are felt over much wider area than their western counterparts. Several of these eastern shocks, have, because of their relatively low maximum intensities, received little or no attention in seismological literature. Three such earthquakes will be described in terms of contemporary accounts: those of March 9, 1828, April 29, 1852, and of August 31, 1861. In no case did the maximum intensity exceed about VI on the Mercalli Scale, yet each was felt over many thousands of square miles. The 1828 shock affected at least 190,000 square miles, and was reported from Pennsylvania to South Carolina. That of 1852 affected about 187,000 square miles, and was reported from New York to North Carolina. That of 1861 affected at least 280,000 square miles, and was reported from Maryland to the Georgia-Alabama border. All three were felt from the Atlantic Coastal Plain westward into Ohio.
Discussion of “earthquake analysis by response spectrum superposition” by R. W. Clough
Authors: Arias S. Arturo , Husid L. Raul 
Published: July 2021

Abstract
A formula for approximating the maximum earthquake response of shear-buildings is given. This formula gives maximum shears as a linear combination of the r.m.s. superposition and the absolute value superposition of modal maxima. A comparison is made with a previously proposed method and some comments are made on the accuracy.
Seismic measurements of large underwater shots
Authors: Willis D. E. 
Published: July 2021

Abstract
A series of 10,000-pound high-explosive shots was fired at various water depths off San Clemente Island, California during August 1961. These shots were recorded on magnetic tape at one fixed station (123 km) and at portable stations located at 180, 196, 500, and 518 km. The effect of water depth on the amplitude and spectra of the seismic waves generated by these shots is discussed, and a comparison is made with the maximum displacement of underground shots. A spectral comparison is also made with a local earthquake recorded at two of the shot recording sites.
Comparison of seismic waves generated by different types of source
Authors: Willis David E. 
Published: July 2021

AbstractA comparison of the seismic waves generated by a nuclear explosion and an earthquake is discussed. The epicenter of the earthquake was located within the Nevada Test Site. Both events were recorded at the same station with the same type of equipment. The earthquake waves contained slightly lower frequency than the waves generated by the nuclear shot. The early P phases of the shot had larger amplitudes while the phases after Pg for the earthquake were larger. Seismic waves from collapses were generally found to be composed of lower frequencies than the waves from the original shot. Aftershocks of the Hebgen Lake earthquake were found to generate seismic waves whose frequency content was related to the magnitude of the aftershock. Spectral differences in quarry shot recordings that correlate with source duration times are also discussed.
Spectral energy density for quarry explosions
Authors: Frantti G. E. 
Published: July 2021

Abstract
Several explosions of varying time duration have been recorded at 156 km along a constant propagation path from a central Michigan limestone quarry. Energy density for body waves and surface waves is examined as a function of frequency and observed to peak between 1 and 10 cps. A correlation between spectral amplitudes and source duration time is revealed and is emphasized at shot durations which approximate the dominant period of seismic waves. A study of the data suggests that seismic energy levels may be controlled, in part, by regulating the time duration of delayed quarry blasts. This parameter (total duration time) has been generally neglected in published studies involving commercial blasts.
Energy spectra for underground explosions and earthquakes
Authors: Frantti G. E. 
Published: July 2021

Abstract
Energy density for the entire seismogram is examined as a function of frequency for underground explosions and earthquakes. Anomalous differences in the spectra appear to correlate with the time duration of the source. Ratios of aftershock to earthquake energy show a relatively flat frequency dependence. In contrast, corresponding ratios for nuclear shot-collapse events change rapidly with increasing frequency.
Analysis of these data suggests that measurements of total seismogram energy might be usefully applied in the seismic source discrimination problem.
Amplitude, energy, and phase angles of plane SV waves and their application to earth crustal studies
Authors: Costain John K. , Cook Kenneth L. , Algermissen S. T. 
Published: July 2021

Abstract
Energy ratios from Knott's energy equation and amplitude ratios and phase angles from the Zoeppritz equations were calculated for a plane SV wave incident on a plane elastic discontinuity. All computations were programmed in Fortran for an IBM 1620 digital computer. Incident angles were varied from 0° to 90° in increments of two degrees except near the critical angles, where the ratios were calculated in increments of 0.25 degree generally. Both real and imaginary coefficients were considered in the calculations. The varying parameters were the velocity ratio and density ratio across each interface, and the angle of incidence. Poisson's ratio was kept constant at 0.25. Compressional velocity ratios (transmitted/incident) of 0.7, 0.8, and 0.9, and density ratios (transmitted/incident) of 0.7, 0.8, 0.9, and 1.0 were used. The data are presented in an integrated album which consists of a total of 144 curves (48 curves for each of the 3 characteristics studied). The theoretical amplitudes of PS converted waves, which are seismic body waves resulting from the conversion of an incident parent P wave at a boundary within the earth's crust to a refracted vertically polarized SV wave, were computed (using a fortran program on an IBM 1620 digital computer) for several multi-layered hypothetical and actual crustal models. Preliminary results indicate that the amplitudes of successive PS converted waves arriving from successively deeper layers will continually increase provided that the velocity ratios (upper medium/lower medium) continually decrease with depth. The effects of the wave period have not yet been considered. Particle-motion diagrams obtained from seismograms of two underground nuclear explosions show some shear motion in the first ten seconds which is provisionally interpreted to be from PS converted waves.
Some theories of microseisms in the light of more recent findings
Authors: Hjortenberg Erik 
Published: July 2021

Abstract
A review of a few recent discussions concerning different theories of generation and propagation of the 2–10 sec. microseisms is given and it is shown that Dr. Jensen's (1961) large number of determinations of direction of approach confirms some of the older findings, e.g. the microseismic barrier in the eastern North Sea. Furthermore it is shown that the dependence of microseisms on air temperature in the source area can be explained satisfactorily in terms of Longuet-Higgins theory.
After a short discussion about correlation between microseisms and meteorological data, including wave height observations, a discussion is given of an attempt to correlate microseisms in Greenland with observed waves at a certain weathership. The result was negative as far as the variation from day to day is concerned, but the characteristics of the seasonal variation of the two variables give some support to the Longuet-Higgins theory of the origin of microseisms.
The seismic sea wave of 22 May 1960 along the Chilean coast
Authors: Sievers C. Hellmuth A. , Villegas C. Guillermo , Barros Guillermo 
Published: July 2021

Abstract
This paper details the efforts of the Chilean Navy in warning of the tidal waves that followed the earthquakes of May 1960 and the efforts made to collect information concerning the tsunami. Details of time of arrival, damages, wave height and run up are presented for almost all ports in the affected area beginning at Puerto Aysen and working northward. Changes in water depth, caused by erosion, deposition, and changes in land elevation are reported.
The fates of several ships caught in the great waves are described in detail. Marigrams of the tsunami are given for all available Chilean ports.
The times of high and low tides in the Gulf of Chiloé changed following the earthquakes.
The tsunami of 23 May 1960 in the Hawaiian Islands
Authors: Cox Doak C. , Mink John F. 
Published: July 2021

ABSTRACT
The tsunami of 23 May 1960 was detected in Hilo Bay at 0007 hours HST and recorded on the Honolulu tide gauge at 0033 HST. Runup heights ranged from 2 to 17 feet except in Hilo where the wave formed a bore and reached 35 feet. Sixty-one people were killed and 282 injured in spite of elaborate warning 5 hours in advance of the arrival of the tsunami.
Damage and effects are discussed for all the Hawaiian Islands and recommendations are made to prevent future catastrophes. A brief history of Hawaiian tsunamis is given.
Relation between geology and the effects of the earthquakes of May 1960 in the city of Castro and vicinity, Chiloé
Authors: Galli O. Carlos , Sanchez R. Joaquin 
Published: July 2021

ABSTRACT
The rocks and sediments of the region have been divided into eight units: metamorphic rocks of pre-Mesozoic age, composed of mica schists; volcanic rocks, columnar andesites, tentatively assigned to the Tertiary, that outcrop in a small area to the west of Castro; fluvioglacial deposits, uncemented sands and gravels that in almost all cases overlie three terraces of Pleistocene age that are indicated on the map as morphologic units; slope deposits, friable hybrid material neither classified nor consolidated, that cover one of the most dangerous areas in which to construct; beach deposits—unconsolidated coastal sediments; unconsolidated alluvial sediments distributed in the beds of rivers and in the river deltas presently in formation; and deposits of artificial fill, gravels, sands, bricks, trash, etc.
Damage to structures is clearly related to the geology. In areas of artificial fill and of slope deposits, catastrophic destruction was caused almost exclusively by geologic and morphologic factors. Some areas with a favorable morphology, such as the intermediate and high terraces, are formed of sound material, such as metamorphic rocks, and had little or no damage.