1,720,961 research outputs found
Along and across strike variations in the structure, material and fault properties of the Sumatran Subduction Zone
No full textEarthquake ruptures offshore of north-central Sumatra in 2004 (Sumatra-Andaman segment) and 2005 (Nias segment) exhibited variable shallow slip behaviour that is well resolved by tsunami, seismologic, and geodetic observations. Closely spaced 2D MCS profiles collected covering these rupture segments, the segment to the south (Mentawai segment), and the segment boundaries allow an unprecedented opportunity to study the detailed along- and across-strike variation in the structure and properties of the wedge and plate boundary that may be related to the variable shallow slip behaviour. The large tsunami generated by the 2004 earthquake is thought to have been the result of unexpected shallow slip on the shallow plate boundary of the southern Sumatra-Andaman segment; whereas in the Nias segment the shallow plate boundary showed evidence of significant afterslip and the 2005 earthquake did not generate a significant tsunami. In the northern Mentawai segment, Batu Segment Boundary Zone, and southern Nias segment the shallow plate boundary is relatively weak and the weakened plate boundary is likely related to dehydration reaction occurring below the frontal prism and potential fluid flow focussing on basement topographic highs. In these areas, imbricate faulting in the frontal prism occurs along landward and/or seaward dipping faults. At the mid-slope break, the slip rate along these imbricate faults, formed in the frontal prism, decreases and they are potentially crosscut by out-of-sequence faults. In the southern Sumatra-Andaman segment, our findings of a relatively strong plate boundary fault are consistent with increased compaction and early dehydration of material within the thick incoming section which strengthens the incoming section and results in a potentially seismogenic shallow plate boundary. The accretionary prism here is characterised by an unusual prism profile with a narrow steep toe and broad flat plateau. We propose that the steep prism toe is built up by coeval faulting on both seaward and landward dipping faults. At the break in slope, underplating becomes the dominant prism and the transition from frontal accretion to underplating contributes to the development of the unusual prism geometry. Within our study area, we find that there is significant variability in the frictional strength of the shallow plate boundary and mechanisms of accretion, which can be correlated with the geometry and faulting within the prism. We show that these changes are related to a combination of subducting plate topography, trench sedimentation rates, overall sediment thickness and sediment/fault permeability
Downgoing plate topography stopped rupture in the A.D. 2005 Sumatra earthquake
No full textEarthquakes in subduction zones rupture the plate boundary fault in discrete segments. One factor that may control this segmentation is topography on the downgoing plate, although it is controversial whether this is by weakening or strengthening of the fault. We use multichannel seismic and gravity data to map the top of the downgoing oceanic crust offshore central Sumatra, Indonesia. Our survey spans a complex segment boundary zone between the southern termination of the Mw = 8.7, A.D. 2005 Simeulue-Nias earthquake, and the northern termination of a major 1797 earthquake that was partly filled by an Mw = 7.7 event in 1935. We identify an isolated 3 km basement high at the northern edge of this zone, close to the 2005 slip termination. The high probably originated at the Wharton fossil ridge, and is almost aseismic in both local and global data sets, suggesting that while the region around it may be weakened by fracturing and fluids, the basement high locally strengthens the plate boundary, stopping rupture propagation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Controls on spatial and temporal evolution of prism faulting and relationships to plate boundary slip offshore north-central Sumatra
No full textAcross- and along-strike variations in the morphology and structure of the north-central Sumatran forearc (~1.5°S to 1°N) are broadly coincident with subducting plate topography and an earthquake segment boundary zone below the Batu Islands. We present a detailed interpretation of multichannel streamer seismic reflection data collected offshore north-central Sumatra, to better characterize the morphological and structural variations, provide insight into fault development, and relate structure to plate boundary rupture and seismicity patterns. We interpret two relatively continuous, major fault structures that divide the prism into three strike-parallel belts that can be characterized by the relative fault slip rates along major and minor fault structures. The midslope break fault(s) and upper slope-bounding fault(s) are major, potentially out-of-sequence thrusts accommodating a significant component of the compressional strain. We propose that the upper slope-bounding fault represents the more mature end-member of an evolving fault system. Landward vergent structures are associated with a relatively thin sedimentary section near the deformation front in the center of our study area and suggest a potentially weak shallow plate boundary associated with the subducting Wharton Fossil Ridge
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