bluuebunny/crossref_metadata_2025 huggingface dataset:
Educação em tempo integral na educação infantil: pressupostos, indicativos legais, ações governamentais e institucionais
Authors: Celio Sobrinho Reginaldo , Gomes Nubia Rosetti Nascimento , Victor Sonia Lopes , Pantaleão Edson
Published: September 2021

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Segundo a legislação brasileira, a educação em tempo integral é um processo educativo formal, ofertada para crianças e adolescentes matriculados na educação básica, nas etapas da educação infantil, ensino fundamental e ensino médio. Associando-nos à literatura (Moll e Leclerc, 2012; Mauricio, 2009; Brandão, 2008; Gadotti, 2009), desenvolvemos uma investigação que objetivou problematizar aspectos das indicações legais, das ações governamentais e institucionais que operacionalizam o programa educação em tempo integral na educação infantil no município de Vitória ES/BRA. Em termos metodológicos, recorremos ao estudo de documentos que regulamentam esse programa em âmbito municipal, e realizamos entrevistas semiestruturadas envolvendo professores; assistentes de educação infantil; a diretora escolar; a pedagoga e a coordenadora do programa; as famílias das crianças que participavam do programa e técnicos da secretaria de educação. Tomamos como espaço empírico de investigação, um Centro Municipal de Educação Infantil (cmei), que atende 325 crianças com idades de 6 meses a 6 anos, pertencente ao sistema municipal de ensino. Os dados indicam que o programa de educação em tempo integral pode contribuir no processo educativo das crianças, embora, observa-se a necessidade de melhorias das/nas práticas pedagógicas cotidianas adotadas com os alunos, da/na estrutura física das instituições de ensino e da/na formação continuada dos profissionais. Compreendemos que, na condição de política pública específica, o programa de educação em tempo integral precisa se constituir como dispositivo impulsionador de debates sistemáticos capazes de redimensionar nossas concepções políticas e pedagógicas relativas à infância e ao processo educativo da criança pequena.
Algılanan Yönetici Desteğinin Psikolojik Sözleşmenin İçeriği ve Yerine Getirilmesi Üzerindeki Etkileri
Authors: GERÇEK Merve , ELMAS-ATAY Sevgi
Published: September 2021

Psikolojik sözleşme, işveren ve çalışan arasındaki istihdam ilişkisindeki dinamikleri açıklamak için kullanılan bir kavramdır. Psikolojik sözleşme, çalışanların örgütsel yükümlülüklere ilişkin öznel algılarını ifade etmektedir. Örgütsel politikalar, prosedürler, uygulamalar ve yöneticiler, çalışanlardan beklenenler ile örgütün çalışana sağlamakla yükümlü bulunduğu unsurlar hakkında bilgi aktarımı sağlamaktadır. Özellikle her kademeden yöneticinin, çalışanların örgüte yönelik algıları üzerinde etkin rol oynadığı varsayılmaktadır. Yöneticilerin, örgüt temsilcisi olarak psikolojik sözleşmenin oluşumu ve sürdürülmesi üzerinde etkili olduğu öne sürülmektedir. Bu çalışmanın amacı, algılanan yönetici desteğinin psikolojik sözleşmenin içeriği ve yerine getirilme düzeyi üzerindeki etkilerinin belirlenmesidir. Özel sektörde çalışan 224 beyaz yakalı katılımcı ile yapılan çalışmada, yönetici desteğinin psikolojik sözleşme unsurlarının örgüt tarafından vaat edilme düzeyini olumlu yönde etkilediği görülmüştür. Ayrıca, yönetici desteği arttıkça, psikolojik sözleşmenin yerine getirilme düzeyinin de arttığı belirlenmiştir.
Constitucionalismo y democracia: análisis desde el caso colombiano en los 30 años de la expedición de la constitución de 1991
Authors: Celemin Caicedo Yenny Andrea
Published: September 2021

El artículo hace un balance de la propuesta de la Constitución Colombiana de 1991 en relación con las instituciones de gobierno representativo y de sus diversas reformas durante los últimos 30 años. El propósito de este examen es analizar los efectos de la falta de atención que el constitucionalismo colombiano le ha puesto a la democracia, específicamente, para comprender lo que realmente ha sucedido con su reconfiguración y su nueva apariencia. El escrito sostiene que se trata de una democracia que ya no luce como democracia parlamentaria, tal y como fue originalmente pensado por los constituyentes de 1991, sino que desde las reformas subsiguientes ha avanzado a la modalidad de democracia de partidos.
Language Learning in the Time of COVID-19: ELT Students’ Narrated Experiences in Guided Reflective Journals
Authors: Wilson Amanda , Lengeling M. Martha
Published: September 2021

This article presents the results of a qualitative study of the lived experiences and emotional responses regarding language learning of 29 students in a bachelor's degree in English language teaching (elt) offered at a public university in central Mexico. The study was grounded in sociocultural theory and was carried out at a time when the students' classes changed overnight to online learning due to the worldwide covid-19 pandemic. In this program, students learn a foreign language within a theoretical framework of second language acquisition (sla) and document their language learning experience (lle) through reflective journals. One month into the new online modality, they were asked to write in their journals about a historical artifact that would represent their experience dur­ing the pandemic for a historian 100 years in the future. A constant comparative method of analysis of their narrated stories reveals the challenges faced and ensu­ing emotions: from overwhelming anxiety to youthful optimism. These results provide an appreciation of students’ complex emotions regarding their language learning process while in the midst of a worldwide pandemic and highlight the importance of creating activities that promote reflection.
SÍNTESIS Y CARACTERIZACIÓN DE POLVOS DE HIDROXIAPATITA CARBONATADA TIPO B CON DIFERENTES CONTENIDOS DE CARBONATO
Authors: Ochoa Gómez Maria Isabel
Published: September 2021

La Hidroxiapatita Estequiométrica (HA) es un material ampliamente utilizado en aplicaciones biológicas, aunque su aplicación en muchas ocasiones se limita debido a su estabilidad en ambientes fisiológicos. Es por esto que surge como alternativa, la Hidroxiapatita Carbonatada tipo B (HAC), la cual posee mayor similitud al hueso biológico debido a la presencia del ion carbonato en su estructura. Para su obtención se han utilizado distintos métodos de síntesis, sin embargo, la complejidad y poca reproducibilidad de muchos ha llevado a que sea un tema cada vez más investigado. En este trabajo se muestra la síntesis y caracterización de la HA y la HAC tipo B por el método de precipitación en vía húmeda de tipo inverso, con 3 contenidos de carbonato diferentes, denotados como C2, C3 y C4 con relaciones carbono/fósforo (C/P) de 0,25, 0,375 y 0,5 respectivamente, siendo C4 la HAC con mayor contenido de carbonato. Los polvos sintetizados se caracterizaron mediante difracción de rayos X (DRX), fluorescencia de rayos X (EDX), espectroscopia infrarroja con transformada de Fourier (FTIR) y microscopia electrónica de transmisión (TEM)
POSITION OF THE UKRAINIAN-CANADIAN SCIENTIST JAROSLAV RUDNYTSKYJ IN THE SETTELMENT OF THE LANGUAGE CONFLICT OF IMMIGRANTS
Authors: Solonska Nataliia , Borysovych Galina
Published: September 2021

The article analyzes one of the problems of personal relations belonging to the ethnic minority of the immigration community and the English- and French-speaking majority of the elite nation of the country of new immigrants, highlights the problem of preserving the national identity of Ukrainians in the Canadian diaspora through persistent, consistent and tolerant steps. Ukrainian linguist, folklorist, Slavist, librarian, organizer of science, teacher, public figure, Professor J. Rudnytsky in opposition to the linguistic assimilation of his own people; the principledness of the scientist in resolving the linguistic conflict, which gave a positive solution for both parties - Canada and the Ukrainian diaspora. The importance of the civic position and significant potential opportunities to influence the official circles of the country, government commissions, committees, international organizations and public opinion of authoritative intellectual work in society and academia, which, using historically sound evidence, proves the objectivity of his point of view. in this way he protects the national dignity of his people, their ancient and rich culture and defends his moral principles and beliefs. A bibliographic review of J. Rudnytsky's scientific work was carried out, where on the basis of historically balanced facts, historical-political, linguistic analysis he investigated the essence of language assimilation, which is equal to the destruction of national identity. It is shown that lexicographical works, conclusions from them gave the scientist a basis to win the struggle for the Constitutional recognition of the Ukrainian language in Canada, which supported the policy of official languages and multiculturalism in the country. It is emphasized that scientific conclusions gave the scientist the opportunity to summarize and summarize the research and became the basis for the introduction into public circulation of a capacious definition - linguocide (language murder), which is now widely used in scientific works.
UKRAINIANS IN St. PETERSBURG IN SCIENTIFIC AND PUBLIC ACTIVITY OF TETIANA LEBEDYNSKA
Authors: Тsymbal Tetiana
Published: September 2021

The article presents the results of a study of scientific, educational and ascetic activities of one of the brightest representatives of the modern Ukrainian diaspora in Russia - Tetiana Lebedynska, a daughter of Ukrainian writer Mykola Shpak. T.M. Lebedynska is PhD in Philosophy, translator, writer, member of the Ukrainian Union of Writers, author of exhibitions dedicated to Ukrainian St. Petersburg, holder of the Order of Princess Olga III degree.
The multifaceted scientific and educational activity of Tetiana Mykolajivna is considered. It is emphasized that she initiated and organized the International Scientific Seminar «St. Petersburg – Ukraine», which resulted in the publication of twenty collections of articles from 2000 to 2020. T.M. Lebedynska is the author of more than 200 scientific works, including unique publications: «Shevchenko's places of St. Petersburg», «St. Petersburg and Ukraine», «M.P. Hrebinka - town-planning of St. Petersburg», «Ukrainian necropolis of St. Petersburg», «I. Mazepa - Commander of the Order of St. Andrew the First-Called», dictionary»Outstanding figures of science and culture of Russia who came from Ukraine», etc.. T.M. Lebedynska was published in Western Europe, the United States, and Arab countries.
It is noted that the heroine of our intelligence pays most attention to the study of the life and work of the Great Kobzar, who had many life events in St. Petersburg: here he studied and worked, gained freedom and communicated with many prominent cultural figures, wrote poems and paintings and became an academician of arts. It was Tetiana Mykolajivna who was one of the initiators of the installation in St. Petersburg of the monument to Taras Shevchenko by Canadian sculptor Leo Mol (Leonid Molodozhanin), she collected signatures against the relocation of the site from the city center near the university to the outskirts, also she initiated and participated in the installation of a memorial to Kobzar at the Smolensk cemetery. Among other things Tetiana Lebedynska‟s ascetic activity is represented, by a study of the Ukrainian necropolis of St. Petersburg, as most graves and tombstones are in a state of destruction and may disappear for the future without restoration. And with them the memory of our compatriots who found eternal peace in the land of North Palmira will be destroyed.
The article states that today, when Crimea is annexed and the Russian occupation of Donbass continues, it is very important to study the experience of our contemporaries - Ukrainians in Russia, who do not lose their identity in conditions of strong informational, ideological and linguistic pressure.
YURI SHEVELОV’S CONTRIBUTION TO THE ESTABLISHMENT OF UKRAINIAN STUDIES IN THE UKRAINIAN ART MOVEMENT
Authors: Denysiuk Serhiy
Published: September 2021

The article examines the research of famous Ukrainian scientist Yuri Shevelov developing Ukrainian studies associations in period of emigration after World War II, when Ukrainian novelists were united in Ukrainian Аrt Movement (1945-1948). The attention is focused on those meetings which have been arranged by Shevelov and his confederates for the unification of different segments of Ukrainian creative intelligentsia in difficult conditions that were caused by emigration from the motherland. During those years, the scientist was considering questions among the important problems of Ukrainian studies about originality of Ukrainian literature, emigration purpose, provinciality and the methods of its overcoming.
It is proved that the concept of national organic style, as a constant of Ukrainian literary and artistic life, was extremely important in the scientist's views. Yuri Shevelov made its main provisions like one of the leading ideologists of Ukrainian Аrt Movement during the existence of this association. The original idea of national organic style had caused the rejection from some part of Ukrainian emigrants and led to a boisterous discussion where there were considered important questions about Ukrainian originality of national literature and its place in European and world culture. The article highlights the essence of discrepancy of views on national organic style between Yuri Shevelov and his opponents. The most famous of them was Volodymyr Derzhavin.
There is an emphasis that Ukrainian Аrt Movement went beyond just literature organization due to Shevelov's efforts. It had opened not only a grand literature, but even publishing and research activities and became an important branch in the history of Ukrainian literature in a relatively short period of time.
APPROACHES AND EFFECTIVE METHODS OF INSTRUCTION IN THE FOREIGN LANGUAGE FOR SPECIAL PURPOSES
Authors: Kuznetsova O. , Zlatnikov V.
Published: September 2021

At the present stage of expanding international contacts in various fields of activity for students it is becoming increasinglyimportant to expand their knowledge of languages outside of everyday foreign language (English). Learning foreign languages hasa number of benefits, including facilitating effective communication and building partnerships, business and military relationships with people from other countries/cultures. Since there are a number of factors that affect the effective acquisition of a foreign language in the context of bilin gualism, modern methods of teaching foreign languages have their own characteristics, considering the target areas and standards. There are many approaches to foreign language teaching developed at the end of the last centurythat have become widely used in teaching foreign languages for special purposes in higher education at the present stage of learning. The range of teaching methods varies depending on which aspects of language acquisition they emphasize – from teaching grammar to the lexicographic component of modern English-language culture of business and professional communication, which are seen as an element of communication skills of young military and civilian professionals [1]. As there is a wide range of different approaches and methods of teaching a foreign language for professional purposes used in lessons, the question will be whether there is evidence that some methods are more effective in acquiring and maintaining acquired skills. The article presents practical recommendations for motivating students to free oral/written communication in a foreign language, taking into account professional needs; the sequence of stages at which new programs for studying a foreign language of special purpose are logically executed, and also offers concerning a vocabulary is provided. The article evaluates and analyzes the latest trends in the methodology of teaching foreign languages, which provides a basis for effective study of a foreign language for professional purposes, taking into account the communicative orientation military, business and professional communication.
Implications of Archambeau's earthquake source theory for slip on faults
Authors: Molnar Peter , Jacob Klaus H. , McCamy Keith
Published: September 2021

abstract

Archambeau's source theory predicts a distinct peak in the displacement amplitude spectrum of body waves radiated into the far-field. If the assumption that earthquakes may alternatively be described by dislocation theory is valid, then this peak in the spectrum can occur only (1) if different parts of the fault, but on the same side of the fault, slip in opposite directions or (2) if the fault slips back after exceeding the maximum displacement. Data at the present time do not provide strong evidence for a peak in the displacement spectrum. The peak in Archambeau's spectrum may be caused by the absence of frictional damping in his model.
Polar radiation patterns of P and SV waves in a multi-layered medium
Authors: Lee Tien-Chang , Teng Ta-Liang
Published: September 2021

abstract

The displacement field in a multi-layered medium due to incident plane P or SV waves is formulated in terms of Haskell's layer matrices. Based on the reciprocity theorem, the far-field polar radiation patterns of single force, double force, single couple, double couple, and dilatation in a multi-layered medium can be obtained from the displacement field and its first derivatives with respect to the spatial coordinates. Numerical results for models of one layer overlying a half-space indicate that (1) the radiation patterns are sensitive to the variation of focal depth, (2) the layering has a more pronounced effect on SV-wave radiation patterns than on P-wave radiation patterns, (3) the radiation patterns become simpler as the wavelength increases, (4) polarity may reverse abruptly somewhere beyond the critical angle in SV-wave radiation patterns, (5) radiation may be discontinuous across interfaces for some assumed focal mechanisms applied slightly above and below the interfaces, and (6) no clearcut distinction among the various radiation patterns can be used to single out one type of the assumed focal mechanisms from the rest.
Microearthquakes and water flooding in Los Angeles
Authors: Teng T. L. , Real C. R. , Henyey T. L.
Published: September 2021

abstract

To prevent inadvertent triggering of earthquakes by fluid injection, the Geophysical Laboratory of the University of Southern California is engaging in a detailed study of microearthquake activities along a portion of the Newport-Inglewood Fault where the accumulating tectonic stress is interacting with massive oil pumping and water flooding. Microearthquake monitoring began in February 1971 and has since operated without interruption. A detailed crustal structure was obtained of the Los Angeles basin from well-logging data and is used satisfactorily in accurate epicenter location. Many seismic events connected with the Newport-Inglewood fault system were accurately located to a third of a kilometer and fault-plane solutions were obtained for some. Hundreds of other events were recorded throughout southern California including the complete aftershock sequence of the San Fernando earthquake of February 9, 1971. Also recorded were the Amchitka nuclear shot and several Nevada Test Site events. Water flooding and oil production data have been compiled for several oil fields in our network operating area. Correlation between microearthquake events and water flooding is suggested.
A low-cost observatory tape recorder
Authors: Choudhury Mansur A. , Houri André
Published: September 2021

abstract

A new principle of recording earthquakes on magnetic tape by triggering is described. Utilizing the multiplex FM system, an ordinary tape recorder is run both as memory and as storage equipment. The recorder runs normally forward during a cycle of about 10 min. If no earthquake has triggered the system, the tape is rewound to its initial position; but if a seismic pulse surpasses the trigger level, the “rewind” function of the recorder is postponed, and every time this level is surpassed, a new period of postponement begins. Thus, a continuous and complete record of an earthquake is obtained.
Generation of SH-type motion by torsion-free sources
Authors: Singh Sarva Jit
Published: September 2021

abstract

The problem of a spherical cavity in an infinite medium is re-examined. The spectral displacement and stress fields are derived when arbitrary tractions are prescribed over the surface of the cavity. This also yields the solution of the problem of the release of pre-existing stress within a spherical zone. The particular case when the radius of the cavity is small in comparison with the wavelength under consideration is discussed in detail. The nature of the tractions is obtained which, when applied at the surface of the cavity, yield the same displacement field as radiated by various point sources. Equivalent body forces are obtained for the release of pre-existing tensile and shear stresses within a spherical zone of small radius. In the course of the analysis, it is shown that an apparently torsion-free source is capable of generating SH-type motion.
The effect of simple topography on seismic waves: Implications for the accelerations recorded at Pacoima Dam, San Fernando Valley, California
Authors: Boore David M.
Published: September 2021

abstract

A precise analysis of the influence of topographic and geological effects on the significant ground motions recorded near Pacoima Dam during the San Fernando, California, earthquake of February 9, 1971, is an immensely complicated task. Calculations for simple models give results that suggest the following general conclusions: (1) the topography should have influenced the recorded ground motion, and (2) this influence seems to be an amplification of the higher-frequency accelerations by as much as 50 per cent, but is relatively unimportant at the lower frequencies (which control the maximum particle velocities).
Earthquake magnitude probabilities and statistical independence for Mexico City earthquakes
Authors: Ferraes Sergio G.
Published: September 2021

The absolute and the conditional earthquake magnitude probabilities are defined by direct enumeration of the successive earthquake magnitude observations.

We make the assumption of independence of earthquake magnitude events in Mexico City earthquakes and then show by experimental data that the assumption of randomness, and consequently the model, is not a good one. Using the X2 statistic to check the statistical dependence, it is found that there is some statistical association between the magnitudes of 221 successive earthquakes felt in Mexico City with magnitude 4.5 or greater. In other words, the observed sequence of discrete earthquake magnitudes for the Mexico City area is nonrandom.

Finally, the concept of energy is used to give a physical interpretation of the significance of the nonrandomness.
Theoretical and observed noise in a high-sensitivity long-period seismograph
Authors: Fix James E.
Published: September 2021

Theoretical expressions for the spectra of the noise in a galvanometer, a seismometer, and a seismometer-galvanometer seismograph are derived from electrical analog circuits and from the Johnson noise of the resistive elements in these circuits. The contributions of the internal damping of the seismometer and of the galvanometer, and of the series resistor to the total potential energy of the thermal noise in a high-sensitivity long-period seismograph are explicit in the expressions. The theoretical thermal spectra agree with observations made at Las Cruces, New Mexico (LC-NM), and at Queen Creek, Arizona (QC-AZ). At LC-NM, the outputs from two matched vertical seismographs were subtracted to obtain estimates of the individual seismograph noise at periods from 4 to 800 sec. Additional experiments demonstrated that the seismograph noise between 10 and 1,000 sec could be estimated equally well by replacing the seismometer: (1) with a resistor, (2) with a coil and magnet oriented vertically or north-south, or by (3) rigidly blocking the seismometer mass. The observed spectra from LC-NM indicate an excess noise in the electronics of the galvanometer phototube amplifier (GPTA) having a one-over-f character at periods longer than 300 sec. At QC-AZ, seismograph noise was recorded with a resistor substituted for the seismometer. The observed noise spectra agree identically with the theoretical noise spectra at periods from 25 to 60 sec and with theoretical noise spectra plus a 1/f noise in the GPTA electronics at periods out to 2,560 sec. The QC-AZ observed and theoretical noise spectra are plotted from 3 to 2,560 sec as the mean-square voltage at the seismograph output and as the root-mean-square displacement of the ground that would produce the same signal as the noise. Typical minimum vertical amplitude spectra of the microseismic background are above the instrument noise spectra in the period range from 3 to 2,560 sec. The agreement between the theoretical thermal noise spectra and the two sets of observational spectra confirms the validity both of the theoretical expressions and of the experimental procedures.
Evidence for a high-velocity lithospheric plate under northern Nevada
Authors: Koizumi Carl J. , Ryall Alan , Priestley Keith F.
Published: September 2021

P-wave residuals at stations of the Nevada seismic network are analyzed for 80 teleseisms distributed over a range of azimuth and epicentral distance. For South American earthquakes (azimuth 120° to 140° from Nevada), teleseismic P arrivals at northern Nevada stations Lovelock, Battle Mountain, and Elko are early by as much as 1.4 sec relative to the Tonopah station to the south. The North Reno station has early arrivals, relative to Tonopah, for Leeward Islands earthquakes, at an azimuth of 100° from the station. Interpretation of these residuals indicates the presence of a high-velocity lithospheric plate, striking northeast and dipping southeast, under northern Nevada. The high-velocity plate is interpreted as a paleosubduction zone.
Magnitude-recurrence relation for central Mississippi Valley earthquakes
Authors: Nuttli Otto W.
Published: September 2021

abstract

Earthquake magnitudes are estimated for all known felt earthquakes in the central Mississippi River valley seismic region for the interval 1833 through 1972. The resulting data-set is examined for completeness, and used to determine a magnitude-recurrence relation. The value of the slope b in the recurrence equation is found to be 0.87 ± 0.11 for 95 per cent confidence limits using the maximum likelihood method, and 0.92 ± 0.08 using weighted least squares.
An ocean-bottom seismometer capsule
Authors: Prothero William A.
Published: September 2021

abstract

An ocean-bottom seismometer capsule containing a 1-Hz vertical seismometer and triggered digital recording system has been developed and tested off the coast of San Diego. The output of the seismometer is continuously digitized at 64, 128, or 256 samples per second. The digital data is mixed with a time code and passed through a 256 sample shift register which acts as a delay line. It is then mixed with synchronization characters, serialized, encoded, and recorded on a SONY TC800B tape recorder which is turned on when a seismic event occurs. The event trigger occurs when the seismic signal jumps to at least twice the time-averaged input signal. Data are recovered using the same recorder for playback and a decoder which provides an analog output for field data interpretation or a digital output for computer analysis. The capsule itself falls freely to the ocean bottom. After a predetermined time it is released from a 150-lb steel tripod and floats to the surface. A dual timer and explosive bolt system provides a high recovery reliability. A number of seismic events have been measured in field tests and the system has proven to be extremely simple to check out, diagnose, and deploy.
Weakly coupled potentials for high-frequency elastic waves in continuously stratified media
Authors: Richards Paul G.
Published: September 2021

A simple construction is given, in terms of potentials, for assigning P and S components of elastic-wave displacement in media with depth-dependent density and Lame parameters. Attention is focused on spherically symmetric media, with radial dependence of material properties, and the asymptotic methods used are expected to be accurate for seismic body waves and surface waves with period less than about 1 min. Novel features of the construction include: (a) its completeness (all possible displacements are represented by the potentials), (b) the development of second-order wave equations, for the P and S potentials, which explicitly display a coupling coefficient, and (c) demonstration of the way in which P and SV components of displacement decouple as frequency increases. Previous work has given constraints on the medium such that P and SV decouple completely: these constraints are here simplified and are seen to arise naturally in the context of the present potential representation. The coupling coefficient (between P and SV) is examined in a variety of earth models.
Source mechanisms for Wilmington Oil Field, California, subsidence earthquakes
Authors: Kovach Robert L.
Published: September 2021

abstract

An unusual set of man-made “earthquakes” was generated in the Wilmington Oil Field, California, during the exploitation of this field. The Wilmington Oil Field was the classic example of an elliptically shaped subsidence bowl produced by the extensive withdrawal of the underlying oil. This surface subsidence produced horizontal shear stresses relieved several times by damaging sudden horizontal movements on very shallow slippage planes. Damaging shocks occurred in 1947, 1949, 1951, 1954, 1955, and 1961. These shocks produced seismograms, primarily composed of surface waves, which present an interesting opportunity to study seismic source mechanisms inasmuch as the focal depth, amount of slip, and source dimensions are known. Rayleigh-wave amplitude spectra for these events reveal seismic moments ranging from 5 × 1022 to 1.7 × 1023 dyne-cm, in good agreement with moments inferred from field observations. A key feature of the subsidence shocks is that very low rupture velocities (0.1 to 0.3 km/sec) were involved. The inferred stress drops indicate that the subsidence shocks must have involved a significant fraction of the available strain energy.
The solution of theoretical seismic problems by best rational function approximations for Laplace transform inversion
Authors: Longman I. M. , Beer T.
Published: September 2021

In a recent paper, the first author has developed a method of computation of “best” rational function approximations ḡn(p) to a given function f̄(p) of the Laplace transform operator p. These approximations are best in the sense that analytic inversion of ḡn(p) gives a function gn(t) of the time variable t, which approximates the (generally unknown) inverse f(t) of f̄(p in a minimum least-squares manner. Only f̄(p) but not f(t) is required to be known in order to carry out this process. n is the “order” of the approximation, and it can be shown that as n tends to infinity gn(t) tends to f(t) in the mean. Under suitable conditions on f(t) the convergence is extremely rapid, and quite low values of n (four or five, say) are sufficient to give high accuracy for all t ≧ 0.

For seismological applications, we use geometrical optics to subtract out of f(t) its discontinuities, and bring it to a form in which the above inversion method is very rapidly convergent. This modification is of course carried out (suitably transformed) on f̄(p), and the discontinuities are restored to f(t) after the inversion.

An application is given to an example previously treated by the first author by a different method, and it is a certain vindication of the present method that an error in the previously given solution is brought to light.

The paper also presents a new analytical method for handling the Bessel function integrals that occur in theoretical seismic problems related to layered media.
Deep structures of the southern Tyrrhenian basin and P-wave residuals at Messina
Authors: Bottari Antonio
Published: September 2021

In this article, P travel-time residuals for the Messina station are analyzed in order to investigate the Tyrrhenian upper mantle, which is considered to be crossed by a lithospheric slab.

A first set of 24 residuals derived from deep earthquakes of the southern Tyrrhenian Sea show early arrivals of, on the average, −1.3 sec at Messina. In addition, these negative residuals are associated with initial motion of the dilatation type. On the contrary, the few deep earthquakes which produce, as first motion, a compression at the Messina station, are associated with late arrivals of about 1 sec. These results are considered and discussed in order to analyze the hypocentral mechanism and P-wave transmission through the lithospheric slab.

A second and wider analysis is then extended to 206 earthquakes which have, with respect to Messina, an epicentral location in the distance range 16° to 103° and azimuthal orientation Z in the interval 180° to 380°. The first conclusion from this analysis is that the P travel times observed at Messina for epicentral distances in the range 20° to 103° and 245° ≦ Z ≦ 380° are generally 0.5 to 3 sec less than those given in the Jeffreys-Bullen tables.

Finally, a further improvement on the foregoing result has been obtained. This gives further confirmation of the consistency of regional variations of the P travel times with a slab model for the Tyrrhenian deep structures. As a matter of fact, the comparison between the travel times of Messina and a standard provided by observations in the stations of Rome and Trieste confirms early arrivals of about 1 sec on the seismic paths which cross the upper mantle in the southern Tyrrhenian region.
Statistical analysis and interpretation of surface-wave anelastic attenuation data for the stable interior of North America
Authors: Herrmann Robert B. , Mitchell Brian J.
Published: September 2021

As a byproduct of determining the source characteristics of some earthquakes and underground nuclear explosions, a body of fundamental-mode Rayleigh- and Love-wave anelastic attenuation values is available for propagation paths in the stable interior of North America in the 5- to 50-sec-period range. The anelastic attenuation values were obtained from four earthquakes occurring in the New Madrid seismic region, one earthquake in the northern Hudson Bay region, and three underground nuclear explosions in the western United States. In obtaining the anelastic attenuation data, a simple statistical test was applied to test the reliability of the observations. The anelastic attenuation coefficients are presented together with their 95 per cent confidence levels.

A stochastic form of the Backus-Gilbert inverse formalism was applied to a subset of these data to yield a Qβ model for the stable interior of North America. The model is characterized by relatively low Qβ values for the upper crust and a rapid transition to much higher values for the lower crust.
Crustal structure in central New Mexico interpreted from the gasbuggy explosion
Authors: Toppozada Tousson R. , Sanford Allan R.
Published: September 2021

abstract

Interpretation of a seismic profile extending 548 km southward from the GASBUGGY nuclear test of December 10, 1967 resulted in a crustal model for central New Mexico. The crust is 39.9 km thick below the Paleozoic “basement”. It consists of an upper crust 18.6 km thick having P velocity 6.15 km/sec, and a lower crust 21.3 km thick having P velocity 6.5 km/sec. The apparent upper mantle velocity is 8.12 km/sec. This model applies near the crossover distance, 50 km west of Albuquerque. Additional information from earthquakes and explosions suggests that the upper crustal velocity drops to 5.8 km/sec in the Rio Grande rift, and that the true upper mantle velocity is 7.9 km/sec. The low upper crustal velocity in the Rio Grande rift can be detected on the record section of the GASBUGGY profile.
Crustal structure in Southern Central America
Authors: Matumoto Tosimatu , Ohtake Masakazu , Latham Gary , Umana Jorge
Published: September 2021

abstract

Seismic data from explosions and local earthquakes are used to determine shallow crustal structure near Managua, Nicaragua, and to derive a complete crustal model for northern Costa Rica. A new method, referred to as the minimum apparent velocity (MAV) method, has been developed and applied in the analysis of local earthquake data. The results indicate that the MAV method of multilayer analysis, when combined with well-determined station corrections, can be quite useful in regions of high seismicity. Based upon the analysis presented here, the total thickness of the crust beneath the central volcanic province of northern Costa Rica is about 43 km. Four crustal layers are identified with compressional-wave velocities of 2.6, 5.1, 6.2, and 6.6 km/sec. The upper mantle velocity is 7.9 km/sec. The major features of this model closely resemble those of other seismically active, marginal zones of the Pacific.
Seismic risk in linear source regions, with application to the San Andreas fault
Authors: Douglas Bruce M. , Ryall Alan
Published: September 2021

abstract

A method is described for determining recurrence times as a function of distance to the causative fault and magnitude, for earthquakes distributed along a linear source zone. The method takes into account rupture length, which is scaled to magnitude, and permits direct calculation of approximate return periods for peak ground-motion parameters for large earthquakes, when the appropriate attenuation functions are known. Several examples are presented using instrumentally determined seismicity along the San Andreas fault zone. Results illustrate the necessity of incorporating rupture length in calculations related to seismic risk; for large earthquakes, it is also necessary to use a source region large enough to contain the rupture zones of all such events. For a site in the San Andreas fault zone we find that the recurrence time to be within 10 km of the causative fault of an earthquake with M ≧ 8 is 200 to 300 years, depending on the choice of maximum magnitude (8.6 or 8.4). For a site on the fault in the Hollister region, we find that recurrence times to be within 10 km of the rupture due to events of M ≧ 5, 6 and 7 are, respectively, 12, 45 and 105 years.
The accuracy of soil response estimates using soil-to-rock spectral ratios
Authors: Beresnev Igor A. , Wen Kuo-Liang
Published: September 2021

Spectral ratios between soft soil and reference rock sites are often used to predict the sedimentary site response to earthquakes. However, their relationship with the genuine site-specific amplification function is often unclear. We compare the soil-to-rock spectral ratios between the stations that are 3.3 km apart with the “genuine” response given by the ratios between the surface and 17 and 47 m downhole. Data from the SMART1 array in Taiwan are used. The “weak” and “strong” motion records are addressed separately to allow for nonlinear soil response. The soil-to-rock spectral ratios are nearly identical to the “true” amplification at the frequencies from 1 to 10 Hz, if the finite depth of the borehole is taken into account. They correctly capture the strong-motion deamplification effect. However, the soil-to-rock spectral ratios are roughly 1.4 times more uncertain than surface-to-47-m ratios. In summary, the soil-to-rock spectral ratios can be considered as the reliable estimates of the real site response.
Earthquake slip rise time and rupture propagation: Numerical results of the quantum earthquake model
Authors: Rydelek Paul A. , Selwyn Sacks I.
Published: September 2021

We continue to investigate the properties of an earthquake model that is based on the physically reasonable assumption that some small section of the fault, referred to as a quantum, must have the same failure criteria (Sacks and Rydelek, 1995). In the simplest case studied to date, the failure criteria is controlled by the physics of Coulomb failure. When this section fails, there is a redistribution of the stress drop onto nearest neighbors. These neighboring quanta, if already near failure, may produce further rupture and so forth for neighbors of neighbors. For larger events comprised of many failed quanta, this cascade process produces a rupture front of limited width and with a variable rate of propagation. In the rupture front, there can be multiple reactivation (i.e., the cycle of fracturing and healing), which governs the duration of the rise time; this rise time is found to be of much shorter duration than the total rupture time of the event. In addition, even though the failure parameters of the quanta are somewhat similar (within 20%), the chaotic behavior of the faulting process and the stress redistribution from numerous smaller events leading up to a large event can give rise to apparent nonphysical asperities, i.e., subregions with larger than average slip. That such characteristics are observed in real earthquakes lends support to the underlying physics that governs our model.
Far-field aftershocks of the 1906 earthquake
Authors: Steeples Don W. , Steeples Dan D.
Published: September 2021

During the 24 hr following the great San Francisco, California, earthquake of 18 April 1906, separate seismic events were felt at Paisley, Oregon; Phoenix, Arizona; Los Angeles, California; and Brawley, California (MMIX). Using probability theory, we show that the occurrence of felt earthquakes in each of these widespread locations on the same day would constitute a rare event. Rates of felt-earthquake occurrences over a 9-yr period from 1897 to 1906 were determined for the four different regions that experienced earthquakes within 24 hr after the 1906 event. We modeled the likelihood of occurrence of these aftershocks in the spirit of the “ball-in-the-box” probability problem, and the results indicated a very high probability that the aftershock zone of the great earthquake extended at least 500 km beyond the extent of ground breakage, implying a disturbance of the stress field over an area at least two to three times longer than the fault break itself.
Reflected seismic waves and their effect on strong shaking during the 1989 Loma Prieta, California, earthquake
Authors: Catchings R. D. , Kohler W. M.
Published: September 2021

Our data indicate that critical and postcritical reflections from crustal layers and the Moho produced increased shaking at discrete distances along the San Francisco Peninsula during the 1989 Loma Prieta earthquake. These reflections may have produced an increase in amplitude that is as much as 10 times greater than that of the direct arrival. Peak amplitude-distance patterns measured from explosive sources, synthetic seismograms, aftershocks, and the mainshock of the 1989 Loma Prieta earthquake indicate that (1) point sources, such as explosions, produce similar peak amplitude-distance relations as distributed, double-couple sources when the crustal structure is approximately a Poisson solid; (2) peak amplitudes from smaller point sources (explosions) may be scaled to those of larger sources (earthquakes); and (3) reflections caused a pattern of high amplitudes at specific distances along the San Francisco Peninsula that geographically correlates with areas of reported damage following from the Loma Prieta mainshock. Our study indicates that critical and postcritical reflections were stronger influences on the locations of strong shaking than local geology because a number of sites around the San Francisco Bay that are underlain by unconsolidated sediments experienced much less shaking than sites that were underlain by hard rock. Furthermore, some severely shaken hard-rock sites were farther from the epicenter than many of the less severely shaken “soft-sediment” sites. Models of the regional crustal structure and seismic-wave propagation paths may be useful in identifying sites around the San Francisco Bay region that are at risk due to reflected seismic energy, and this type of analysis may be useful in other seismically active regions.
Predominant seismic source distance and magnitude maps for Los Angeles, Orange, and Ventura Counties, California
Authors: Cramer Chris H. , Petersen Mark D.
Published: September 2021

Hazard deaggregation at each grid point of a probabilistic seismic hazard map can provide maps of the most probable seismic source distance and magnitude. Maps of predominant seismic source distance and magnitude for PGA, and 5% damped spectral acceleration (SA) at 0.3-, 1.0-, and 2.0-sec periods are produced for the first time for Los Angeles, Orange, and Ventura counties in southern California. These maps show that large earthquakes on faults local to any site generally dominate the 10% probability of exceedence in 50- and 100-yr hazards in southern California. Major faults, like the San Andreas, San Jacinto, and Elsinore faults, dominate mainly in their vicinity. At spectral periods beyond 2 sec, earthquakes on these major faults can dominate out to larger distances.
Microearthquakes at intermediate spreading-rate ridges: The Cleft segment megaplume site on the Juan de Fuca Ridge
Authors: Hildebrand John A. , McDonald Mark A. , Webb Spahr C.
Published: September 2021

We discuss models for earthquake generation at intermediate spreading-rate ridges and present results from an ocean bottom seismograph (OBS) deployment on the Cleft segment of the Juan de Fuca Ridge (JDFR). Although the Cleft segment is spreading at approximately 6 cm/yr, an intermediate spreading rate, it has no seismic activity detectable by land networks, which provide a detection threshold of ML ≧ 4, or by northeast Pacific underwater hydrophone arrays, with a detection threshold of ML ≧ 2. To monitor seismicity, four OBSs were deployed at the Cleft segment for 11 days during August 1990. These OBSs detected 34 regional earthquakes associated with adjacent transform faults. In addition, 10 local microearthquakes (ML = 0 to 1) were observed over a 10-km segment of the ridge crest. Four local events were detected sufficiently well by multiple instruments to allow their hypocenters to be determined; all these events occurred within the rift valley of the Cleft segment spreading axis. Three events lie directly beneath a linear surface zone of hydrothermal venting. This zone has been identified as the site of a seafloor volcanic eruption, dike injection, and large-scale hydrothermal venting or “megaplume” event that occurred during 1986 and 1987. These earthquakes were located at depths coincident with the dike injection zone. A possible mechanism for earthquake production might be tectonic release of stress acquired during the dike injection, either along the dike zone or along the bounding faults of the rift valley. An alternative mechanism may be stress release associated with hydrothermal activity and cooling of the dike. A fourth event was located southeast of the linear hydrothermal venting and dike injection zone, at a depth coincident with the spreading center crustal melt zone. These observations suggest that the Cleft segment may primarily experience seismic events correlated with periods of volcanic intrusion.