1,721,007 research outputs found
Pronounced increase in slope instability linked to global warming: A case study from the eastern European Alps
Full text linkIn recent decades, slope instability in high-mountain regions has often been linked to increase in temperature and the associated permafrost degradation and/or the increase in frequency/intensity of rainstorm events. In this context we analyzed the spatiotemporal evolution and potential controlling mechanisms of small- to medium-sized mass movements in a high-elevation catchment of the Italian Alps (Sulden/Solda basin). We found that slope-failure events (mostly in the form of rockfalls) have increased since the 2000s, whereas the occurrence of debris flows has increased only since 2010. The current climate-warming trend registered in the study area apparently increases the elevation of rockfall-detachment areas by approximately 300 m, mostly controlled by the combined effects of frost-cracking and permafrost thawing. In contrast, the occurrence of debris flows does not exhibit such an altitudinal shift, as it is primarily driven by extreme precipitation events exceeding the 75th percentile of the intensity-duration rainfall distribution. Potential debris-flow events in this environment may additionally be influenced by the accumulation of unconsolidated debris over time, which is then released during extreme rainfall events. Overall, there is evidence that the upper Sulden/Solda basin (above ca. 2500 m above sea level [a.s.l.]), and especially the areas in the proximity of glaciers, have experienced a significant decrease in slope stability since the 2000s, and that an increase in rockfalls and debris flows during spring and summer can be inferred. Our study thus confirms that “forward-looking” hazard mapping should be undertaken in these increasingly frequented, high-elevation areas of the Alps, as environmental change has elevated the overall hazard level in these regions
Linking slab break-off, Hellenic trench retreat, and uplift of the Central and Eastern Anatolian plateaus
No full textThe Central and Eastern Anatolian plateaus are integral parts of the world's third largest orogenic plateau. In the
past decade, geophysical surveys have provided insights into the crust, lithosphere, and mantle beneath Eastern
Anatolia. These observations are now accompanied by recent surveys in Central Anatolia and new data
constraining the timing and magnitude of uplift along its northern and southernmargins. Together with predictions
from geodynamic models on the effects of various processes on surface deformation and uplift, the observations
can be integrated to identify probable mechanisms of Anatolian Plateau growth.
A changeover fromshortening to extension along the southern margin of Central Anatolia that is coevalwith the
start of uplift can bemost easily associatedwith oceanic slab break-off and tearing. This interpretation is supported
by tomography, deep seismicity (or lack thereof), and gravity data. Based on the timing of uplift, geophysical
and geochemical observations, and model predictions, slab break-off likely occurred first beneath Eastern Anatolia
inmiddle to lateMiocene time, and propagatedwestward toward Cyprus by the latestMiocene. Alternatively,
the break-off near Cyprus could have occurred in late Pliocene to early Pleistocene time, in association with collision
of the Eratosthenes Seamount (continental fragment) with the subduction zone. Uplift at the northern
margin of Central Anatolia appears to result fromcrustal shortening starting in the lateMiocene or early Pliocene,
which has been linked to the broad restraining bend of the North Anatolian Fault. The uplift history of the interior
of Central Anatolia since the lateMiocene is unclear, although shortening there appears to have ended by the late
Miocene, followed by NE–SW extension. This change in the deformation style broadly coincides with faster
retreat of the Hellenic trench as well as uplift of the northern and southern margins of Central Anatolia.
These different events throughout the plateau may be linked, as faster retreat of the Hellenic trench has been predicted
to occur after slab break-off, which could have induced extension of Central Anatolia and helped to form
the North Anatolian Fault through accelerated westward movement of Anatolia relative to Eurasia. Correlative
geochronologic evidence thatwe summarize here supports the hypothesis that the geodynamic activity throughout
the Aegean–Anatolian domain starting in latestMiocene to early Pliocene time defines a series of events that
may all be linked to slab break-off
Sediment export from an Alpine proglacial area under a changing climate: Budgets, rates, and geomorphological processes
Full text linkProglacial areas in the European Alps and other high-elevation mountains are currently undergoing rapid change due to global warming. Because of rising temperatures, glaciers and glacier forefields are subjected to increased melting and associated sediment export. This observation is increasingly important with respect to high-elevation geomorphological and ecological dynamics, emerging natural hazards and mitigation efforts, and hydropower plant management. It is therefore crucial to analyze the factors and feedback mechanisms governing sediment production, transport, and deposition in these rapidly changing areas. In this study, we investigated the sediment dynamics of a proglacial area located in the Eastern Italian Alps over the period 1969–2021 with the aims of: i) identifying the areas of sediment production; ii) quantifying volumes and rates of bedload sediment transport; and iii) determining the relative contribution of glacial export and fluvial erosion to the total sediment budget. We found that i) apart from glaciers, moraines and fluvial channels have been the most important sediment sources, albeit with substantial differences in terms of connectivity and thus supply rates; ii) the volumes and rates of sediment erosion varied by one order of magnitude (between tens and hundreds of mm per year), and were generally higher along the channel network; and iii) for a relatively shorter time interval between 2005 and 2021, the relative contribution of glacial bedload input with respect to the total sediment budget ranged between 34 % and 37 %, whereas 45 % to 59 % was derived from lateral fluvial erosion. Only a relatively small sediment volume was generated by net channel bed incision. These results imply that most of the sediment released from the proglacial area of the Sulden glacier is progressively transferred to the downstream sector of the channel network, with volumes that range between 931 and 1017 tons yr−1 km−2. These values are in the typical range of sediment export volumes from glaciated basins and highlight the high dynamicity of this region of the Alps. In general, our results confirm the complexity – in terms of spatial and temporal variability – of Alpine proglacial systems and highlight the need to systematically study these areas on a wide spatial and temporal scale, since the information provided by single locations or individual sectors of the sediment cascade, may not be adequate for understanding the dynamics acting in the entire proglacial regions
Uplift of the SE margin of the Central Anatolian plateau: Temporal constraints from the Adana Basin, southern Turkey
No full textSedimentary evidence for late Messinian uplift of the SE margin of the central Anatolian Plateau: Adana Basin, Southern Turkey
No full textThe Adana Basin of southern Turkey, located at the SE margin of the Central Anatolian Plateau in
the vicinity of the Arabia-Eurasia collision zone, is ideally suited to record Neogene and Quaternary
topographic and tectonic changes in the easternmost Mediterranean realm. On the basis of our correlation of 34 seismic reflection profiles with corresponding exposed units along the margins of the
Adana Basin, we identify and characterize the seismic facies that corresponds to the upper part of the
Messinian Handere Formation (ca. 5.45 to 5.33 Ma), which consists mainly of fluvial conglomerates
and marls. The seismic reflection profiles indicate that ca. 1100 km3 of the Handere Formation
upper sub-unit is distributed over ca. 3000 km2, reflecting local sedimentation rates of up to
12.5 mm year1. This indicates a major increase in both sediment supply and subsidence rates at
ca. 5.45 Ma. Our provenance analysis of the Handere Formation upper sub-unit based on clast
counting and palaeocurrent measurements reveals that most of the sediment is derived from the
Taurus Mountains at the SE margin of the Central Anatolian Plateau and regions farther north. A
comparison of these results with the composition of recent fluvial conglomerates and the present-day
drainage basins indicates major changes between late Messinian and present-day source areas. We
suggest that these changes in drainage patterns and lithological characteristics result from uplift and
ensuing erosion of the SE margin of the plateau. We interpret the tectonic evolution of the southern
flank of the Anatolian Plateau and the coeval subsidence and sedimentation in the Adana Basin to be
related to deep lithospheric processes, particularly lithospheric delamination and slab break-off
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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