bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monotonic Neural Network for Ground-Motion Predictions to Avoid Overfitting to Recorded Sites
Authors: Okazaki Tomohisa , Morikawa Nobuyuki , Fujiwara Hiroyuki , Ueda Naonori 
Published: July 2021

Abstract
Data-driven machine-learning approaches are being increasingly applied to construct empirical ground-motion models (GMMs). It is a standard practice to divide observational records into learning and test datasets to correctly evaluate the predictive performance of a developed model. However, in this study, we show that division based on records or earthquakes is inappropriate for evaluating the generalization performance on recorded sites when GMMs include site-condition proxies as input variables. Complex models exhibit small residuals at sites used in the training process, but exhibit large residuals at new sites owing to overfitting to the trained sites. As a simple solution, we propose a neural network model that has monotonic dependence on some of the input variables. The model successfully obtains the generalization performance on recorded sites, although it lacks ability to represent oversaturation with input variables suggested in extreme ground-motion ranges. Therefore, alternative methods should be investigated to develop robust data-driven models under general conditions. Dividing the sites into learning and test data would play a fundamental role in developing such robust models.
On the possibility of the seismic detection of explosions from the signs of first onsets
Authors: Scheidegger A. E. 
Published: July 2021

Abstract
It is shown that, for an earthquake region, critical areas can be derived inside which one would expect seismic stations to observe a dilatation in the first onsets. Thus, if compressions are observed inside the critical area, one has grounds for the assumption that the “earthquake” was an explosion. As an example, critical areas are calculated for Turkmenia and the Tien Shan region.
Resonances in seismic noise under arctic sea-ice
Authors: Milne A. R. , Clark S. R. 
Published: July 2021

abstract
Spectrograms of underwater seismic noise between 0.2 and 2.0 cps from the bottom of relatively shallow ice-covered seas show a line structure which indicates that vertical resonances occur within layers bounded at depth by the Mohorovičić discontinuity. The line structure appears with most clarity when recognizable transients are excluded. Under these quasi-stationary noise conditions, measurements of pressure spectra indicate that the seismic noise of the observed level can be generated by a vertical bobbing of the ice field as a whole.
First motions from seismic sources near a free surface
Authors: Burridge R. , Lapwood E. R. , Knopoff L. 
Published: July 2021

abstract
The radiation patterns of first motions are calculated for the sudden occurrence of an arbitrarily oriented fault (dislocation) at the surface of a half space; the dislocation in the fault plane is also arbitrarily oriented and is assumed to occur over a very small area of the fault plane. Initially the source is considered at a finite depth and the solution is obtained by allowing the depth to tend to zero.
In general the results show a surprising directionality for the radiation of SV. In the focal plane projection the first motions of P and SH for a strike-slip fault show the familiar four-lobed radiation patterns. The first motions of SV show some reversals in polarity with angular distance from the source.
The first motions for all components of motion for a dip-slip fault have characteristics governed strongly by the presence of the free surface, and hence differ markedly from the usual radiation patterns for a deeply imbedded source.
The Hindu Kush earthquake of March 4, 1949 as recorded in Europe
Authors: Lehmann I. 
Published: July 2021

abstract
The European records from distances 36°-50° of the deep Hindu Kush earthquake of March 4, 1949 were studied. The many clearly recorded deep-focus reflections lend to the records a characteristic appearance which is repeated in many other shocks from the same focal region. The ratios of the amplitudes of these phases vary somewhat from one shock to another. In the shock here considered sP and sPP are exceptionally large at most stations; in the Italian stations they are not so large, while pP is a clear phase. pP is not very well defined at most other stations.
Most of the 1949 records were from the old type long-period instruments having their highest magnification for periods from about 5 sec to 12 sec. Present day instruments of quite short or of very long proper period while admirable for many purposes do not record waves in this period range very well and therefore do not produce a satisfactory picture of the forerunners of earthquakes. The difference between the records obtained on different instruments is illustrated.
It is shown in examples that the amplitude ratio PP:P may differ strongly at the same epicentral distance and also that pP may vary greatly with azimuth.
The deficiency of station readings is noted.
Travel times and their residuals are tabulated and travel times plotted versus epicentral distances.
Central U.S. crust—Upper mantle structure from Love and Rayleigh wave phase velocity inversion
Authors: McEvilly T. V. 
Published: July 2021

abstract
Fundamental mode Rayleigh and Love wave phase velocities in the period range 5 to 80 seconds have been measured in the central U. S. Using the concept of constant partial derivatives of phase velocity with respect to layer parameters in a least-squares inversion scheme a structural model for the area was determined. Several parameters were constrained on the basis of other available data. It was not possible to fit satisfactorily both Rayleigh and Love data with a simple isotropic model. Conclusions require either anisotropy in the upper mantle or systematic errors in the phase velocity measurements.
Detection of small arrivals
Authors: De Bremaecker J. Cl. 
Published: July 2021

Abstract
Even, inverse noise filters have been used in an automatic scheme for the detection of small arrivals. Precursors have not been created by this method. The significance level is estimated by computing the number of points in a normal noise record which have the same amplitude. The method has been successfully tested on actual earthquakes. Starting with a digitized seismogram, it automatically finds the arrivals, prints their time, their direction, and their standard deviation, and plots the spectra and the seismograms. Examples are given.
Auditory discrimination of seismic signals from earthquakes and explosions
Authors: Frantti G. E. , Levereault L. A. 
Published: July 2021

Abstract
Magnetic tape recordings of short-period seismic signals from approximately 200 earthquakes and explosions were time-compressed by a factor of up to 512 to shift seismic frequencies to the audible range. These seismic data include the inhomogeneities introduced by substantial variations in the locations of sources and receivers (world-wide), propagation path length (32 to 7000 km), and source magnitude (M = 0.5 to M = 6.5). Subjects were trained with a representative set of the “seismic sounds.” Auditory experiments were conducted to determine the ability of the human auditory system to distinguish between seismic signals from earthquakes and explosions. The results of the experiments suggest that a trained listener can identify approximately two-thirds of the seismic sounds presented, where one half corresponds to chance performance.
Transmission of Rayleigh waves past a step change in elevation
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 incident upon a step change in the elevation of the surface of a homogeneous half-space. Several versions of these approximations are given, differing principally by the method in which the surface waves on the vertical face of the step are taken into account.
A seismic refraction and gravity study of the earth's crust in British Columbia
Authors: White W. R. H. , Savage J. C. 
Published: July 2021

Abstract
Explosion refraction studies have been carried out in areas adjacent to Vancouver Island, including the Strait of Georgia and Johnstone Strait and along the west coast of the Island. A refraction line has also been observed from a large explosion in Seymour Narrows, eastward through the mountains and for some distance across the plains of Alberta. Although the surficial strata complicate the interpretation, a series of short refraction profiles consistently reveal the presence of an intermediate layer with velocity of about 6.8 km/sec. in the coastal area. The depth to the upper boundary of this layer varies from about 11 km. along the west coast of the Island to less than 5 km. in the Strait of Georgia and along the east side of the Island. The longer range observations parallel to the coast indicate this layer to be more than 40 km. thick. On the profile eastward through the mountains a velocity of 7.8 km/sec. has been found for Pn, from an unreversed profile, with a crustal thickness of approximately 30 km.
Computer simulation of multi-storey structures subjected to ground motion
Authors: Ward H. S. 
Published: July 2021

AbstractA hybrid computer system has been used to simulate some five-storey structures excited by ground motion. Five types of buildings were investigated to find the effect of some structural parameters on the dynamic response of the buildings. The factors that have been considered are the distribution of stiffness and mass in the structure, the type of foundation condition, and the action of viscous damping.The results indicate that it may be reasonable to calculate the base shear forces, created by ground motion, as a function of the fundamental period of the building. In the case of lightly damped structures, however, the distribution of forces through the height of the structure is also shown to be dependent on the other dynamic characteristics of the building, as well as the frequency content of the ground motion.Viscous damping considerably reduces the forces acting on a structure, and also tends to eliminate modes of vibration other than the fundamental. A pinned-end foundation condition is also shown to reduce the forces acting on the lower storeys of a building compared with the fixed-end condition.
Iberian Peninsula crustal structure from surface waves dispersion
Authors: Payo G. 
Published: July 2021

abstract
Phase velocity of Rayleigh waves traveling from Toledo to Málaga have been determined from seven selected earthquakes. The direction of approach of the wave front in relation to the ground particle motion at the standard Spanish stations (Toledo and Málaga) and at Porto (Portugal) is discussed.
Also these three Observatories are considered as a triangular array to determine the phase velocity through the lberian Peninsula region; this result is compared with the dispersion data determined by the two stations at Toledo and Málaga.
Two similar crustal-mantle structures, named IB1 and IB2, have been obtained for this Region, by modifying the models Dorman 8021 and CAN-SD respectively, and by means of the partial derivatives of the phase velocity with respect to the parameters of the layers. Both models IB1 and IB2 are almost identical and their corresponding dispersion curves fit the data with an error less than 0.1 km/sec. The crustal thickness given by these structures is about 33 km.
Group velocities of Love and Rayleigh waves from near earthquakes have been also studied. Some Algerian earthquakes yielded a dispersion curve for the arm of the Mediterranean Sea between Algeria and Spain. The curve appears almost typically oceanic.
Transmission of explosive sound through a fluid layer over an infinitely deep elastic bottom
Authors: Rosenbaum J. H. 
Published: July 2021

abstract
The transmission of explosive sound through a thin fluid layer above an infinitely deep elastic bottom is described by means of an asymptotic theory. Special attention is paid to early oscillatory arrivals at large horizontal distances for the case of a high-velocity bottom, and it is found that these arrivals do not decay exponentially with horizontal distance. When the shear wave velocity in the bottom is low, the over-all response is very similar to the case of a fluid bottom, except for the Rayleigh mode, which becomes an important feature of the late signal. The response at long times may involve standing waves of finite horizontal wavelengths.
A portable strain meter with continuous interferometric calibration
Authors: Blayney J. L. , Gilman Ralph 
Published: July 2021

Abstract
A strain meter has been designed embodying techniques not used in earlier models. Minimum use of heavy and permanent auxiliary fixtures has made possible a portable instrument in which no components need be abandoned in order to change location. Provision for frequent or continuous interferometric calibration, and a photographic record therof, has provided uninterrupted strain measurements with long-term dependability. Also included is the usual continuous low-speed ink recorder for tidal and secular variations, and a high-gain band-pass recorder for the observation of long period waves and free oscillations of the earth. Details are given describing the method used for interpreting the interferometer image and its conversion to strain measurement.
The dynamic analysis of an apartment building
Authors: Shepherd R. 
Published: July 2021

abstract
The normal-mode, response-spectra approach to the design of earthquake resistant structures forms the background to many design codes including the New Zealand one.
In order to apply these codes, and thus establish the seismic design loads, predictions of the elastic dynamic characteristics of a building must be made as part of the design process.
This paper describes the analysis undertaken using an electronic digital computer for the purpose of predicting the dynamic characteristics of one of New Zealand's tallest apartment buildings, the sixteen story Jerningham Apartments in Oriental Bay, Wellington.
Body wave radiation patterns from force applied within a half space
Authors: Gupta Indra N. 
Published: July 2021

abstract
Expressions are derived for the horizontal and vertical displacements at an arbitrary depth within a homogeneous, isotropic, elastic half space when plane harmonic P, SV or SH waves are incident at any given angle. On the basis of the reciprocity theorem, these expressions represent also the far-field polar radiation patterns of P, SV and SH waves due to horizontal and vertical forces applied at a point within the half space. Numerical results for a few selected values of depth are shown for a solid half space.
The effect of initial stress or residual stress on elastic energy calculations
Authors: Burridge R. , Knopoff L. 
Published: July 2021

abstract
The first aim of this paper is to define a stress-energy function which coincides with the conventional strain-energy function in a non-prestressed medium, but which has a more natural physical interpretation than strain energy for prestressed media.
The second aim is to show how consideration of prestress or residual stress may drastically change theoretical energy estimates for earthquakes.
Surface displacements due to an underground explosion
Authors: Bycroft G. N. 
Published: July 2021

abstract
A simple solution to the problem of the surface displacements on an elastic half-space caused by an underground explosion is presented. The analysis is based on deriving the transient case for a point source from the steady state point source and then proceeding to the case of a finite spherical cavity by means of a retarded potential.
Theoretical values of maximum displacement compare favorably with measured values from the underground test shot Rainier, a nuclear explosion of Operation Plumbob.
A phase sensitive parametric seismometer
Authors: Rodgers P. W. 
Published: July 2021

abstract
The steady-state response characteristics of a seismometer do not depend on the phase of the input. A phase-dependent response is obtained by parametric excitation of the seismometer, which is achieved with an electromagnetic spring. A theory is developed for this device and comparisons are made with experimental data. The construction of the seismometer and its application are discussed.
On the structure of the upper mantle
Authors: Lehmann I. 
Published: July 2021

Abstract
From apparent velocities of first arrivals across the Tonto Forest array for epicentral distances from 11° to 29° Niazi and Anderson derived a structure of the upper mantle deviating markedly from other structures as determined of late. It is found that on a different interpretation their data are in good accord with the Lehmann structure of the upper mantle.
Standing waves in a layered half space
Authors: Gupta I. N. 
Published: July 2021

Abstract
In a homogeneous elastic half space, plane harmonic waves give rise to standing waves only when on reflection there is no conversion from one wave-type to another. The existence of standing waves in a horizontally-layered half space is established for vertically propagating plane harmonic P, SV or SH waves. Expressions are derived for the particle displacements at the free surface and at any given depth. The layered system acts as a complicated filter suppressing certain periods while amplifying others. The results obtained may be helpful in an understanding of the ‘ground factor’, ambient seismic body-wave noise, and the vibration problem of a structure due to earthquake motion.
Dynamic response of a two-story steel frame structure
Authors: Bouwkamp J. G. , Blohm J. K. 
Published: July 2021

Abstract
A two-story steel rigid frame building with shear walls along two adjacent sides was subjected to dynamic tests. The tests were performed using a vibration generator to excite the building in its various modes.
Two rotational modes were investigated in considerable detail. Mode shapes and frequencies were determined for each mode of vibration, and values of damping were computed. A computer analysis of the building was made to study the comparison between experimental and analytical results.
The anticipated response of the building under an actual earthquake (El Centro) was determined also.
Model and theoretical seismicity
Authors: Burridge R. , Knopoff L. 
Published: July 2021

abstract
A laboratory and a numerical model have been constructed to explore the role of friction along a fault as a factor in the earthquake mechanism. The laboratory model demonstrates that small shocks are necessary to the loading of potential energy into the focal structure; a large part, but not all, of the stored potential energy is later released in a major shock, at the end of a period of loading energy into the system. By the introduction of viscosity into the numerical model, aftershocks take place following a major shock. Both models have features which describe the statistics of shocks in the main sequence, the statistics of aftershocks and the energy-magnitude scale, among others.
Scale-model study of refraction along an irregular interface
Authors: Howell B. F. , Baybrook T. G. 
Published: July 2021

abstract
An irregular boundary scatters waves refracted along it, acting as a low-pass filter. This effect is similar to that produced by refraction along an intermediate velocity layer or by a linear-gradient transition zone. Such scatter could explain why reflections from the Mohorovicic discontinuity are hard to record. If this is the case, they should be easier to record if frequencies above 5 cps are filtered out of the seismogram.
Scattering of steady elastic waves by surfaces of arbitrary shape
Authors: Sharma Darbari L. 
Published: July 2021

abstract
The three-dimensional problem of scattering of steady elastic waves from an arbitrarily shaped body is formulated in terms of simultaneous singular integral equations. These basic equations defining the displacement potentials at the surface are two-dimensional Fredholm integral equations of the second kind over the surface of the body. In contrast to other formulations, this procedure is not restricted to a particular shape of the scattering object or to the nature of the incoming wave. However, by assuming the scatterer to be a body of revolution, the integral equations are reduced to one-dimensional Fredholm equations along the axis of the scatterer. The formulation is presented for a fixed rigid scatterer.
The integral equations are solved by approximating the potential functions by a set of polynomials and by satisfying the integral equations in the sense of least squares. The solution yields the surface potentials from which the field potentials or the field displacements are obtained by surface integrals. The numerical results are in good agreement with those obtained by the eigenfunction method for an incoming wave which is a plane shear or longitudinal wave.
Investigation of a method for determining stress accumulation at depth
Authors: Eisler Joseph D. 
Published: July 2021

abstract
Measurement of stress accumulation at depth could serve as the basis for predicting earthquakes. Based on laboratory measurements of rock samples, stress accumulation in the earth can be estimated from changes in the compressional velocity of seismic waves traversing the stressed region, provided the travel times can be determined with precision. An initial field experiment performed in the Gabilan Range near Salinas, California, using 100-kilogram charges, demonstrated that seismic energy could be reliably detected up to 42 kilometers away, that the character of the recorded signal was closely repeatable for successive shots, and that the precision of timing was better than ±1 millisecond.
Local seismic monitoring—Fairview Peak Area, Nevada
Authors: Westphal W. H. , Lange A. L. 
Published: July 2021

Abstract
Four portable seismographs were used in January-February and April to August 1965 to record local earthquakes in the Fairview Peak Area of west-central Nevada. During these recording periods, which totalled 129 days, over 1300 local shocks were recorded of which 224 were large enough for determination of focal points. These hypocenters defined the active faults of the region and provided a means for mapping the probable extent of these faults at depth.
Preliminary determination of crustal structure in the Katmai National Monument, Alaska
Authors: Berg Eduard , Kubota Susumu , Kienle Jurgen 
Published: July 2021

AbstractSeismic and gravity observations were carried out in the active volcanic area of Katmai in the summer of 1965. A determination of hypocenters has been aftempted using S and P arrivals at a station located at Kodiak and two stations located in the Monument. However, in most cases, deviations of travel times from the Jeffreys-Bullen tables were rather large. Therefore hypocenters are not well located. A method based on P- and S-wave arrivals yields a Poisson's ratio of 0.3 for the upper part of the mantle under Katmai. This higher value is probably due to the magma formation. The average depth to the Moho from seismic data in the same area is 38 km and 32 km under Kodiak. Using Woollard's relation between Bouguer anomaly and depth to the Moho, a small mountain root under the volcanoes with a depth of 34 km was found dipping gently up to 31 km on the NW side. The active volcanic cones are located along an uplift block. This block is associated with a 35 mgal Bouguer anomaly. The Bouguer anomaly contour map for the Alaska Peninsula is given and an interpretation attempted.
Seismoscope results from three earthquakes in the Hollister, California, Area
Authors: Cloud William K. 
Published: July 2021

Abstract
Seismoscope records from a magnitude 5.0 earthquake on January 19, 1960, and from magnitudes 5.6 and 5.5 earthquakes on April 8, 1961, in the Hollister, California, area, like those from the Parkfield, California, main shock of June 27, 1966, indicate that the maximum amplitude of transient motion in close proximity to the San Andreas Fault was oriented at a large angle to the strike of the fault.