1,720,975 research outputs found
The structural setting of the Monte di Vezzi area, Ischia Island, derived from geophysical data
No full textWe present a magnetic and gravimetric study of the structural setting of the Monte di Vezzi area, in the Ischia Island. The study was performed carrying out an analysis of a new high-resolution aeromagnetic data set and a previous gravity data set. The aeromagnetic survey covered the entire area of the island with a flight line spacing and a clearance of 300 meters. The analysis of the magnetic data set, that included reduction to the pole and computation of the horizontal derivative of data, lead to the location of the source of the anomaly measured over Monte di Vezzi and allowed mapping the main magnetic lineaments of the area. A 2D simultaneous magnetic and gravity modeling yield the definition of a model of the mount in terms of density and magnetic susceptibility, bringing new insights into the geo-volcanological and structural characteristics of the area
Magnetic signature of submarine volcanoes in the Phlegrean Fields-Ischia Ridge (North-Western side of the Bay of Naples, Southern Italy)
Full text linkThis paper presents a study of the Phlegrean Fields-Ischia submarine ridge by the analysis and interpretation of high-resolution aeromagnetic data recently acquired in the Western Procida offshore. The investigated area is located along the ridge connecting Ischia to the Phlegrean Fields and is characterized by the existence of several monogenetic volcanoes aligned on a NE-SW system of faults. The high-resolution magnetic data yielded new information on the area, highlighting particularly the signature of a volcanic body located between Pt. Serra and the Ruommoli shoal. This structure has not been clearly described before and we named it as the Pt. Serra submarine volcano. The computation of the analytic signal and horizontal gradient of the data distinctly located this structure and definined the position of its rims. A 2D modeling and 3D inversion of data provided information on the volcanos thickness, width and magnetization, disclosing a meaningful igneous body extending down to several hundred meters b.s.l
Seismically-induced landslide susceptibility evaluation: Application of a new procedure to the island of Ischia, Campania Region, Southern Italy
No full textIn this paper we present an approach for evaluating landslide susceptibility in seismic areas. It is known that
earthquake-induced landslide susceptibility is related to several, often interplaying, factors. Nevertheless, an
effective grade-2 zonation should be characterized by a good balance between simplicity, quickness and
reliability. The GIS-based procedure we present employs only three factors that we believe are the most
significant in this susceptibility assessment: the type of outcropping rocks/soils, the slope angle and the MCS
intensity. The local annual precipitation, certainly an essential factor, is considered here as a parameter whose
seasonal pattern is constant in time and space. Each of the three parameters is expressed as a Significance
percentage and the resulting Seismic Landslide Susceptibility level of an area is given by the average of the
significance of the first two factors multiplied by the significance of the third factor. The procedure was set and
tested on the volcanic island of Ischia (southern Italy), which was affected by several historical earthquake-induced
landslides. The results of this susceptibility zonation test at Ischia show a very good match between
the distribution of the sources of historical landslides and the areas we identified as the most susceptible ones
Seismically-induced landslide susceptibility evaluation: application of a new procedure to the island of Ischia, Campania Region, Southern Italy
No full textIn this paper we present an approach for a qualitative base evaluation of landslide susceptibility in seismic areas. It is known that earthquake-induced landslide susceptibility is related to several, often interplaying, factors. Nevertheless, an effective grade-2 zonation should be characterized by a good balance between simplicity, quickness and reliability. The GIS-based procedure we present employs only three factors that we believe are the most significant in this susceptibility assessment: the type of outcropping rocks/soils, the slope angle and the peak horizontal acceleration at the surface. The local annual precipitation, certainly an essential factor, is considered here as a parameter constant in time and space. Each of the three parameters is expressed as a Significance percentage and the resulting Seismic Landslide Susceptibility level of an area is given by the product of the three significances. The procedure was set and tested on the volcanic island of Ischia (southern Italy), which was affected by several historical earthquake-induced landslides. The results of this susceptibility zonation test at Ischia show a very good match between the distribution of the sources of historical landslides and the areas we identified as the most dangerous ones
Macroseismic Attenuation in the Campanian Area, Southern Italy
No full textThe main objective of the present study is to evaluate seismic attenuation relationships for the Campanian area (southern Italy) using felt intensity report data obtained from a comprehensive historical databases (DOM 4.1). We focused our attention on the Campania region because it is characterized by a high seismic hazard and risk, particularly in the Naples area and its suburbs. In order to derive an attenuation relationship for the area we fitted the observed data by using several functions. We found that a linear plus logarithmic model gives the best fits for the data in the Campanian region. Most of the attenuation relationships proposed up to now for the Italian peninsula have an isotropic behavior and do not always properly describe the macroseismic attenuation. Therefore, in order to check a possible dependence of the attenuation on the azimuth of the seismic rays, we divided our data set in octants and performed for each of them the same analysis we did for the whole data set. The obtained results are different from octant to octant and the differences, besides being connected to source effects, could be interpreted as possibly due to the existence of crustal lateral variations at different depths of the lithological and physical features that could affect the attenuation patterns
2nd Grade Zonation on hazard of earthquake-triggered landslides: an application to the Ischia volcanic area and Irpinia Southern Apennines, Italy
No full textThe integration of remote sensing magnetic data in the Neapolitan volcanic district
No full textIn this paper we present an example of the integration of airborne and marine magnetic data sets measured in the Neapolitan area, southern Italy. The integration involved detailed data measured recently in the Phlegrean Fields, in the Somma-Vesuvis area and in the Bay of Naples, that produced a high-resolution magnetic map of the whole active volcanic district. The data sets partially overlapped and characterized varying flight height and line spacing. Integration was therefore performed through several procedures including continuation between general surfaces. The integration produced a new, detailed, draped magnetic data set of the Neapolitan region characterized by a terrain clearance of 200 m, giving a meaningful overall view of the volcanic area. The study of the main magnetic features of the area was carried out by computing the horizontal gradient of the pole-reduced draped data. The analysis of the obtained map showed the presence of lineaments of preferential magma upwelling and buried volcanic structures and allowed the delineation of a geovolcanological and structural framework of the whole Neapolitan volcanic district
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
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