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Investigating the Seismic Gap in North Carolina: A Seismic Survey of the Deep River Basin in Central North Carolina
Get PDFThe Deep River Basin is one of a series of Triassic rift basins along the east coast of the
United States that make up the Newark Supergroup (Olsen et al. 1989). The supergroup of
basins formed from preliminary extension during the breakup of Pangaea before the Atlantic
Ocean began to spread (Olsen et al. 1989). The Deep River Basin consists of three sub-basins,
the Wadesboro sub-basin, the Sanford sub-basin, and the Durham sub-basin (Olsen et al. 1989).
A bed of shale and coal known as the Cumnock formation surfaces along the northern margin of
the Sanford sub-basin (Olsen et al. 1991). In the past, this has been exploited by coal mining
operations. More recently, however, it has been the focus of local gas companies. Recent
legislation suggests that hydraulic fracturing operations may occur in the Sanford sub-basin in
the near future. While hydraulic fracturing itself does not cause seismicity large enough to be
recorded by the type of data analyzed here, the reinjection of wastewater into basement rocks has
been linked to more significant seismicity in certain areas. Although it is unknown whether or
not hydraulic fracturing or the associated reinjection of wastewater will occur in the Sanford sub-basin,
a baseline of natural seismicity can be recorded before operations to be used for any
comparative studies of seismicity.Bachelor of Scienc
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Variability in Slab Structure and Behavior Within and Among the South American and Eastern Mediterranean Subduction Systems
No full textAs subduction science advances, it is becoming increasingly clear that the conventional model of subduction driven by cold, strong, dense slabs sinking cohesively in the mantle is insufficient to explain observed heterogeneities across a range of scales. The breadth of observed features of subduction zones is expanding at the same time as along strike variability is revealed within individual subduction systems. Not surprisingly, the driving components of subduction zones, and by extension this variability, are the subducting slabs. Thus, in order to revisit the traditional model of subduction, this dissertation uses seismic imaging techniques in four distinct studies to characterize the structure and behavior of the subducting slabs across two extensive subduction systems: South America and the Eastern Mediterranean. These two systems serve as the ideal test cases for characterizing variability within and across subduction zones because they represent end-member styles of subduction: Andean-type subduction and Mediterranean-type subduction, respectively.
The first study presents the results of a regional-scale teleseismic tomography inversion surrounding the Sierras Pampeanas of Argentina. This study targets the observable response of the slab-mantle interaction to subduction of the hot spot-generated Juan Fernández Ridge, identifying entrainment of hot subslab asthenosphere and induced tearing of the subducting Nazca slab. Through this study I also present a model for explaining the infrequent distribution of subslab slow seismic velocity anomalies in subduction systems globally. The second study presents the results of a continental-scale teleseismic tomography inversion across the Anatolian sub-continent in the Eastern Mediterranean. This study targets the response of the slab to the major tectonic transition seen in central Anatolia from ocean subduction in the west to continental collision in the east. The resulting seismic images show an increasingly deforming slab from west to east that illustrates the evolutionary process of subduction termination. The third study presents new software developed to automatically extract slab geometry from teleseismic tomography models. The efficacy of the software is presented through applications to the Juan de Fuca/Gorda and Nazca slabs, signifying its broad utility in interpreting tomographic images. The fourth study utilizes this new software along with a continental-scale teleseismic tomography model across South America to present a detailed model of Nazca slab geometry from the surface into the lower mantle. The results of this study reveal that the slab penetrates the 660 km discontinuity uninhibited while instead interacting with a lower mantle discontinuity. This result has far reaching implications for geodynamic models of South American evolution.
Together, these studies reveal a broad consistency across subduction zones – that slabs do not remain cohesive during their descent in the mantle. Instead, the presence of heterogeneities in the downgoing plate induces slab tearing and possibly fragmenting within the upper mantle. Despite the relative complexity of the multi-plate Eastern Mediterranean system compared to the two-plate South American system, both systems display significant variability along the margins, including regions with varying degrees of slab tearing. This observation directly contradicts the traditional view of cohesive, strong slabs sinking in the mantle, which has related implications for the role of subducting slabs in mantle convection and material recycling over geological timescales
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Mantle dynamics of the Andean Subduction Zone from continent-scale teleseismic S-wave tomography
Get PDFThe Andean Subduction Zone is one of the longest continuous subduction zones on Earth. The relative simplicity of the two-plate system has makes it an ideal natural laboratory to study the dynamics in subduction zones. We measure teleseismic S and SKS traveltime residuals at >1000 seismic stations that have been deployed across South America over the last 30 yr to produce a finite-frequency teleseismic S-wave tomography model of the mantle beneath the Andean Subduction Zone related to the Nazca Plate, spanning from ~5°N to 45°S and from depths of ~130 to 1200 km. Within our model, the subducted Nazca slab is imaged as a fast velocity seismic anomaly. The geometry and amplitude of the Nazca slab anomaly varies along the margin while the slab anomaly continues into the lower mantle along the entirety of the subduction margin. Beneath northern Brazil, the Nazca slab appears to stagnate at ~1000 km depth and extend eastward subhorizontally for >2000 km. South of 25°S the slab anomaly in the lower mantle extends offshore of eastern Argentina, hence we do not image if a similar stagnation occurs. We image several distinct features surrounding the slab including two vertically oriented slow seismic velocity anomalies: one beneath the Peruvian flat slab and the other beneath the Paraná Basin of Brazil. The presence of the latter anomaly directly adjacent to the stagnant Nazca slab suggests that the plume, known as the Paraná Plume, may be a focused upwelling formed in response to slab stagnation in the lower mantle. Additionally, we image a high amplitude fast seismic velocity anomaly beneath the Chile trench at the latitude of the Sierras Pampeanas which extends from ~400 to ~1000 km depth. This anomaly may be the remnants of an older, detached slab, however its relationship with the Nazca-South America subduction zone remains enigmatic.Fil: Rodríguez, Emily E.. University of Arizona; Estados UnidosFil: Portner, Daniel Evan. No especifíca;Fil: Beck, Susan L.. University of Arizona; Estados UnidosFil: Rocha, Marcelo P.. Universidade do Brasília; BrasilFil: Bianchi, Marcelo B.. Universidade de Sao Paulo; BrasilFil: Assumpção, Marcelo. Universidade de Sao Paulo; BrasilFil: Ruiz, Mario. Escuela Politécnica Nacional; EcuadorFil: Alvarado, Patricia Monica. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Condori, Cristobal. Universidade do Brasília; BrasilFil: Lynner, Colton. University Of Delaware; Estados Unido
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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