bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation on the attractive forces controlling clay particles' interactions
Authors: de Morais L. P. , Tarantino A. , Cordão Neto M. P.
Published: September 2021

Modelling clay behaviour is a challenging task because many of the microscopic features are still unknown including interparticle forces and particle association, which may explain the different behaviours of clay when subjected to hydro-mechanical loading. This paper presents an experimental study to investigate the micromechanical interactions of clay particles. Kaolinite samples were compacted to high vertical stresses and granulometry laser tests were carried out to investigate particle agglomeration. Samples were compacted in a dry state, with 10% water content and 10% dispersant solution content. The results show that loading generated agglomeration. When comparing specimens compacted using different pore fluids, the agglomeration process is more pronounced at high values of dielectric permittivity (water). This study concludes that the association of particles forming agglomerates is due to van der Waals forces. This was mainly inferred from the observation that agglomeration occurred even when compacted samples were prepared with dispersant solution. This also indicates that association of particles occurs in face-to-face mode due to the high stress applied. A similar response of samples compacted with water and sodium hexametaphosphate solution and the environmental scanning electron microscope images of compacted samples also show this type of arrangement. The comprehension of interparticle forces and particle associations can improve discrete modelling of fine-grained materials.
Mukozal ve Kutanöz Tutulum ile Seyreden Liken Planus Hastalarında Subklinik Kardiyovasküler Hastalık Riskinin Değerlendirilmesi
Authors: ERDOĞAN Mehmet , KASAPKARA Hacı Ahmet , BAŞTUĞ Serdal , ALSANCAK Yakup , AKTAŞ Akın , SAATÇİ YAŞAR Ayşe
Published: September 2021

Amaç: Liken planus (LP) kronik enflamatuvar bir hastalıktır. Karotis intima-medya kalınlığı (KİMK) ölçülmesi ve lipid profilinin değerlendirilmesi aterosklerotik risk tahmini için kabul görmüş bir metottur. Bu çalışmada LP hastalarında kardiyovasküler hastalık (KVH) risk faktörlerinin prevelansı ve subklinik ateroskleroz riskinin değerlendirilmesi amaçlanmıştır.

Gereç ve Yöntemler: Bu olgu-kontrolü çalışmaya LP tanısı alan 60 hasta grubu ile yaş ve demografik özellikler açısından benzer 60 kontrol grubu dahil edildi. Gruplar arasında bazal karakteristik özellikleri, KVH risk faktörleri, biyokimyasal ve hematolojik parametreleri, konvansiyonel 2-boyutlu ve Doppler transtorasik ekokardiyografik parametreleri, sol ventrikül kitle indeksi (SoVKİ) ve KİMK karşılaştırıldı.

Bulgular: Çalışmaya yaş ortalaması 46±13 yıl olan, 73’ü kadın (%61), 47’si erkek (%39) olmak üzere toplam 120 hasta alındı. Total kolesterol (TK) seviyeleri LP grubunda kontrol grubuna kıyasla daha yüksek bulundu (sırasıyla 209, 192, p=0.038). Gruplar arasında SoVKİ ve konvansiyonel ekokardiyografik ölçümler benzer bulundu. LP grubunda KİMK 0.88±0.16 mm iken kontrol grubunda 0.59±0.10 mm olarak ölçüldü (p< 0.001). Kutanöz LP ile mukozal LP arasında ise KİMK benzer bulunmuştur. LP grubunda hastalık süresi ile KİMK arasında güçlü bir korelasyon izlenmiştir (r=0.61, p
Diversidad de plantas leñosas en el bosque tropical caducifolio y subcaducifolio de Sierra de Vallejo, Nayarit, México
Authors: Ángeles-García Amairany Y. , Suárez-Torres Joanna J. , Carrillo-Reyes Pablo , Peña-Joya Karen E. , Quijas Sandra
Published: September 2021

Background: Deciduous and sub-deciduous tropical forests are distinguished by their floristic diversity, their remarkable concentration of endemic species, high turnover, and low species similarity.
Questions: What is the alpha and beta diversity of the woody plant species of the deciduous and sub-deciduous tropical forest in Sierra de Vallejo?
Study site and dates: Sierra de Vallejo, which is part of the Natural Resources Protection Area, Sierra de Vallejo-Río Ameca, Nayarit-Jalisco; August 2017 to May 2018.
Methods: 15 transects (0.1 ha) were established, identifying each woody plant with diameter at the breast height (DBH) ≥ 3 cm. Alpha diversity was analyzed considering true diversity based on the effective number of species and abundance range curves. Beta diversity was analyzed with similarity, turnover and nestedness.
Results: We counted 1,556 individuals belonging to 45 families, 99 genera, and 126 species¸ 22 species endemic to Mexico, one species endemic to the region, 84 native and four exotics. Sites were characterized by low observed species richness (13-37 species), high variation in abundance (44-229 individuals), low true diversity (q0, 18-49 species), high turnover (91-96 %), low nestedness (0.9-1 %) and low similarity (8 %).
Conclusions: The floristic diversity values show the importance of preserving the greatest number of areas with tropical forest in Sierra de Vallejo, reinforcing the conservation and management strategies of this type of forest within this Natural Protected Area of Natural Resources.
Edible flowers commercialized in local markets of Pachuca de Soto, Hidalgo, Mexico
Authors: Figueredo-Urbina Carmen Julia , Álvarez-Ríos Gonzalo D. , Cortés Zárraga Laura
Published: September 2021

Background: Edible flowers are important food resources due to their high content of nutrients and bioactive compounds. In Mexico these resources have been part of the diet of indigenous and mestizo, and are also important sources of income for the families that cultivate, gather and sell them.
Questions: What are the species of edible flower commercialized in local markets in Pachuca de Soto, Hidalgo, Mexico? How are they prepared? What are their nutritional contents and conservation risk categories according to literature?
Studied species: Agave salmiana, A. mapisaga, Aloe vera, Arbutus xalapensis, Chenopodium berlandieri subsp.nuttalliae, Cucurbita pepo ssp. pepo, C. moschata, Dasylirion acrotrichum, Erythrina americana, Euphorbia radians, Myrtillocactus geometrizans, Phaseolus coccineus, Yucca filamentosa.
Study site and dates: Local markets of Pachuca de Soto, Hidalgo, Mexico. January 2019 to March 2020.
Methods: Interview-purchase with sellers and direct observations in markets. Bibliographic review of the nutritional contents of the recorded species and their conservation status.
Results: We recorded 13 species of edible flowers and eight preparation methods. Five species are cultivated, five are gathered from the pine-oak forest or xerophilous scrub ecosystems and three are obtained from crops and natural ecosystems. The gualumbos (Agave salmiana and A. mapisaga) are the most commercialized flowers and had the most forms of preparation (six). Seven of the species traded are placed in a conservation risk category.
Conclusions: The diversity of edible flowers used, and their preparation methods exemplify the traditional knowledge of the groups that handle them and their importance as food and economic sustenance.
The return of Rosie the Riveter: Contemporary popular reappropriations of the iconic World War II image
Authors: du Plooy Belinda
Published: September 2021

The iconic image of Rosie the Riveter played an important role in American patriotic ideological processes during World War II. Aimed at the recruitment of women for wartime work, particularly in factories and traditionally masculine occupations, this representation of a woman in overalls and head scarf, with sleeves rolled up, showing her bicep and balled fist, declaring 'We can do it', has been a contentious point of discussion for its significance in feminist agendas since its first appearance. While building on, and playing to, the suffrage agendas of first wave feminism, the popular image of Rosie was transcended by second wave concerns about depictions of women in the workplace, such as those in films like Norma Rae (Ritt 1979), Silkwood (Nichols 1983), North Country (Caro 2005) and Made in Dagenheim (Cole 2010). But Rosie is making a comeback. The image has recently been appropriated in various ways and for various purposes - naively, ironically, satirically, as bricolage, pastiche and in sexualised portrayals - to represent contemporary women's issues and concerns, as well as arguably forming part of a backlash culture against feminism. Contemporary depictions have, for example, ranged from Hilary Clinton, Sarah Palin, Michelle Obama, Malala Yousafzai and Beyoncé. This paper considers the development and transformation of the image of Rosie the Riveter and its contradictory (re)-appropriations in various contemporary popular cultural discourses. Keywords: feminist expression, Michel Foucault, gender roles, popular culture, Rosie the Riveter.
When is a choice not a choice?: Experiences of individual agency and autonomy by South African female breadwinners
Authors: Parry Bianca
Published: September 2021

As part of a larger Master's study, this paper focuses on the individual experiences of agency and autonomy communicated by a group of South African women who have overcome traditional notions of gender through their role as primary financial provider for their families. Using data collected from in-depth, unstructured interviews, and reading these through a phenomenological feminist perspective, I shed some light on the perceptions of ten female breadwinners (FBW) in this paper. It is the aim of this research to represent these women's voices in order to understand how they make meaning of and negotiate their spaces and roles as breadwinners. In the course of the interviews and analyses, the realities faced by these FBW stemming from the Mpumalanga and Gauteng provinces expose the hegemonic and heteronormative prescriptions of gender that still exist within our society, often concealed behind constructions of reform advocating gender equality. Keywords: Female Breadwinner, South Africa, Gender Roles, Feminism, Psychology, Phenomenology.
DIRECTOR AND EXECUTIVE REMUNERATION CLAWBACKS: A SUGGESTED APPROACH FOR SOUTH AFRICA
Authors: Vela Madlela
Published: September 2021

The purpose of this article is to explore clawbacks as a means of addressing problematic executive remuneration through an examination of the approaches adopted by the US, Australia, and certain European Union (EU) member states and to highlight the lessons that South Africa may draw from the experiences of these jurisdictions. The article first considers the intentions and assumptions of remuneration reforms, which have introduced clawbacks in these international jurisdictions. It then moves on to provide an overview of the US, Australian and EU clawback reforms, identifying and analysing the potential benefits and shortcomings of the regulatory reforms in each jurisdiction. The article asserts that the absence of a requirement for the clawback of incentive-based remuneration in South Africa is not in the interests of companies and their stakeholders since shareholders will have to institute often protracted and costly legal proceedings in order to recover erroneously awarded incentives. The article then makes recommendations on how remuneration clawbacks could be effectively incorporated into the South African regulatory framework.
SOME COMPARISONS BETWEEN THE NIGERIAN AND SOUTH AFRICAN FISCAL REGIMES REGARDING AN INDIVIDUAL’S TAX RESIDENCE
Authors: Nuhu Musa Idris
Published: September 2021

Internationally, one of the most widely adopted criteria for determining the jurisdictional basis of a state’s taxing power is that of the taxpayer’s “residence”, “principal residence” or “ordinary residence”. However, statutory definitions often complicate these concepts, as is the case in Nigeria, and it is common for relief to be granted where the application of these criteria would expose the taxpayer in question to tax on the same income in more than one tax jurisdiction. In Nigeria, the determination of the residence of taxable persons involves the application of statutory criteria and moreover, the legislation makes it necessary to locate residence within a particular state of Nigeria. In the interpretation of the statutory criteria, precedence is given to decisions of the Nigerian courts.
A BIBLICAL LAZARUS: DEREGISTRATION OF A COMPANY AND THE REVIVAL OF RIGHT TO MINERALS A discussion of Palala Resources (Pty) Ltd v Minister of Mineral Resources and Energy 2016 (6) SA 121 (SCA)
Authors: Heleen van Niekerk  , Shamila Mpinga
Published: September 2021

The notion of death and resurrection is intriguing. As part of a religious teaching, rising from the dead is often associated with an act of a deity for the salvation of humankind. Holding the ultimate power of having defeated death, the resurrected deity often has the ability to perform the miracle of commanding others to rise from the dead. For some, these religious beliefs are of the utmost importance and, frequently, take centre stage in the believer’s life. While it is generally accepted that people have the freedom to choose their religious beliefs, we should tread cautiously when the law assumes the characteristic of performing miracles. This need to tread cautiously is well illustrated in Palala Resources (Pty) Ltd v Minister of Mineral Resources and Energy 2016 (6) SA 121 (SCA) (hereinafter “Palala Resources (SCA)”).The case concerns the interpretation of section 56(c) of the Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA) and section 73(6A) of the Companies Act 61 of 1973. According to section 56(c) of the MPRDA, rights to minerals lapse when a company is deregistered. Section 73(6A) of the 1973 Companies Act provides an opportunity for a company that was deregistered for failing to submit annual returns to be restored to the companies register. According to the Supreme Court of Appeal (SCA), the restoration of a company according to section 73(6A) constitutes a “Biblical Lazarus moment” (par 5 and 12) for a prospecting right that lapsed according to section 56(c) of the MPRDA: upon restoration of the company, the prospecting right miraculously revives from the dead.In this case discussion, we investigate whether the revival of rights to minerals in the manner allowed in the Palala case accords with the objectives of the MPRDA. We specifically investigate the correct interpretation of section 56(c) of the MPRDA in the particular circumstances of the case, namely, when companies that hold prospecting rights are deregistered for failing to submit annual returns. Although not discussed here, our arguments can be extended to all rights to minerals and to all scenarios envisaged in section 73 of the 1973 Companies Act; i.e., where companies are removed from the register without being wound up. Our arguments do not cover the voluntary or involuntary winding up of solvent companies (s 80 and 81 of the Companies Act 71 of 2008 (the 2008 Companies Act)) or the winding up of insolvent companies (s 344 of the 1973 Companies Act).At all material times during the dispute, the 1973 Companies Act, and not the 2008 Companies Act, was operational. We compare the position in the 2008 Companies Act throughout the discussion.
The 6th conference "Baltic Applied Astroinformatics and Space Data Processing" (BAASP 2019) dedicated to the 25th anniversary of the VIRAC
Authors: BEZRUKOVS V , PAULIKS RP
Published: September 2021

The Engineering Research Institute "Ventspils International Radio Astronomy Centre" of Ventspils University of Applied Sciences (ERI VIRAC of VUAS) founded in 1994, celebrated its 25th anniversary in 2019. One of the main events dedicated to this date was the conference "The 6th Baltic Applied Astroinformatics and Space Data Processing" (BAASP 2019) held in Ventspils from 21 to 23 August 2019.
First molecular cloud measurement with Irbene RT-32 radio telescope
Authors: ABERFELDS A , VASYUNIN A
Published: September 2021

This paper describes the efforts of the Ventspils International Radio Astronomy Center (VSRC) astrochemist and observation groups to study the formation of massive stars from chemical evaluation and radio emission point of view. By observing all four selected sources chemists group observations can provide important feedback to models, mainly an information for molecules with maser emission. Based on detection of masers in young stellar object (YSO) observations provide information that there are parts of molecular clouds where gas density and molecular abundances are higher by a few orders than in typical young star forming clouds.
[RETRACTED] UNBS CBD Gummies Shocking Facts Revealed? v1
Authors: F Pinter Stefan
Published: September 2021

[RETRACTED]

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Conservative treatment of early hormone-dependent breast cancer in elderly patients (65 years and older)
Authors: Manikhas A. G. , Pasekova D. S.
Published: September 2021

Background.Standard treatment for hormone-dependent operable breast cancer includes surgery, hormone therapy (HT), and radiation therapy and chemotherapy (when necessary). Some elderly patients do not undergo surgery because of the high risk or refuse to be operated on. In such case, the only possible option is conservative treatment with hormones (± radiotherapy).

Objective:to compare progression-free survival, local relapse-free survival, and metastasis-free survival between elderly patients with hormone-dependent breast cancer receiving different treatments (surgery + HT vs HT alone).

Materials and methods.This study included 60 patients with stage I–II hormone-dependent breast cancer aged 65 years and older. Thirty patients in the experimental group received HT only, while 30 patients in the control group received surgery + adjuvant HT. All patients were treated at Saint Petersburg Clinical Oncology Dispensary. Patients were followed up for 3 years.

Results.During 3 years of the study, three women from the experimental group (10 %) were found to have local tumor growth despite treatment. Three patients in the control group (10 %) also had disease progression, but it was associated with the development of bone metastases.

Conclusion.The conservative approach to treatment of early hormone-dependent breast cancer in elderly patients is a possible option in routine clinical practice; however, it requires the analysis of indications and identification of patients who will benefit from this approach.
Telecuidado no serviço de atenção domiciliar para continuidade do cuidado na pandemia COVID-19: estudo descritivo
Authors: Auxiliadora Rodrigues Maria , Ferreira Santana Rosimere , Beatriz Serra Hercules Ana , Costa Bela Julianna , Nogueira Rodrigues Julianna
Published: September 2021

Objetivo: Identificar as intervenções de enfermagem realizadas por teleconsulta ao idoso e seu cuidador no Serviço de Atenção Domiciliar (SAD) na pandemia da COVID-19. Método: Estudo transversal das intervenções de enfermagem realizadas com 140 idosos e 106 cuidadores, no município de São Gonçalo-RJ. Para tanto, elaborou-se um instrumento semiestruturado fundamentado nos diagnósticos de enfermagem Síndrome do Idoso Frágil, Risco de contaminação e Tensão do papel do cuidador da Taxonomia da NANDA-I(12), intervenções e atividades de enfermagem NIC(13) e no Protocolo de Manejo Clínico do Coronavírus (COVID-19), na Atenção Primária à Saúde do Ministério da Saúde(14). Resultados: Em 66,4% dos casos houve mudança na rotina para se adequar ao cuidado do idoso, sem diferença significativa para os idosos com mais de 85 anos; 53,6% tiveram dificuldades em manter o isolamento social e 49,3%, em realizar cuidados de higiene.
TRA1 BÖLGESİ KONUT PİYASASINDA FİYAT OLUŞUMU BALON MU?
Authors: Çadırcı Bülent Diclehan , Güner Bilal
Published: September 2021

Bu çalışmada, Türkiye’de bölgesel sınıflandırmada Kuzeydoğu Anadolu Bölgesi olarak adlandırılan ve Erzurum, Erzincan ve Bayburt illerini kapsayan TRA1 bölgesi için 2013-2020 yılları arası aylık reel konut fiyat endeksi kullanılarak konut piyasasında fiyat balonunun oluşup oluşmadığı incelenmiştir. SADF ve GSADF sağ kuyruklu birim kök testlerinin kullanıldığı analiz sonucuna göre TRA1 bölgesi konut piyasasında çoklu fiyat balonları gözlemlenmiştir. Ayrıca her iki test bulgularına göre 2019 yılının ikinci yarısında başlayan balonun çalışma dönemi itibariyle devam ettiği sonucuna ulaşılmıştır.
Dynamics of building-soil interaction
Authors: Jennings Paul C. , Bielak Jacobo
Published: September 2021

abstract

In this study of the dynamics of building-soil interaction, the soil is modeled by a linear elastic half-space, and the building structure by an n-degree-of-freedom oscillator. Both earthquake response and steady-state response to sinusoidal excitation are examined. By assuming that the interaction system possesses n+2 significant resonant frequencies, the response of the system is reduced to the superposition of the responses of damped linear oscillators subjected to modified excitations. The results are valid even though the interaction systems do not possess classical normal modes. For the special cases of single-story systems and the first modes of n-story systems, simplified approximate formulas are developed for the modified natural frequency and damping ratio and for the modified excitation. Example calculations are carried out by the approximate and more exact analysis for one-story, two-story and ten-story interaction systems.

The results show that interaction tends to decrease all resonant frequencies, but that the effects are often significant only for the fundamental mode for many n-story structures and are more pronounced for rocking than for translation. If the fixed-base structure has damping, the effects of interaction on the earthquake responses are not always conservative, and an increase or decrease in the response can occur, depending on the parameters of the system.
Faulting process of the San Fernando earthquake of February 9, 1971 inferred from static and dynamic near-field displacements
Authors: Mikumo Takeshi
Published: September 2021

abstract

The faulting process of the San Fernando earthquake of February 9, 1971 has been investigated using the following seismic and geodetic data: vertical and horizontal displacements, strain and tilt changes, dynamic ground motions in the near-field, focal mechanism, spatial distribution of aftershocks and features of surface fault breaks. A synthetic study suggests that the earthquake was caused by thrust faulting with a slip of 233° to 244° over a fault plane with dimensions 19 by 14 km, dip 50° to 52° and strike N64° to 70°W, which ruptures the ground surface over a distance of about 12 km. The fracture initiating at the hypocenter of the main shock seems to have propagated radially over the fault plane with a velocity about 2.5 km/sec. A small dislocation less than 30 cm at initiation probably increased rapidly during propagation and reached 3.5 to 4 m at the ground surface.

A pronounced uplift and small subsidence of the ground north and south of the fault traces, and the overall pattern of the observed vertical and horizontal displacements can be explained well by the above model, but the recorded strain and tilt offsets are not always consistent with theoretical predictions. The wave forms and amplitudes for some of the integrated ground displacements from accelerograms at the Pacoima Dam and Pasadena are in fairly close agreement with those of the computed displacements. The seismic moment and stress drop of this earthquake were found to be 1.1 × 1026 dyne·cm and 40 to 65 bars, respectively.
The Qir, Iran earthquake of April 10, 1972
Authors: McEvilly Thomas V. , Razani Reza
Published: September 2021

abstract

The destructive earthquake, Ms = 7.1 (BRK), occurred at 0537 a.m. local time, near an agricultural center in the mountainous Zagros Range of the Fars Province in the south of Iran. Leveling virtually all structures in the epicentral region, the shock killed nearly 25 per cent of the population of about 23,000 people in the devastated villages within a radius of about 50 km from the epicenter. Hardest hit was the valley complex of Qir, Karzin, and Afzar. The high percentage of death was mainly caused by structural failure and the collapse of the heavy roof of almost all adobe and masonry residential structures in the area. Structural failure of buildings with modern steel-beam roofs and of the traditional adobe and masonry-walled buildings with heavy timbered roofs in the region was due primarily to the lateral shear failure of poorly constructed adobe and masonry, lack of earthquake-resistant vertical load-carrying columns or elements, and lack of bracing and adequate tie-in in the roofs. Engineered buildings also collapsed, generally, because of defects in engineering and construction practices. Only minor cases of ground failure were observed, mainly slides in steep mountainous regions and some collapse of steep banks of rivers and irrigation channels.
The Koyna earthquake and the damage to Koyna Dam
Authors: Chopra Anil K. , Chakrabarti P.
Published: September 2021

abstract

The Koyna earthquake (surface-wave magnitude 6.5) occurred on December 11, 1967 near Koyna Dam in a region of India which was considered to be stable and nearly nonseismic. The relationship between the recent increase in number of earthquake occurrences in the vicinity of Koyna Dam and the filling of the reservoir behind the dam is discussed. The response of the dam to the strong ground motion recorded during the Koyna earthquake is analyzed by the finite element method including dynamic effects of the reservoir. The cracking anticipated in the monoliths of Koyna Dam on the basis of stresses obtained from these analyses and strength of concrete in the dam is consistent with the earthquake damage. On the basis of analytical results, it would be useful to provide relatively higher strength concrete in selected parts of gravity dams; appropriate suggestions are made in this connection. Present design criteria need to be improved to recognize that significant tensile stresses occur in gravity dams during earthquakes and to provide for the consequences of these tensile stresses.
Regional Sn velocities and shear velocity in the upper mantle
Authors: Huestis Stephen , Molnar Peter , Oliver Jack
Published: September 2021

abstract

Determinations by various authors of the apparent velocity of the seismic shear wave Sn, which propagates in the uppermost mantle, are presented for several of the Earth's stable regions. Measurements of the velocity over two additional shield areas, India and Western Australia, were made and gave values of 4.72±0.03 km/sec and 4.75-4.87 km/sec, respectively. In general, the Sn velocity is greater than 4.7 km/sec. As the stable regions cover most of the Earth's surface and this velocity is representative of the shear velocity in the uppermost mantle, it is useful as a constraint in inversion of seismic data to determine upper-mantle structure.
Aftershocks and source characteristics of the 1969 Coyote Mountain earthquake, San Jacinto Fault zone, California
Authors: Thatcher Wayne , Hamilton Robert M.
Published: September 2021

abstract

The Coyote Mountain earthquake (ML = 5.8) occurred as an abrupt northwesterly extension of the aftershock zone of the ML = 6.4 Borrego Mountain event of a year earlier. Locations of 127 aftershocks in the Coyote Mountain area outline a zone of scattered activity about 10 km across, with most hypocenters clustered at depths between 10 and 13 km. Aftershock activity was unusually low for an earthquake of this magnitude. Nine of the larger aftershocks showed first-motion patterns consistent with right-lateral strike-slip movement on northwest-trending faults. The mainshock focal mechanism is similar, but with some dip-slip motion also indicated. Teleseismic P-wave spectrum measurements suggest a relatively small source dimension and large stress drop for the mainshock. The unusual characteristics of this sequence may have been the result of a de-stressing of the upper 10 km of this section of the San Jacinto Fault zone by two earlier events greater than magnitude 6 and a concentration of stresses below that depth in a small area at the northwest end of the Borrego Mountain zone.
Seismic moment and long-period radiation of underground nuclear explosions
Authors: Müller Gerhard
Published: September 2021

abstract

The moment function of an explosion is introduced, using the equivalence of an explosive point source and three mutually perpendicular linear dipoles. The seismic moment of an explosion is the final value, for large times, of the moment function. Its relation to source parameters is similar to that of the moment of an earthquake: M1 = (λ + 2μ)S1D1 (λ, μ = Lamé's parameters, S1 = surface area of a sphere surrounding the explosion in the elastic zone, D1 = static radial displacement on this sphere). From strain observations of other authors (Romig et al., 1969; Smith et al., 1969), the moment of the underground nuclear explosion BENHAM is estimated to be about 1024 dyne cm. This moment value supports the assumption that the source-time function for the long-period radiation from large nuclear explosions (periods greater than about 10 sec) is essentially a step-function. On the other hand, a quantitative estimate of the long-period P-wave spectrum of the explosions JORUM, HANDLEY and MILROW and a comparison with observed spectra of Molnar (1971) for JORUM and HANDLEY and Wyss et al. (1971) for MILROW support the assumption of an impulsive source-time function. This discrepancy, which is typical of current opinions among seismologists, is not resolved. It is concluded that an explosive point source is possibly not a sufficient model for the long-time radiation and the static displacement field of a nuclear underground explosion whose elastic radius is about equal to its depth and which is detonated in a prestressed medium.
Contributions to love-wave transformation theory: Earth-flattening transformation for love waves from a point source in a sphere
Authors: Kausel Edgar , Schwab Fred
Published: September 2021

abstract

By means of the Biswas-Knopoff (1970) transformation, programs for the computation of the Love-wave response to a point source in a flat structure can be modified, quite easily, to compute the response in a sphere.
Surface- and body-wave spectra of CANNIKIN and shallow Aleutian earthquakes
Authors: Hasegawa H. S.
Published: September 2021

abstract

Rayleigh waves and P codas of CANNIKIN and shallow Aleutian earthquakes are studied in order to determine the parameters most influential in shaping the respective teleseismic amplitude spectra and in governing the surface (MS) and bodywave (mb) magnitudes. For surface-wave generation, the dipole strength (Po) of the underground nuclear explosion, and the seismic moment (Mo) of the earthquake are the important parameters. The MS for these events are comparable when Mo is approximately 3 to 4 times greater than Po. Theoretical considerations of bodywave spectra indicate that the important parameters are the permanent offset in the reduced displacement potential [ψ(∞)] of explosions and the product of area of faulting (S) and average dislocation (D̄) of earthquakes. These source parameters are related by Po = 4π(λ + 2μ) ψ(∞) and Mo = μ SD̄ where λ and μ are the elastic Lamé parameters. An additional parameter, namely, the peak frequency (fp) in the explosion P-coda spectrum and the corner frequency (fc) in the earthquake spectrum, is of paramount importance in determining the respective mb. For the events considered, fp is from 5 to 10 times greater than fc and this is manifest in the corresponding mb, where the mb for CANNIKIN is at least a unit greater than that of the earthquakes. The linear dimensions of the respective sources appear to exert a major influence upon fc and fp.

The large scatter between theoretical and actual mb values, unfortunately, precludes a firm confirmation of the above theoretical considerations.
A method for relocating seismic events using surface waves
Authors: Crough S. T. , Van der Voo R.
Published: September 2021

abstract

Seismic events can be relocated relative to a reference event by using the group-velocity dispersion curves of surface waves. Since group velocity is a function of the travel path, surface waves from two events in the same locale should show identical group velocities when viewed at any one seismograph station. A computer technique has been developed for comparing the group-velocity curves of any event with the curves of a reference event and for determining the relocation which causes the curves to best coincide. The method is evaluated by relocating eight intermediate-size nuclear explosions of the Nevada Test Site series. With precise curve fitting, the surface-wave locations are slightly more accurate in southern Nevada than the standard body-wave determinations. The surface-wave origin times are considerably more accurate. In areas of sparse station coverage or of many small earthquakes, the surface-wave method can be expected to improve seismic locations significantly.
Scattering approximations for thick and thin scatterers
Authors: Kennett B. L. N.
Published: September 2021

abstract

Two methods for handling seismic scattering problems have been developed in the last few years: one applies to interfacial irregularities or obstacles on interfaces, the other to larger scatterers. This paper examines some properties of these two methods and the relation between them.
Teleseismic p-wave transmission through slabs
Authors: Sleep Norman H.
Published: September 2021

abstract

Theoretical ray paths through velocity models constructed from numerically calculated thermal models of slabs were computed. The results were in good agreement with observed travel times. First motion amplitudes of P waves at teleseismic distances were measured from long- and short-period WWSSN records of intermediate focus earthquakes in the Tonga, Kermadec, and Kurile regions and of nuclear explosions and shallow earthquakes in the Aleutian region. These amplitudes were corrected for source mechanism. The Aleutian data were sufficient to show that intermediate focus earthquakes in that region occur in the colder regions of the slab. At short periods, for regions other than the Aleutians, shadowing effects which could be associated with the slab were not very marked, less than a factor of 2 reduction for epicentral distances between 30° and 50°. No systematic effects due to plates were found in the long-period data. Some stations in the predicted shadow zone of a Tonga earthquake recorded low amplitude precursors which probably were greatly defocused waves which ran the full length of the slab. Simple diffraction is incapable of explaining the short-period results.
Seismicity in the Rangely, Colorado, area: 1962-1970
Authors: Gibbs James F. , Healy John H. , Raleigh C. Barry , Coakley John
Published: September 2021

abstract

Seismic data recorded for a 7-year period at the Uinta Basin Observatory were searched for earthquakes originating near an oil field at Rangely, Colorado, 65 km ESE of the observatory. Changes in the number of earthquakes recorded per year appear to correlate with changes in the quantity of fluid injected per year. Between November 1962 and January 1970, 976 earthquakes were detected near the oil field by the UBO station; 320 earthquakes were larger than magnitude 1.

Richter local magnitudes are estimated from both S-wave and P-wave measurements; a method based on the duration of the seismic signal is used to estimate the magnitude of the larger shocks. Magnitude of the two largest shocks was 3.4 and 3.3. The total seismic energy released was 1017 ergs. During this same period, the energy used for water injection, measured at the wellhead, was 1021 ergs.
SH pulse in an elastic wedge
Authors: Abo-Zena A. M. , King Chi-Yu
Published: September 2021

abstract

This paper gives an analysis of the response of an elastic wedge of arbitrary angle to an impulsive SH source applied on the wedge surface along a line parallel to the edge of the wedge. A two-dimensional time-dependent Green's function for SH waves is constructed from an integral-transform approach. The result is given in a closed form for the incident and the reflected pulses and in an integral form for the diffracted pulse from the edge. For the special case that the wedge angle is an integral fraction of π, the result is interpretable in terms of a finite set of image sources with no diffraction effect. Numerical examples are given for illustration.
Interpretation of strain steps accompanying two New Zealand earthquakes
Authors: Gerard V. B.
Published: September 2021

abstract

Clearly recorded strain steps from three New Zealand earth strain stations for two earthquakes are interpreted by means of Press' strain-field maps. The agreement between calculated and observed steps is excellent when some of the fault parameters are deduced from the earthquake magnitude and used to restrict the possible solutions.
Surface-wave propagation under initial tension or compression
Authors: Brunelle E. J.
Published: September 2021

The propagation of Rayleigh waves in a half-space and the propagation of Love waves in a welded layer and half-space are examined when initial tensile or compressive stresses are present. Using the perturbed and linearized equations of elasticity, which include the effects of initial stress, a modified Rayleigh equation and a modified Love equation are obtained. The solution of the equations shows a dramatic change in the phase speeds of the two wave types under initial tension or compression. Numerical results are presented.
S-wave attenuation in the crust in northern Greece
Authors: Hatzidimitriou P. M.
Published: September 2021

The attenuation of shear waves in the crust is estimated, for frequencies between 1.5 and 12.0 Hz, by applying a single-station method based on the rate of decay of the S-wave to coda-wave amplitude ratio with distance. The data used come from local earthquakes that occurred in the Thessaloniki area, northern Greece, during the period 1983 through 1989 and were recorded by the telemetered network of the Geophysical Laboratory of the University of Thessaloniki. The Qs values obtained are 115, 244, 477, and 755 for 1.5, 3.0, 6.0, and 12.0 Hz, respectively. These values are very close to the coda Q values estimated for the same area using the S-to-S single scattering model for lapse times between 30 and 100 sec but they are higher than the coda Q values for lapse times between 10 and 30 sec. The estimated Qs is found to be strongly frequency dependent, proportional to f0.91, which is very close to the frequency dependence of the coda Q.
Sediment-induced amplification in the Northeastern United States: A case study in Providence, Rhode Island
Authors: Fischer Karen M. , Salvati Lynn A. , Hough Susan E. , Gonzalez Edward , Nelsen Chad E. , Roth Erich G.
Published: September 2021

We employed ambient-noise measurements to assess the potential for seismic site response in sediment-filled valleys that intersect beneath downtown Providence, Rhode Island. At eight valley stations and at two sites on an adjacent bedrock highland, we recorded ground motion from two types of sources: pile drivers at a local construction site and ambient microtremors. At all valley sites where sediment thicknesses exceed 10 m, spectral ratios contain amplitude peaks at frequencies of 1.5 to 3.0 Hz. In contrast, spectral ratios from the two sites on the bedrock highland where sediment cover is less than 4-m thick are relatively flat within this frequency range. A variety of borehole logs identified two fundamental sediment types (soft sediment and a consolidated glacial till) and were used to map layer thicknesses over the entire study region. Refraction data constrained P-wave velocity in the bedrock to be 3680 ± 160 m/sec and indicated two soft-sediment layers with P-wave velocities of 300 ± 50 and 1580 ± 120 m/sec. Using a one-dimensional reflection matrix technique, we matched the spectral-ratio peak observed at each valley site with the frequency of fundamental resonance predicted for local layer thicknesses and velocities. A positive correlation between the best-fitting soft-sediment velocities and bedrock depth may reflect greater compaction in the deepest sediments or a locally two-dimensional sediment resonance at the deepest sediment sites. We conclude that unconsolidated sediment layers under downtown Providence have the potential to amplify earthquake ground motion at frequencies damaging to engineered structures.
Scaling relations for strong ground motion prediction models with M2 terms
Authors: Fukushima Yoshimitsu
Published: September 2021

In most previous studies on the attenuation relation of strong ground motion, the increase in amplitude with earthquake magnitude was expressed by a linear relation. However, if the ω−2 source model is assumed, the corner period of the spectrum varies with the magnitude, and the scaling law of the source spectrum amplitude becomes a complicated function of magnitude. The scaling relation of the spectrum amplitude with MW can be simply approximated as a quadratic function, and the coefficient of the MW2 term should be negative. On the contrary, positive coefficients of the ML2, mbLg2, and MJ2 (MJ: magnitude of Japan Meteorological Agency) terms have been derived by regression analyses of strong ground motions.

Based on the ω−2 model, semi-empirical relations between Mo and the magnitudes were derived. Further, the seismological scaling law of the source spectrum obtained from the relation between Mo and the magnitudes was approximated as a quadratic function of the magnitude, and positive coefficients of the squared magnitude terms were obtained. These results stem from the definitions of magnitude derived from amplitudes of seismograms around a specific period of 1.0 sec for ML and mbLg and of 5.0 sec for MJ.
P-wave backazimuth anomalies observed by a small-aperture seismic array at Pinyon Flat, southern California: Implications for structure and source location
Authors: Lin Cheng-Horng , Roecker S. W.
Published: September 2021

Seismograms of earthquakes and explosions recorded at local, regional, and teleseismic distances by a small-aperture, dense seismic array located on Pinyon Flat, in southern California, reveal large (±15°) backazimuth anomalies. We investigate the causes and implications of these anomalies by first comparing the effectiveness of estimating backazimuth with an array using three different techniques: the broadband frequency-wavenumber (BBFK) technique, the polarization technique, and the beamforming technique. While each technique provided nearly the same direction as a most likely estimate, the beamforming estimate was associated with the smallest uncertainties. Backazimuth anomalies were then calculated for the entire data set by comparing the results from beamforming with backazimuths derived from earthquake locations reported by the Anza and Caltech seismic networks and the Preliminary Determination of Epicenters (PDE) Bulletin. These backazimuth anomalies have a simple sinelike dependence on azimuth, with the largest anomalies observed from the southeast and northwest directions. Such a trend may be explained as the effect of one or more interfaces dipping to the northeast beneath the array. A best-fit model of a single interface has a dip and strike of 20° and 315°, respectively, and a velocity contrast of 0.82 km/sec. Application of corrections computed from this simple model to ray directions significantly improves locations at all distances and directions, suggesting that this is an upper crustal feature. We confirm that knowledge of local structure can be very important for earthquake location by an array but also show that corrections computed from simple models may not only be adequate but superior to those determined by raytracing through smoothed laterally varying models.
Rupture directivity and slip distribution of theM4.3 foreshock to the 1992 Joshua Tree earthquake, Southern California
Authors: Mori Jim
Published: September 2021

Details of the M 4.3 foreshock to the Joshua Tree earthquake were studied using P waves recorded on the Southern California Seismic Network and the Anza network. Deconvolution, using an M 2.4 event as an empirical Green's function, corrected for complicated path and site effects in the seismograms and produced simple far-field displacement pulses that were inverted for a slip distribution. Both possible fault planes, north-south and east-west, for the focal mechanism were tested by a least-squares inversion procedure with a range of rupture velocities. The results showed that the foreshock ruptured the north-south plane, similar to the mainshock. The foreshock initiated a few hundred meters south of the mainshock and ruptured to the north, toward the mainshock hypocenter. The mainshock (M 6.1) initiated near the northern edge of the foreshock rupture 2 hr later. The foreshock had a high stress drop (320 to 800 bars) and broke a small portion of the fault adjacent to the mainshock but was not able to immediately initiate the mainshock rupture.
Comparison of magnitudes estimated by the Japan Meteorological Agency with moment magnitudes for intermediate and deep earthquakes
Authors: Katsumata Akio
Published: September 2021

The magnitude, MJMA, estimated by the Japan Meteorological Agency (JMA) is generally referred to in Japan for the regional seismicity in the area. MJMA is determined from maximum displacement amplitudes of the total seismic wave traces. For earthquakes shallower than 60 km, MJMA is determined by Tsuboi's formula, and for earthquakes deeper than 60 km, by Katsumata's formula. These relations were designed to give almost the same magnitude value as that of Gutenberg and Richter. We compared MJMA with moment magnitude, MW, which can be calculated from the centroid moment tensor (CMT) solutions. It was found that the average difference between MJMA and MW is not significant for shallow earthquakes in the magnitude range from 5 to 7, but it is significant at a low level for the earthquakes of deeper foci. The averaged difference reaches about 0.4 magnitude units for the focal depth of 600 km. We derived an attenuation function for the maximum displacement amplitude assuming the validity of the moment magnitude. This relation between epicentral distance and amplitude for shallow earthquakes is almost identical to the one calculated from Tsuboi's formula. It is suggested that the estimated attenuation function for deep-focus earthquakes reflects the specific Q and velocity structure that is peculiar to the subduction zone.
Shear-wave velocity of the sedimentary basin in the upper Mississippi embayment usingS-to-Pconverted waves
Authors: Chen Kou-Cheng , Chiu Jer-Ming , Yang Yung-Tun
Published: September 2021

From mid-October 1989 to August 1992, 40 three-component PANDA (Portable Array for Numerical Data Acquisition) stations were deployed in the central New Madrid seismic zone. Three-component digital seismograms recorded by the PANDA stations in the region are characterized by (1) the very weak direct S arrivals on the vertical component, which can be identified unambiguously from the two horizontal components, and (2) at least two prominent secondary arrivals between the direct P and S arrivals, one (Sp) dominant on the vertical component and another (Ps) with smaller amplitude on the two horizontal components. Travel-time differences between the Sp and S and between the P and Ps are the same for different earthquakes recorded at the same station but are different at different stations even for the same event. Polarization analyses of three-component seismograms and travel-time measurements confirm the interpretation that these two secondary arrivals are the P-to-S (Ps) and S-to-P (Sp) converted waves that occur at the bottom of the sedimentary basin beneath each station. Since abundant well-log data are available in the upper Mississippi embayment, the thickness of the sediments beneath each seismic station can be estimated. Travel-time differences between the direct and the converted waves can be used to calculate average shear-wave velocity for the sediments beneath each station. The estimated shear-wave velocities of the sediments beneath PANDA stations vary from 0.45 to 0.67 km/sec. The higher shear-wave velocity associated with thicker sediments can be interpreted as a consequence of increasing compaction of unconsolidated sediments due to increasing overburden.