bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relation between the geology and the effects of the earthquakes of May 1960 in the city of Ancud and vicinity, Chiloé
Authors: Galli O. Carlos , Sanchez R. Joaquin 
Published: July 2021

ABSTRACT
The rocks and sediments of Ancud and suburbs have been grouped into five units. The volcanic rocks are included in a unit, or geologic formation, called the Volcanic Complex of Ancud. The complex is tentatively considered to be Tertiary or Quaternary in age and is formed of andesites, welded tuffs, breccias and agglomerates that outcrop in almost all the hilly region, the coast, and the surroundings of Ancud. In some sections terraces have been formed over the rocks of this complex. The outcrops of the complex are weathered to a reddish-yellow material easily disaggregated with a hammer. Terrace deposits are observed in some of these terraces to be poorly cemented gravel, clay, and limonite. The alluvial deposits are distributed in the stream courses of Rio Pudeto and in Matadero and La Toma Creeks; they are composed of unconsolidated gravels, sands, silts, and clays. Beach deposits are observed along the length of the coast, and are principally a poorly consolidated aggregate of gravels and sands. Artificial fill is deposited in the coastal zone; its materials are gravels, sands, silts, bricks, wood, debris, etc.
There is a relation between the geology and the damage produced by the earthquakes in works of man. The areas underlain by the Volcanic Complex of Ancud are those that best resisted the effects of the earthquakes, and these are suggested as the most suitable for the expansion of the city. The most serious damage from the earthquakes are observed over the alluvial deposits and at the edges of one of the terraces. The last observation suggests that these areas are unfavorable, and that any future plans for construction over these should be preceded by a study of soil mechanics. It is indicated that the geographic position of Ancud with respect to tidal waves is unfavorable. It is suggested that the construction be prohibited near the sea, and that absolutely indispensible coastal buildings should be carefully studied with regard to a possible repetition of the phenomena.
Studies made between Arauco and Valdivia with respect to the earthquakes of 21 and 22 May 1960
Authors: Alvarez S. Leonardo 
Published: July 2021

ABSTRACT
The earthquake of 21 May was felt as a brusque horizontal movement; the large shock of 22 May was felt as a suave movement of large amplitude similar to a ship at sea. Lebu was extensively damaged. The shoreline at Lebu was elevated 1.5 meters, rendering docks and waterside facilities useless; a large expanse of new beach was exposed. Rio Lebu is no longer navigable because of the uplift. Details of tsunami are reported for several towns on the Arauco Peninsula and south to Tolten.
Relation between the geology of Valdivia, Chile, and the damage produced by the earthquake of 22 May 1960
Authors: Doyel William W. , Moraga B. Aldo , Falcon M. Eduardo 
Published: July 2021

ABSTRACT
A study was made to determine the relation between the damage caused by the earthquake of the 22nd of May, 1960, in Valdivia, Chile, and the geology of the city. A geologic map and an investigation of the damage was made. There was no evidence in the area of fault movements produced by the earthquake. The inundation of extensive areas of Valdivia and its environs are attributed more to compaction of Recent sediments than to a general sinking of the coast. Validivia is situated in the basin of the Rio Valdivia. The geologic formations that crop out there are composed of Pleistocene and Recent sediments. Six mapable units have been selected for the preparation of this report. The great part of the damage in the city of Validivia was caused by defective construction; nevertheless, the greatest damage is observed in areas where Unit QV 6, Recent alluvium or artificial fill, crops out. More detailed geologic studies should be made upon which to base construction and future planning. The studies should be complemented by drilling, gravimetric investigations, and soil studies.
Geologic report on the effects of the earthquake of 22 May 1960 in the city of Puerto Varas
Authors: Thomas Herbert , Bowes William , Bravo S. Nelson 
Published: July 2021

ABSTRACT
Damage in Puerto Varas was largely confined to the low, central part of the town, to the steeper slopes, and to the edges of terraces. The topography and geology are discussed and recommendations made as to steps to be taken to prevent future damage.
Field observations made between Puerto Montt and Maullin
Authors: Thomas Herbert , Bowes William , Bravo S. Nelson 
Published: July 2021

ABSTRACT
The effects of the earthquakes between Puerto Montt and Maullin were lurches in soft material and a possible fault movement just east of Los Muermos.
Pine forests were killed by submergence of the land and the city of Maullin has descended at least 1.5 meters and several of the streets are now inundated.
Model experiments on refraction arrivals from a linear transition layer
Authors: Nakamura Yosio 
Published: July 2021

abstract
Ultrasonic model experiments were performed to examine the effect of a transition layer on the frequency spectra of refraction arrivals. Two-dimensional, layered structures with transition layers constructed from polystyrene and Plexiglas sheets served as the models. The materials were so chosen that the model simulated the relation between the crust and the mantle. A pulsed sinusoidal wave with variable frequency and a square-wave pulse were used. The amplitude of the refraction arrivals showed a rapid decrease with increasing frequency starting at a frequency f0 which was found to have the value 1.7 k, where k is the velocity gradient in the transition layer. It is expected that a similar effect will be observed for the refraction arrivals from the Mohorovičić discontinuity if a transition layer exists at the boundary.
Higher mode surface waves and their bearing on the structure of the earth's mantle
Authors: Kovach Robert L. , Anderson Don L. 
Published: July 2021

abstract
A detailed numerical investigation of surface wave dispersion and particle motion associated with the higher Love and Rayleigh modes over realistic earth models has been carried out as a preliminary to the routine use of these waves in studies of the crust-mantle system. The suggestion that the so-called channel waves, such as the Lg, Li, and Sa phases, can be interpreted by higher mode group velocity dispersion curves is verified in detail. Furthermore, Sa should have a higher velocity across shield areas than across normal continental areas and a higher velocity across continents than across oceans.
Higher mode Rayleigh wave data are presented for long oceanic paths to Pasadena. The observed data favor the CIT 11 model of Anderson and Toksöz (1963) over the 8099 model of Dorman et al. (1960) and indicate that under the Pacific Ocean the low-velocity zone extends to a depth perhaps as deep as 400 km followed by an abrupt increase in shear velocity.
Improvement of array seismic recordings by digital processing
Authors: Ryall Alan 
Published: July 2021

abstract
This paper contains a brief review of the operations that are involved in digital processing of array seismic recordings by the methods of velocity filtering, summation, cross-multiplication and integration, and by combinations of these methods (the UK method and multiple correlation).
Analyses by the several techniques were made on array recordings that were obtained by the U. S. Geological Survey of seismic waves from chemical and nuclear explosions in the western United States.
Seismograms were synthesized, using recordings of seismic noise and a Pn signal, such that the signal-to-noise ratio, onset time and apparent velocity of the signal were predetermined for the synthetic records. These records were then analyzed by summation, cross-multiplication and the UK method, and the results were compared.
From the examples presented, it appears that for recordings with initial peak-signal-to-rms-noise ratio less than about 0.8, the best improvement can be obtained by the process of velocity filtering and summation of all the traces. For a six-element array improvement can be obtained by this method on records which have an original signal-to-noise ratio of 0.4 or greater. When the initial signal-to-noise ratio is greater than 0.8, multiplicative compounding yields about the same improvement as a process involving additive compounding and subsequent raising of the summation trace to large powers.
The velocity of shear fracture
Authors: Mansinha L. 
Published: July 2021

abstract
The maximum velocity of fracture in an homogeneous isotropic elastic medium under pure shear stress and with an added compressive stress is computed by an extension of Yoffe's method. The maximum velocity of shear fracture is smaller than the velocity of transverse waves in the medium. It increases as Poisson's ratio increases and decreases as the compressive stress increases. The maximum velocity of pure shear fracture is higher than the velocity of pure tensile fracture in the same medium. For a medium with Poisson's ratio of 0.25 the former is 0.775 and the latter is 0.631 of the transverse wave velocity.
The effect of boundaries on wave propagation in a liquid-filled porous solid: V. Transmission across a plane interface
Authors: Deresiewicz H. , Rice J. T. 
Published: July 2021

abstract
The passage of plane body waves across a plane interface from one to another, contiguous, porous aggregate is examined, with particular attention paid to motions involving wave lengths large in comparison with cross-sectional pore dimensions. The results are obtained for a rather general set of boundary conditions which take account of possible resistance to flow due to partial nonalignment of pores at the interface. It is found that when certain conditions of equality of material constants for the two media are met one or more of the reflected and transmitted waves are extinguished.
Tsunamis and seismic seiches reported from the eastern Atlantic south of the Bay of Biscay
Authors: Berninghausen William H. 
Published: July 2021

abstractTsunamis have been reported from widely distributed locales with the area under consideration. They seem to be more common in the Azores and the Iberian peninsula than elsewhere. This may result partly from the lack of, or inavailability of data rather than the absence of the phenomena.
Earthquake mechanism determination by S-wave data
Authors: Stevens Anne E. 
Published: July 2021

ABSTRACT
The nature of force systems at the foci of earthquakes can be studied by analyzing initial longitudinal (P) and transverse (S) displacements produced by them on the surface of the earth. The force system described in this paper results from a superposition of three mutually orthogonal double forces which act at a point focus. A family of equations is derived which depends only on S polarization angles and not on initial P displacements to determine the orientation of this generalized force system. An IBM 1620 computer has been programmed to solve the family of equations for two particular focal mechanisms—the single couple (Honda's Type I) and the double dipole (Honda's Type II). Two possible force systems are thus calculated for each earthquake using only S angles. The appropriate mechanism for each earthquake is selected by comparing the distribution of initial P displacements actually recorded, with that predicted from the solutions of the mechanism equations making use of S data.
Computer solutions are presented for 32 earthquakes for which data are available in the literature. The orientation of the force system for each earthquake calculated from S data alone is in general agreement with that determined from P data.
Spheroidal free periods of the earth observed at eight stations around the world
Authors: Alsop L. E. 
Published: July 2021

ABSTRACT
Spectral peaks corresponding to the spheroidal free periods of oscillation of the earth exist in the spectra of eight seismograms written at stations in different parts of the world shortly after the great Chilean earthquake of 22 May 1960. These data have been combined with those previously reported by various authors to obtain a very precise phase velocity vs period curve for Rayleigh waves in the period range of 200 to 3200 seconds. The observed spectral amplitudes lend some support to the assumption of a moving source, but they also indicate that the present theory is not adequate. The vertical motion is found to be symmetric with respect to reflections through the pole.
Seismicity of northern California and western Nevada
Authors: Niazi Mansour 
Published: July 2021

abstract
Nearly 1500 recent northern California and western Nevada earthquakes of magnitude 2 and above have been used to study aspects of the seismicity of the region. In an area covering 512 degrees of latitude by 8 degrees of longitude, each square degree was subdivided into 16 approximately equal quadrilateral blocks. The seismic energy and associated strain release in each block were computed for time intervals up to five years. The computed representations of strain release for each year are contoured to define the distribution of seismic zones in the area and to give a dynamic measure of thier variation.
The observed surface creep along the San Andreas fault at the Vineyard seismographic station is compared with the intensity of the seismic activity in the immediate neighborhood of the fault zone. The frequency distribution of earthquakes of different magnitude is discussed.
Sedimentary velocities of the western North Atlantic margin
Authors: Houtz R. E. , Ewing J. I. 
Published: July 2021

Abstract
During the 1954 cruise of the USS San Pablo and USS Rehoboth, 27 seismic refraction profiles were shot primarily to obtain detailed sedimentary data in the western North Atlantic. This work combined with later work, which also emphasized sedimentary data, provides 60 profiles in which gain and filter settings were adjusted to give coherent sedimentary arrivals. Good agreement was found among solutions obtained by several different methods for sediment thickness and velocity. Results indicate that velocity gradients are variable and are greatest near the liquid-sediment interface; wide-angle sedimentary arrivals in the deepsea profiles are reflections; refracted arrivals from the sediments are restricted to a zone shoreward of about halfway up to the continental rise.
Dispersion of Rayleigh waves in the Gulf of Mexico and Caribbean Sea
Authors: Papazachos Basil C. 
Published: July 2021

Abstract
Group and phase velocities of Rayleigh waves along 57 paths between Central America and the central United States were determined. The waves examined were of period between 15 and 60 seconds and crossed the Gulf of Mexico and Caribbean Sea in many directions. The following conclusions about the structure of the region are drawn:
Along the paths crossing the western and central Gulf and the regions near the coast of Texas and the eastern coast of Mexico the velocities were found to be very low. This is attributed to the great thickness of the sediments in these regions.
The velocities along paths crossing the eastern Gulf and westernmost Caribbean were found to be higher than the typical continental velocities. This is considered as an indication of a difference in structure between the eastern and western Gulf of Mexico. Along one path in the western Caribbean Sea between Colombia and Cuba the velocities were almost continental. High velocities found for part of the eastern Caribbean indicate an almost oceanic character for this region.
For each earthquake examined the initial phases were determined with an error less than ± π/4. For a given earthquake in all cases except two the initial phases were found to be the same at all stations.
A comparison of multiple solutions of focal mechanisms
Authors: Stauder William 
Published: July 2021

Abstract
The occurrence of focal mechanism solutions of the same earthquake by different authors is examined. Of 42 instances of such multiple solutions for earthquakes which occurred around the borders of the Pacific Ocean, it is found that of 84 possible pairs of multiple solutions agreement is excellent in 8 cases, good in 13, fair in 19, poor in 19, and no agreement in 25. The implication for focal mechanism studies is illustrated by examining the focal mechanism solutions of deep-focus earthquakes under the Sea of Japan.
The significance of regularities in multiple fault plane solutions of a single earthquake
Authors: Fara H. D. , Scheidegger A. E. 
Published: July 2021

Abstract
During the statistical evaluation of fault plane solutions of earthquakes, one problem is posed by the fact that, for many earthquakes, a whole series of fault plane solutions (by different investigators) is available, from which, somehow, a “representative” solution must be extracted. The significance of regularities in such multiple solutions is discussed; it is shown that the P(maximum compressional) and T(maximum tensional) directions are representative of preponderant readings on the seismograms concerned. It then follows that a “representative” solution can be obtained by treating the individual P and T directions as if they were dilatational and compressional “readings,” respectively, and by constructing a fault plane solution from them. An example is given.
Near earthquakes recorded with long-period seismographs
Authors: Berckhemer H. , Schneider G. 
Published: July 2021

AbstractIt has been observed that long-period seismographs respond to near-earthquakes in an unexpected manner. In order to explain this phenomenon true ground motion has been computed by multiple integration of the seismograph equation using an electric analog computer. It can be shown that after transit of the S-phase a permanent ground displacement (order of magnitude 10 μ) and true tilt (order of magnitude 10−2″) occur. Synthetic seismograms support these results.These phenomena could be caused only by the “near-field” (amplitude decreasing according to r2) and not by the “wave field”.Vertical seismometers are less suited to such studies. The helical spring of these instruments can be excited to almost undamped transverse oscillations which cause a second order disturbance.
Earthquake-induced water-level fluctuations from a well in Dawson County Georgia
Authors: Vorhis Robert C. 
Published: July 2021

Abstract
A water well at the Georgia Nuclear Reactor site in north Georgia has recorded a surprising number of earthquake-induced water-level fluctuations. These fluctuations are the subject of this paper. In the period from September 4, 1956 to June 17, 1958—during which time a water-level recorder was in operation—a total of 42 were recorded in this one well.
Dispersion of Rayleigh waves originating in the Mid-Atlantic Ridge
Authors: Ossing Henry A. 
Published: July 2021

Abstract
Dispersion curves, plotted for earthquakes originating in ten designated Mid-Atlantic Ridge areas and recorded at five standard stations, were compared with model, oceanic dispersion curves derived by Dorman, Oliver, and Santo for determinations of oceanic structural variations, and for the influence of the Mid-Atlantic Ridge on the dispersion of Rayleigh-waves. The observed curves indicate, in general, that the model shear velocities should be higher for the Atlantic crustal layer. Trinidad dispersion curves do not demonstrate oceanic dispersive characteristics and, with gravity anomalies, imply a regional crustal and sedimentary layer thickening between the Trinidad station and the Ridge. Group velocity and ridge-path percentage comparisons suggest little influence of the Mid-Atlantic Ridge on the dispersion of Rayleigh-waves.
Evaluation of marginal adaptation of CAD/CAM vs conventional all-ceramic crowns on an implant abutment: An in vitro study
Authors: Aeran Himanshu , Sagar Megha , Seth Jyotsna 
Published: July 2021

The survival of fixed prosthodontic restorations depends on the state of the marginal adaptation. Marginal gaps can create a favourable condition for biofilm deposition, thereby contributing to the development of caries and periodontal disease. The longevity of fixed prosthodontic restorations depends on the condition of the marginal adaptation to the abutment teeth. The presented work aimed to study, evaluate and compare the marginal adaptation of All-Ceramic crowns fabricated using conventional laboratory procedures with those fabricated using the CAD/CAM technology.To compare the marginal fit and adaptation of All- Ceramic crowns obtained by conventional techniques and crowns obtained by CAD/CAM technique. The presented study focused on a total of 20 samples divided into two groups viz. Group I (Conventional) and Group II (CAD/CAM) having 10 sample each. The samples were prepared with the straight abutment having a standardized collar height of 2mm, HIOSSEN that was mounted on acrylic blocks using implant analogue, HIOSSEN. A set of crowns was produced by 5-axis milling lithium disilicate using glass-ceramic blocks with laboratory fabrication methods. Another set of zirconia crowns was produced using CAD/CAM technology. Circumferential marginal gap measurements were taken at 12 measurement locations on the hexagonal die marked equidistant to each other. Both the samples were measured for marginal discrepancy at under the stereomicroscope.The results obtained showed that the mean vertical gap for the group II samples showed the least variation in the marginal discrepancy. Although the mean obtained for both the groups showed that the mean vertical marginal discrepancy was within the clinically acceptable level.It can be concluded that within the limitation of the study the data obtained showed that The Mean vertical gap was the maximum for Group I (Conventional group) i.e. 49.25 µm showing maximum variation in marginal fit. While the CAD/CAM Group had shown least vertical marginal discrepancy which depicts statistically significant better marginal fit than those fabricated using conventional laboratory procedures.
Prevalence of Helicobacter Pylori Antibody among Outpatients of Federal Medical Center, Yenagoa, Niger Delta Region of Nigeria
Authors: Olorode Dr Oluwayemisi Agnes , Ogba Ofonime M. , Ebisin Williams E. 
Published: July 2021

Helicobacter Pylori is the most common chronic bacterial infection (acquired early childhood) in humans affecting 50% of the world population and much attention has not been paid to this. This study was carried out between February and October 2019 to test for the presence of Helicobacter Pylori antibody among asymptomatic individuals attending Federal Medical Center, Yenagoa, Bayelsa State. A total of 200 {114(57%) males, 86(43%) females} blood samples were collected at ramdom into Ethylene diamine tetraacetic acid (EDTA) bottles and immediately transported to the laboratory for analysis using Helicobacter pylori Serology rapid blood test kit. Age was stratified to allow for comparison because the entire outcome was age dependent. Chi square analysis was conducted for the categorical variable. Findings showed that out of 200 samples examined, 88(44%) forty (40 (45%) males and 48(55%) females were positive to Helicobacter pylori infection while 112(56%) were negative. Females of age range 24 -33 had the highest prevalence of 24 (27%) while male of age group 14 to 23 had 21(24%); females of 34 to 44 was 16(18%); 54-63 had 4(05%) and the least was 44 to 53 years with prevalence of 3(03%). There was a significant difference across the age group and socio-demographic characteristic at p-value = 0.0001 < 0.05 and p-value =0.002068 < 0.05, p-value = 0.000916 <0.05 respectively. Observations showed the higher prevalence in females (53%) than their males (47%) counterparts; likewise the infected individuals host this organism ignorantly and busy treating out of line. Study with more than one diagnostic technique is recommended to determine the presence of Helicobacter pylori, as rapid blood test is limited due to the presence of antibody in the serum for long after eradication. In conclusion, routine medical examination on Helicobacter pylori is encouraged among individuals in respective of age and status.