177,334 research outputs found
Zero Modes and Low-Energy Resolvent Expansion for Three Dimensional Schrödinger Operators with Point Interactions
No full text
Point-Like Perturbed Fractional Laplacians Through Shrinking Potentials of Finite Range
No full textWe construct the rank-one, singular (point-like) perturbations of the d-dimensional fractional Laplacian in the physically meaningful norm-resolvent limit of fractional Schrodinger operators with regular potentials centred around the perturbation point and shrinking to a delta-like shape. We analyse both possible regimes, the resonancedriven and the resonance-independent limit, depending on the power of the fractional Laplacian and the spatial dimension. To this aim, we also qualify the notion of zeroenergy resonance for Schrodinger operators formed by a fractional Laplacian and a regular potential
Control of the aspect ratio of the chamber roof on caldera formation during silicic eruptions
No full textSeveral factors may control the development of a silicic caldera during an eruption: here we match previous studies of caldera forming eruptions with analogue experiments to consider the role of the aspect ratio (thickness/width) of the magma chamber roof. These data suggest that large silicic caldera formation is controlled by: 1) the availability of magma; 2) initial explosive eruption through a conduit connecting the reservoir and the surface; 3) fast depressurization of the reservoir; 4) chamber roof collapse, with newly-formed fractures connecting the reservoir with the surface and creation of a continuous ring conduit feeding annular vents, capable of sustaining the eruption. The occurrence of the latter condition may depend upon the aspect ratio of the chamber roof: lower ratios (1.6) form incoherent collapse, which may hinder the continuation of the eruption after an initial partial emptying of the chamber. The aspect ratio of the chamber roof should therefore be considered as a further factor, capable of controlling the formation of large silicic calderas
Preliminary evaluation of the volcanic hazard in the southern valley of Mexico
No full textLa ciudad de México está ubicada en el centro de un campo volcánico activo en la cuenca del Valle de México. Dejando de lado la actividad histórica del gran estratovolcán Popocatépetl, la última actividad de este campo volcánico fue la del volcán monogénico Xitle. Esta erupción ocurrió el año 2500 A.C. En este trabajo se calculo la tasa de erupción para el campo volcánico del sur del Valle de México por varios métodos diferentes. La tasa de erupción media se comprobó que es de 10-3 erupciones/año. La máxima probabilidad de erupción en el sur del Valle de México está situada en una banda E-0 que pasa a través de la Sierra de Chichinautzin. Por razones de seguridad, la expansión del área metropolitana de la ciudad de México deberá alejarse de la Sierra de Chichinautzin.
doi: https://doi.org/10.22201/igeof.00167169p.1979.18.1.109
Analisi GIS e determinazione della mappa di rischio vulcanico del Monte Etna su base statistica dell’attività storica
No full textLa valutazione del rischio vulcanico è un obiettivo primario della ricerc a
scientifica sui vulcani. La quantificazione del rischio richiede conoscenza
della storia e delle modalità di eruzione, circostanza che per il Monte Etna è
assicurata dalla redazione di alcuni cataloghi ufficiali dell’attività vulcanica
(cataloghi Romano e Sturiale, Tanguy). In questo lavoro effettuiamo un’analisi
statistico-probabilistica delle eruzioni dei crateri laterali per i quali i cataloghi
hanno informazioni più dettagliate. L’analisi ci permette di calcolare una
mappa di rischio che viene incorporata in una rappresentazine GIS del territorio
del Monte Etna
Nuovi scenari di rischio nell’area vesuviana
No full textWhile waiting for the Census data for 2011, which will be used for a re-evaluation of the «social risk» due to volcanic eruptions of Vesuvius as a result of the combination of different variables, a re-evaluation of the volcanic risk per number of inhabitants was made on the basis of the Istat data of 2010 published in the Bilancio demografico e popolazione residente al 31 Dicembre. In fact, we need to do new research and update works in progress in order to have detailed information on the municipalities exposed to very high and high risk. For the purpose of providing backup to the strategic management of potential emergencies and defining a specific framework, we also provide an analysis of the recent demographic variations, taking into consideration the natural and
the migratory balance. This work also tries to provide a basis for future papers which intend to involve also the municipalities of the Phlegraean Fields (Campi Flegrei), according to comparable models, in order to draw up a classification of the Italian municipalities faced with the highest volcanic ris
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