1,720,974 research outputs found
Vertical displacement time series from GNSS stations in the Po river basin area
No full textASCII files reporting the daily GNSS vertical ground displacement time series, in the Eurasia-fixed reference frame, from January 2010 to September 2022 of continuous stations located in the Po river basin. The time series are obtained by analyzing the raw GPS observations using the GAMIT/GLOBK (version 10.71) software, following the standard procedures of the repro2 IGS reprocessing scheme (http://acc.igs.org/reprocess2.html). This is part of a large processing effort, including>4000 stations in the Euro- Mediterranean and African regions (Serpelloni et al., 2022), where sub-networks, made up of <50 stations dynamically and optimally selected based on daily data availability, are processed independently with GAMIT and later tied together using common sub-net tie sites and IGb14 core stations using the GLOBK software. This time series are used to study the effect of the drought occurring since 2021 in Northern Italy.
The columns of the files are: Time, U, Su, site, long, lati, representing, respectively, epoch (in decimal years), displacement in the Up component (in mm), uncertainty (one standard deviation) of the Up component (in mm), Station ID, Longitude of the station (°), Latitude of the station (°)
Geological control of hydrological transient deformation in the Venetian Southern Alps (Italy)
No full textHydrological-induced horizontal deformation have been already detected and precisely measured in the Eastern Southern Alps and Northern Dinarides from the analysis of GPS displacement time-series (Serpelloni et al., 2018). Since they appear to be temporally correlated with cumulated precipitation time-series, in this work we investigate how the hydrological cycle affect GPS time series in a portion of the Venetian Southern Alps, a region of particular tectonic interest since it is where large part of the Adria-Eurasia convergence is accommodated. Here the GPS network is denser than the surrounding regions; furthermore, we included new GPS stations and updated the time series in order to take into account the flood event that occurred in this area during October 2018. Ground-displacements time series from GPS stations have been analysed by applying a blind source separation algorithm based on variational Bayesian Independent Component Analysis. This analysis highlighted two annual common mode signals and a transient deformation signal. The latter is characterized by a spatially variable response in the horizontal components, causing a succession of horizontal extensions and contractions occurring about normal to natural fractures. We demonstrated that this transient signal is caused by the variation of the water storage in the hydrological basin of this area. Water storage has been modeled by using rainfall-runoff hydrological models, which describe how the precipitation over a basin turns into river flow once given as input rainfall, temperature and potential evapotranspiration. In order to understand how water storage variations generate the observed ground displacements, we built a 2D numerical model, accounting for the geological and topographical features of the study area. Then, we tested different sources of deformation in order to find the one that best reproduces the displacements obtained from the geodetic analysis. We found that the backthrust of the Bassano-Valdobbiadene fault, a major thrust of the south-verging seismogenic Venetian fold-and-thrust belt, is the preferred source of deformation. This backthrust fault is located north of a karstified mountain chain, corresponding to the anticline associated with the Bassano-Valdobbiadenet thrust fault. We made the hypothesis that the meteoric water penetrates through karst fractures at the top of the anticline and flows along the rock layers, converging to a sub-vertical fracture down to 1 km in correspondence of the backthrust of the main thrust fault. Here, the water accumulates because of the larger permeability of the fractured fault rocks, varying its level up to tens of meter and then generating pressure changes that cause the observed ground displacements. The largest pressure changes, associated with periods of larger displacements, cause significant increase/decrease of the Coulomb stress values down to 3 km, at seismogenic depths of the Bassano-Valdobbiadene thrust fault. Reference: Serpelloni, E., Pintori, F., Gualandi, A.,Scoccimarro, E., Cavaliere, A., Anderlini, L., et al. (2018). Hydrologically induced karst deformation: Insights from GPS measurements in the Adria-Eurasia plate boundary zone. Journal of Geophysical Research: Solid Earth, 123. https://doi.org/10.1002/2017JB01525
Rainfall Induced Horizontal Deformation in the European Eastern Alps Measured by GPS
No full textWe analyzed the time-series of continuous GPS stations operating in the Italian, Austrian, Slovenian and Croatian Alps and Dinarides with a blind-source-separation algorithm based on a variational Bayesian Independent Component Analysis method, characterizing the spatiotemporal evolution of ground displacements and crustal deformation associated to hydrological processes over a vast area of ~70.000 km2. The study area is part of the broad zone of deformation where the N-S Adria-Eurasia convergence and the E-ward escape of the Eastern Alps toward the Pannonian basin are accommodated. We characterized the spatial response and the temporal evolution of several signals, among which the most significant ones are two annual signals with spatially uniform response in the vertical and horizontal components, respectively, and a time-variable, non-cyclic, signal characterized by a spatially variable response in the horizontal components. Because of its non-uniform spatial response, this latter signal induces a succession of extensional/compressional deformation, which is larger in areas characterized by karst geology, varying in amplitudes during the study time-span (2007-2016). The orientation of the principal time-variable strain-axes is normal to the orientation of lineaments and fractures detected from the analysis of a digital elevation model and parallel to the direction of tectonic stress. We have compared the time evolution of this signal with hydrological observations by exploiting the availability of gridded datasets for the European area. The detected deformation signal is highly correlated with cumulated rainfall over a period of 180 days, suggesting that the opening of fractures in karst rocks caused by cumulated rainfall is likely the primary mechanism of this deformation signal, whose kinematics is guided by the orientation of rock's fractures. We discuss the implication that this time-variable non-tectonic deformation may have for the estimate of the long-term interseismic strain accumulation and the seismic potential of active faults in the study area
Vertical displacement time series from GNSS stations in the great Alpine area
No full textASCII files reporting the position time-series, in the Eurasia-fixed reference frame, of GNSS in the great Alpine area (excluding Switzerland). The columns are: Time, U, Su, site, long, lati, representing, respectively, epoch (in decimal years), displacement in the Up component (in mm), uncertainty (one standard deviation) of the Up component (in mm), Station ID, Longitude of the station (°), Latitude of the station (°)
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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