1,720,994 research outputs found
Active interplay between strike-slip and extensional structures in a back-arc environment, Bay of Plenty, New Zealand
No full text(paper presented at American Geophysical Union - Fall Meeting, San Francisco, 8-12 Dec 2003
Normal fault growth and linkage in the Whakatane Graben, New Zealand, during the last 1.3 million years (abstract of paper presented at AGU Fall Meeting, San Francisco, 8-12 Dec 2003)
No full textConstraining fault growth rates and fault evolution in New Zealand
No full textUnderstanding how faults propagate, grow and interact in fault systems is important because they are primarily responsible for the distribution of strain in the upper crust. They localise deformation and stress release, often producing surface displacements that control sedimentation and fluid flow either by acting as conduits or barriers. Identifying fault spatial distribution, quantifying activity, evaluating linkage mechanism, and estimating fault growth rates are key components in seismic risk evaluation.
Scientists from the National Institute of Water and Atmospheric Research (NIWA), New Zealand, and the Southampton Oceanography Centre (UK) are working on a collaborative project which aims to improve understanding of the processes of faulting in the Earth’s crust. The program comprises two research cruises to survey the Whakatane Graben, New Zealand, which is a zone of intense seismicity, active extensional faulting, and rapid subsidence within the back-arc region of the Pacific-Australia plate boundary zone (Fig. 1). Few places in the world offer the same potential to study the mechanisms by which major crustal faults have grown from small to large scale structures capable of generating moderate to large magnitude earthquakes. The aim of the project it to provide new insights into fundamental questions such as: (i) how do faults interact and link together to form fault systems, and (ii) how do fault propagation and linkage change with time? One of the most exciting results from the work in the Whakatane Graben is the potential for improving understanding of how and at what rates faults grow.
The first survey was funded by the New Zealand Foundation for Research Science and Technology (FRST), and took place in November 1999 during which conventional marine geophysical data were collected. The second cruise is funded by the British Natural Environment Research Council (NERC), and is scheduled for January 2001. It will focus on the acquisition of high frequency shallow seismic and sidescan sonar data
. This study of the Whakatane Graben will represent the most detailed regional investigation of active marine faults undertaken anywhere in the New Zealand region. Arguably, it could also become a case study of extensional fault growth and continental rift development of global significance.<br/
Faulting and Extension Rate over the last 20,000 Years in the Offshore Whakatane Graben, New Zealand Continental Shelf.
No full textOblique rifting in the offshore Taupo Volcanic Zone, New Zealand, is expressed in widely distributed active normal faulting in the 20 km-wide Whakatane Graben. Active faults are identified along seafloor scarps and displacements of the post-last glacial transgressive ravinement surface (<20ka), using a network of seismic reflection data and multibeam bathymetry. The rifting involves basement blocks back-tilted by 12-16°, controlled by large NW-dipping faults with intersecting antithetic faults within the 3 km-thick sedimentary sequence. Faults along the graben border parallel the rift axis, while those in the centre are moderately oblique to it. We present a novel method to estimate the age of a post-glacial surface (7.5 to 20.5 ka), with consideration to spatially varying subsidence and uplift, and measure fault throw across >400 faults. We derive an extension rate at seismogenic depths (6-10 km) across the graben of 13 ± 6 mm/yr, by summing surface measurements, assuming an average crustal fault dip of 45±15º, and correcting for the discrepancies between surface and deep crustal extension estimates. Structural and kinematic data implies an extension direction 20º oblique to the rift axis, resulting in up to 4.6 ± 2.1 mm/yr of dextral motion parallel to the rift axis. The strike-slip motion is accommodated by dip-slip displacements on oblique faults in the centre of the graben, and oblique-slip faulting along the rift margins. Pure dip-slip in the graben centre represents >50% of the total slip, with the Rangitaiki Fault accommodating 25% of the total extension in the graben
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
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