DSpace Community:

Curie isotherm depth from aeromagnetic data constraining shallow heat source depths in the central Aeolian Ridge (Southern Tyrrhenian Sea, Italy)

Tue, 19 Mar 2013 23:00:00 GMT

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.

Integrating geologic fault data into tsunami hazard studies

Thu, 18 Apr 2013 22:00:00 GMT

Title: Integrating geologic fault data into tsunami hazard studies Authors: Basili, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Tiberti, M. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Kastelic, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Romano, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Piatanesi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Selva, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Lorito, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: We present the realization of a fault-source data set designed to become the starting point in regional-scale tsunami hazard studies. Our approach focuses on the parametric fault characterization in terms of geometry, kinematics, and assessment of activity rates, and includes a systematic classification in six justification levels of epistemic uncertainty related with the existence and behaviour of fault sources. We set up a case study in the central Mediterranean Sea, an area at the intersection of the European, African, and Aegean plates, characterized by a complex and debated tectonic structure and where several tsunamis occurred in the past. Using tsunami scenarios of maximum wave height due to crustal earthquakes (Mw=7) and subduction earthquakes (Mw=7 and Mw=8), we illustrate first-order consequences of critical choices in addressing the seismogenic and tsunamigenic potentials of fault sources. Although tsunamis generated by Mw=8 earthquakes predictably affect the entire basin, the impact of tsunamis generated by Mw=7 earthquakes on either crustal or subduction fault sources can still be strong at many locales. Such scenarios show how the relative location/orientation of faults with respect to target coastlines coupled with bathymetric features suggest avoiding the preselection of fault sources without addressing their possible impact onto hazard analysis results.

The Volcano-Seismic Clock of the South American Pacific Margin - A Possible First Link Between Natural Disasters Prevention and Expanding Earth

Fri, 30 Nov 2012 23:00:00 GMT

Title: The Volcano-Seismic Clock of the South American Pacific Margin - A Possible First Link Between Natural Disasters Prevention and Expanding Earth Authors: Scalera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Editors: Scalera, Giancarlo; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: A volcano-seismic correlation was for a long time suspected to occur on the Pacific margin of South America. Scalera (2008) using the data available in 2006 in the Smithsonian Institution Catalogue of the volcanic eruptions, has revealed evidence that earthquakes happened into the South-American Wadati-Benio zone – with magnitude greater than 8.4 –are associated to an enhanced rate of volcanic eruptions, but has been impossible to determine the causal chain between the two phenomena. After 2006, the effort of the Smithsonian Institution to improve our knowledge of this region has resulted in a greatly increased completeness of the catalogue, adding the new eruptions for the 2000- 2010 interval, but also an additional 50% of new entries in the list of the Andean volcanoes. The occurrence of the Chilean earthquake of Maule – 27 February 2010 (M=8.8); occurred at five decades from the 1960 quake – has been the occasion to rework all the data searching for additional clues able to indicate a preferred causal direction eruptions-earthquakes or earthquakes-eruptions – or from a third more general cause (e.g. a mantle movements) to both eruptions and earthquakes. This short note discusses the three above-said hypotheses and tries to establish if these results could be useful to the aims of the Civil Protection in the programs of prevention and/or forecasting of natural disasters.

Biogenic/Abiogenic Hydrocarbons Origin - Possible Role of Tectonically Active Belts

Fri, 30 Nov 2012 23:00:00 GMT

Title: Biogenic/Abiogenic Hydrocarbons Origin - Possible Role of Tectonically Active Belts Authors: Scalera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Editors: Scalera, Giancarlo; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Boschi, Enzo; University of Bologna; Cwojdzinski, Stefan; Polish Geological Survey Abstract: The creation of hydrocarbons is linked to tectono-geologic processes and particularly to orogenesis, rifting, overthrusts, erosion, deposition of sediments, deep gas emissions, etc.. Many have claimed the inadequacy of plate tectonics in linearly explain a number of phenomena involved in hydrocarbons generation and geological processes, and many others have defended the synthesis of hydrocarbons starting from inorganic minerals, proposing di erent geochemical processes. In this paper a possible mechanism for production of abiogenic hydrocarbons is proposed, linking it to a previously proposed orogenic isostatic model. While in plate tectonics the cold slab travels in contact with the lithosphere of the continental side, oxidizing materials faced to oxidizing materials, in this model the hightemperature reducing environment of the undepleted mantle rises up and come in contact with the relatively cold oxidizing lithospheric environment. Non-lithostatic overpressures and a number of chemical reactions are then favoured in this sort of tectonic oxidizingreducing pile, leading to a multiple origin of the hydrocarbons. The actual situation along the Italian Apennines orogenic belt seems in accord to the proposed model in which an important role should have the abiogenic hydrocarbons in particular those produced by the tectonic working at the western margin of the Adriatic plate. However, albeit a continuous accumulation of abiogenic hydrocarbons is witnessed by a number of planetary bodies of the Solar system, still no evaluation of the abiogenic/biogenic hydrocarbons rate is possible on our planet.

The Earth Expansion Evidence – A Challenge for Geology, Geophysics and Astronomy

Fri, 30 Nov 2012 23:00:00 GMT

Title: The Earth Expansion Evidence – A Challenge for Geology, Geophysics and Astronomy Authors: Scalera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Boschi, E.; University of Bologna; Cwojdzinski, S.; Polish Geological Survey Editors: Scalera, Giancarlo; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Boschi, Enzo; University of Bologna; Cwojdzinski, Stefan; Polish Geological Survey

Distensional Mediterranean and World Orogens - Their Possible Bearing to Mega-Dykes Active Rising

Fri, 30 Nov 2012 23:00:00 GMT

Title: Distensional Mediterranean and World Orogens - Their Possible Bearing to Mega-Dykes Active Rising Authors: Scalera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Editors: Scalera, Giancarlo; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Boschi, Enzo; University of Bologna; Cwojdzinski, Stefan; Polish Geological Survey Abstract: An overview of the modern progresses of the expanding Earth conceptions as they come out from new data and their possible interpretations is provided in this paper. The starting point of this review is the new detailed 3D distributions of relocated hypocenters laying under orogenic belts. The similarity of the hypocentral patterns under the Tethyan orogenic belts, and under the South American Pacific orogenic margin is considered to be a major font of information on which to build a more realistic global geodynamic model. Clusters and filaments of hypocenters are recognizable instead of regular patterns. These clusters taper downwards, leading to the idea of a deep origin in narrow regions of disturbance, besides other important facts that witness in favour of surfaceward movements of deep material along what can be called "mega-dykes". The outpouring of the material on the surface produces gravitational nappes and their overthrust on the sediments of the preexisting trough, forcing them on a burial path which emulate the subduction process, but without reaching depths greater than 50-70 km. Phenomenons like metamorphism, mixing, migmization, upward transport of fragments of the buried lithosphere etc. are possible at the boundary between uplifting material and down-pushed crust and lithosphere. Additional clues can be collected that confirm the new proposed framework. The astronomical indications of a coseismic displacement of the instantaneous Earth’s rotation axis in the occasion of the great Sumatra (Mw=9.3) and Honshu (Mw=9.0) earthquakes are especially significant because in complete disagreement with the plate tectonics modelled axis shift and in agreement with the shift expected in the new conception. Because of analogous opposite predictions of the length of day variation following the extreme magnitude earthquakes (ΔLOD<0 vs ΔLOD>0), future improvements of the time measurement techniques could allow a final choice between rival geodynamical models.

The Earth Expansion Evidence – A Challenge for Geology, Geophysics, Astronomy and General Knowledge

Fri, 30 Nov 2012 23:00:00 GMT

Title: The Earth Expansion Evidence – A Challenge for Geology, Geophysics, Astronomy and General Knowledge Authors: Scalera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Boschi, E.; University of Bologna; Cwojdzinski, S.; Polish Geological Survey Editors: Scalera, Giancarlo; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Boschi, Enzo; University of Bologna; Cwojdzinski, Stefan; Polish Geological Survey Abstract: The 37th Workshop of the International School of Geophysics held on 4-9 October 2011 in Erice (Sicily, Italy), was a long awaited occasion which allowed to gather the small scientific community of expansionists. Aims, results, discussions and varia umanità of this important event are presented thereafter.

Clues from joint inversion of tsunami and geodetic data of the 2011 Tohoku-oki earthquake

Thu, 26 Apr 2012 22:00:00 GMT

Title: Clues from joint inversion of tsunami and geodetic data of the 2011 Tohoku-oki earthquake Authors: Romano, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Piatanesi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Lorito, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; D'Agostino, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Hirata, K.; Meteorological Research Institute, Japan Meteorological Agency, 1-1 Nagamine, Tsukuba, Ibaraki 305-0052, Japan; Atzori, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Yamazaki, Y.; Department of Ocean and Resource Engineering, University of Hawaii at Manoa, Honolulu, Hawaii, USA; Cocco, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: The 2011 Tohoku-oki (Mw 9.1) earthquake is so far the best-observed megathrust rupture, which allowed the collection of unprecedented offshore data. The joint inversion of tsunami waveforms (DART buoys, bottom pressure sensors, coastal wave gauges, and GPS-buoys) and static geodetic data (onshore GPS, seafloor displacements obtained by a GPS/acoustic combination technique), allows us to retrieve the slip distribution on a non-planar fault. We show that the inclusion of near-source data is necessary to image the details of slip pattern (maximum slip ,48 m, up to ,35 m close to the Japan trench), which generated the large and shallow seafloor coseismic deformations and the devastating inundation of the Japanese coast. We investigate the relation between the spatial distribution of previously inferred interseismic coupling and coseismic slip and we highlight the importance of seafloor geodetic measurements to constrain the interseismic coupling, which is one of the key-elements for long-term earthquake and tsunami hazard assessment.

The tectonic puzzle of the Messina area (Southern Italy): Insights from new seismic reflection data

Fri, 30 Nov 2012 23:00:00 GMT

Title: The tectonic puzzle of the Messina area (Southern Italy): Insights from new seismic reflection data Authors: Doglioni, C.; Dipartimento di Scienze della Terra, Universit`a Sapienza, Roma; Ligi, M.; Istituto di Scienze Marine, CNR, Bologna; Scrocca, D.; Istituto di Geologia Ambientale e Geoingegneria, CNR, c/o Dipartimento di Scienze della Terra, Universit`a Sapienza, Roma; Bigi, S.; Dipartimento di Scienze della Terra, Universit`a Sapienza, Roma; Bortoluzzi, G.; Istituto di Scienze Marine, CNR, Bologna; Carminati, E.; Dipartimento di Scienze della Terra, Universit`a Sapienza, Roma; Cuffaro, M.; Istituto di Geologia Ambientale e Geoingegneria, CNR, c/o Dipartimento di Scienze della Terra, Universit`a Sapienza, Roma; D' Oriano, F.; Istituto di Scienze Marine, CNR, Bologna; Forleo, V.; Dipartimento di Scienze della Terra, Universit`a Sapienza, Roma; Muccini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Riguzzi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia Abstract: The Messina Strait, that separates peninsular Italy from Sicily, is one of the most seismically active areas of the Mediterranean. The structure and seismotectonic setting of the region are poorly understood, although the area is highly populated and important infrastructures are planned there. New seismic reflection data have identified a number of faults, as well as a crustal scale NE-trending anticline few km north of the strait. These features are interpreted as due to active right-lateral transpression along the north-eastern Sicilian offshore, coexisting with extensional and right-lateral transtensional tectonics in the southern Messina Strait. This complex tectonic network appears to be controlled by independent and overlapping tectonic settings, due to the presence of a diffuse transfer zone between the SE-ward retreating Calabria subduction zone relative to slab advance in the western Sicilian side.

Active compressional tectonics, Quaternary capable faults, and the seismic landscape of the Po Plain (N Italy)

Sat, 31 Dec 2011 23:00:00 GMT

Title: Active compressional tectonics, Quaternary capable faults, and the seismic landscape of the Po Plain (N Italy) Authors: Michetti, A.; Università dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Como, Italy; Giardina, F.; Università dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Como, Italy; Livio, F.; Università dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Como, Italy; Mueller, K.; University of Colorado, Department of Geological Sciences, Boulder, CO, USA; Serva, L.; ISPRA, Dipartimento Difesa del Suolo/Servizio Geologico d’Italia, Rome, Italy; Sileo, G.; Università dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Como, Italy; Vittori, E.; ISPRA, Dipartimento Difesa del Suolo/Servizio Geologico d’Italia, Rome, Italy; Devoti, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Riguzzi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Carcano, C.; Burren Resources Petroleum Ltd, Baza Burren, Burun Field, Balkanabat, Turkmenistan; Rogledi, S.; ENI Exploration and Production, San Donato Milanese (Milan), Italy; Bonadeo, L.; Università dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Como, Italy; Brunamonte, F.; Università dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Como, Italy; Fioraso, G.; Istituto di Geoscienze e Georisorse, Consiglio Nazionale delle Ricerche (CNR), Turin, Italy Abstract: It is commonly believed that the Po Plain is an area of low seismic haz- ard. This conclusion is essentially a combination of two factors: (1) the historical record of earthquakes, which shows a relatively small number of events of moderate magnitude, and only two significant earthquakes, which occurred in the Middle Ages; and (2) the lack of ad-hoc research on the geology of earthquakes in this area, as although many studies have highlighted the local Quaternary tectonics, only a very few of them have discussed the observed evidence in terms of seismic hazard. In contrast, the data presented in the present study strongly suggest that the level of earthquake hazard in the Po Plain is comparable to that of the well- known seismic areas of the Apennine range, at least in terms of maxi- mum magnitudes. Indeed, the high population density and the concentration of industrial facilities make the Po Plain today one of the more high-risk areas of the Italian territory. The Po Plain represents the foredeep of two growing mountain belts, the southern Alps and the north- ern Apennines. Recently, modern active tectonics studies have been con- ducted along its margins to the south, along the northern Apennine Piedmont belt, and to the northeast, along the eastern southern Alpine Piedmont belt. However, in the central and western sectors of the Po Plain, where the south-verging western southern Alpine front links up with the north-verging Monferrato, Emilia and Ferrara arcs, the Qua- ternary history of tectonic deformation and faulting are still relatively poorly understood. These lie beneath the relatively flat alluvial surface of the Po River, and provide the evidence for paleoseismicity and the result- ing seismic hazard. In this review, we compile the data from the literature to reassess the style and magnitude of the ongoing crustal deformation and the associated earthquake faulting. This includes detailed informa- tion on historical and instrumental seismicity, extensive subsurface in- formation from the ENI industrial exploration, structural interpretation of three regional seismic reflection profiles, analysis of novel global posi- tioning system data, field mapping at selected key areas, and new paleo- seismological investigations. We show that along the western southern Alpine belt between Lake Garda and Lake Maggiore, the active tectonic setting is characterized by a segmented belt of fault-propagation folds. These are 50 km wide, and are controlled by the growth of out-of-se- quence, 10-to-20-km-long, north and south verging thrusts. Regional global positioning system data show ongoing shortening rates of the order of 1 mm/yr. Quaternary fault slip rates typically range between 0.2 mm/yr and 0.4 mm/yr. Pleistocene shortening is obvious not only along the western southern Alpine outer fronts that are buried beneath the Po Plain, but also along the south Alpine foothills between Brescia and Varese. Similar styles and rates of active folding and thrusting have also been documented along the frontal sector of the northern Apennine arcs, from Torino to Ferrara, and along the base of the Apennine mountain front between Piacenza and Bologna. We selected the Brescia and Como sectors in the western southern Alps and the Monferrato and Mirandola structures in the northern Apennines as examples to illustrate the seismic landscape of the study area, in terms of typical active structural, geo- morphic and paleoseismic features. We argue that the level of earthquake hazard in the Po Plain is comparable to that of the Apennine range. On May 20, 2012, a few days after this review was formally accepted for pub- lication, a M W 5.9 earthquake ruptured the Mirandola structure. The seismic sequence following this mainshock is ongoing, and we have added further information about this event (updated on June 3rd, 2012), which substantially confirms the conclusions arrived at here.