bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the variation of seismic hazard along the San Andreas fault
Authors: Howell B. F. 
Published: July 2021

AbstractRecurrence probabilities of earthquakes were evaluated at 33 locations along the San Andreas fault using Gumbel's method. Two minima in the mode of the largest annual earthquakes occur, one north of San Francisco centered around 38.75°N latitude and the other centered in the Carizzo Plain area at 35.25°N latitude. The latter is offset by an unusually large ratio of large to small earthquakes, so that only one minimum (around 38.75°N) is observed in the expected 100-yr earthquake size. This broad minimum closely coincides with where the San Andreas fault broke in 1906, and may be only temporary.There appears to be a slight, systematic tendency for the observed largest 50-year earthquake to become larger than the expected 50-yr earthquake as the size of the area being studied is reduced. The preferred explanation for this is that the pattern of size as a function of frequency becomes nonlinear when the size of the area studied is less than the focal area of the largest earthquakes.
Are reservoir-induced earthquakes of magnitude ≧ 5.0 at Koyna, India, preceded by pairs of earthquakes of magnitude ≧ 4.0?
Authors: Gupta Harsh K. , Iyer H. M. 
Published: July 2021

AbstractForeshocks of Koyna, India, earthquakes of magnitude ≧ 5.0 are investigated using data from the Poona WWSSN Seismic Station situated at a distance of 120 km from Koyna. Schemes for estimating earthquake magnitude on the SPZ component seismogram at Poona have been developed. These schemes are applicable to earthquakes of magnitude ≧ 2.0 occurring in the Koyna region.Earthquakes of magnitude ≧ 5 on 13 September 1967, 10 December 1967, and 17 October 1973 in the Koyna region were each preceded by two earthquakes of magnitude ≧ 4.0 occurring within the preceding 15 days. In comparison, the activity of September 1980 was different. An earthquake of magnitude ≧ 5.0 occurred on 2 September and two more ≧ 5.0 earthquakes occurred on 20 September. These earthquakes were not preceded by pairs of ≧ 4.0 events. All events of magnitude ≧ 4.0 during 1974 through 1976 were singular (no two such events occurred within 15 days of one another). There appears to be a 50 per cent probability of occurrence of a magnitude ≧ 5.0 earthquake if two earthquakes of magnitude ≧ 4.0 are closely spaced in time (within 15 days) in the Koyna region.
The Anza array: A high-dynamic-range, broadband, digitally radiotelemetered seismic array
Authors: Berger Jon , Baker L. M. , Brune J. N. , Fletcher J. B. , Hanks T. C. , Vernon F. L. 
Published: July 2021

AbstractA small aperture seismic array has been deployed along a 30-km stretch of the San Jacinto fault in the vicinity of the town of Anza, California. The array was installed to study specifically the scaling laws of body-wave spectra, the character of high-frequency ground motion, the physical interpretation of seismic stress drops, and the interaction of earthquakes. This region was chosen for these studies due to its high rate of seismic activity in the 2 ≦ M ≦ 4.5 range, the likelihood of a M &gt; 6 event in the next decade, and the existence of the Southern California Batholith on either side of the fault, reducing problems associated with attenuation and large scale anisotropy. These studies employ an instrument package with a frequency response of 100 Hz, a dynamic range of 138 dB, a sampling rate of 250 times per second per component, and a 16-bit A/D converter. The array consists of 10 three-component stations, telemetered via digital VHF radio to a nearby mountain peak and thence via a microwave link to La Jolla, California. A minicomputer system monitors the array's performance, detects events, and records data upon demand. Initial results demonstrate the feasibility of digital transmission with an inherent increase in data quality over analog systems.
Numerical studies of the coda falloff rate of multiply scattered waves in randomly layered media
Authors: Menke William , Chen Rolin 
Published: July 2021

AbstractWe study the falloff rate of the coda of acoustic signals after transmission (net forward-scattering) through a stack of thin layers (compared to the wavelength of the signal) with randomly fluctuating impedances. We find that the change in coda energy with time after the first arrival can be modeled as a decaying exponential with falloff rate c ∝ ω − 1 x − 3 / 2 σ − 1 where ω is the center frequency of a frequency band of the coda, x is the source-receiver distance, and σ is the standard deviation of the impedance fluctuation in a band centered about 2 ω. The dependence of the falloff rate of net forward-scattered coda on ω and σ is opposite to that of single back-scattered coda, and distinguishes the two types of scattering.
Evidence of tectonic release from underground nuclear explosions in long-periodSwaves
Authors: Wallace Terry C. , Helmberger Donald V. , Engen Gladys R. 
Published: July 2021

AbstractThe SH waves from 21 underground nuclear explosions at Pahute Mesa (NTS) were used to investigate tectonic release. The equivalent double-couple representation of the tectonic release, which was constrained by waveform modeling and the polarity of sP, is very similar for all the explosions. The average orientation is a right-lateral, strike-slip fault trending N15°W. Seismic moments were determined on the basis of comparisons with two western United States strike-slip earthquakes. BENHAM has the largest tectonic release moment (5.6 × 1024 dyne-cm) and STILTON (0.1 × 1024 dyne-cm) the smallest of the events studied. In general, the seismic moments increase with the size of the explosion, but the location of the explosion relative to previous explosions can strongly affect the tectonic release. The Pahute Mesa events can be separated into two populations: (1) events which are well separated (&gt;4 km) from previous explosions, and (2) those events which are close (&lt;4 km) to previous explosions. Those events which are close to previous explosions show a marked decrease in tectonic release. A least-squares fit of seismic moment to event size (as determined from the world wide, average ab amplitude) shows that the two populations are approximately parallel, but offset. The fact that the trends remain separated even at small yields (e.g., PIPKIN and SCOTCH) suggests that for Pahute Mesa there is not a threshold for tectonic release. Since spatial position gives the best separation of high and low tectonic release events, a volume model is favored for the source mechanism. The preferred model is motion on a system of faults and joints.
Modeling of the Koyna, India, aftershock of 12 December 1967
Authors: Langston Charles A. , Franco-Spera Mariaclare 
Published: July 2021

AbstractShort-period teleseismic and near-regional long-period waveforms from a large aftershock (mb = 5.3, origin time 06:18:36.8 UTC) of the 10 December 1967 Koyna main event were modeled to determine source depth and focal mechanism. Identification of pP and sP on the short-period waveforms yielded a well-constrained source depth of 3.5 to 4.0 km. The focal mechanism was determined using a systematic trial and error (grid-testing) technique in which seven P first motions, two SH first motions, two teleseismic pP/P ratios, one teleseismic sP/P ratio, and one regional SH/P ratio were included. This heterogeneous, but sparse, data set yielded a constrained normal fault mechanism at 100° ± 20° strike, 40° ± 10° dip, and 240° ± 20° rake. Rupture directivity is inferred from consistently high surface reflection/direct wave amplitude ratios. A circular fault of 1 km radius with a rupture initiation point at the lower edge and an assumed rupture velocity of 0.9 Vs explains the anomalously high amplitude ratios and yields a seismic moment of 3.8 × 1023 dyne-cm. The shallow source depth is similar to that found for the main event (4.5 km) and the 13 September foreshocks (5 km) in previous modeling studies and is consistent with the premise that the Koyna earthquakes were triggered by the impoundment of the Koyna reservoir. However, the normal fault mechanism differs substantially from the previous events which were left-lateral strike-slip faults trending NNE. The differing aftershock mechanism is probably due to the reactivation of old faults in the Koyna area caused by stress readjustment after the Koyna main event.
The breaking of a single asperity: Analysis of an aftershock of the 1975 Oroville, California, earthquake
Authors: Das Shamita , Boatwright Jack 
Published: July 2021

AbstractAccelerations and acceleration envelopes of S waves from a small (ML = 3.6) aftershock of the 1975 Oroville, California, earthquake have been interpreted using a dynamic model of the failure of a single, isolated asperity on a fault plane. It is shown that the distinctive characteristics of the asperity radiation are a prolonged, emergent onset followed by a two-sided acceleration pulse. This energetic pulse is radiated at the completion of failure of the asperity. Our purpose is to demonstrate the characteristics of asperity radiation using a specific event as an example rather than a trial and error modeling of this event.
Fault slip in southern California
Authors: Louie John N. , Allen Clarence R. , Johnson David C. , Haase Paul C. , Cohn Stephen N. 
Published: July 2021

AbstractMeasurements of slip on major faults in southern California have been performed over the past 18 yr using principally theodolite alignment arrays and tautwire extensometers. They provide geodetic control within a few hundred meters of the fault traces, which complements measurements made by other techniques at larger distances. Approximately constant slip rates of from 0.5 to 5 mm/yr over periods of several years have been found for the southwestern portion of the Garlock fault, the Banning and San Andreas faults in the Coachella Valley, the Coyote Creek fault, the Superstition Hills fault, and an unnamed fault 20 km west of El Centro. These slip rates are typically an order of magnitude below displacement rates that have been geodetically measured between points at greater distances from the fault traces. Exponentially decaying postseismic slip in the horizontal and vertical directions due to the 1979 Imperial Valley earthquake has been measured. It is similar in magnitude to the coseismic displacements. Analysis of seismic activity adjacent to slipping faults has shown that accumulated seismic moment is insufficient to explain either the constant or the decaying postseismic slip. Thus the mechanism of motion may differ from that of slipping faults in central California, which move at rates close to the plate motion and are accompanied by sufficient seismic moment. Seismic activity removed from the slipping faults in southern California may be driving their relatively aseismic motion.
Pnobservation and interpretation in Washington
Authors: Zervas Chris E. , Crosson Robert S. 
Published: July 2021

abstractThe travel-time characteristics of Pn waves in the state of Washington were investigated using regional earthquakes as seismic sources and stations of the state-wide University of Washington telemetered network as receivers. There is a significant difference in upper mantle velocity between eastern Washington (8.20 ± 0.02 km/sec) and western Washington (7.79 ± 0.02 km/sec). Modifications of the time-term method were used to find the dependence of P velocity on distance and azimuth to the source. Pn velocity in eastern Washington depends on the distance to the source, implying a velocity gradient with depth in the upper mantle. No significant distance dependence was found for western Washington. Azimuthal anisotropy was found for Pn with a northwest direction of maximum velocity in eastern Washington and a north-northwest direction in western Washington. Assuming no lateral crustal velocity gradients, the Pn refracting interface dips to the west approximately 0.8° in eastern Washington and to the southeast approximately 3.2° in western Washington. Contour maps of the station time terms indicate significant variations in crustal structure across the state. The combination of low Pn velocity and small Moho dip beneath western Washington suggests that the subducting lithospheric slab underlying the continental margin lies below the level of transition to upper mantle velocity over much of this region.
Sutton, Alaska, earthquake of 1984: Evidence for activity on the Talkeetna segment of the Castle Mountain fault system
Authors: Lahr J. C. , Page R. A. , Stephens C. D. , Fogleman K. A. 
Published: July 2021

Abstract
A magnitude 5.7 mb (5.2 Ms) earthquake occurred on 14 August 1984, 14 km north of Sutton, in the vicinity of the mapped trace of the Talkeetna segment of the Castle Mountain fault system. The focal mechanism of the earthquake and the spatial distribution of well-controlled aftershock hypocenters indicate that the shock involved dextral slip at 13- to 20-km depth on the Talkeetna fault segment. The depth of the shocks is consistent with the lack of observed surface breakage. The Sutton earthquake sequence, plus recent small shocks recorded by the southern Alaska seismograph network, provide definitive evidence that the Talkeetna segment of the fault system is active.
Reciprocity principle and the approximate solution of the wave equation
Authors: Razavy M. , Lenoach B. 
Published: July 2021

Abstract
In this paper, we examine the validity of reciprocity when certain approximations are applied to the wave equation. We focus on some of the approximation techniques which are frequently used in investigating seismic waves, particularly in the context of synthetic seismograms, namely, asymptotic ray theory and finite difference methods. The main result is that the reciprocity property is not necessarily preserved when an approximation is used. This conclusion is shown to be valid for both ray theory and finite difference techniques. We give some concrete examples as well as numerical results to illustrate the practical effect of nonreciprocity. We also show that reciprocity breaks down when analytical approximation is required to solve the problem in question.
Multi-channel deconvolution ofPwaves at seismic arrays
Authors: Der Zoltan A. , Shumway Robert H. , Lees Alison C. 
Published: July 2021

AbstractThe results of a new multi-channel deconvolution method applied to NORSAR and EKA array recordings of teleseismic P waves are presented and interpreted in terms of possible surface reflections and other arrivals from the Nevada Test Site and Kazakh nuclear explosions. The deconvolution method utilizes the well-known fact that P-wave spectra can be decomposed into source and receiver spectral factors. For most events, the source-time functions appear to contain a pP arrival but they also show later, unexplained arrivals. The site functions are also complex in many cases. About half of the late coda in P appears to be due to each source and receiver. The recordings for a presumed Kazakh cratering event show a distinctly different source function when compared to deeper, buried explosions at the same test site. From the deconvolved source-time functions, the cratering to noncratering mb bias is estimated to be between 0.09 and 0.22 magnitude units.
Estimation of magnitudes in central and eastern North America using intensity and felt area
Authors: Sibol M. S. , Bollinger G. A. , Birch J. B. 
Published: July 2021

AbstractOver 480 earthquakes from central and eastern North America having instrumental mb magnitudes and maximum Modified Mercalli intensities (I0) were examined using exploratory data analysis techniques and modeled with robust estimation methods (91 of those earthquakes also have felt area data). A previously undocumented distinct offset of magnitudes is observed between Modified Mercalli intensities VI and VII in both the central and eastern North America data set and a separate western North American catalog of earthquakes. The offset is most probably a characteristic of the Modified Mercalli scale and brings into question the often assumed linear relationship between magnitude and intensity. (In particular, linear regression models could not accurately estimate magnitudes for larger, I0 = VII or VIII, events.) Instead, robust estimates of center and spread for individual intensity interval distributions are recommended. In studies where conversion of intensity to magnitude for groups of earthquakes is required (e.g., studies involving the Gutenberg-Richter recurrence relation), the underlying distribution of magnitudes (or its approximation) for each intensity should be used.Linear regression models using I0 and/or felt area (and several transformations were tested. The robust linear regression modelsm b = 2.48 + 0.0769 log 2 ( F A ) and m b = 2.16 + 0.0219 l 0 2 + 0.0596 log 2 ( F A )(where FA is felt area in square kilometers) proved to be the most accurate magnitude estimation models for central and eastern North America earthquakes. A comparison of regional felt area models indicates that regional differences in attenuation of seismic waves may exist between central and eastern North America that becomes apparent only for events of sufficient magnitude. Those differences appear as larger felt areas for earthquakes of central North America as compared to earthquakes of eastern North America.
Radiation characteristics of elastodynamic line sources buried in layered media with periodic interfaces. I.SH- wave analysis
Authors: Varadan Vijay K. , Lakhtakia Akhlesh , Varadan Vasundara V. , Langston Charles A. 
Published: July 2021

AbstractUsing the T matrix method, or the extended boundary condition, the solution for a class of problems involving an SH line source in an elastic wave guide is determined. The boundaries of the wave guide may be periodically corrugated and the wave guide may be embedded between elastic media. Numerical results are given for a seismically interesting case of wave propagation in a one-layer crustal model over a mantle half-space with a corrugated free surface representing the Basin and Range topography in the Western United States. Analysis of the scattered fields at the surface, and of the fields radiated into the half-space, shows complicated field behavior, even with sinusoidal free surface corrugation. These results are directly applicable to regional wave propagation and scattering.
Menakar Pentingnya Perencanaan Karier untuk Warga Belajar Pada Penyelenggaraan Pendidikan Non Formal Program Pendidikan Kesetaraan
Authors: Prihatiningsih Riskiyana 
Published: July 2021

Abstract: This study was conducted with the aim of knowing the importance of career planning guidance for kelompok belajar paket B. The method used in this article is literature studies. The data used comes from sources such as journals and books relevant to the research theme. From some of the research that has been done, there is a positive relationship between career planning guidance and student career readiness.
Abstrak: Kajian ini dilaksanakan dengan tujuan untuk mengetahui pentingnya bimbingan perencanaan karier bagi warga belajar pada penyelenggaraan Pendidikan non formal. Kajian ini Metode yang digunakan dalam penulisan artikel ini adalah Kajian Literatur. Data yang digunakan berasal dari sumber-sumber seperti jurnal dan buku yang relevan dengan tema penelitian. Dari beberapa hasil penelitian yang sudah dilakukan, terdapat hubungan yang positif antara bimbingan perencanaan karier dengan kesiapan karier peserta didik.
“NO OLHO DO FURAÇÃO”: A CONSTRUÇÃO PROJETO DE ISOLAMENTO SOCIAL FRENTE AO COVID-19, EM UM GRUPO INDÍGENA NA AMAZÔNIA
Authors: Junior Petrônio Lauro Potiguar 
Published: July 2021

Expomos aqui este relato de experiência, fruto de uma viagem de cinco meses de pesquisa de campo na aldeia Mapuera, onde vivem vários grupos indígenas denominado genericamente de “Etnia Wai Wai”, na cidade de Oriximiná, no noroeste do Pará, por conta da fase final da tese de doutorado que está em curso. Apresentamos aqui os momentos de angustias e inquietações vividos pelo autor desse relato e indígenas nesse local, nas primeiras manifestações da pandemia da Covid-19, denominado aqui de “olho do furacão”, em março de 2020.Tal experiência nos direcionou ao seguinte questionamento: como antropólogo poderia contribuir em contexto de pandêmico em grupos indígenas, em especial, em Mapuera? A partir dessa pergunta, articulações foram feitas envolvendo cacique geral, lideranças, Conselho de Saúde da Mapuera, lideranças da igreja evangélica local, professores e profissionais da saúde que prestam serviço no local pela Fundação Ovídio Machado, frente ao Distrito Sanitário Guamá Tocantins- DSEI-GUATOC, incidido na elaboração de um projeto de isolamento social. Até a primeira quinzena de junho de 2020, momento da saída de campo, o referido projeto não tinha sido usado, pois nenhum caso de covid-19 acometera qualquer indígena no local, mas somente atingido alguns deles que estavam fora desse espaço, como na cidade de Belém, Santarém e Oriximiná, inclusive com óbito. Também notícias dão conta que, apesar de não adesão ao “projeto de Isolamento Social” pelo DSEI-GUATOC, sua produção serviu de parâmetro para a feitura de um plano de proteção à equipe de saúde e aos indígenas do local, revelando um dos objetivos dessa proposição, inspirar ações de políticas públicas em tempos de pandemia para a proteção dos povos indígenas na Amazônia, independentemente de quem quer que seja.
Uso desigual del espacio recreativo público en el contexto de la COVID-19 en Lima Metropolitana
Authors: Chambi Chamorro Gloria Estefany , Huachaca Pozo Josselin , Poma Monrroy Eva Alejandra 
Published: July 2021

El aislamiento obligatorio producido por la pandemia de la COVID-19 ha evidenciado la necesidad de poder recrearse o generar un vínculo social, no solamente para gozar de un bienestar físico, sino mental es realmente tal: una necesidad. Ante la «nueva normalidad», el gobierno peruano ejecutó medidas para la reincorporación de las actividades recreativas individuales, así surge la necesidad de analizar las desigualdades socioespaciales para acceder a un espacio recreativo público de calidad próximo al lugar de residencia, el uso y frecuencia en función del antes, durante y después de la cuarentena, y las políticas públicas que se vienen ejecutando para el adecuado uso de los espacios recreativos públicos en Lima Metropolitana, las cuales fueron evaluadas a través de una encuesta virtual. Se concluye que es necesario proporcionar espacios de calidad que aseguren el uso seguro y equitativo, para satisfacer las necesidades sociales e individuales y evitar el desplazamiento en búsqueda de espacios idóneos, a fin de reducir el incremento de contagios.