1,721,195 research outputs found
Slip imaging of the May 20, 2012, MW 5.8, Po Plain (Northern Italy) earthquake from the inversion of the source time functions
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Comment on the paper by Barreca et al.: “The Strait of Messina: Seismotectonics and the source of the 1908 earthquake” (Earth-Science Reviews 218, 2021, 103685)
Full text linkWe discuss the new causative source model for the 1908 Messina Straits earthquake recently proposed by Barreca et al. (2021), where an aseismic slip of 1.13 m along a low-angle discontinuity, preceding the 1908 earthquake, have mechanically destabilized a set of overlying faults, therefore leading them to the rupture. The lack of significant variations of the relative sea level in the Messina harbor area, in the time period relevant for the levelling data (1907–1908) analyzed by Barreca et al., and at least for the decade preceding the event proves the inconsistency of the assumed pre-earthquake aseismic slip. A careful interpretation of crustal earthquake distribution in the Strait does not support the presence of the low-angle discontinuity. The modelled horizontal coseismic pattern reveals a scenario that is not supported by any other independent geological and geophysical observation. We conclude that the source model proposed by Barreca et al. for the 1908 Messina Straits earthquake can not be considered as a viable hypothesis for the causative fault
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
Le persone dell'Istituto Nazionale di Geofisica e Vulcanologia a venti anni dalla sua istituzione
Full text linkL’Istituto Nazionale di Geofisica e Vulcanologia (INGV) nasce dall’accorpamento di enti e istituti pubblici di ricerca in ambito geofisico e vulcanologico. Nei primi venti anni dalla legge istitutiva del 1999, l’INGV ha visto un notevole sviluppo, alternando momenti di espansione, con sensibili incrementi della dotazione finanziaria e del numero di dipendenti, a lunghi periodi di stasi. Durante questi anni è molto cresciuto il numero di persone assunte con contratti a tempo determinato, anche per far fronte alle necessità del monitoraggio sismico e vulcanico del territorio italiano, realizzato sulla base di convenzioni con il Dipartimento di Protezione Civile.
Dopo venti anni, è tempo di delineare un quadro della situazione presente e del processo evolutivo che l’ha determinata. Con questo obiettivo abbiamo realizzato un’analisi dell’evoluzione dell’INGV in questi venti anni, dalla sua costituzione al 2019, in riferimento ad aspetti come la composizione del personale, la sua distribuzione nelle Sezioni, l’età, il genere, il ruolo, la carriera lavorativa, con l’intento di fornire uno strumento per la valutazione del percorso compiuto e per la programmazione degli sviluppi futuri.
La presenza di un elevato numero di precari, distribuiti in modo disomogeneo nelle Sezioni dell’ente, per molti anni ha rappresentato il problema principale dell’INGV, ma non il solo. La contrazione dei finanziamenti e il blocco delle assunzioni hanno anche frenato lo sviluppo delle carriere del personale in ruolo. Altri elementi critici sono rappresentati dallo scarso equilibrio di genere tra il personale di ricerca, e dall’età media elevata del personale. L’opportuno riequilibrio delle eterogeneità, finalizzato alla massima funzionalità e a una crescita efficace dell’ente, dovrebbe essere la sfida per i prossimi anni. Il futuro dell’INGV dipenderà dalle scelte che saranno fatte oggi e la conoscenza della sua evoluzione fino a oggi dell’ente costituisce un elemento imprescindibile per una corretta programmazione.The Istituto Nazionale di Geofisica e Vulcanologia (INGV) was born from the unification of public research institutions in the field of geophysics and volcanology. In the first twenty years from the foundation law of 1999, the INGV has seen a remarkable development, alternating moments of expansion, with significant increases in funding and number of employees, with long periods of stagnation. During these years the number of people hired with fixed-term contracts has grown, also to meet the needs of seismic and volcanic monitoring of the Italian territory, carried out on the basis of agreements with the Department of Civil Protection.
After twenty years, it's time to outline a picture of the present situation and the evolutionary process that determined it. With this objective, the following analysis of the evolution of INGV was carried out in the period between its establishment and 2019, with reference to aspects such as the composition of the personnel, its distribution in the Sections, age, gender, role, career, with the aim of providing a tool for evaluating the progress made and planning future developments. The presence of a large number of precarious workers, distributed unevenly in territorial offices, for many years represented the main problem of the INGV, but not the only one. The contraction of the funding and the hiring freeze also slowed the development of the careers of researchers and other employers. The poor gender balance among the personnel, in particular among researchers, and the high average age represents further critical elements.
The appropriate rebalancing of heterogeneities, aimed at maximum functionality and effective growth of the institute, should be the challenge for the next years. The future of INGV will depend on the choices that will be made today and the knowledge of the evolution of the institution until today is an essential element for proper programming
The signal to noise ratio and the completeness magnitude: The effect of COVID19
No full textWe analyse the earthquakes catalogues for Italy, South California, and Greece across the COVID-19 lockdown period for each country. The results for Italy and Greece show that, even if the reduction of the signal to noise ratio has improved the earthquake detection capability, the completeness magnitude remains substantially unchanged, making the improved detection capability ineffective from the statistical point of view. A slight reduction (0.2) of the completeness magnitude is observed for South California, likely related to the relatively higher number of seismic stations located close to urban areas. Our findings suggest that—given the present configuration of the seismic network considered here—only an important decrease in the station spacing can produce a significant decrease of the completeness magnitude
Concentrated Slip and Low Rupture Velocity for the May 20, 2012, MW 5.8, Po Plain (Northern Italy) Earthquake Revealed From the Analysis of Source Time Functions
Full text linkWe analyse the rupture properties of the May 20, 2012, MW 5.8, Po Plain (Northern Italy) earthquake by using two different modeling procedures based on the source time functions: a forward modeling and a global inversion Bayesian method. While the forward modeling allows to retrieve general information on the source characteristics, the global inversion allows to explore a substantially larger number of possible solutions, with more parameters, providing a quantitative estimate of the misfit. We invert for the spatial slip distribution and for the rupture velocity on a planar fault model. The unknown slip is given at the nodes of the subfaults (control points) and then given at the elementary subfaults through a bilinear interpolation. The number of control points is progressively increased to move from a high‐ to low‐wavelength description of final slip on the fault plane. The optimal model parameter set is chosen according to the Akaike Information Criterion. The uncertainty on the slip distribution and rupture velocity has been estimated by a statistical analysis of the model ensemble and, in particular, through the weighted mean model and the standard deviation. We find that the most earthquake slip occurred in the regions located northeast and southwest of the hypocenter, consistent with the forward modeling. Moreover, we find a low rupture propagation velocity (0.4 compressional Mach number) similarly to what has been observed for the close 29 May, MW 5.6, and radiation efficiency suggesting that half of the strain energy was used to create new fracture
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
Long-period P waveform modeling of upper mantle phases in the West Mediterranean basin
No full textLong-period P waveforms of some Italian crustal earthquakes recorded at the WWSSN stations located in the Iberian Peninsula have been modeled to derive a 1D upper matle compressional velocity model. A technique based on the Cagniard-de Hoop method has been used to compute synthetic seismograms. Waveforms have first been computed for published velocity models referred to different tectonic provinces and compared with the data. A model that strongly improves the fits to the data is then presented. The proposed model, called WMP, is characterized by a 100 km thick lid overlaying a low velocity zone, a 1% velocity discontinuity located at 313 km depth, that is required to fit a lower amplitude phase, and an abrupt increase in the velocity gradient starting from 370 km. This latter is preferred to the sharp discontinuity located at about 400 km that is present in various models obtained for upper mantle structure with analogous techniques. Within the lid and the low-velocity zone, WMP displays features that are typical of old ocean structures like the Northwest Atlantic Ocean.JCR Journalope
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