http://hdl.handle.net/2122/193 2013-05-22T08:56:48Z http://hdl.handle.net/2122/8669 Title: Curie isotherm depth from aeromagnetic data constraining shallow heat source depths in the central Aeolian Ridge (Southern Tyrrhenian Sea, Italy) Authors: De Ritis, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Ravat, D.; Department of Earth and Environmental Sciences, University of Kentucky; Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Chiappini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The Salina, Lipari, and Vulcano volcanic ridge and the surrounding sea sectors (Aeolian Archipelago, Southern Tyrrhenian Sea, Italy) are characterized by vents responsible for a recent (<40 ka—1889/1890 AD) effusive and explosive subareal activity and repeated, 56 to 7 ka in age, submarine explosive eruptions from source areas located between Lipari and Vulcano. A spectral depth estimation of the magnetic bottom using a fractal method on aeromagnetic data from Vulcano, Lipari, and Salina volcanic ridge allows us to constrain the Curie isotherm depth. The elevated portion of the isotherm is between 2 and 3 km below Salina and Vulcano and about 1 km below Lipari. The Curie depth results in the context of other geological and geophysical evidence suggest that the rise of the Curie isotherm is mainly due to the occurrence of shallow heat sources such as magma ponds and associated hydrothermal systems. The short-wavelength magnetic anomaly field reflects magnetic contrasts from highly magnetized volcanic bodies, low-magnetization sediments, and hydrothermally altered rocks. Borehole temperature data verify the Curie temperature derived from the magnetic methods on the island of Vulcano.We conclude that the whole Vulcano, Lipari, and Salina volcanic ridge is active and should be monitored. 2013-03-19T23:00:00Z http://hdl.handle.net/2122/8610 Title: Trioctahedral micas in xenolithic ejecta from recent volcanism of the Somma-Vesuvius (Italy): crystal chemistry and genetic inferences. Authors: Balassone, G.; Dipartimento di Scienze della Terra, Università “Federico II”, via Mezzocannone 8, I-80134 Napoli, Italy; Scordari, F.; Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari, via Orabona 4, I-70125 Bari, Italy; Lacalamita, M.; Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari, via Orabona 4, I-70125 Bari, Italy; Schingaro, M.; Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari, via Orabona 4, I-70125 Bari, Italy; Mormone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Piochi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Petti, C.; Dipartimento di Scienze della Terra, Università “Federico II”, via Mezzocannone 8, I-80134 Napoli, Italy; Mondillo, N.; Centro Museale “Musei delle Scienze Naturali”, Università “Federico II”, via Mezzocannone 8, I-80134 Napoli, Italy Abstract: This study reports the first crystal chemical database resulting from a detailed structural investigation of trioctahedral micas found in xenolithic ejecta produced during the AD 1631, 1872 and 1944 eruptions, three explosive episodes of recent volcanic period of Vesuvius volcano (Southern Italy). Three xenolith types were selected: metamorphic/metasomatic skarns, pyrometamorphic/hydrothermally altered nodules and mafic cumulates. They are related to different magma chemistry and effusive styles: from sub-plinian and most evolved (AD 1631 eruption) to violent strombolian with medium evolution degree (AD 1872 eruption) to vulcanian-effusive, least evolved (AD 1944 eruption) event, respectively. Both xenoliths and micas were investigated employing multiple techniques: the xenoliths were characterized by X-ray fluorescence, inductively-coupled plasma-mass spectrometry, optical microscopy, X-ray powder diffraction, and quantitative energy-dispersive microanalysis; the micas were studied by electron probe microanalysis and single crystal X-ray diffraction. The mica-bearing xenoliths showvariable texture and mineralogical assemblage, clearly related to their different origin. Based on the major oxide chemistry, only one xenolithic sample falls in the skarn compositional field fromthe Somma-Vesuvius literature, some fall close to the skarns and cumulate fields, others plot close to the syenite/foidolite/essexite field. A subgroup of the selected ejecta does not fall or approach any of the compositional fields. Trace and rare earth element patterns show some petrological affinity between studied xenoliths and erupted magmas with typical Eu, Ta and Nb negative anomalies. Strongly depleted patterns were detected for the 1631 metamorphic/metasomatic skarns xenoliths. Three distinct mica groups were distinguished: 1) Mg-, Al-rich, low Ti-bearing, low to moderate F-bearing varieties (1631 xenolith), 2) Al-moderate, F- and Mg-rich, Ti-, Fe-poor varieties (1872 xenolith), and 3) Al-, Ti- and Fe-rich, F-poor phases (1944 xenolith). All the analyzed mica crystals are 1Mpolytypes with the expected space group C2/m. Micas from xenoliths of the 1631 Vesuvius eruption are phlogopites characterized by a combination of low extent of oxy-type and variable extent OH−→F− substitutions, as testified by the range of F concentration (from ~0.20 to 0.80 apfu). Micas from xenoliths of the 1872 Vesuvius eruption exhibit structural peculiarities typical of fluorophlogopites, i.e. OH−→F− substitution is predominant. Micas from the xenolith of the 1944 Vesuvius eruption display features typical of oxy-substituted micas. The variability of the crystal chemical features of the studied micas is consistentwith the remarkable variation of their host rocks. Micas from1631 nodules are related to metasomatic, skarn-type environment, deriving from the metamorphosed wall-rocks hosting the magma reservoir. The fluorophlogopites from the 1872 xenoliths testify for strongly dehydrated environmental conditions compared to those of the 1631 and 1944 hosts. Finally, magma storage condition at depth, associated to a decreasing aH2O may have promoted major oxy-type substitutions in 1944 biotites. 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8609 Title: Enhanced crystal fabric analysis of a lava flow sample by neutron texture diffraction: A case study from the Castello d’Ischia dome Authors: Walter, J. M.; Mineralogisch-Petrologisches Institut, Universität Bonn, Poppelsdorfer Schloss, D-53115, Bonn,; Iezzi, G.; Dipartimento di Ingegneria e Geologia (INGEO), Università G. d’Annunzio, Chieti, Italy; Albertini, G.; Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Università Politecnica delle Marche,; Gunther, M. E.; Department of Geological Sciences, University of Idaho, Moscow, Idaho, USA; Piochi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Jansen, E.; Mineralogisch-Petrologisches Institut, Universität Bonn, Bonn, Germany; Fiori, F.; Di.S.C.O., Sez. di Biochimica, Biologia e Fisica, Università Politecnica delle Marce, Ancona, Italy Abstract: The crystal fabric of a lava has been analyzed for the first time by neutron texture diffraction. In this study we quantitatively investigate the crystallographic preferred orientation of feldspars in the Castello d’Ischia (Ischia Island, Italy) trachytic exogenous dome. The crystallographic preferred orientation was measured with the monochromatic neutron texture diffractometer SV7 at the Forschungszentrum Jülich in Germany and a Rietveld refinement was applied to the sum diffraction pattern. The complementary thin section analysis showed that the three-dimensional crystal shape and the corresponding shape preferred orientation are in agreement with the quantitative orientation distributions of the neutron texture data. The (0k0) crystallographic planes of the feldspars are roughly parallel to the local flow bands, whereas the other corresponding pole figures show that a pivotal rotation of the anorthoclase and sanidine crystals was active during the emplacement of this lava dome. In combination with scanning electron microscopy investigations, electron probe microanalysis, XRF, and X-ray diffraction, the Rietveld refinement of the neutron diffraction data indicates a slow cooling dynamic on the order of several months during their crystallization under subaerial conditions. Results attained here demonstrate that neutron texture diffraction is a powerful tool that can be applied to lava flows. 2013-01-30T23:00:00Z http://hdl.handle.net/2122/8597 Title: Experimental Evidence of a Non-Extensive Statistical Physics Behavior of Electromagnetic Signals Emitted from Rocks Under Stress up to Fracture. Preliminary Results Authors: Vallianatos, F.; Technological Educational Institution of Crete, Laboratory of Geophysics and Seismology, Chania, Crete, Greece; Nardi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Carluccio, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Chiappini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The application of mechanical stress on a rock sample can induce electromagnetic emissions. Such emissions can be detected experimentally and in principle could be used as precursors of the upcoming failure. Using experimental observations of stress-induced electromagnetic emissions (SIEME), we apply the concepts of non-extensive statistical physics (NESP) to the time intervals between consecutive SIEME. The application of NESP is appropriate to systems such as fracture-induced effects, where non-linearity, long-range interactions and scaling are important. We find that the SIEME energy release distribution and the inter-event time distribution reflect a sub-extensive system with thermodynamic q-values of the order of qE = 1.67 and qτ ≈ 1.7, respectively. 2012-05-31T22:00:00Z http://hdl.handle.net/2122/8596 Title: Innovative Seismoeletromagnetic Research at the front of the Hellenic Arc Authors: Makris, J. P.; Dept. of Electronics, Technological Educational Institute of Crete, Chania, Greece; Chiappini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Nardi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Carluccio, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Rigakis, H.; Dept. of Electronics, Technological Educational Institute of Crete, Chania, Greece; Hloupis, G.; Dept. of Electronics, Technological Educational Institute of Athens, Athens, Greece; Fragkiadakis, K.; Dept. of Electronics, Technological Educational Institute of Crete, Chania, Greece; Pentaris, F.; Dept. of Electronics, Technological Educational Institute of Crete, Chania, Greece; Saltas, V.; Dept. of Natural Resources & Environment, Technological Educational Institute of Crete, Chania, Greece; Vallianatos, F.; Dept. of Natural Resources & Environment, Technological Educational Institute of Crete, Chania, Greece Abstract: Taking into account the complex nature and rarity of strong seismic events, as well as the form multiplicity and timing variety of possible preseismic signatures, the predominant view of the scientific community still seems nowadays to lean against earthquake prediction, especially the short-term one. On the other hand, seismoelectromagnetic (SEM) research appears to be a promising approach to earthquake prediction research. In this context, the project TeCH-SEM [Technologies Coalescence for Holistic Seismoelectromagnetic Research (Lithosphere-Atmosphere-Ionosphere Coupling)] aims to establish an integrated approach to SEM investigation, by developing and implementing novel-innovative technologies for the study of pre-seismic electric, magnetic and electromagnetic signatures in a broadband spectrum (ULF-ELF-VLF-LF-HF). In this framework, at the natural laboratory of the seismically active south- and south-western part of the Hellenic Arc (broader region of Crete) is being developed a permanent network of ULF-ELF seismoelectromagnetic stations featuring novel design that provides real-time telemetry, extended autonomy, light-weight and small-size but robust and powerful datalogging and self-diagnostics for reliable, long-term operation. This network is complemented by the simultaneous deployment of an innovative ELF-VLF seismoelectromagnetic telemetric network that will attempt to detect, in real conditions, VLF electromagnetic transients that have been repeatedly observed in the laboratory to be emitted from rock samples with various lithologies subjected to fracture under uniaxial compression. Both networks, it is anticipated to remain in operation for many years. 2013-04-06T22:00:00Z http://hdl.handle.net/2122/8342 Title: A new biaxial apparatus integrated within a pressure vessel to test the physical properties of brittle rock: the state-of-the-art Authors: Di Stefano, Giuseppe; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Collettini, Cristiano; Universita' Perugia, Italy; Carpenter, Brett; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Mollo, Silvio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Romeo, Giovanni; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Scarlato, Piergiorgio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Tesei, Telemaco; Universita' Perugia, Italy; Vinciguerra, Sergio; Universita' Torino, Italy Abstract: A main goal of the European Research Council, Starting Grant, GLASS (InteGrated Laboratories to investigate the mechanics of ASeismic vs Seismic faulting), is to develop a prototype rock deformation biaxial apparatus to examine the physical properties of brittle rocks. Two layers of fault rock are sandwiched between three steel block by a normal load applied using a horizontal oil-dynamics piston. A vertical oil-dynamics piston pushes the internal rock sample of the sandwich in order to slide at constant velocity. With GLASS we are going to build-up a confining pressure around the rock samples under load stress (tri-axial mode) and to measure the fluid flow properties of the rock during the deformation. Working in tri-axial mode with a fluid circulation, the machine is able to measure and to characterize frictional properties of faults on the sample for a wide spectrum of realistic conditions. We have concurrently been working to improve the control and the acquisition system for having a machine very flexible and easy to use for several applications and capable to detect different signals on the rock during frictional sliding in a fluid-rich environment with the goal of comparing these signals to those observed in nature. We began designing the servo controlled machine in October 2010 and have recently installed the apparatus in the HP-HT lab at the INGV in Rome. First tests of this biaxial apparatus confirm the main target of the project. 2012-08-15T22:00:00Z http://hdl.handle.net/2122/8159 Title: Volcanic edifice weakening via decarbonation: A self-limiting process? Authors: Mollo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Heap, M. J.; CNRS; Iezzi, G.; Università di Chieti; Hess, K.-U.; Ludwig Maximilians Universität; Scarlato, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Dingwell, D. B.; Ludwig Maximilians Universität Abstract: The inherent instability of volcanic edifices, and their resultant propensity for catastrophic collapse, is a constant source of volcanic risk. Structural instability of volcanic edifices may be amplified by the presence of carbonate rocks in the sub-volcanic strata, due to the debilitating response of carbonates to thermally-induced alteration. Nonetheless, decarbonation reactions (the primary weakening mechanism), may stall when the system becomes buffered by rising levels of a reaction product, carbon dioxide. Such thermodynamic stalling might be inferred to serve to circumvent the weakness of volcanic structures. However, the present study shows that, even when decarbonation is halted, rock physical properties continue to degrade due to thermal microcracking. Furthermore, as a result, the pathways for the escape of carbon dioxide are numerous within a volcanic edifice. Therefore, in the case of an edifice with a subvolcanic sedimentary basement, the generation of carbon dioxide via decarbonation is unlikely to hinder its impact on instability, and thus potentially devastating flank collapse. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8158 Title: Heterogeneous nucleation mechanisms and formation of metastable phase assemblages induced by different crystalline seeds in a rapidly cooled andesitic melt Authors: Mollo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Iezzi, G.; Università di Chieti; Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Cavallo, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Scarlato, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: Pt-capsules loaded with a Pt-coil and two crystalline seeds immersed into an andesitic melt were rapidly cooled from 1300 to 1100 °C with a rate of 3 °C/min at atmospheric pressure and air oxygen fugacity. Results show that the Pt-coil does not induce any heterogeneous crystallization process as well as iron diffusion process from the melt into the platinum substrate. In contrast, the presence of crystalline seeds in a solidifying andesitic melt significantly alters the phase assemblage, composition and texture of the new-forming crystals in response to a heterogeneous nucleation mechanism and the formation of metastable phases. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8027 Title: Sequential integrated inversion of tomographic images and gravity data: an application to the Friuli area (Northeastern Italy) Authors: Bressan, G.; Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Cussignacco (UD), Italy; Gentile, G. F.; Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Cussignacco (UD), Italy; Tondi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; de Franco, R.; Consiglio Nazionale delle Ricerche, Ist. Dinamica dei Processi Ambientali, Milano, Italy; Urban, S.; Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Cussignacco (UD), Italy Abstract: The three-dimensional pattern of elastic moduli (bulk modulus, Young modulus, shear modulus) of the upper crust (0-10 km depth) has been determined in the Friuli area (north-eastern Italy) from the 3D Vp, Vp/Vs and density structures. Firstly, 3D Pwave velocity and P to S velocity ratio were modeled by joint inversion for hypocentres and velocity structure. Then, we apply the tomographic inversion method of Sequential Integrated Inversion (SII) to recover the three dimensional density structure. The pattern of the elastic moduli is characterized by marked lateral and depth variations that reflect the geologic-structural heterogeneity of the area, produced by the superposition of several tectonic phases with different orientations of the principal axes of stress. The bulk (K), Young (E) and shear (G) moduli image a high rigidity body with an irregular shape, at 4-8 km depth. The body is characterized by G ≥ 3.2·1010 N·m-2, K ≥ 6.8·1010 N·m-2 and E ≥ 8.4·1010 N·m-2 and is associated to platform limestones and dolomitic rocks. The seismicity is mainly located along the sharp variations of the moduli pattern, in or adjacent to high rigidity zones. The most severe earthquakes (ML between 4.5 and 6.4), occurred in the study area from 1976 to the present day, are located in a transition zone from high to low rigidity patterns. Our interpretation is that the elastic moduli variations, closely related to variability in rock mechanical properties, influence the occurrence of earthquakes by processes of stress concentrations. The values of the elastic moduli recently obtained from laboratory measurements on the main lithologic units fall in the middlehigh range of the values obtained with the present investigation. Keywords: Seismic tomography, gravity anomalies, seismicity, elastic moduli, Friuli, NE Italy 2012-05-31T22:00:00Z http://hdl.handle.net/2122/7898 Title: Relating seismic velocities, thermal cracking and permeability in Mt. Etna and Iceland basalts Authors: Vinciguerra, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: and columnar basalt from Seljadur (Iceland). Measurements were made in a servo-controlled steady-state-flow permeameter at effective pressures from 5–80 MPa, during both increasing and decreasing pressure cycles. Selected samples were thermally stressed at temperatures up to 900 1C to induce thermal crack damage. Acoustic emission output was recorded throughout each thermal stressing experiment. At low pressure (0–10 MPa), the P-wave velocity of the columnar Seljadur basalt was 5.4 km/s, while for the Etnean lava flow basalt it was only 3.0–3.5 km/s. On increasing the pressure to 80 MPa, the velocity of Etnean basalt increased by 45%–60%, whereas that of Seljadur basalt increased by less than 2%. Furthermore, the velocity of Seljadur basalt thermally stressed to 900 1C fell by about 2.0 km/s, whereas the decrease for Etnean basalt was negligible. A similar pattern was observed in the permeability data. Permeability of Etnean basalt fell from about 7.5 10 16m2 to about 1.5 10 16m2 over the pressure range 5–80 MPa, while that for Seljadur basalt varied little from its initial low value of 9 10 21m2. Again, thermal stressing significantly increased the permeability of Seljadur basalt, whilst having a negligible effect on the Etnean basalt. These results clearly indicate that the Etnean basalt contains a much higher level of crack damage than the Seljadur basalt, and hence can explain the low velocities (3–4 km/s) generally inferred from seismic tomography for the Mt. Etna volcanic edifice 2004-12-31T23:00:00Z