bluuebunny/crossref_metadata_2025 huggingface dataset:
Travel times, apparent velocities and amplitudes of body waves
Authors: Julian Bruce R. , Anderson Don L.
Published: July 2021

abstract

Surface wave studies have shown that the transition region of the upper mantle, Bullen's Region C, is not spread uniformly over some 600 km but contains two relatively thin zones in which the velocity gradient is extremely high. In addition to these transition regions which start at depths near 350 and 650 km, there is another region of high velocity gradient which terminates the lowvelocity zone near 160 km. Theoretical body wave travel time and amplitude calculations for the surface wave model CIT11GB predict two prominent regions of triplication in the travel-time curves between about 15° and 40° for both P and S waves, with large amplitude later arrivals. These large later arivals provide an explanation for the scatter of travel time data in this region, as well as the varied interpretations of the “20° discontinuity.”

Travel times, apparent velocities and amplitudes of P waves are calculated for the Earth models of Gutenberg, Lehmann, Jeffreys and Lukk and Nersesov. These quantities are calculated for both P and S waves for model CIT11GB. Although the first arrival travel times are similar for all the models except that of Lukk and Nersesov, the times of the later arrivals differ greatly. The neglect of later arrivals is one reason for the discrepancies among the body wave models and between the surface wave and body wave models.

The amplitude calculations take into account both geometric spreading and anelasticity. Geometric spreading produces large variations in the amplitude with distance, and is an extremely sensitive function of the model parameters, providing a potentially powerful tool for studying details of the Earth's structure. The effect of attenuation on the amplitudes varies much less with distance than does the geometric spreading effect. Its main effect is to reduce the amplitude at higher frequencies, particularly for S waves, which may accunt for their observed low frequency character.

Data along a profile to the northeast of the Nevada Test Site clearly show a later branch similar to the one predicted for model CIT11GB, beginning at about 12° with very large amplitudes and becoming a first arrival at about 18°. Strong later arrivals occur in the entire distance range of the data shown, 1112°. to 21°. Two models are presented which fit these data. They differ only slightly and confirm the existence of discontinuities near 400 and 600 kilometers.

A method is described for predicting the effect on travel times of small changes in the Earth structure.
The frequency-magnitude relation of microfracturing in rock and its relation to earthquakes
Authors: Scholz C. H.
Published: July 2021

abstract

During the deformation of rock in laboratory experiments, small cracking events, i.e., microfractures, occur which radiate elastic waves in a manner similar to earthquakes. These radiations were detected during uniaxial and triaxial compression tests and their frequency-magnitude relation studied. They were found to obey the Gutenberg and Richter relation

log N = a + b M

Where N is the number of events which occurred of magnitude M, and a and b constants. The dependence of the parameter b on rock type, stress, and confining pressure was studied. It was found to depend primarily on stress, in a characteristic way. The frequency-magnitude relation for events which accompanied frictional sliding and deformation of a ductile rock was found to have a much higher b value than that observed in brittle rock. The Gutenberg and Richter formulation of the frequency-magnitude relation was derived from a statistical model of rock and crustal deformation. This analysis demonstrates the basis of similarity between rock deformation experiments in the laboratory and deformation of the crust.
Early earthquakes in North-Central Iran
Authors: Ambraseys N. N.
Published: July 2021

In this paper a comparison between historical earthquakes and recent seismic activity in northern Iran is presented. It is shown that for certain parts of the world which have a long well-documented history the problem of earthquake frequency can be solved approximately on the basis of seismic history and local tectonics. Considering the state of development of instrumental seismology and of its interpretation, it is not only inadequate to attempt the assessment of seismicity without due consideration to the earthquake history but it may also be misleading.
Crustal structure in the Himalayan foothills area of north India, from ‘P’ wave data of shallow earthquakes
Authors: Kaila K. L. , Reddy P. R. , Narain Hari
Published: July 2021

Travel times of Pg, P* and Pn waves of twenty shallow earthquakes with epicenters in the Himalayas and recorded at New Delhi, Chatra, Dehradun, Bokaro and Shillong Observatories of India were analyzed statistically to determine the crustal structure. A short seismic refraction profile about 15 kms long shot by the ONGC in the Punjab foothills enabled us for the first time to take into account, in the evaluation of crustal structure, the effect of the sedimentary layers which had been invariably neglected by the earlier workers. From the present study, the most probable crustal structure in the Himalayan foothills area of northern India, appears to consist of sedimentary layer 6 ± 1 kms (velocity 2.7 km/sec average), granitic layer 8 ± 5 kms (velocity 6.2 ± 0.1 km/sec) and basaltic layer 14 ± 7 kms (velocity 6.9 ± 0.1 km/sec), giving a total crustal thickness of 28 ± 8 kms. The upper mantle velocity in this area was found to be 8.2 ± 0.1 km/sec.
Geologic structure of the Taltal Area, Northern Chile, in relation to the earthquake of December 28, 1966
Authors: Arabasz Walter J.
Published: July 2021

abstract

The Taltal area, which lies within the coastal cordillera of northern Chile, is dominated by a group of major active faults that cut a eugeosynclinal section of predominantly Jurassic andesites overlying Paleozoic metamorphic and plutonic rocks and intruded by Late Mesozoic plutons. The Atacama fault, a suggested regional strike-slip fracture parallel to the coastline, has been obliquely cut and left-laterally offset 10 km by the Taltal fault, which passes through the town of Taltal. Three distinctive features were found to be consistently offset 10 km by the Taltal fault: the easternmost strand of the Atacama fault, an intrusive contact, and a unique volcanic unit. Former continuity of the Atacama fault through the Taltal region is proposed, and subsequent disruption by the Taltal fault appears to have caused major structural readjustments in the still-active Atacama fault zone.

The tentative offshore epicenter and aftershock distribution of the December 28 earthquake are not directly correlative with faults that have been mapped in the nearby on-shore areas; this lack of correlation is not surprising in view of the suggested depths of hypocenters in the lower crust or upper mantle.
The perturbation of Love wave spectra
Authors: Harkrider David G.
Published: July 2021

abstract

The equations governing the variational principles for Love wave spectra are investigated. It is shown that assumptions used by earlier authors are not necessary to the validity of the variational techniques.

Moreover it is demonstrated that except for a homogeneous plate, these assumptions are false for plane multilayered media and lead to incorrect expressions for group-velocity perturbations. The correct expressions are determined and examples of their use are given.
Rayleigh wave group velocities in central California
Authors: Sutton D. J.
Published: July 2021

abstract

Experimentally determined Rayleigh-wave dispersion curves of group velocity are given for five paths from NTS to stations in the network operated by the Seismographic Station at U.C. Berkeley. Periods observed range from 4 to 14 seconds. Although, as expected, two different paths from NTS to the western edge of the Sierra Nevada resulted in similar curves, efforts to find empirical curves appropriate to the Great Valley and the Coast Ranges on the assumption of provinces with parallel boundaries were not successful. Estimates of group velocity across the Great Valley along the path NTS to BRK indicate velocities, in the period range 5–9 seconds, considerably lower than would be expected from crustal models so far suggested.
A study of P nodal solutions (1922-1962) in the Wickens-Hodgson Catalogue
Authors: Stevens Anne E. , Hodgson John H.
Published: July 2021

abstract

Computer-determined P nodal solutions in the Wickens-Hodgson Catalogue were compared with earlier visually-determined solutions for the same earthquakes. Good agreement was found in about 40 per cent of the solutions. Lack of agreement was due chiefly to poor distribution of data in azimuth about the epicenter. Necessary, but not sufficient, conditions for well-defined nodal plane solutions were determined: there must be a minimum of 100 observations with at least two in each 90° segment of azimuth; data must be at least 80 per cent consistent with the selected nodal planes. Fourteen of the 618 earthquakes in the Catalogue met these requirements.
Diffraction of elastic waves by a rigid 90° wedge Part II
Authors: Kraut Edgar A.
Published: July 2021

abstract

Integrals representing the reflected and diffracted elastic waves generated by the incidence of a plane compressional wave on a rigid quarter-plane are evaluated by an application of the Cagniard-De Hoop technique. It is shown that diffracted spherical waves radiate away from the tip of the quarter-plane at the shear and compressional wave speeds. The spherically spreading compressional wave excites secondary shear waves on the surfaces and edges of the quarter-plane. These secondary spherical wavelets envelope a ruled surface which is conical in shape at the edges of the scatterer. The envelope propagates away from the quarter-plane at the critical angle and forms a Mach wave or bow wave. The usual reflected shear and compressional plane waves are also present and combine with the diffracted waves to form the geometric shadow of the quarter-plane.
Estimation ofPcPtravel times and the depth to the core
Authors: Taggart James , Engdahl E. R.
Published: July 2021

Based on a new P velocity distribution and observed PcP travel times from nuclear explosions, the core is estimated to have a mean radius = 3477 ± 2.0 km (depth = 2894 ± 2.0 km). Five velocity models were tested for the lower-most 90 km of the mantle. The PcP data suggest that the P velocity increases slightly with depth in this region. Tables of PcP travel times have been computed for the preferred model and a core radius of 3477 km.
Regional variations inPtravel times
Authors: Herrin Eugene , Taggart James
Published: July 2021

Azimuthally dependent station corrections for 321 seismological stations were estimated using data from 400 large earthquakes (1961-1964) and 30 large explosions. In the estimation procedure only data for epicentral distances in the range 20° to 105° were used, and the data were truncated to remove gross errors. In addition, estimates of variance of station error distributions were computed.
Laser interferometer calibration system for extensometers
Authors: Hade G. , Conner M. , Kuo J. T.
Published: July 2021

A laser interferometer technique has been developed for calibrating extensometers at the Ogdensberg Station of Lamont Geological Observatory. It provides remotecontrolled calibration of both horizontal and vertical extensometers within the linear range of the transducer output.

The present calibration system consists of an electromagnetic driving unit and a Michelson interferometer. The transducer end of the extensometer is displaced longitudinally with an electromagnetic driving unit, which is excited by a variable low-frequency oscillator with a bandwidth of 0.0005 to 60 kHz. The resultant displacement is detected by counting fringe displacements of the interferometer with an Ne-He laser source. With this calibration system, motion as small as 0.03 micron can be determined with excellent repeatability and with errors of less than 5 per cent, in comparison with errors of more than 40 per cent for the optical calibration method previously used.
Universal dispersion tables
Authors: Anderson Don L. , Harkrider David G.
Published: July 2021

The universal dispersion theory, presented in Part I, is extended to allow computation of group velocity and amplitude partial derivatives. Tables giving the effect of a change in any parameter on phase velocity, group velocity and amplitude are given for two earth models, one oceanic and one continental shield. Tables are given for the fundamental and first three higher Love modes.

These tables make it possible to compute dispersion parameters for the first four Love modes for any realistic earth model or to invert observations to an earth model. Attenuation of Love waves for an arbitrary distribution of Q versus depth can also be computed by using techniques previously described.
Aftershocks of the Truckee, California, earthquake of September 12, 1966
Authors: Greensfelder Roger
Published: July 2021

On September 12, 1966, at 16h 41m, an earthquake of magnitude 6.0 to 6.5 occurred about 10 km northeast of Truckee, California. Hypocenters of 158 after-shocks that occurred between September 14 and 25 were found to be within a volume 3 km wide by 10 km long by 12 km deep. The magnitude-frequency curve appears anomalous, as there seem to be too many shocks greater than magnitude 2 compared to the number of small ones under magnitude 0.5.

Nodal-plane determinations indicate two modes of faulting for the aftershocks. Strike-slip faulting with nodal planes striking N. 40°W. and N. 50°E. is dominant; secondary normal faulting occurs on nodal planes striking nearly north. An attempt is made to relate the strain release pattern of these aftershocks to major regional right-lateral shear and extension.
Measurement of static and dynamic response of the Green Building at the MIT campus to insolation and wind
Authors: Simon I. , Strong P. F.
Published: July 2021

Static and dynamic response of a 20-story concrete building (the Green Building at MIT, Cambridge, Mass.) to solar heating and wind was measured by means of a diamagnetic tiltmeter. Insolation of the front of the building causes a temporary tilt northwards of approximately 30 arc sec (measured on the 19th floor). Wind causes both tilting leewards and vibration of the building. The natural frequency of the cantilever mode of vibration of the building is 0.77 c/s. The bending stiffness of the building was determined both from the vibrations and from the steady tilt due to the average wind loading.
The ground effects of the Skopje July 26, 1963 earthquake
Authors: Poceski Apostol
Published: July 2021

Damage distribution in Skopje can be explained in terms of the seismic response of surficial soils. There exists a generally good correlation between the distribution of damage, the thickness of the surficial soil layer, and the predominant periods of microtremors. The most heavily damaged region is covered with about 20 to 30 meters of alluvium, and the predominant period of this alluvium is about 0.36 seconds. The alluvium in this heavily damaged region probably was shaken near its resonant frequency, and soil amplification may have reached three.

The greatest destruction was recorded along a belt which is defined by an abrupt change of the thickness of the alluvium. However, heavy destruction was also recorded on the shallow alluvium side, and no clear explanation exists for this.
Rayleigh wave dispersion in Australia
Authors: Thomas L.
Published: July 2021

The “two-station approximation” method of Brune, Nafe and Oliver (1960) has been used to find Rayleigh-wave phase velocities over nine paths between Australian WWSSN stations. Some simple shear-velocity distributions for each path have also been found, by inversion of the phase-velocity data. The lack of uniqueness of solutions to this inversion problem is illustrated by the presence of several distinct but numerically equally-good solutions for each set of phase-velocity data. Solutions (i.e., shear-velocity distributions) expected to represent the crust-mantle system more faithfully have been selected from these. The values, obtained in this way for shear-velocity distributions in the Australian paths studied, have been compared, and show that there is little variation between different parts of the continent.
The influence of geologic environment on seismic response
Authors: Alcock E. D.
Published: July 2021

A brief review is given of the state-of-the-art and the theory involved in the influence of geology on seismic response. Several field experiments are described which were performed to determine the dynamic amplification of seismic response by alluvium. In the Dry Lake area (saturated alluvium) resonant depths of alluvium were observed at 500 feet and 1400 feet. This is in approximately the harmonic ratio as predicted by theory. In the Hidden Valley area (dry alluvium) the resonant depth of alluvium was observed at 300 feet. The ratio of 500 feet to 300 feet for the two areas is in fair agreement with the ratio of 7000 feet to 5300 feet for the velocities of the alluvium in the two areas as determined by the refraction surveys.
A technique for the analysis of transient seismic signals
Authors: Dziewonski A. , Bloch S. , Landisman M.
Published: July 2021

An analytical method, called the “multiple filter technique,” is shown to be a fast and efficient means of studying multi-mode dispersed signals. Amplitudes and phases, as functions of period and velocity, are determined from the output of a set of narrow-band digital filters. The group velocities and other dispersion parameters determined by this technique are concordant with theoretical values when the method is tested with synthetic seismograms. It can recover broader portions of the dispersion present in ordinary seismic recordings compared to the classical peak and trough method. A simple diagnostic diagram is introduced in order to study the time and frequency resolution permitted by this analytic technique.
Application of strain seismographs to the discrimination of seismic waves
Authors: Shopland Robert C. , Kirklin Richard H.
Published: July 2021

abstract

Examination of microseisms recorded by strain and inertial seismographs at Wichita Mountains Observatory (WMO) has shown that the outputs of vertical strain and vertical inertial seismographs when combined through a linear filter do not provide a significant improvement of the signal-to-noise ratio in the frequency range 0.2 to 10 Hz. However, the ability of a combination of horizontal strain and inertial seismograph outputs to azimuthally discriminate between long-period surface waves arriving simultaneously from different epicenters is successfully demonstrated. The predicted response of strain seismometers to earth motion is verified by the existence of the proper phase and amplitude relationship, and high coherence among selected seismographs for single-source signals.
Precise determination of epicenters and origin times of surface focus seismic events
Authors: Arora S. K. , Manekar A. M.
Published: July 2021

abstract

Epicenters and origin times pertaining to surface focus events, mainly underground nuclear explosions, have been determined using the method described in this paper with estimates comparable to those of United States Coast and Geodetic Survey (USCGS) determinations. Data used are crude estimates of apparent phase velocity and backbearing, supplied by a medium aperture seismic-array station (at Gauribidanur in South India) using time lags across the array arms, and the preliminary seismogram readings available from just four Indian World-Wide Network of Standard Seismographs (WWNSS) stations and less than five foreign stations. The method essentially solves a system of time-term equations until an ideal “minimum variance” is achieved to best fit the observed onset times. Provision has also been made in the method to give an allowance for onset-reading errors, if any to the extent of ±0.53 second for epicentral distances up to 10,000 km. Twenty-five Russian tests, LONGSHOT in the Rat Islands and five Nevada tests were tried with the present technique and results compared with corresponding USCGS and United Kingdom Atomic Energy Authority (UKAEA) determinations. For the epicentral regions under study, station time-residuals have also been obtained.
Static deformation of a spherical earth model by internal dislocations
Authors: Ben-Menahem Ari , Singh Sarva Jit , Solomon Faïza
Published: July 2021

abstract

A localized displacement dislocation is placed inside a homogeneous non-gravitating elastic sphere. The ensuing deformation is obtained in the form of rapidly converging series for arbitrary values of the Poisson ratio and the source parameters. Surface displacements and strains are computed for various sources for an average earth model. The numerical results are mapped on tangential planes and displayed in several forms.

It is found that in the range 30° < θ < 120° the elongation strains fall off with the epicentral distance like Δ−α where 114 < α < 6, provided one proceeds along an arc which does not intersect a nodal line. In the lower hemisphere (90° < θ < 180°) relative to the source, seismic events such as the Chilean earthquake of May, 1960, should produce strains of the order of 10−9, which are on the threshold of detectability of modern extensometers, tiltmeters and rotationmeters.

The range in which the half-space approximation is valid is determined. It is demonstrated that global deformation patterns of major earthquakes can serve as a useful diagnostic tool for recovering the source's spatial characteristics.
Amplitude variations of Rayleigh waves—propagation across a continental margin
Authors: McGarr Arthur
Published: July 2021

abstract

Seismograms from Berkeley and from a site on the deep ocean bottom off California were compared to ascertain the effect on Rayleigh waves of propagation across the continental margin. Amplitude ratios as a function of period were formed by dividing the spectral component at one recording site by that at the other recording site. In the period range from 14 to 25 sec and for near-normal incidence, the amplitudes of vertical displacement on the ocean bottom were two-thirds to one-third as large as those at Berkeley. Amplitude ratios for waves propagating in either direction across the margin are consistent within experimental error.

Comparison of the experimental amplitude ratios with ratios that were calculated by using a variational technique recently advanced by McGarr and Alsop suggests that there is a striking contrast in structure between Berkeley and the ocean-bottom site, which is about 235 km WNW of Berkeley. The velocities and densities of the lower crust and upper mantle beneath the oceanic site are much higher than those beneath Berkeley; this result is in qualitative agreement with the results of geophysical studies in this region using other techniques.
Electromagnetic seismograph constants by least-squares inversion
Authors: Mitchell B. J. , Landisman M.
Published: July 2021

abstract

A least-squares method has been developed to determine the free periods and damping constants of an electromagnetic seismograph from its calibration pulse. The resulting values are correct to within a few tenths of one per cent for synthetic calibration pulses, even when moderate levels of microseismic noise are present.

The seismograph constants of the long-period vertical component at Dallas, Texas were determined from in situ measurements and compared with those calculated from the calibration pulse. The results agreed to within four per cent or better for the free periods and damping constants, after correcting for the linear trend and the base coordinate system of the observed pulse. The values differed by as much as 30 per cent when the linear trend and base coordinate corrections were ignored.

Two sets of instrumental constants from an unmatched pair of horizontal seismographs were determined from their calibration pulses. Directions of particle motion for a Love wave train recorded on the same instruments were computed before and after instrumental corrections; the results differed by as much as 8 degrees.
Spectral and correlation analysis of ground-motion accelerograms
Authors: Liu S. C. , Jhaveri D. P.
Published: July 2021

The autocorrelation function and the power-spectral density function of twelve strong-motion earthquake and three underground nuclear explosion accelerograms are obtained using a digital computer. The physical implications of the results and their application in modeling ground accelerations are studied. Simulations by the spectral approach, using filtered stationary processes, and simulations by the correlation approach, using linear, particularly autoregressive processes, are discussed in some detail.
Crust-mantle system in the central Aleutian region—A hypothesis
Authors: Murdock James N.
Published: July 2021

Seismic data acquired during the 1964 VELA UNIFORM Aleutian experiment have been used to construct a model of the local crust-mantle system. The M discontinuity of the model has a synclinal structure whose axis coincides with the islands of the arc. Just south of the islands, the shoaling M is terminated by a northward dipping thrust fault, resulting in a wedge-shaped crustal block sandwiched between mantle components.
An investigation of the Dasht-e Bayāz, Iran earthquake of August 31, 1968
Authors: Bayer Kenneth C. , Heuckroth Lorne E. , Karim Rajab A.
Published: July 2021

abstract

On Augus>t 31, 1968 at 10:47:37.4 G.M.T., the Khorassan Province of northeastern Iran was shaken by one of the most destructive earthquakes in Iranian history. The epicenter of the earthquake was about 250 kilometers south-southwest of Mashad, approximately 10 kilometers east of the measured surface fault. Its magnitude (Ms) was 7.3. A field investigation revealed that a number of villages were extensively damaged or destroyed, resulting in about 10,000 fatalities> and 60,000 homeless residents.

Surface fractures were noted in several areas. Maximum horizontal displacement was a left-lateral movement of 4.1 meters east of Dasht-e Bayāz. The measured fault length was 25 kilometers. Inaccessibility to part of the area and a time limitation factor curtailed a more complete analysis of the possible fault extensions both to the west and east.

The extensive property damage is attributed principally to poor construction in the region. However, the location of some of the villages on alluvium with a shallow water table was a contributing factor in some instances.

In particular this paper analyzes the regional intensities, the effects on local structures, and the fresh surface faulting phenomenon resulting from the earthquake. Also presented are the results of the investigations on the temporal, spatial, and magnitude characteristics of all recorded seismic activity, before, after, and including the major event.
On the propagation of SH waves in a heterogeneous sphere
Authors: Roy Arabinda
Published: July 2021

abstract

A complete solution for the wave propagation of an SH torque pulse in a heterogeneous sphere in which density and shear modulus vary as the power of the distance from the center of the sphere is worked out. The solution which is obtained in the form of an infinite series of Legendre polynomial, is transformed into an integral and the integral is evaluated at a saddle point. It is found that times of arrival of different reflected phases agree with those predicted by geometrical ray theory. Further, the expectations in case of a homogeneous earth are also valid in the heterogeneous case.
A dislocation model for the Fairview Peak, Nevada, earthquake
Authors: Savage J. C. , Hastie L. M.
Published: July 2021

abstract

Maruyama's equations have been used to calculate both vertical and horizontal surface displacements for a Volterra dislocation in a uniform half space. The shape of the dislocation surface is assumed to be a plane rectangle. A least-squares procedure has been used to determine the dislocation surface which best fits the geodetic data for the Fairview Peak, Nevada, earthquake of December 16, 1954. The best model strikes N9°E, has a total length of 50 km, a width of 8. ± 2. km, a dip of 57° ± 6°, and a fault displacement of 2.3 ± 0.4 m normal dip slip and 2.9 ± 0.4 m dextral strike slip. The width of the model is probably somewhat less than the true width of the fault, but the other parameters appear to be quite reasonable. The N9°E strike of the model is thought to be more realistic than the N4°W to N11°W strikes indicated by nodal-plane solutions. It appears that the Dixie Valley earthquake of December 16, 1954 was associated with normal slip on a fault plane parallel to, but offset from, the fault plane of the Fairview Peak earthquake.
Seismicity off the coast of Northern California determined from ocean bottom seismic measurements
Authors: Auld Bruce , Latham Gary , Nowroozi Ali , Seeber Leonardo
Published: July 2021

abstract

Approximately 190 local earthquakes (Δ < 4°) with suboceanic epicenters have been recorded over a 14-month period by the Ocean Bottom Geophysical Station of the Lamont-Doherty Geological Observatory. The station is located 200 km west-northwest of San Francisco and 220 km south of the Mendocino Fracture Zone at a water depth of 3.9 km. Most of the observed earthquakes are spatially related to the Mendocino fracture system. Only 20 per cent of the earthquakes recorded at the ocean bottom station were observed at an equidistant land station at Point Arena, California. P and S phases detected at the ocean bottom bottom have greater amplitudes and higher frequencies than the same phases recorded at the nearby land station. This is ascribed to a combination of near-receiver crustal resonance effects and attenuation on transmission across the continental/oceanic interface. Observations of Sn and epicentral locations support the hypothesis that the Mendocino fracture system is a transform fault. Phases converted from P to S at the base of the sediment layer beneath the ocean bottom station are used to compute the average shear-wave velocity and thickness of the sediment layer. The resulting values are 0.34-0.40 km/sec for the average shear velocity and a sediment thickness of 0.78-0.88 km. A phase tentatively identified as the False S of Byerly is observed on records from a coastal land station, but is not observed on the ocean bottom records.
Rayleigh waves in Southern New Guinea
Authors: Brooks J. A.
Published: July 2021

abstract

A profile to 300 km beneath the southern New Guinea shield region reveals lower average shear velocities than beneath the Canadian Shield and slightly lower than the Gutenberg model. Disparity with Brune and Dorman's CANSD profile is greatest (0.3 km/sec) immediately beneath the Moho, but persists to more than 200 km depth and is interpreted to mean that upper mantle mineralogy beneath southern New Guinea differs from that beneath the Canadian shield.

The numerical inversion technique of Dorman and Ewing was employed in a combined reduction of fundamental and first higher Rayleigh mode “single-station” phase velocities after isolating the approximate value of initial source phase using group velocities as a reference.

Average crustal thickness, from fundamental mode data alone, is 33 ± 1 km over about 1500 km of southern New Guinea path, a figure consistent with an average Poisson's Ratio for the crust of 0.23 to 0.32.
Effects of thin soft layers on body waves
Authors: Landers Tom , Claerbout Jon F.
Published: July 2021

abstract

The inability of simple layered models to fit both Rayleigh wave and Love wave data has led to the proposal of an upper mantle interleaved with thin soft horizontal layers. Since surface-wave dispersion is not sensitive to the distribution of soft material but only to the fraction of soft material a variety of models is possible. The solution to this indeterminancy is found through body-wave analysis. It is shown that body waves are dispersed according to the thinness and softness of the layers. Three models, each of which satisfy all surface-wave data, are examined. Transmission seismograms calculated for these models show one to be impossible, one improbable and the other possible. Synthesis of the seismograms is accomplished through the use of time domain theory as the complicated frequency response of the models makes a frequency oriented Haskell-Thompson approach impractical.
Free oscillation observations through 1968
Authors: Derr John S.
Published: July 2021

abstract

All observations of the free oscillations of the Earth published through 1968 are weighted to produce a set of means and standard errors of the means. Fundamental orders 0 to 97 for spheroidal and 2 to 99 for torsional are treated, as well as many overtones up to order 49. Statistical tests indicate that some observations are path dependent at the 99 per cent confidence level. Comparison of these means and standard errors with published Earth models indicate that they form a consistent basis for inversion of free oscillation observations to infer Earth structures.
Transient and residual strains from large underground explosions
Authors: Smith Stewart W. , Archambeau Charles B. , Gile William
Published: July 2021

abstract

Tectonic strain readjustments associated with large underground explosions have been observed at the Nevada Test Site. The Benham event of December 19, 1968 produced a peak quasi-static radial strain of 1.2 × 10−7 at a distance of 29 km. This strain transient was followed by an exponential return to the initial state with a time constant of 13 minutes, and is interpreted as the direct elastic response of the medium to a time varying pressure in the Benham cavity. An upper bound on the tectonic strain release was determined to be 0.7 × 10−8. Using these measurements it is estimated that the permanent and quasi-static strains associated with this explosion could significantly effect local earthquake occurrences out to distances of about 15 km. The size distribution of aftershocks of this explosion resembles that seen in model experiments of brittle fracture, in which the distribution is controlled by the dimensions of inhomogeneities in the medium.
Amplitude and frequency characteristics of elastic wave types generated by the underground nuclear detonation, Boxcar
Authors: Hays W. W.
Published: July 2021

abstract

Elastic wave types generated by the Boxcar underground nuclear detonation were identified and analyzed to determine their amplitude and frequency characteristics as a function of distance. The amplitude characteristics of the identified wave types were determined to vary with source to recording station distance and frequency. Within each body wave subset, the refracted wave amplitude decays most rapidly and the reflected wave amplitude least rapidly with distance. Fourier amplitude spectra of the P, S, and surface wave time windows exhibit maxima which occur at different spectral frequencies for stations on rock, ranging from a dominant frequency of about 0.8 Hz for the P-wave window to about 0.25 Hz for the surface wave window. The frequency of the maximum amplitude of each of the three wave mode window spectral sets is essentially unaffected by increase in propagation distance over the distance range 22.2-79.1 km.
Response spectra for Pahute Mesa nuclear events
Authors: Lynch Robert D.
Published: July 2021

abstract

Empirical equations for the prediction of pseudo-relative velocity response spectra (PSRV) are obtained from ground motions recorded at 64 seismic stations from 11 nuclear events detonated on Pahute Mesa at the Nevada Test Site (NTS). The spectra are related to the yield of the nuclear device and the distance between the source and receiver by multiple regression analysis. Exponents on yield and distance are derived at 40 separate periods in the period range from 0.05 to 2.469 seconds. Families of predicted mean PSRV curves are included to show the spectral development as a function of yield and distance.
Seismic energy efficiency of underground nuclear detonations
Authors: Mueller R. A.
Published: July 2021

abstract

The amount of energy going into the formation of elastic waves in the far field radiation zone was determined for the underground nuclear explosions Boxcar, Benham, Salmon, Schooner, Shoal and Sterling. The method is based on Sharpe's spherically symmetric model. The analytical solution of Sharpe's problem is developed into an energy equation and applied to the experimental results. The results obtained in this manner are in the same range found by other investigators. A basic conclusion is that seismic energy efficiency appears to be significantly lower for cratering events than for contained events.
REPRESENTASI ASPEK PERLAWANAN PADA DOMINASI PATRIARKI BUDAYA BALI DALAM KARYA I GAK MURNIASIH DAN CITRA SASMITA
Authors: Nisa Fika Khoirun
Published: July 2021

In the current Indonesian art discourse, the reading of works is no longer limited only to the results of the analysis and interpretation of formal elements, but also considering the relationship with the socio-cultural factors of artists so as to give a picture of the multifaceted character of art. This study was designed to identify the representation of resistance aspects in the dominance of Balinese cultural patriarchy in Indonesian fine art and interpret its symbols. The artists whose works were chosen as a case study in this study are I Gusti Ayu Kadek Murniasih and Citra Sasmita. This study used a multidisciplinary approach (Feminism and Semiotics). Based on the results of the analysis, the aspect of resistance is represented through visual symbols that are typical in the two works of artists tend to be born from the experience of the environment that is close to everyday life to a traumatic experience that gives birth to pain and fear. For both of them, painting is a catharsis process and as a medium to transform ideas and alignments so that the message to be conveyed can reach a wider scope.
Future dental device- 3-dimensional printing approach in dentistry
Authors: Grover Deepak , Kaur Navneet , Kaur Gurpreet
Published: July 2021

The three-dimensional printing has been used since very long ago in the field of medicine as well as in dentistry. The evolution of 3-dimensional imaging and modelling in dentistry is progressing towards a more efficient and cost-effective workflow using state-of-the-art technology. The practicability of this technique is expanding in several dental fields such as prosthodontics, oral and maxillofacial surgery and prosthesis, and production of surgical guides or physical models in dental implant treatment. The key of success in this technique depends on the usage of various materials such as, metal, resin, plastic etc. which is most commonly used in dentistry. With introduction of this recent advanced technology, it is used in various surgical procedures such as ridge augmentation, sinus lift and guided implant surgery, implant fixtures, preparation of customized scaffold with or without stem cell therapy, education models as well as in drug delivery technology. The 3-dimensional printing technology is becoming more economical technique and able to produce replica of dental models with a high resolution and accuracy.
Prosthetic management of an adult cleft patient with velopharyngeal appliance and airway evaluation by acoustic pharyngometry
Authors: Jain Vaibhav , Chahar Pramod K , Sarkar Abir , Udayshankar Vishvnathe
Published: July 2021

Cleft lip and palate is the most common congenital malformation in oro-facial region. In adult cases where defect is large and paucity of tissue is there, prosthetic management of the defect with palatal obutrator and velopharyngeal appliance is the treatment of choice. It requires scrupulous clinical skills and detailed knowledge of anatomy to prevent airway obstruction and discomfort during function. Acoustic pharyngometry (AP) is an advanced tool to evaluate the airway in 3D during function without radiation exposure. In this case report palatal obturator with speech aid prosthesis was fabricated to rehabilitate an adult cleft palate patient. AP test was done to ensure adequate airway space with prosthesis.
Acomparative study on the effect of cross legged sitting with flat feet sitting position on blood pressure reading among normotensive young adults in selected college, Guwahati, Assam
Authors: Kumari Sujata , Jayalakshmi M
Published: July 2021

Blood pressure(BP) measurement is a basic clinical procedure and perhaps the most frequently performed clinical procedure in any health care setting, it strongly depends both on the number of measurements and the body position during the procedure. Many important therapeutic decisions rely on the accuracy of assessment ,Unfortunately , blood pressure measurement is one of the most inaccurately performed procedure done by healthcare provider. Inspire of studies having shown that many errors are made while recording BP, crucial decisions about treatment are made based on these inaccurate measurements. Efforts have continuously been made to standardize the procedure, but remain difficult to reach a consensus among different official guidelines for BP measurement

A comparative study on the effect of cross legged sitting with flat feet sitting position on blood pressure reading among normotensive young adults in selected college, Guwahati, Assam.

Army Institute of Nursing ,C/O- 151 Base Hospital, Basistha, Guwahati, Assam.

Descriptive comparative design.

A descriptive comparative design was adopted for the study ,sixty normotensive young adults were selected using purposive sampling technique from the selected college of Guwahati, Assam. The data was collected by a questionnaire and blood pressure measurements were documented.Automated sphygmomanometer (OMRON HEM -8712 ,SERIAL NO 20190604417VG). The measurement was taken 5 minutes elapse before the first reading and then one minute gap between next three readings in flat feet and cross legs at knee level. The data were analysed using percentage, frequency, mean, SD Statistical significance was set at p<.05.

The data were coded and organized in a master sheet and were analyzed by using the SPSS Version 24.

Total of sixty normotensive young adults were included in the BP measurements taken from flat feet sitting position and cross-legged sitting position and results indicates systolic blood pressure increases significantly (p<.05)with the cross-legged sitting position.

Cross legged sitting position can affect systolic blood pressure reading significantly among normotensive young adults.
Successful management of status epilepticus with yoga prana vidya healing as a complementary therapy: A case study of atypical febrile seizure
Authors: Nanduri Venkata Satyanarayana , Khatri Rajkumari
Published: July 2021

: Epilepsy is one of the most common disorders of the nervous system and affects people of all ages, races, and ethnic backgrounds, and seen more commonly in children. Atypical febrile seizure with Status epilepticus is a disorder known for significant morbidity and mortality. Despite newer antiepileptic drugs, 30 % of subjects are refractory to the conventional treatment with a risk of recurrence and neuro-developmental disorder. This paper presents one such case of a child handled successfully by Yoga Prana Vidya (YPV) Energy healing complementarily to conventional therapy.

This is a prospective case study of a 2-month-old infant, an emergency case of atypical febrile seizures with status epilepticus, where YPV Healing intervention was done from the beginning while admitting doctors had given a guarded prognosis.

This case study reports the normal physical, mental & psychological development of the subject following YPV Healing with 3-year follow up, and the subject was observed to be normal without any recurrence of the disease or neuro-developmental abnormality.

: Although the use of Complementary and Alternative Medicine (CAM) has been evaluated globally, there are few studies available on the use of Energy healing in various ailments. YPV Healing has been emerging as an effective modality of treatment for various physical, psychological ailments without any side effects. It can be effectively used from distance even without physically examining the subject. It has been used as a complementary or alternative modality of treatment in some severe life-threatening emergency conditions, and further studies may be conducted with appropriate sample sizes.
May I Calculate Your Taxes?: The Effect of Bookkeeping on Tax Compliance under a Simplified Regime
Authors: Bando Rosangela , Canozzi Otavio , Martínez José , Dezolt Ana Lucía
Published: July 2021

Many countries worldwide face significant miss reporting in tax declarations. Miss reporting leads to undesired low revenue and economic distortions. This paper discusses the extent to which the residual bookkeeping burden faced by small firms in simplified regimes influence tax declarations. A randomized control trial among 1,500 irregular firms in Piaui, Brazil showed that adding the tax amount due and records on transactions to a warning notification improved compliance in 21 percentage points and increased the reported revenue in 39 percent. Firms without an accountant were less likely to regularize their status without the added information. These findings suggest the use of third party information to support voluntary compliance may present an opportunity for digital services to improve tax revenue services.
¿Qué pasó en Ecuador en octubre de 2019?
Authors: Izurieta Belén
Published: July 2021

Durante once días, las calles de Ecuador fueron un campo de batalla. Civiles, policías, indígenas y militares se enfrentaron los unos con los otros. Las protestas comenzaron el 3 de octubre como consecuencia de la insatisfacción de los ecuatorianos con un decreto presidencial que anularía los subsidios a los combustibles. Violencia, terrorismo, vandalismo, robos, represión, heridos y muertes fueron el resultado de las protestas. A lo largo de esos días, los ecuatorianos experimentaron conductas rebeldes, perdieron su identidad individual y mostraron sentimientos racistas y de polarización. A causa de lo ocurrido durante las protestas, este artículo pretende explicar el comportamiento y la conducta de los ecuatorianos desde una perspectiva psicológica.
PRIMEROS REGISTROS DE GEOFAGIA EN SUSTRATOS ARTIFICIALES POR PASERINOS DE ECUADOR
Authors: Cadena-Ortiz Héctor , González-Camacho Gerardo , Maya Danny , Alarcón Ibeth
Published: July 2021

La geofagia es la ingesta intencional de suelo, existen pocos registros de este comportamiento en paserinos y ninguno reportado formalmente en el Ecuador. Describimos la observación de Gorrión Europeo Passer domesticus, Jilguero Encapuchado Spinus magellanicus, Picogrueso Ventrioro Pheucticus chrysogaster y Semillero Sencillo Catamenia inornata ingiriendo material mineral de sustratos artificiales.
VAQUERO BRILLOSO Molothrus bonariensis Y HORNERO PATIPÁLIDO Furnarius leucopus: PARASITISMO DE PUESTA
Authors: Navas Hojas Ignacio Benjamín
Published: July 2021

Se registró en vídeo una relación parasita entre un juvenil de M.bonariensis y como hospedador, un Hornero del Pacífico (Furnarius leucopus). Este registro se ubica en un parque al sur de la ciudad de Guayaquil, Ecuador, entre los días 24-25 de junio del 2020. El parque se encuentra en una zona urbana bastante ruidosa, sin embargo, esto no impidió la notoria insistencia de la cría para ser alimentada por el hospedador. Algo que se debe destacar es que estaban presentes y cercanos dos individuos de F. leucopus pero solo a uno de ellos era al que perseguía el juvenil con insistencia, inclusive ambos desplazándose a través de cables y árboles cercanos a la zona.
PREDATION ON SNAKE AND FROG BY THE BARE-THROATED TIGER HERON Tigrisoma mexicanum (ARDEIDAE) IN COSTA RICA
Authors: Acosta Chaves Víctor J. , Acosta Chaves Paula C , Acosta Chaves Adriana P.
Published: July 2021

Reportamos dos eventos de depredación sobre una Ratonera neotropical (Senticolis triaspis) y una Rana ternero (Leptodactylus savagei) por una Garza tigre cuellinuda (Tigrisoma mexicanum) en el Golfo de Nicoya, Costa Rica.