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Caramanna G.,University of Nottingham | Voltattorni N.,Istituto Nazionale di Geofi sica e Vulcanologia | Mercedes Maroto-Valer M.,University of Nottingham
Greenhouse Gases: Science and Technology | Year: 2011

Developing reliable detection and monitoring techniques for underwater CO 2 seepage and its effects on the marine environment is important for a wide range of topics; for example: volcanic surveillance, risk assessment of potential leakages from sub-seabed CO 2 storage sites, and to forecast the effects of ocean acidifi cation. A novel approach is to use areas where natural release of CO 2 is present as 'field-laboratories' for validation of CO 2 monitoring techniques and procedures. One such area was identifi ed close to the volcanic island of Panarea (Italy). Here, CO 2 seeps from the seafl oor in shallow water allowing scuba divers to collect the needed data. Moreover, the coastal setting allows use of small boats for the marine operations, thus strongly reducing the costs. The applied study techniques examined are mainly sampling methods for free and dissolved gases, direct measurement of the CO 2 fl uxes, pH measurement along the water column, and verifi cation of the impact of CO 2 on the local environment. From these fi rst results, the submarine degassing area of Panarea can be realistically considered a natural laboratory where it is possible to test and validate detection methods for the prompt identifi cation of potential seepage from sub-seabed CO 2 storage areas. The particularly favorable environment permits the use of simplifi ed logistics, thus reducing the costs of the research to almost negligible values if compared with any high-seas operation. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd. Source

Etiope G.,Istituto Nazionale di Geofi sica e Vulcanologia | Etiope G.,Babes - Bolyai University | Schoell M.,GasConsult International Inc.
Elements | Year: 2014

Abiotic gaseous hydrocarbons comprise a fascinating, but poorly understood, group of Earth fluids generated by magmatic and gas-water-rock reactions that do not directly involve organic matter. At least nine different inorganic mechanisms, including Fischer-Tropsch type reactions, occur over a wide range of temperatures. Trace amounts (typically parts per million by volume) are formed in volcanic and geothermal fluids, but considerable amounts of methane, reaching 80-90 vol%, are now recognized in an increasing number of sites in Precambrian crystalline shields and serpentinized ultramafi c rocks. Surface manifestations of abiotic gas related to serpentinization release gas directly to the atmosphere in ways that are similar to seepages of ordinary biotic gas from petroliferous areas. Abiotic methane is more widespread than previously thought. It also likely exists in sites undergoing active serpentinization and may be present in petroleum systems in the vicinity of serpentinized rocks. Source

Porreca M.,Istituto Nazionale di Geofi sica e Vulcanologia | Cifelli F.,Third University of Rome | Soriano C.,CSIC - Institute of Earth Sciences Jaume Almera | Giordano G.,Third University of Rome | And 3 more authors.
Geology | Year: 2014

Submarine felsic volcanoes are dominated by hyaloclastic piles hundreds of meters thick, the origin of which, in terms of how and when they form, is far from being completely understood. Here we present a study of the thermal remanent magnetization of the Miocene high-K dacitic El Barronal hyaloclastites (Cabo de Gata, Spain), showing that their formation is dominated by in situ fragmentation with small or negligible transportation and/or rotation of different clasts after their formation. Data indicate that fragmentation progressed down to 210-390 °C, well below the glass-transition temperature estimated at 560-750 °C depending on the water content of the high-K dacite. Hence, hyaloclastite fragmentation in thick lavas may occur over most of the cooling history, as a result of the progressive access of sea water toward the lava interior by development of a complex network of contraction fractures. © 2013 Geological Society of America. Source

Turtu A.,University of Chieti Pescara | Satolli S.,University of Chieti Pescara | Maniscalco R.,University of Catania | Calamita F.,University of Chieti Pescara | Speranza F.,Istituto Nazionale di Geofi sica e Vulcanologia
Journal of Geophysical Research: Solid Earth | Year: 2013

We report on a paleomagnetic study of the southern sector of the Olevano-Antrodoco-Sibillini (OAS) thrust front, which corresponds to the southern limb of the Northern Apennines (Italy) orogenic salient. A lively debate has developed regarding the oroclinal/progressive-arc versus non-rotational nature of the OAS, which has been alternatively interpreted as a dextral strike-slip fault, dextral transpressive fault, or frontal to oblique ramp that reactivated pre-existing Jurassic normal faults. Here, we document the paleomagnetism, integrated with biostratigraphic and structural data, of 52 new sites from both the OAS hanging wall and footwall. On the basis of 39 retained sites, we find a peculiar pattern of tectonic rotations along the OAS thrust that evidences four rotational domains. The thrust footwall is characterized by a southern domain that undergoes an approximately 30° counterclockwise rotation with respect to the stable foreland, and an approximately nonrotated domain. The data from the hanging wall indicate the occurrence of a dextral strike-slip component along the southern sector of the OAS thrust supported by a strong clockwise rotation close to the NE-SW lateral ramp, which rapidly fades 1 km from the thrust front. A slight but significant CW rotation observed in the remaining sites from the hanging wall confirms the progressive nature of the OAS, and its structural position as the southern limb of the Northern Apennines salient. Our detailed paleomagnetic study is crucial in discriminating between progressive-arc- and strike-slip-related components in the main curved orogenic front of the Northern Apennines. ©2013. American Geophysical Union. All Rights Reserved. Source

Ongaro T.E.,Istituto Nazionale di Geofi sica e Vulcanologia | Widiwijayanti C.,Nanyang Technological University | Clarke A.B.,Istituto Nazionale di Geofi sica e Vulcanologia | Clarke A.B.,Arizona State University | And 3 more authors.
Geology | Year: 2011

Volcanic lateral blasts are among the most spectacular and devastating of natural phenomena, but their dynamics are still poorly understood. Here we investigate the best documented and most controversial blast at Mount St. Helens (Washington State, United States), on 18 May 1980. By means of three-dimensional multiphase numerical simulations we demonstrate that the blast front propagation, fi nal runout, and damage can be explained by the emplacement of an unsteady, stratifi ed pyroclastic density current, controlled by gravity and terrain morphology. Such an interpretation is quantitatively supported by large-scale observations at Mount St. Helens and will infl uence the defi nition and predictive mapping of hazards on blast-dangerous volcanoes worldwide. © 2011 Geological Society of America. Source

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