http://hdl.handle.net/2122/270 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/4133 Title: A parametric and comparative study of different tephra fallout models <br/> <br/>Authors: Scollo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Folch, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Costa, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia <br/> <br/>Abstract: We perform a parametric and comparative study on three different tephra dispersal models (FALL3D,HAZMAP, and TEPHRA) applied to two different scenarios expected for Etna volcano. These scenarios are similar to the recent 2002–03 and 1990 Etna eruptions and correspond, respectively, to a weak and to a strong plume eruption. For each model and scenario we perform a parametric study on several inputs in order to quantify how a variation on a given input parameter (i.e. an uncertainty on the model input) affects the results of the model. The study considers topographic effects, different description for the eruption column, column height influence, different fits for terminal velocities of particles, the effect of particle shape and, finally, the variation of the modal grain-size. Model differences are quantified by means of a normalized distance that indicates how close, in average, the results from two different simulations are.We also compare predictions from different models to determine under which circumstances the use of a more elaborated model is justified. Results from our parametric study show that output of the models can be strongly sensitive to the uncertainties and assumptions on input parameters, such as mainly mass eruption rate, column height, distribution of the mass along the column, bulk grain-size distribution. This highlights that, for optimal forecasts, is urgent to improve the description of these parameters and of some important physical processes like fragmentation and eruption column dynamics. Further, differences between models are often lower than those due to the uncertainties of input parameters, although they become more high in simulating weak plumes. Thus the choice of the model mainly depends on the kind of application such as the need to simulate the evolution of volcanic clouds in the atmosphere. Finally, the use of both a semi-analytical (HAZMAP) and a fully computational (FALL3D) model for inverting field data of the 2001 Etna eruption showed that the best-fit parameters are similar for both models, and are consistent with values obtained using independent techniques. http://hdl.handle.net/2122/4132 Title: Sensitivity analysis and uncertainty estimation for tephra dispersal models <br/> <br/>Authors: Scollo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Tarantola, S.; Commiss European Communities, Joint Res Ctr, Ispra, Italy; Bonadonna, C.; Univ Geneva, Sect Sci Terre, CERG, Geneva, Switzerland; Coltelli, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Saltelli, A.; Commiss European Communities, Joint Res Ctr, Ispra, Italy <br/> <br/>Abstract: Sensitivity analysis and uncertainty estimation are crucial to the validation and calibration of numerical models. In this paper we present the application of sensitivity analyses, parameter estimations and Monte-Carlo uncertainty analyses on TEPHRA, an advection-diffusion model for the description of particle dispersion and sedimentation from volcanic plumes. The model and the related sensitivity analysis are tested on two sub-plinian eruptions: the 22 July 1998 eruption of Etna volcano (Italy) and the 17 June 1996 eruption of Ruapehu volcano (New Zealand). Sensitivity analyses are key to (i) constrain crucial eruption parameters (e.g. total erupted mass) (ii) reduce the number of variables by eliminating non-influential parameters (e.g. particle density) and (iii) investigate the interactions among all input parameters (plume height, total grain-size distribution, diffusion coefficient, fall-time threshold and mass-distribution parameter). For the two test cases, we found that the total erupted mass significantly affects the model outputs and, therefore, it can be accurately estimated from field data of the fallout deposit, whereas the particle density can be fixed at its nominal value because it has negligible effects on the model predictions http://hdl.handle.net/2122/4071 Title: Are we going towards a global planetary magnetic change? <br/> <br/>Authors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Qamili, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia <br/> <br/>Editors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baker, R.; Israel Institute of Technology, Israel; Klug, B.; Univ. of Natural Res. & Applied Life Sciences, Austria; Vanicek, P.; University of New Brunswick, Canada; D'El-Rey Silva, L. J. H.; Universidade de Brasilia, Brazil; Foyo, A.; University of Cantabria, Spain; Ercanoglu, M.; Hacettepe University, Turkey; Dordevic, D.; University of Belgrade, Serbia <br/> <br/>Abstract: The dipolar part of the geomagnetic field has been decaying rapidly during the last few hundreds of years. In addition to this classical argument, from Information theory applied to geomagnetism, there are some evidences that the recent Earth magnetic field is showing characteristics typical of a reversal in progress. If this is true, many scientific and environmental questions will arise. For instance, it will be of particular interest to monitor the time-space dynamics the South Atlantic Anomaly, where the magnetic field is strongly reduced (a sort of "planetary magnetic hole"). Here we find one of the most favourite places where Low Earth Orbiting (LEO) satellites are lost or present some damages, due to the vicinity of "clouds" of electric particles (Van Allen belts) to the Earth's surface. The decay of the field will also decrease the screening effect to the solar wind and cosmic charges, so enhancing the cosmic radiation illuminating our planet: possible negative consequences are expected in terms of increase of skin cancers. Also important will be the study of the possible evolution of the core dynamics that will be generating this specific condition of the geomagnetic field. http://hdl.handle.net/2122/4070 Title: Environment and Geoscience <br/> <br/>Authors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baker, R.; Israel Institute of Technology, Israel; Klug, B.; Univ. of Natural Res. & Applied Life Sciences, Austria; Vanicek, P.; University of New Brunswick, Canada; D'El-Rey Silva, L. J. H.; Universidade de Brasilia, Brazil; Foyo, A.; University of Cantabria, Spain; Ercanoglu, M.; Hacettepe University, Turkey; Dordevic, D.; University of Belgrade, Serbia <br/> <br/>Editors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baker, R.; Israel Institute of Technology, Israel; Klug, B.; Univ. of Natural Res. & Applied Life Sciences, Austria; Vanicek, P.; University of New Brunswick, Canada; D'El-Rey Silva, L. J. H.; Universidade de Brasilia, Brazil; Foyo, A.; University of Cantabria, Spain; Ercanoglu, M.; Hacettepe University, Turkey; Dordevic, D.; University of Belgrade, Serbia <br/> <br/>Abstract: This book contains the proceedings of the 1st WSEAS International Conference on Environmental and Geological Science and Engineering (EG'08) which was held in Malta, September 11-13, 2008. This conference aims to disseminate the latest research and applications in Renewable Energy, Mineral Resources, Natural Hazards and Risks, Environmental Impact Assessment, Urban and Regional Planning Issues, Remote Sensing and GIS, and other relevant topics and applications. The friendliness and openness of the WSEAS conferences, adds to their ability to grow by constantly attracting young researchers. The WSEAS Conferences attract a large number of well-established and leading researchers in various areas of Science and Engineering as you can see from http://www.wseas.org/reports. Your feedback encourages the society to go ahead as you can see in http://www.worldses.org/feedback.htm The contents of this Book are also published in the CD-ROM Proceedings of the Conference. Both will be sent to the WSEAS collaborating indices after the conference: www.worldses.org/indexes In addition, papers of this book are permanently available to all the scientific community via the WSEAS E-Library. Expanded and enhanced versions of papers published in this conference proceedings are also going to be considered for possible publication in one of the WSEAS journals that participate in the major International Scientific Indices (Elsevier, Scopus, EI, ACM, Compendex, INSPEC, CSA .... see: www.worldses.org/indexes) these papers must be of high-quality (break-through work) and a new round of a very strict review will follow. (No additional fee will be required for the publication of the extended version in a journal). WSEAS has also collaboration with several other international publishers and all these excellent papers of this volume could be further improved, could be extended and could be enhanced for possible additional evaluation in one of the editions of these international publishers. Finally, we cordially thank all the people of WSEAS for their efforts to maintain the high scientific level of conferences, proceedings and journals.