bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of a seismograph network and electronic computer in near earthquake studies
Authors: Cleary J. , Doyle H. 
Published: July 2021

Abstract
A description is given of the application of a close network of seismograph stations and of an IBM 650 computer program to the study of a sequence of near earthquakes in southeastern Australia. The epicenters, depths, and origin times of a moderate sized earthquake and its aftershocks were determined with unusual accuracy, revealing an interesting pattern of foci. The position and origin time of the main shock were then used to study arrivals at more distant stations; Pn arrivals were found to fit a linear travel-time equation closely to a distance of 15 degrees, with a surface velocity of 8.16 ± 0.03 km/sec. The Sn phase was not clear and gave an approximate velocity of 4.7 ± 0.2 km/sec. The possibility of a small velocity decrease in the upper mantle below eastern Australia is discussed.
Generation of earthquakes by a volume source with moment
Authors: Scholte J. G. J. , Ritsema A. R. 
Published: July 2021

abstract
The theory developed in paper I* has been used to determine the influence of the focal radius on the P and S wave radiation from a spherical source on which the stress τz=Tyr0eivt acts. The result has been applied to two earthquakes of which the P and S wave distribution around the focus was studied in paper II. † In an appendix, the present model of the focus is compared with similar models that are described in literature.
* This bulletin p. 711 † This bulletin p. 723
Particle motion near a nuclear detonation in halite
Authors: Weart Wendell D. 
Published: July 2021

abstract
Strong motion parameters from the Project gnome operation were measured in the region extending 60 to 480 meters from the center of detonation or working point along both vertical and horizontal radii.
Travel time data from the horizontal radius reveals three distinct arrivals. First arrivals are propagated through a polyhalite layer with a velocity of 4.839 km/sec. This is followed by the direct elastic wave arrival in the salt horizon (4.318 km/sec) and the plastic wave which decreases in velocity as the stress level diminishes.
Vertically, the velocity varies from 5.1 km/sec at about 60 meters above the shot to 0.785 km/sec a few meters below the surface.
Peak accelerations in the salt are best fitted by the relations A = 890 R−5.3 from 60 to 122 meters and A = 560 R−2.7 from 122 to 480 meters. (R in hundreds of meters and A in units of gravity.) Peak particle velocity in the salt is given by U = 13 R−3.56 from 60 to 100 meters and U = 13 R−1.36 from 100 to 480 meters.
Motion of the ground above the shot reveals that spalling occurred at several horizons. The deepest spall separation was below 92 meters. These effects were most pronounced at the surface where the initial acceleration, velocity and displacement peak values were A = 25 g, U = 5.6 m/s, and D = 168 centimeters. Residual upward displacement at surface zero at +5 minutes was 79 centimeters.
Regional variations in Pn velocity and their effect on the location of epicenters
Authors: Herrin Eugene , Taggart James 
Published: July 2021

abstract
Evidence from recent earthquakes and explosions is presented showing substantial regional variations in the velocity of Pn in the United States. These variations have a significant effect on the location of epicenters by the least-squares method. We have included a contour map of Pn velocity in the United States. A new method for computer location of epicenters is described, and is shown to decrease the error of location for events in the western United States by as much as an order of magnitude.
Ground effects from the gnome and logan explosions
Authors: Carder D. S. 
Published: July 2021

abstractSeismic waves resulting from a low yield nuclear detonation 1200 feet deep in a salt bed near Carlsbad, New Mexico were measured by strong-motion seismographs operated by the Coast and Geodetic Survey on the surface in the distance range from 0.5 to 8.8 miles and underground in a potash mine 8.7 to 11.2 miles distant. In addition, many temporary and permanent seismographs were operated by the Coast and Geodetic Survey and other organizations on a continentwide and a world-wide basis. Ground particle accelerations exceeded those from the Logan shot, a like detonation in tuff, by a factor of about 4, and accelerations underground in the salt bed were about half those on the nearby surface. There was no evidence of damaging accelerations in nearby commercial operations or dwellings. Nearby transient ground particle displacements were about the same as those from the logan shot, except that the frequencies were higher. Attenuation with distance across the plains to the east was relatively low as compared with similar effects in the mountain and plateau area toward the west. Upper mantle velocities likewise were higher toward the east, 8.3 to 8.4 km/sec, as compared with 7.8 to 8.1 km/sec toward the north, west, and northwest. The estimated magnitude of the gnome shot was from 4.5 to 5.0, depending on the choice of data.
Travel times and amplitudes of principal body phases recorded from gnome
Authors: Romney Carl , Brooks Billy G. , Mansfield Robert H. , Carder Dean S. , Jordan James N. , Gordon David W. 
Published: July 2021

abstract
gnome, an undergound nuclear explosion in salt near Carlsbad, New Mexico, produced seismic waves which were recorded widely throughout the United States and at a few foreign stations. The travel times of P were strongly dependent on the path of propagation, and were as much as 12 seconds earlier in the eastern United States than at equivalent distances in the western part of the United States. At the few stations more distant than 25°, P was about 2 seconds earlier than predicted by the Jeffreys-Bullen table for surface focus. Amplitudes of Pn were similarly dependent upon the path of propagation; although the measurements showed great scatter, amplitudes to the east were generally larger than those to the west. Pn travel time and amplitude anomalies suggest a systematic relationship to crustal thickness. There is evidence from the difference in the speeds and attenuation rates that Lg and P are not transmitted along analogous paths through the crust. Short period body waves were two or three times larger than expected from an explosion of the same energy in tuff at the Nevada Test Site. Surface waves, however, were relatively weak compared with explosions of similar yield in tuff.
Computer program for a fault-plane solution
Authors: Kasahara Keichi 
Published: July 2021

Abstract
In its earthquake mechanism studies the Dominion Observatory has been producing solutions graphically, but a program based on a probability function defined by Knopoff has been written for the IBM 1620 which permits the best solution to be obtained by a series of successive approximations from a given first approximation. The program prints out the strike and dip of the two nodal planes, their standard errors, the azimuth and plunge of their line of intersection, and a list of the stations producing inconsistent data. Weights can be assigned to each station; in practice these weights would depend on the past reliablity of the station.
The machine time required depends on the number of stations used, the accuracy of the first approximation and other factors; in general 20 to 30 minutes is required for a solution involving 30-40 stations.
Comparative spectra of microseisms and swell
Authors: Haubrich R. A. , Munk W. H. , Snodgrass F. E. 
Published: July 2021

Abstract
Spectra of seismic and ocean wave recordings near San Diego, California, show closely related features. The wave spectra consist of a sharp peak whose frequency, f(t), increases linearly with time and consistent with the expected dispersive behaviour from a source at 6150 nautical miles (presumably a storm in the Ross Sea). The seismic spectra show peaks at f(t) and at 2 f(t); the double frequency peak contains 100 times the energy of the peak at the primary frequency. A comparison between the peak frequencies and band widths of the seismic and ocean wave spectra, and an estimate of the direction and beam width of the seismic radiation, leads to the following conclusions: that the microseismic generation area is predominantly local, being confined to a distance of 100 miles up or down the coast. For the primary frequencies the generative strip is presumably confined to shallow water; for the double frequencies it extends 200 miles seaward.
Propagation of an SH-torque pulse in a layered solid
Authors: Pekeris C. L. , Alterman Z. , Abramovici F. 
Published: July 2021

Abstract
In this investigation we determine the motion of the surface of a layered elastic half-space produced by a torque-pulse from a point-source situated inside the layer. The axis of the torque is vertical (SH) and its time variation is represented by a step-function with rounded shoulders. The displacement due to the source approaches a saw-tooth shape at large distances. The displacement of the surface was evaluated exactly by the ray-theory method for ranges r = 100 H and r = 400 H, H denoting the thickness of the layer. The spectrum of the forerunner ground wave and of the Love wave can be interpreted in terms of the normal mode theory. The form of the displacement-curve is found to be sensitive to the width Δ of the pulse at the source. For small Δ the Love wave starts with a strong high frequency amplitude comparable to that of the Airy phase arriving later. This is due to a peak in the excitation function of the first mode. As Δ grows, this peak disappears and the Love wave builds up in the normal fashion to a maximum amplitude at the time of arrival of the Airy phase. For the pulse shape assumed, the normal mode theory predicts a factor of [sin2 (ωΔ/2)]/Δ in the amplitude, where ω denotes the frequency. This is verified in the displacement curves obtained.
The effect of diagonal bracing on the earthquake performance of a steel frame building
Authors: Clough Ray W. , Jenschke Victor A. 
Published: July 2021

abstract
Diagonal bracing, intended to increase the lateral strength of two steel frame buildings at the University of Concepcion, was broken by the Chile earthquake of May 21, 1960. The unbraced structures then resisted the earthquake of May 22 with no further structural damage, thus raising the question whether the bracing was either necessary or beneficial. To examine this question, a digital computer study was made of the strengthening effect of the diagonal bracing when the buildings were subjected to ground motions recorded at three different earthquakes. The results indicate that for some earthquakes, the bracing may be beneficial. However, for other cases, the bracing induces increased forces in the frame which exceed the strengthening effect of the bracing. Thus, the braced structure actually may be less earthquake resistant than if it were unbraced.
Axially symmetric elastic waves in an unbounded inhomogeneous medium with exponentially varying properties
Authors: Lock M. H. 
Published: July 2021

Abstract
The propagation of elastic waves in a traversely inhomogeneous medium of infinite extent is studied. A method to separate the governing equations of motion is described and solutions are obtained for the elastic waves generated by an impulsive P type point source. These solutions are compared with the corresponding solution for the homogeneous case and the various effects introduced by the inhomogeneity of the medium are discussed.
A new short-period seismometer for field and observatory use
Authors: Willmore P. L. , Connell D. V. 
Published: July 2021

Abstract
The new seismometer is developed from the original Willmore instrument, using the same principle of a suspended magnet and five spoke suspension to yield a compact portable instrument capable of either horizontal or vertical operation. In the new version the flux linkage has been more than doubled to give an e.m.f. exceeding 200 volts/m/sec. from a 500 ohm coil. A device has been introduced which enables the period to be adjusted between 0.6 and 3.0 seconds, and the use of new elastic material for the springs enables the instrument to operate without readjustment over a temperature range of ±50°C. Multi-tap coils are provided to give any desired degree of damping for a low impedance load up to critical at 0.6 second periods and up to five times critical at 3 seconds. The case has been modified to improve the water-proofing, whilst allowing access to the period and mass-position adjustments from outside.
Source-mechanism from spectra of long-period seismic surface waves.
Authors: Ben-Menahem Ari , Toksöz M. Nafi 
Published: July 2021

AbstractSource-mechanism is derived from amplitude and phase spectra of mantle Love and Rayleigh waves of the Alaska earthquake of July 10, 1958. The signals R2, R3, G2, G4, G5 recorded on the Gilman 80–90 and the Press-Ewing 30–90 seismograph systems at Pasadena, California, are separated, digitized, filtered and Fourier-analyzed. An agreement between theory and observations is obtained for a unilateral fault of 300–350 km, which ruptured with a speed of 3-3.5 km/sec in the direction N40°W. Fault length is in good agreement with the extent of aftershock distribution in the month of July, 1958, and the time of rupture checks with the duration of an impressive T-phase recorded at Hawaii. The phases of the signals are corrected for propagation, instrumental shift and the source finiteness. Initial phases thus obtained agree on a mechanism of a right double-couple with a unit step-function in time.
The stress changes that accompany strike-slip faulting
Authors: Chinnery M. A. 
Published: July 2021

Abstract
In a previous paper (Chinnery, 1961) an investigation of the deformation of the ground around a strike-slip fault was described. This work is now extended to a calculation of the change in stress distribution that is brought about by such a fault. Contour maps of the components of the stress change are included, both for the general rectangular fault, and for the limiting case of a long shallow fault. These maps have a number of interesting features, and show clearly the complexity of the stress change in the neighborhood of the edges of the fault plane. The assumptions involved in the calculation are discussed at some length.
Uncoupled equations of motion in nonhomogeneous elastic media
Authors: Alverson R. C. , Gair F. C. , Hook Joseph F. 
Published: July 2021

Abstract
The method of Helmholtz has been recently employed by Hook to obtain uncoupled equations of motion from the vector wave equations governing the propagation of elastic waves in certain types of nonhomogeneous media. The work reported on in this paper casts the method of Helmholtz in terms of matrices and extends the work of Hook to media with variable Poisson's ratio. It is found that the constitutive parameters must satisfy a pair of nonlinear ordinary differential equations. These differential equations are integrated in a special case and a useful and interesting example of a nonhomogeneous medium is given.
The tsunami of 22 May 1960 in French Polynesia
Authors: Vitousek Martin J. 
Published: July 2021

ABSTRACT
Except for the Marquesas Islands, the islands of French Oceania are relatively safe from tsunamis because of well-developed reefs, inner lagoons, and steep offshore slopes, hence the Chilean tsunami of 22-23 May 1960 was not well developed. Detailed data are given for Tahiti. The greatest runup height was 3.4 meters above low water, the average was 1.7 meters. Runup of 1 meter was observed in the Leeward Islands. In the Austral Islands the highest wave reached 1.8 meters. The Tuamotu Archipelago suffered water level changes of about 1 meter. In the Marquesas Islands runups of about 3 meters were observed.
No human casualties were reported from French Polynesia and damage was slight.
Further observations of geologic and geomorphic changes resulting from the catastrophic earthquake of May 1960, in Chile
Authors: Weischet Wolfgang 
Published: July 2021

ABSTRACT
A geomorphic study of the region in which the earthquake occurred, made after the earthquakes is compared with a similar study made before the earthquakes. Evidence is presented to show changes in land level. Discussion of the effects of the tsunami as it affected geomorphic and geologic processes is presented. Landslides are listed and analysed. Distribution of intensity is discussed.
The distribution of the damage caused by the earthquake in Valdivia in relation to the form of the terrane
Authors: Weischet Wolfgang 
Published: July 2021

ABSTRACT
The western part of the city of Valdivia is more severely damaged than the eastern part. This is because the eastern part is underlain by a firm continuous bed, actually a terrace, of cancagua, a fine-grained soil composed of volcanic ash. The western part consists of a discontinuous surface marked by isolated mesa-like remnants of this terrace, surrounded by soft, incompetent fill. Vibration of the mesa-like columns was severe because of the lack of contiguous support at the contact with the incompetent fill material. Construction on artificial fill was very seriously damaged.
Relation between geology and the damage in Puerto Montt, Chile, caused by the earthquake of 22 May 1960
Authors: Dobrovolny Ernest , Lemke Richard , Bowes William , Thomas Herbert , Bravo S. Nelson 
Published: July 2021

ABSTRACT
The damage in Puerto Montt resulted from landsliding, debris flows, mud flows, and settling of unconsolidated alluvium and artificial fill. Structures on high terraces, away from the edges, were undamaged.
Geologic report on the effects of the earthquake of 22 May 1960 on the city Llanquihue
Authors: Thomas Herbert , Bowes William , Bravo S. Nelson 
Published: July 2021

ABSTRACT
Damage occurred from landsliding and mass movement on the steep slopes of terraces and from subsidence and inundation in the swampy central zone of Llanquihue. Large structures located on well-drained terraces were undamaged. The glacial history of Lake Llanquihue is discussed.
Crustal structure southwest of the San Andreas fault from quarry blasts
Authors: Hamilton Robert M. , Ryall Alan , Berg Eduard 
Published: July 2021

abstract
To determine a crustal model for the southwest side of the San Andreas fault, six large quarry blasts near Salinas, California, were recorded at 27 seismographic stations in the region around Salinas, and along a line northwest of the quarry toward San Francisco. Data from these explosions are compared with results of explosion-seismic studies carried out by the U.S. Geological Survey on a profile along the coast of California from San Francisco to Camp Roberts. The velocity of Pg, the P wave refracted through the crystalline crust, in the Salinas region is 6.2 km/sec and the velocity of Pn is about 8.0 km/sec. Velocities of the direct P wave in near-sur-face rocks vary from one place to another, and appear to correlate well with gross geologic features. The thickness of the crust in the region southwest of the San Andreas fault from Salinas to San Francisco is about 22 kilometers.
The response of simple nonlinear systems to a random disturbance of the earthquake type
Authors: Goldberg J. E. , Bogdanoff J. L. , Sharpe D. R. 
Published: July 2021

abstract
Stationary properties of the response of simple nonlinear systems to earthquake type (nonstationary) random disturbances are determined. The method used consists in generating member functions of the input processes, integrating the equations of motion using these as inputs to obtain output member functions, and then, from this ensemble of outputs, determining the statistical properties of interest. The method is flexible in that it is easy to apply to simple as well as complex linear and nonlinear systems; it yields a variety of statistical properties of engineering significance; it provides a method for approaching the design of aseismic structures; and more generally, shock resistant structures on a practical basis.
In addition to determining and displaying input and corresponding output member functions, we determine individual as well as average velocity spectra, first passage time probabilities, and extreme value distributions of relative displacements. Comments are also offered on the utility of these results in design.
On elastic strain of the earth in the period range 5 seconds to 100 hours
Authors: Major Maurice W. , Sutton George H. , Oliver Jack , Metsger Robert 
Published: July 2021

abstract
Observations of earth strains, covering a wide spectrum of periods, have been made with a three component installation located 1800 feet below the surface in a deep mine at Ogdensburg, New Jersey. This paper is a description of the strain meters and their environment and is a report of several studies based largely on strain observations.
The instruments, modeled after those of Benioff, employ quartz tubes as their standard of length, use variable capacitor transducers, and record simultaneously tidal data at low gain and seismic data at a sensitivity about 40 times that of the tidal signal. A significant reduction of the noise level in the seismic spectrum has been achieved by sealing the tube rooms against air pressure fluctuations.
The present secular strain rate is less than 1.7 × 10−8 per month, almost an order of magnitude less than that observed by Benioff in California, and almost two orders of magnitude less than that observed by Takada in Japan.
A transient strain with a duration of about 100 hours was associated with the storm tide which damaged the eastern coast of the United States on March 5-8, 1962. The strain corresponds to that produced by an anomalous high water mass whose seaward extent was limited to 100 ± 30 km in the azimuth southeast from Sandy Hook. Direct observation of the seaward extent of such storm tides, for areas off coastlines bordering the open ocean, has not been possible in the past because of the lack of deep water tide recorders.
Love's number h and Shida's number l are determined to be 0.53 and 0.037, respectively, from observations of strains associated with the M2 tidal constituent, on the basis of the assumption that the ocean load generated strain has the same phase on both horizontal instruments. The uncertainty in h and l is large, as it is in other measurements of these numbers, because of the effect of ocean load. This uncertainty is examined in a quantitative manner by mapping h and l as functions of ocean load amplitude and phase in the vicinity of the solution.
Strain seismograms of the Kenai Peninsula earthquake of September 5, 1961, and the Prince Edward Island earthquake of December 29, 1961, are unique. The exceptional long period response of the strain seismometers has made it possible to record, on the first pass, waves associated with the group velocity maximum of the Rayleigh wave dispersion curve over a purely continental path across North American and an almost pure oceanic path across the Atlantic. Such data have never before been reported. The shield area of North America is characterized by higher than average Rayleigh wave velocities. The Atlantic data, when compared with data from the Pacific, do not indicate any appreciable difference between the mantle structure below the Atlantic and that below the Pacific.