1,721,285 research outputs found
The Sub-Himalayan fold-thrust belt in the 1905-Kangra earthquake zone: A critical taper model perspective for Seismic Hazard Assessment
No full textWe investigate the broader epicentral area of the M=7.8, 1905 Kangra earthquake(s), North India, affecting the Sub-Himalayan hills. The tectonics of the area is characterised by two major rentrants (Kangra and Dehradun) interposed by the Nahan Salient. The first order topography between the Himalayan Frontal Thrust and the Main Boundary Thrust shows a marked lateral variation along strike of the mean gradient, characterised by a very small mean slope angle (ca. 1°) in correspondence with the reentrants and higher values (ca. 3°) in the salient. These tectonic and topographic features also show a good correspondence with the peculiar macroseismic field of the 1905 event(s), which is characterised by two distinct intensity maxima, separated by a distance of about 150 km, clearly overlapping the two major tectonic reentrants. In this paper, based on available geological and geophysical information and a critical analysis of the general mechanical constraints, the seismogenic volume of the external sector of the chain is investigated in terms of critical taper model attempting to clarify the possible correlations between tectonics, topography and seismicity in the Sub-Himalayan belt. Based on different assumptions three possible seismotectonic scenarios are explored in order to constrain their likelihood and therefore suggest a potential seismic gap in the area corresponding to the Nahan Salient, which may experience in the future an event of significant magnitude
Relief distribution versus seismicity along the Sub-Himalayan belt, NW India: inferences for the seismic hazard of the region.
No full textThe frontal Himalayan region, India, represents a classical example of relief developed in a compressional tectonic setting. The major relief development processes are mainly related to dip-slip reverse faulting along major thrusts and the consequent uplift of the hanging-wall block(s). The southernmost of these major fault planes, i.e. the Himalayan Frontal Thrust (HFT), also marks the tectonic and topographic boundary between the Himalayan orogen and the Indo-Gangetic alluvial plain representing its foredeep basin. The hanging-wall block of the HFT comprises the so-called Sub-Himalayan mountain belt characterized by low-relief hills variably dissected by the ongoing erosion. This major tectonic unit is in turn delimited to the north by the Main Boundary Thrust (MBT). The relatively young age of the Sub-Himalayan hills provides an opportunity to investigate the thrust-related evolution of the relief, especially in the early stages of nucleation and propagation of a thrust as well as the relationships between large-scale topography and local seismicity. The new data presented in this paper mainly pertains to the first order topography of the uplifted hanging-wall block of the HFT. These data reveal a marked lateral variation along the strike of the Sub-Himalayan belt, in terms of both topographic features and mean topographic gradient. The main controlling factor seems to be the distance between the two major bounding thrust faults, i.e. the MBT and the HFT. In areas where thise distance is larger, the mean topographic gradient is generally lower, whereas it increases with decreasing distance between the two major thrusts. The relief distribution and associated topographic features characterizing the northwestern sector of the Sub-Himalayan belt also show a good correspondence with the peculiar macroseismic field of the M=8.4, 1905 Kangra earthquake, where the two distinct intensity maxima, separated by a distance of about 100 km, clearly overlap the two major tectonic reentrants. Also more recent instrumental records seems to support this relationships
Thrust related relief development and seismicity of the Indian Sub-Himalaya: a critical taper model perspective
No full textThe frontal Himalayan region, India, represents a classical example of relief evolved and evolving within a compressional
tectonic setting. Relief-creation processes are mainly induced by dip-slip reverse faulting along major
low-angle thrusts and the consequent uplift of the hanging-wall block(s). The most external of these major fault
planes, i.e. the Himalayan Frontal Thrust (HFT), also marks the tectonic and topographic boundary between the
Himalayan orogen and the Indo-Gangetic alluvial plain representing its foredeep basin. The hanging-wall block
of the HFT consists of clastic deposits belonging to the Siwalik Group and geographically coincides with the socalled
Sub-Himalayan mountain belt characterized by low-relief hills variably dissected by the ongoing erosion.
This major tectonic unit is in turn delimited to the north by the Main Boundary Thrust (MBT). The relatively
young age of the Sub-Himalayan hills provides an opportunity to investigate the thrust-related evolution of the
relief, especially in the early stages of nucleation and propagation of a thrust as well as the relationships between
large-scale topography and local seismicity. The new data presented in this paper mainly pertains to the first order
topography of the uplifted hanging-wall block of the HFT. They reveal a marked lateral variation along the strike
of the Sub-Himalayan belt, in terms of both topographic features and mean topographic gradient. Two major settings
are recognised; the one characterised by a very small mean slope angle (ca. 1), the other by typically higher
values (ca. 3). Transitions between the two topographies are relatively sharp that allows to distinguish different
sectors within the Sub-Himalayan belt roughly reflecting the occurrence of the well-known Kangra and Dehradun
reentrants and Nahan salients. Both relief distribution and associated topographic features also show a good correspondence
with the peculiar macroseismic field of the M=7.8, 1905 Kangra earthquake, which is characterised by
two distinct intensity maxima, separated by a distance of about 100 km, clearly overlapping the two major tectonic
reentrants. A similar dichotomy is observed in the distribution of the recent instrumental seismicity. Moreover,
based on available geological information and constraints, we analyse the area in terms of critical taper model attempting
to clarify the possible correlations between tectonics, morphology and seismicity in the Sub-Himalayan
belt. The analysis allows constraining possible seismotectonic scenarios and hence suggesting the existence of a
seismic gap in the area corresponding to the Nahan Salient, which may experience an event possibly of significant
magnitude
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
Role of Internal Thrusts in NW Sub-Himalaya, India, for SHA
No full textContinuous convergence of the Indian and Eurasian plates along the Himalayan arc is manifested as uplifted topography, short and long term shortening rates and inter-seismic strain. The proportion in which each of the above said elements contributes is, however, different along different sectors of the Himalaya. For example, the bulk shortening along the central part of the Himalaya is mainly accommodated along the Himalayan Frontal Thrust (HFT) (Wesnousky et al., 1999; Lave and Avouac, 2000). Accordingly, it has been hypothesized that the tectonic wedge of the Sub-Himalaya represents an expanding mountain front, in the central part. The present study is aimed at testing this hypothesis in the NW Himalaya of India by integrating field observations and results of geomorphic investigations
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
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
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