http://hdl.handle.net/2122/281 Ricerca nel canale cerca http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/6036 Titolo: Predicting the impact of lava flows at Mount Etna, Italy<br/><br/>Autori: Crisci, G.; Department of Earth Sciences, University of Calabria, 87036 Rende, Italy; Avolio, M. V.; Department of Mathematics, University of Calabria, 87036 Rende, Italy; Behncke, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; D'Ambrosio, D.; Department of Mathematics, University of Calabria, 87036 Rende, Italy; Di Gregorio, S.; Department of Mathematics, University of Calabria, 87036 Rende, Italy; Lupiano, V.; Department of Earth Sciences, University of Calabria, 87036 Rende, Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Romgo, R.; Department of Earth Sciences, University of Calabria, 87036 Rende, Italy; Spataro, W.; High Performance Computing Centre, University of Calabria, 87036 Rende, Italy<br/><br/>Abstract: Forecasting the time, nature, and impact of future eruptions is difficult at volcanoessuch as Mount Etna, in Italy, where eruptions occur from the summit and on the flanks,affecting areas distant from each other. Nonetheless, the identification and quantificationof areas at risk from new eruptions are fundamental for mitigating potential humancasualties and material damage. Here, we present new results from the application of amethodology to define flexible high‐resolution lava invasion susceptibility maps based ona reliable computational model for simulating lava flows at Etna and on a validationprocedure for assessing the correctness of susceptibility mapping in the study area.Furthermore, specific scenarios can be extracted at any time from the simulation database,for land use and civil defense planning in the long term, to quantify, in real time, theimpact of an imminent eruption, and to assess the efficiency of protective measures. Wed, 28 Apr 2010 00:00:00 GMT http://hdl.handle.net/2122/6032 Titolo: Theoretical study on SO2 and ash volcanic plume retrievals using ground TIR camera. Sensitivity analysis and retrieval procedure developments<br/><br/>Autori: Corradini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Tirelli, C.; Università La Sapienza Roma; Gangale, G.; Università di Modena e Reggio Emilia; Pugnaghi, Sergio; Università di Modena e Reggio Emilia; Carboni, E.; Atmospheric, Oceanic, and Planetary Physics, Atmospheric, Oceanic, and Planetary Physics, Clarendon Laboratory, University of Oxford<br/><br/>Abstract: In this paper, a sensitivity analysis and procedure development for volcanic-plume sulfur dioxide and ash retrievals using ground thermal infrared camera have been carried out. The semiconductor device camera, considered as a reference, has a spectral range of 8–14 μm with noise equivalent temperature difference that is better than 100 mK at 300 K. The camera will be used to monitor and assess the hazards of Mt. Etna volcano to mitigate the risk and impact of volcanic eruptions on the civil society and transports. A minimum number of filters have been selected for sulfur dioxide (SO2) and volcanic ash retrievals.The sensitivity study has been carried out to determine the SO2 and volcanic ash minimum concentration detectable by the system varying the camera geometry and the atmospheric profiles. Results show a meaningful sensitivity increase considering high instrument altitudes and low camera-elevation angles. For all geometry configurations and monthly profiles, the sensitivity limit varies between 0.5 and 2 g · m−2 for SO2 columnar abundance and between 0.02 and 1 for ash optical depth. Two procedures to detect SO2 and ash, based on the least square fit method and on the brightness temperature difference (BTD) algorithm, respectively, have also been proposed. Results show that high concentration of atmospheric water vapor columnar content significantly reducesthe ash-plume effect on the BTD. A water vapor-correction procedure introduced improves the ash retrievals and the cloud discrimination in every season, considering all the camera geometries. Mon, 01 Mar 2010 00:00:00 GMT http://hdl.handle.net/2122/5952 Titolo: Physical-Mathematical modeling and numerical simulations of stress-strain state in seismic and volcanic regions<br/><br/>Autori: Scandura, Danila<br/><br/>Abstract: The strain-stress state generated by faulting or cracking and influenced by the strong heterogeneity of the internal earth structure precedes and accompanies volcanic and seismic activity. Particularly, volcanic eruptions are the culmination of long and complex geophysical processes and physical processes which involve the generation of magmas in the mantle or in the lower crust, its ascent to shallower levels, its storage and differentiation in shallow crustal chambers, and, finally, its eruption at the Earth’s surface. Instead, earthquakes are a frictional stick-slip instability arising along pre-existing faults within the brittle crust of the Earth. Long-term tectonic plate motion causes stress to accumulate around faults until the frictional strength of the fault is exceeded. The study of these processes has been traditionally carried out through different geological disciplines, such as petrology, structural geology, geochemistry or sedimentology. Nevertheless, during the last two decades, the development of physical of earth as well as the introduction of new powerful numerical techniques has progressively converted geophysics into a multidisciplinary science. Nowadays, scientists with very different background and expertises such as geologist, physicists, chemists, mathematicians and engineers work on geophysics. As any multidisciplinary field, it has been largely benefited from these collaborations. The different ways and procedures to face the study of volcanic and seismic phenomena do not exclude each other and should be regarded as complementary.Nowadays, numerical modeling in volcanology covers different pre-eruptive, eruptive and post-eruptive aspects of the general volcanic phenomena. Among these aspects, the pre-eruptive process, linked to the continuous monitoring, is of special interest because it contributes to evaluate the volcanic risk and it is crucial for hazard assessment, eruption prediction and risk mitigation at volcanic unrest.large faults. The knowledge of the actual activity state of these sites is not only an academic topic but it has crucial importance in terms of public security and eruption and earthquake forecast. However, numerical simulation of volcanic and seismic processes have been traditionally developed introducing several simplifications: homogeneous half-space, flat topography and elastic rheology. These simplified assumptions disregards effects caused by topography, presence of medium heterogeneity and anelastic rheology, while they could play an important role in Moreover, frictional sliding of a earthquake generates seismic waves that travel through the earth, causing major damage in places nearby to the modeling procedureThis thesis presents mathematical modeling and numerical simulations of volcanic and seismic processes. The subject of major interest has been concerned on the developing of mathematical formulations to describe seismic and volcanic process. The interpretation of geophysical parameters requires numerical models and algorithms to define the optimal source parameters which justify observed variations. In this work we use the finite element method that allows the definition of real topography into the computational domain, medium heterogeneity inferred from seismic tomography study and the use of complex rheologies. Numerical forward method have been applied to obtain solutions of ground deformation expected during volcanic unrest and post-seismic phases, and an automated procedure for geodetic data inversion was proposed for evaluating slip distribution along surface rupture. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/2122/5947 Titolo: Modeling ground deformations of Panarea volcano hydrothermal/geothermal system (Aeolian Islands, Italy) from GPS data<br/><br/>Autori: Esposito, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Anzidei, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Atzori, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Devoti, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Giordano, G.; Università degli Studi di Roma Tre; Pietrantonio, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia<br/><br/>Abstract: Panarea volcano (Aeolian Islands, Italy) was considered extinct until November 3, 2002, when a submarine gas eruption began in the area of the islets of Lisca Bianca, Bottaro, Lisca Nera, Dattilo, and Panarelli, about 2.5 km east of Panarea Island. The gas eruption decreased to a state of low degassing by July 2003. Before 2002, the activity of Panarea volcano was characterized by mild degassing of hydrothermal fluid. The compositions of the 2002 gases and their isotopic signatures suggested that the emissions originated from a hydrothermal/geothermal reservoir fed by magmatic fluids. We investigate crustal deformation of Panarea volcano using the global positioning system (GPS) velocity field obtained by the combination of continuous and episodic site observations of the Panarea GPS network in the time span 1995–2007. We present a combined model of Okada sources, which explains the GPS results acquired in the area from December 2002. The kinematics of Panarea volcano show two distinct active crustal domains characterized by different styles of horizontal deformation, supported also by volcanological and structural evidence. Subsidence on order of several millimeters/year is affecting the entire Panarea volcano, and a shortening of 10−6 year−1 has been estimated in the Islets area. Our model reveals that the degassing intensity and distribution are strongly influenced by geophysical-geochemical changes within the hydrothermal/geothermal system. These variations may be triggered by changes in the regional stress field as suggested by the geophysical and volcanological events which occurred in 2002 in the Southern Tyrrhenian area. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/2122/5937 Titolo: Understanding stress and deformation in active volcanoes<br/><br/>Autori: Gudmundsson, A.; Univ. London Royal Holloway; Acocella, V.; Univ. Roma 3; Vinciguerra, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia<br/><br/>Abstract: No eruption, no caldera collapse, and no landslide can take place in a volcano unless its state of stress is suitable for the associated type of rock failure. The state of stress, in turn, results in deformation, and both stress and deformation depend on the mechanical properties of the rocks that constitute the volcano. Understanding stress and deformation in volcanoes is thus of fundamental importance for understanding unrest periods and for accurate forecasting volcano failure, such as may result in large-scale lateral and vertical collapses and eruptions. Fri, 17 Apr 2009 00:00:00 GMT http://hdl.handle.net/2122/5715 Titolo: A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions<br/><br/>Autori: Mastin, L. G.; U.S. Geological Survey, Cascades Volcano Observatory, Vancouver, WA 98683, USA; Guffanti, M.; U.S. Geological Survey Reston, Virginia, USA; Servranckx, R.; Canadian Meteorological Centre, Québec, Canada; Webley, P. W.; Geophysical Institute, University of Alaska Fairbanks, USA; Barsotti, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Dean, K. G.; Geophysical Institute, University of Alaska Fairbanks, USA; Durant, A. K.; Department of Earth Sciences, University of Bristol, England; Ewert, J. W.; U.S. Geological Survey, Cascades Volcano Observatory, Vancouver, WA 98683, USA; Neri, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Rose, W. I.; Department of Geological and Engineering Sciences, Michigan Technological University, USA; Schneider, D. J.; USGS Alaska Volcano Observatory, Anchorage, AK; Siebert, L.; Smithsonian Institution, Washington, D.C., USA; Stunder, B. J.; Air Resources Laboratory, National Oceanic and Atmospheric Administration, Silver Spring, MD; Swanson, G.; National Oceanic and Atmospheric Administration, Camp Springs, MD, USA; Tupper, A.; Bureau of Meteorology, Darwin, Casuarina, NT, Australia; Volentik, A.; Department of Geology, University of South Florida, Tampa, FL, USA; Waythomas, C. F.; USGS Alaska Volcano Observatory, Anchorage, AK<br/><br/>Abstract: During volcanic eruptions, volcanic ash transport and dispersion models (VATDs) are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind. Those models use input parameters, called “eruption source parameters”, such as plume height H, mass eruption rate Ṁ, duration D, and the mass fraction m63 of erupted debris finer than about 4 or 63 μm, which can remain in the cloud for many hours or days. Observational constraints on the value of such parameters are frequently unavailable in the first minutes or hours after an eruption is detected. Moreover, observed plume height may change during an eruption, requiring rapid assignment of new parameters. This paper reports on a group effort to improve the accuracy of source parameters used by VATDs in the early hours of an eruption. We do so by first compiling a list of eruptions for which these parameters are well constrained, and then using these data to review and update previously studied parameter relationships. We find that the existing scatter in plots of H versus Ṁ yields an uncertainty within the 50% confidence interval of plus or minus a factor of four in eruption rate for a given plume height. This scatter is not clearly attributable to biases in measurement techniques or to well-recognized processes such as elutriation from pyroclastic flows. Sparse data on total grain-size distribution suggest that the mass fraction of fine debris m63 could vary by nearly two orders of magnitude between small basaltic eruptions ( 0.01) and large silicic ones (> 0.5). We classify eleven eruption types; four types each for different sizes of silicic and mafic eruptions; submarine eruptions; “brief” or Vulcanian eruptions; and eruptions that generate co-ignimbrite or co-pyroclastic flow plumes. For each eruption type we assign source parameters. We then assign a characteristic eruption type to each of the world's 1500 Holocene volcanoes. These eruption types and associated parameters can be used for ash-cloud modeling in the event of an eruption, when no observational constraints on these parameters are available. Wed, 30 Sep 2009 00:00:00 GMT http://hdl.handle.net/2122/5501 Titolo: Predicting the impact of lava flows at Mount Etna (Italy)<br/><br/>Autori: Crisci, G.; Department of Earth Sciences, University of Calabria, 87036 Rende, Italy; Avolio, M. V.; Department of Mathematics, University of Calabria, 87036 Rende, Italy; Behncke, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; D'Ambrosio, D.; Department of Mathematics, University of Calabria, 87036 Rende, Italy; Di Gregorio, S.; Department of Mathematics, University of Calabria, 87036 Rende, Italy; Lupiano, V.; Department of Earth Sciences, University of Calabria, 87036 Rende, Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Rongo, R.; Department of Earth Sciences, University of Calabria, 87036 Rende, Italy; Spataro, W.; High Performance Computing Centre, University of Calabria, 87036 Rende, Italy<br/><br/>Abstract: Forecasting the time, nature and impact of future eruptions is difficult at volcanoes such as Mount Etna, in Italy, where eruptions occur from the summit and on the flanks, affecting areas distant from each other. Nonetheless, the identification and quantification of areas at risk from new eruptions is fundamental for mitigating potential human casualties and material damage. Here, we present new results from the application of a methodology to define flexible high-resolution lava invasion susceptibility maps based on a reliable computational model for simulating lava flows at Etna and on a validation procedure for assessing the correctness of susceptibility mapping in the study area. Furthermore, specific scenarios can be extracted at any time from the simulation database, for land-use and civil defence planning in the long-term, to quantify, in real-time, the impact of an imminent eruption, and to assess the efficiency of protective measures. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/2122/5378 Titolo: Caldera unrest prior to intense volcanism in Campi Flegrei (Italy) at 4.0 ka B.P.: Implications for caldera dynamics and future eruptive scenarios<br/><br/>Autori: Isaia, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Marianelli, P.; Dipartimento di Scienze della Terra, Universita` degli Studi di Pisa; Sbrana, A.; Dipartimento di Scienze della Terra, Universita` degli Studi di Pisa<br/><br/>Abstract: The Campi Flegrei caldera is one of the highest riskvolcanic areas on the Earth. Our research documents a150 year-long period of intense volcanism following lessthan 200 years of repose after the Agnano-Monte SpinaPlinian eruption (4.1 ka). The new data show that therenewal of volcanism was preceded by an uplift of a fewtens of meters, triggered by mafic refilling of reservoirs atdepths of 3 km or less. Our studies also indicate for the firsttime the occurrence of contemporaneous eruptions fromat locations in different sectors of the caldera. These resultssuggest that a future eruptive crisis will likely be precededby several meters of caldera-wide uplift in response tomagma movements at depth. The trend of uplift of thecaldera since 1969 may thus represent the unrest expectedbefore a renewal of volcanism within an interval of decadesto centuries. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/2122/5310 Titolo: The occurrence of Mt Barca flank eruption in the evolution of the NW periphery of Etna volcano (Italy)<br/><br/>Autori: Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Del Carlo, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Lo Castro, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; De Beni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Wijbrans, J.; Faculteit Aard-en Levenswetenschappen, Vrije Universiteit, Amsterdam, The Netherlands<br/><br/>Abstract: Geological surveys, tephrostratigraphic study,and 40Ar/39Ar age determinations have allowed us tochronologically constrain the geological evolution of thelower NW flank of Etna volcano and to reconstruct theeruptive style of the Mt Barca flank eruption. Thisperipheral sector of the Mt Etna edifice, corresponding tothe upper Simeto valley, was invaded by the Ellitticovolcano lava flows between 41 and 29 ka ago when the MtBarca eruption occurred. The vent of this flank eruption islocated at about 15 km away from the summit craters, closeto the town of Bronte. The Mt Barca eruption wascharacterized by a vigorous explosive activity that producedpyroclastic deposits dispersed eastward and minor effusiveactivity with the emission of a 1.1-km-long lava flow.Explosive activity was characterized by a phreatomagmaticphase followed by a magmatic one. The geological settingof this peripheral sector of the volcano favors theinteraction between the rising magma and the shallowgroundwater hosted in the volcanic pile resting on theimpermeable sedimentary basement. This process producedphreatomagmatic activity in the first phase of the eruption,forming a pyroclastic fall deposit made of high-density,poorly vesicular scoria lapilli and lithic clasts. Conversely,during the second phase, a typical strombolian fall depositformed. In terms of hazard assessment, the possibleoccurrence of this type of highly explosive flank eruption,at lower elevation in the densely inhabited areas, increasesthe volcanic risk in the Etnean region and widens thealready known hazard scenario. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/2122/5223 Titolo: Insight on recent Stromboli eruption inferred from terrestrial and satellite ground deformation measurements<br/><br/>Autori: Bonaccorso, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Bonforte, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Gambino, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Mattia, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Guglielmino, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Puglisi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Boschi, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia<br/><br/>Abstract: The multi-parametric permanent system (tilt and GPS networks, robotized geodetic station) for monitoring ground deformation at Stromboli volcano was set up in the 1990s and later greatly improved during the effusive event of 2002–2003. Unlike other volcanoes, e.g. Mt. Etna, the magnitude of ground deformation signals of Stromboli is very small and through the entire period of operation of the monitoring system, only two major episodes of deformation, in 1994–1995 and 2000, which did not lead to an eruption but rather pure intrusion, were measured. Similarly to the 2002–2003 eruption, no important deformations were detected in the months before the 2007 eruption. However, unlike the 2002–2003 eruption, GPS and tilt stations recorded a continuous deflation during the entire 2007 eruption, which allowed us to infer a vertical elongated prolate ellipsoidal source, centered below the summit craters at depth of about 2.8 km b.s.l. Due to its geometry and position, this source simulates an elongated plumbing system connecting the deeper LP magma storage (depth from 5 to 10 km) with the HP shallower storage (0.8–3 km), both previously identified by petrologic and geochemical studies. This result represents the first contribution of geophysics to the definition of the plumbing system of Stromboli at intermediate depth. Finally, no deformation due to the plumbing system was measured for a long time after the end of the eruption. Meanwhile, the new terrestrial geodetic monitoring system installed within the Sciara del Fuoco, on the lava fan formed during the eruption, indicated that during the first months after the end of the eruption the ground velocity progressively decreased in time, suggesting that part of the deformation was due to the thermal contraction of the lava flow. Sun, 10 May 2009 00:00:00 GMT