bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismicity in the vicinity of the Ramapo fault, New Jersey-New York
Authors: Page Robert A. , Molnar Peter H. , Oliver Jack 
Published: July 2021

Abstract
Since 1962 the Lamont seismograph network in southeastern New York and northern New Jersey has recorded four small earthquakes with epicenters along the Ramapo fault near the New York-New Jersey border. The northeast trending fault separates the Triassic basin to the southeast from the Precambrian highland to the northwest. The proximity of these events to the fault and the previous earthquake history of the area suggest that much of the seismic activity of the area is associated with this major tectonic feature, which has apparently not been highly active since the Triassic.
Parkfield earthquake of June 28, 1966: Magnitude and source mechanism
Authors: Wu Francis T. 
Published: July 2021

AbstractThe Parkfield earthquake of June 28, 1966 (04:26:12.4 GMT) is studied using short-period and long-period teleseismic records. It is found that (1) Mb = 5.8 and Ms = 6.4 as compared to Mb = 5.4 and Ms = 5.4 for the foreshock (04:08:54), (2) both the Rayleigh and Love wave radiation patterns conform to those of a double couple at a depth of about 8.6 km, (3) the main shock can be represented by a series of shocks separated in space and time.The near-field strong-motion data support the last conclusion. Based on strong-motion seismograms, and the surficial evidences of the dimensions of the fault, the energy is found to be 1021 ergs.
Array design
Authors: Haubrich Richard A. 
Published: July 2021

abstract
Arrays of detectors placed at discrete points are often used in problems requiring high resolution in wave number for a limited number of detectors. The resolution performance of an array depends on the positions of detectors as well as the data processing of the array output. The performance can be expressed in terms of the “spectrum window”.
Spectrum windows may be designed by a general least-square fit procedure. An alternate approach is to design the array to obtain the largest uniformly spaced coarray, the set of points which includes all the difference spacings of the array. Some designs obtained from the two methods are given and compared.
Some statistical aspects of the estimation of seismic travel times
Authors: Tucker William , Herrin Eugene , Freedman Helen W. 
Published: July 2021

AbstractSome of the statistical aspects of estimating travel-time anomalies and station corrections are considered. In order to estimate these quantities using earthquake data the events themselves must first be located. We investigated the use of the Gauss-Newton iterative technique to obtain a least-squares epicenter location employing Monte Carlo methods. Results of these studies indicate that the Gauss-Newton process converges to an absolute minimum and that confidence ellipses computed by linear techniques are reliable for reasonable networks of well-distributed stations. Also the Monte Carlo studies indicate that a least-squares solution may be inaccurate if appreciable travel-time anomalies or station-error means exist. We then expanded the location procedure to include the estimation of travel-time anomalies and station corrections. In order to obtain these estimates data from some 278 large earthquakes were analyzed by using a modified Seidel iterative process.
Multipolar elastic fields in a layered half space
Authors: Ben-Menahem Ari , Jit Singh Sarva 
Published: July 2021

Abstract
Hansen's expansion is used to derive integral expressions for the displacement field due to a localized buried source of the mth order in a layered half space. The dipolar case (m ≦ 2) is worked out in detail for arbitrary source-depth in the layer and in the substratum. A new type of representation of the source is used which gives the final results in a concise form. Explicit expressions for the displacements at the free surface are obtained for a center of explosion, a vertical strike-slip fault and a vertical dip-slip fault. The results for a horizontal thrust are found to be the same as for a vertical dip-slip fault.
The relations between the Galerkin vector and the biharmonic eigenvectors are clarified. It is shown that the Galerkin-Boussinesq solution for the elastic half space cannot be extended to structures of higher complexity, except for a few simple sources. On the other hand, the Hansen Solution is valid for a wide class of sources and structures.
Both dynamic and static regimes are considered.
Engineering seismic risk analysis
Authors: Cornell C. Allin 
Published: July 2021

Abstract
This paper introduces a method for the evaluation of the seismic risk at the site of an engineering project. The results are in terms of a ground motion parameter (such as peak acceleration) versus average return period. The method incorporates the influence of all potential sources of earthquakes and the average activity rates assigned to them. Arbitrary geographical relationships between the site and potential point, line, or areal sources can be modeled with computational ease. In the range of interest, the derived distributions of maximum annual ground motions are in the form of Type I or Type II extreme value distributions, if the more commonly assumed magnitude distribution and attenuation laws are used.
A seismic refraction profile and crustal structure in central interior Alaska
Authors: Hanson Kenneth , Berg Eduard , Gedney Larry 
Published: July 2021

Abstract
An unreversed seismic refraction profile was obtained during the winter of 1966-1967 from several small chemical explosions in an open pit coal mine near Suntrana, Alaska. The profile runs from south to north across the Tanana Basin in central interior Alaska. Both P and S waves, generated by the explosions, were observed out to a distance of 217 km from the shot point. A four-layer crustal model is adopted to explain the first and later prominent seismic phases. The P velocities range from 3.67 km/sec in the sedimentary surface layer to an apparent value of 8.83 km/sec in the upper mantle. It is assumed that the Moho is dipping to the south under the Alaska Range, from a depth of 32 km at Fairbanks to approximately 48 km under the shot point.
Source bias in epicenter determinations
Authors: Herrin Eugene , Taggart James 
Published: July 2021

ABSTRACT
Epicenter determinations using data from stations at distances greater than 20° from the source make use of standard travel times based on a spherically symmetrical Earth. Lateral inhomogeneities in the upper mantle result in relative delays with respect to the standard times. Delays associated with the end of the up-traveling ray can be handled through the use of station corrections. A constant delay beneath the source can not be easily corrected, but it will result only in errors in origin time. However, if the delay arising beneath the source changes with azimuth, a consistent error, here called source bias, will be present in the estimate of the epicenter. Studies of explosions within continental masses have revealed no significant source bias; however, events on two linear, volcanic island chains in the Pacific (Rat Islands-Aleutians and Hawaii) show significant source bias. Errors arising from this effect may be as large as 12 degree and are most likely to occur with events near tectonically active island chains.
A microearthquake swarm in 1965 near Mould Bay, N.W.T., Canada
Authors: Smith T. E. T. , Whitham K. , Piché W. T. 
Published: July 2021

ABSTRACT
In a 30-day period beginning March 29, 1965, some 2026 microearthquakes were recorded at MBC and by the array NPNT. About 10 per cent of them were located. The extent of the epicentral region was 3 sq km and of the hypocentral region 8 cu km. The centroid of the hypocenters was 12.6 km from MBC on an azimuth of 121° and at a depth of 6.8 km, very nearly on the strike of an old fault. Although no foreshock-aftershock series could be distinguished, the events were not independent nor randomly distributed in time.
Particle motion diagrams were drawn for 10 events. These identified the longitudinal and transverse waves and confirmed the azimuths and angles of emergence obtained from amplitude data. The array data also confirmed the azimuths and yielded a P-wave velocity of 4.33 km/s near the surface.
The magnitudes ranged from − 1.1 to 2.9 and the frequency-magnitude relation was:
log N = 2.46 ( ± 0.01 ) − 0.68 ( ± 0.01 ) M L .
The coefficient 0.68 suggests tectonic activity. The partition of energy between P and S, and the observed directions of motion (all compressions at MBC) are compatible with the double couple model of focal mechanism and motion on the old fault. However, magma movement cannot be entirely ruled out as there exists geomagnetic evidence of abnormally high upper mantle temperatures.
The following energy-magnitude relation was determined from 100 events in the range 0.1 ≦ ML ≦ 1.6:
log E = 10.1 ( ± 0.3 ) + 1.91 ( ± 0.03 ) M L .
Crustal structure of the Mediterranean Sea Part II. Phase velocity and travel times
Authors: Payo Gonzalo 
Published: July 2021

Abstract
A large number of observations of phase velocity of Love and Rayleigh waves have been used in order to determine the crust-mantle structure of the Mediterranean Sea. These velocities have been measured by using records from the Standard Stations located in the Mediterranean borders. The empirical dispersion curves have been compared with those of several models computed for this purpose. Travel-time curves of body waves for paths crossing the Mediterranean region, making use of all possible coastal stations and local earthquakes, have been found to substantiate the results from the surface wave dispersion. Also the value of the Bouguer anomaly in different points of the region was considered in the determination of the crustal thickness, as well as some measurements of group velocity from clear observations of higher modes.
The crust-mantle structure under the Mediterranean Sea was found to be formed by two clearly distinct zones which correspond roughly to the areas to the west and east of Italy. The western zone, between Italy and Spain, is of oceanic type with a thin crust (about 14 km) and a low-velocity channel in the Upper Mantle. In the eastern zone, south of Greece, the crust (some 23 km thick) shows a great thickness of the uppermost sedimentary layers, which gives rise to very low velocities of short-period surface waves in that region. Love waves with group velocities smaller than those of Rayleigh have been clearly observed in a large number of earthquakes in this region. The surface wave dispersion as well as the travel-time curves of P and S waves of this zone indicate the existence of a low-velocity channel in the Upper Mantle.
Investigation of a method for determining stress accumulation at depth—II
Authors: Eisler Joseph D. 
Published: July 2021

Abstract
The second of two seismic field experiments designed to study the precision with which the arrival of compressional body waves could be timed over paths up to 42 km in length was performed seven months after the first at the same location in the Gabilan Range near Salinas, California. Results of the second experiment show that the timing of the compressional waves could be carried out to the same order of precision as in the first experiment, i.e., to ±1 msec. In addition, the travel times over certain path lengths increased by about 6 msec within the intervening period. This observation is discussed in terms of the possible release of stress at depth in the region adjacent to the San Andreas Fault.
Simultaneous determination of the seismic moment and attenuation of seismic surface waves
Authors: Tsai Yi-Ben , Aki Keiiti 
Published: July 2021

Abstract
A comprehensive spectral analysis of Love and Rayleigh waves was made on the Parkfield earthquake of June 28, 1966. Using tentative Q values obtained by the usual two-station method for continental and oceanic paths, the observed spectra were corrected for dissipation, and used for obtaining a tentative source model. The resultant model, having the fault length 37 km, the strike direction N43°W and the rupture velocity 2.2 km/sec, is consistent with various near field measurements.
Based on this tentative source model, a least-squares method is applied to separate source, dissipation and interference effects on the spectra. The logarithm of the ratio of the observed to the theoretical spectra was plotted against the epicentral distance for various frequencies. The slope and zero-crossing value of the fitted straight line were used for revising the attenuation coefficient and the seismic moment respectively. The variability of individual station spectra was attributed to the interference effect. The revised value of the seismic moment of the Parkfield earthquake is e (0.33±0.40) ×10 25 dyne-cm. The revised attenuation coefficients indicate that Love waves have consistently higher dissipation than Rayleigh waves at periods 15 to 40 seconds. Both show marked minimum of dissipation (Q over 800 for Love and over 1000 for Rayleigh waves) at periods between 20 and 25 seconds.
We found that our Q data are consistent with a model which has a high-Q zone in the lower crust and uppermost mantle, overlying a low-Q zone which correlates well with the Gutenberg low-velocity zone. There is an indication that the intrinsic Q is dependent on period at depths shallower than 90 kilometers in such a way that it increases with period up to 20 seconds. For periods beyond 20 seconds, the intrinsic Q may be constant for all periods and all depths above 90 kilometers.
A definition of travel-time anomalies
Authors: Lomnitz Cinna 
Published: July 2021

Abstract
Plotting the seismic travel time from a point as a function of azimuth and distance yields a surface called a “chronoid”. The chronoid for the standard earth is a surface of revolution, termed the “standard chronoid”. Local anomalies are defined as the set of coordinate transformations required to bring the local chronoid into least-square coincidence with the standard chronoid. In general this is accomplished by means of two mutually orthogonal translations, plus one rotation in an azimuthal plane.
These operations give rise to three distinct components of the local anomaly; a geophysical interpretation of each of the anomaly components is provided.
A computer program for focal mechanism determination combining P and S wave data
Authors: Udias Agustin , Baumann Dieter 
Published: July 2021

abstract
A computer program has been developed to find the orientation of a double couple source model for the mechanism of an earthquake which best satisfies the data from P and S waves. The relationship between the two axes of the solution given by the equations for the polarization angle of S is used in order to rapidly find the orientation of the source model for which a total error value involving the error of S and P data is a minimum. The program gives best results for data from homogeneous instruments of similar period range. Solutions for three earthquakes, selected because of the orientation of the source, are presented and the reliability of their solutions under ideal conditions is discussed.
The Mudurnu Valley, West Anatolia, Turkey, earthquake of 22 July 1967
Authors: Ambraseys N. N. , Zatopek A. 
Published: July 2021

abstract
A severe earthquake in the west-central part of the Anatolian fault zone occurred on 22 July 1967, causing loss of life and widespread damage. The earthquake was associated with 80 kilometers of fresh faulting, part of which occurred in a zone ruptured ten years earlier. The sense of movement along the fault break is right lateral with the north side downthrown. Maximum relative displacements of 190 centimeters lateral and 120 centimeters vertical were measured. Damage caused by shaking in the immediate vicinity of the fault-break was equal to or smaller than that caused at some distance from the fault. Thus, proximity to the fault-break was found to be an unjustified criterion for higher intensities. The instrumental epicenter of the main shock had been located near the east end of the fault break. The bulk of the aftershocks is concentrated at the other end of the break, in the extreme west.
Damage to reinforced concrete buildings caused by the July 22, 1967 earthquake in Turkey
Authors: Uzsoy Safak Z. , Ersoy Uğur 
Published: July 2021

abstract
An attempt is made to analyze the damage caused to reinforced concrete-framed structures in the towns of İzmit and Adapazarı by the Mudurnu Valley earthquake of July 22, 1967. The observed damage shows that elaborate calculations for the design of structures to withstand earthquake forces are of little use unless they are based upon sound concepts, proper details, and are carried out by construction practice of good quality.
Distribution of earthquake risk in Canada
Authors: Milne W. G. , Davenport A. G. 
Published: July 2021

abstract
Statistical analyses are performed upon the earthquakes in existing catalogues of earthquakes in Canada. A relationship is presented between acceleration amplitude, magnitude, and distance for both eastern and western Canada. It is shown that the same relationship does not hold for each area. An ordered set of acceleration amplitudes is computed for several sites using this relationship. The first analysis makes use of the amplitude distribution from this list. By this method, certain parameters, and the return periods of accelerations of specific amplitudes are computed for a number of points which form a grid on a map. Contour maps are presented for these parameters and return periods. The second analysis makes use of the distribution of annual extremes of acceleration amplitudes to derive a similar and related set of parameters. This method produces an estimation of the acceleration amplitudes with certain return periods for a number of sites. Contour maps are presented showing these data. For both approaches, data are presented for specific sites of interest, and in the case of eastern Canada, a comparison is made with historical records.
Structural response results during the June 27, 1966 earthquake in Nepal-India border region
Authors: Agrawal P. N. 
Published: July 2021

abstract
Six earthquakes with magnitudes 5 and more occurred approximately with the same focus in the Nepal-India border region on June 27 and 28, 1966. The structural response recorders or a set of seismoscopes installed at Bageshwar and Banbassa yielded records. The successive earthquake records have been super-imposed. The two separately identifiable peak accelerations, i.e., in most cases longitudinal and transverse components, recorded by each recorder have been determined.
Short-term seismic activity in the central Aleutian region
Authors: Murdock James N. 
Published: July 2021

abstract
Epicenters of small-magnitude earthquakes, occurring in the central Aleution region during the 1964 Aleutian Experiment, were located by an S minus P method. Shallow earthquakes, occurring mainly just south of the islands, seem to delineate a shallow earthquake belt approximately 20 to 40 km wide. Deeper earthquakes occurred north of the shallow earthquake belt, and they seem to indicate a zone of faulting which dips toward the island arc from the oceanic side of the arc.
Focal mechanism of the Prince William Sound, Alaska earthquake of March 28, 1964
Authors: Harding Samuel T. , Algermissen S. T. 
Published: July 2021

abstract
Two nodal planes for P were determined using a combination of P-wave first motion and S-wave polarization data and from S-wave data alone. The S-wave polarization error, δ∈, is slightly lower for a type Il than for a type I mechanism. The type I mechanism solution indicates a predominately dip-slip faulting on a steeply dipping plane. The preferred solution is a type II mechanism with the following P nodal planes: strike N62°E, dip 82°S, (a plane); strike N22°W, dip 52°W, (b plane). Two solutions are possible: right lateral faulting which strikes northeast; or, left lateral faulting which strikes northwest. Both possible fault planes dip steeply.
Elastic displacements in the near-field of a propagating fault
Authors: Haskell N. A. 
Published: July 2021

abstract
Displacement, particle velocity, and acceleration wave forms in the near field of a propagating fault have been computed by numerical integration of the Green's function integrals for an infinite medium. The displacement discontinuity (dislocation) on the fault plane is assumed to have the form of a unilaterally propagating finite ramp function in time. The calculated wave forms in the vicinity of the fault plane are quite similar to those observed at the strong motion station nearest the fault plane at the Parkfield earthquake. The comparison suggests that the propagating ramp time function is roughly representative of the main features of the dislocation motion on the fault plane, but that the actual motion has somewhat more high frequency complexity. Calculated amplitudes indicate that the average final dislocation on the fault at the Parkfield earthquake was more than an order of magnitude greater than the offsets observed on the visible surface trace. Computer generated wave form plots are presented for a variety of locations with respect to the fault plane and for two different assumptions on the relation between fault length and ramp function duration.
Calculation of response spectra from strong-motion earthquake records
Authors: Nigam Navin C. , Jennings Paul C. 
Published: July 2021

abstract
A numerical method for computing response spectra from strong-motion earthquake records is developed, based on the exact solution to the governing differential equation. The method gives a three to four-fold saving in computing time compared to a third order Runge-Kutta method of comparable accuracy. An analysis also is made of the errors introduced at various stages in the calculation of spectra so that allowable errors can be prescribed for the numerical integration. Using the proposed method of computing or other methods of comparable accuracy, example calculations show that the errors introduced by the numerical procedures are much less than the errors inherent in the digitization of the acceleration record.
Travel times and amplitudes of the Salmon nuclear explosion
Authors: Lehmann I. 
Published: July 2021

Abstract
Travel times and amplitudes of the Pn and P waves generated by the nuclear explosion Salmon fired in the State of Mississippi are studied. To the west the Pn waves are found to be cut off at a distance of about 1800 km, where they are about to enter the mountainous region. An increase of P amplitude with distance goes to confirm that the P velocity increases with depth and to indicate that the time-curve is a continuous, bending curve.