1,721,133 research outputs found
Rates of active compressional deformation in central Italy and Sicily: evaluation of the seismic budget
No full textHistorical and recent seismicity records and available source mechanisms in eastern-central Italy (Marche–Adriatic region), in mainland-southern Sicily and in the Tyrrhenian offshore of northern Sicily show com- parable deformation patterns. Seismotectonic consider- ations indicate that each of the three areas represents a broad seismogenic province of relatively homogeneous deformation. On the basis of the historical earthquake catalogue, the parameters of the Gutenberg–Richter dis- tribution have been calculated by means of a Monte Carlo simulation method. The average moment tensors have been computed from focal mechanism data and the strain rate and velocity tensors evaluated by means of Kostrov’s (in Izv Acad Sci USSR Phys Solid Earth 1:23–44, 1974) relation, which also considers the shape and size of the seismogenic volume. The uncertainties have been system- atically incorporated. The results show that the three seis- motectonic provinces are all undergoing shortening at seismic rates (*0.3 mm/year in the WSW–ENE direction in the eastern Marche–Adriatic region, *0.1 mm/year in the N–S direction in mainland-southern Sicily and *0.2 mm/year in the NW–SE direction in the Southern Tyrrhenian zone). The motion pattern in the Marche– Adriatic and in the Sicilian provinces suggests that these areas undergo active crust-scale deformation along reverse shear zones, in agreement with recent horizontal GPS motion model and other independent evidence.Published2T. Tettonica attivaJCR Journalrestricte
The Attenuation and Scattering Signature of Fluid Reservoirs and Tectonic Interactions in the Central-Southern Apennines (Italy)
Full text linkDespite the high detection level of the Italian seismic network and the risk associated with its fault networks, Central-Southern Italy has no unique geophysical model of the crust able to illuminate its complex tectonics. Here, we obtain seismic attenuation and scattering tomography models of this area; both reveal high attenuation and scattering anomalies characterizing the entire Apenninic Chain and related to its East- and West-dipping extensional Quaternary tectonic alignments. Fault-associated fractured zones become preferential ways for circulating and degassing high-attenuation CO2-bearing fluids. A previously undetected fluid source area is a high-attenuation volume below the Matese complex, while a similar smaller anomaly supports a fluid source near L'Aquila. The most prominent low attenuation and scattering volumes reveal a locked aseismic zone corresponding to the Fucino-Morrone-Porrara fault systems, representing a zone of significant seismic hazard
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
On the use of the HMCPL shielding system in renewing the underground HV power lines in big cities
No full textUsing underground cables in big cities, one of the most important acceptability issues is the magnetic field mitigation. This paper focuses on the joint bays, which are a critical part of the buried power lines regarding the magnetic field generation. For technical reasons, within a joint bay cables have to be arranged in flat configuration with an increment of the cable distances which cause a higher magnetic field generation compared to the trefoil arrangement. For a standard buried power line the magnetic field above a joint bay can be 10 times higher than the one of the trefoil. Joint bays are usually mitigated by means of passive shields. The literature covers comparisons of flat metallic shields, passive loops and passive loops with improved magnetic coupling (called HMCPL). In the renewal of the HV grid of Torino, from 2010 to 2014 sixteen new 220 kV lines were laid. The total length is about 50 km. The cables were provided from three different manufacturers. A total of 70 joint bays were installed. 20 of 70 joint bays required, for their position, a mitigation action. In 14 of them, HMCPL system has been used; in the others 6, the classical passive loops system has been installed. In this paper the results of measurement data concerning a sample of the joint bays are presented. The measurement results serve to compare the magnetic field with joint bays without a mitigation system and also to compare the HMCPL with the classical passive loops. Regarding the innovative HMCPL shielding system, in Torino it has been made the more extensive application; furthermore, the results are very satisfactory: the average value measured at the reference point is reduced of about ten times. We also experienced that the site assembly of the system is fast and flexible
Is there a mantle plume below Italy?
No full textSome of the most diverse igneous rocks found on Earth occur along the length of Italy and in many of the islands in the southeastern Tyrrhenian Sea, all the result of Cenozoic magmatism. Magmas extremely rich in alkalis, particularly potassium, and many undersaturated with respect to silica, were erupted, as well as others of calc-alkalic affinity . Their origin has been the subject of heated debate, and there is still no general consensus about how they formed. Most attribute them to subduction-related processes (Beccaluva et al. 2004, for a review); others consider them to be the result of within-plate magmatism [e.g., Vollmer, 1976; Lavecchia and Stoppa, 1996]. Still others consider magmatism the result of a deep, mantle upwelling within a slab window coupled with mixing between isotopically different reservoirs [Gasperini et al., 2002]
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