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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.

The morphostructural setting of Mount Etna sedimentary basement (Italy): Implications for the geometry and volume of the volcano and its flank instability

Mon, 31 Dec 2012 23:00:00 GMT

Title: The morphostructural setting of Mount Etna sedimentary basement (Italy): Implications for the geometry and volume of the volcano and its flank instability Authors: Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Ferrara, V. Abstract: The reinterpretation of more than 2500 subsurface data, consisting of geoelectric and borehole prospecting undertaken at Mount Etna, allows reconstructing the contour map of the sedimentary basement. This reconstruction highlights a complex asymmetric topography due to the inhomogeneous long-term updoming of the region and the interrelationship between the development of the drainage network and flank instability. These different processes have produced a major morphological difference between the eastern sector, characterised by a 17 km-wide horseshoe-shaped depression, and the other flanks formed by palaeovalleys. The origin of the wide horseshoe-shaped depression can be attributed to the large-scale flank instability processes involving the entire continental margin in the Etna offshore. This depression of the Etna basement was generated by a series of coalescent landslides before the beginning of the eruptive activity of the Timpe phase more than 220 ka ago. This wide depression is the main cause of the flank instability that produced the gravitational slope failures of the Valle del Bove about 10 ka ago. Regarding Mt Etna's geometry, we have estimated a total volume of about 532 km3 that was emplaced during the past 330 ka, resulting in an average rate of volcanic output of 0.0016 km3/a. The reconstruction of the temporal variation of the average eruptive rate highlights a drastic increase of volcanism during the last 100 ka in response to the gradual stabilization of the plumbing system in the Etna region that led to the build-up of the composite stratovolcano structure. The data presented in this paper represent the state of knowledge of the sedimentary basement of Etna, which can be used for future studies aimed at developing a detailed understanding of the deep structure of the volcano's unstable flanks.

Trapped seismic fault zone energy recorded by a high-rate GPS station

Thu, 31 Dec 2009 23:00:00 GMT

Title: Trapped seismic fault zone energy recorded by a high-rate GPS station Authors: Avallone, Antonio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Rovelli, Antonio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Ben-Zion, Yehuda; University of Southern California Abstract: The ground motion of the April 6th 2009 Mw 6.3 L'Aquila (Central Italy) earthquake, occurred on a SW-dipping normal fault, was successfully recorded by one of the GPS stations installed near L'Aquila before the seismic event and acquiring with a high sampling rate (10 Hz). These data provide valuable ground displacement time histories in the near source. GPS and strong motion data provided reliable reconstruction of the main features around the source. However, a low frequency (about 1 Hz) nearly-harmonic large oscillation (about 40 cm peak-to-peak) detected at this GPS station 5 s after the beginning of the coseismic dynamic deformation, and spanning about 6.5 s, was not possible to be fit by reliable source modeling. 1 Hz nearly-harmonic oscillations are also observed by a co-located seismological station installed one year after the mainshock. Both the GPS and the seismic stations are located on the eastern slope of the Mt. Ocre ridge, along which runs the the Monticchio-Fossa fault, a shallow and steep NE-dipping antithetic fault bordering the Aterno Valley graben. We have checked that the late large-amplitude coseismic displacement can be generated by energy trapped in this fault. We have obtained satisfactory results by using a line dislocation in a structure consisting in two quarter-spaces separated by vertical fault layers. Our best fit corresponds to a model characterized by a vertical 200 m-wide fault zone with impedance contrasts with respect to the adjacent left and right quarter-spaces of about 17% and 40%, respectively.

Application of the Post-Widder Laplace inversion algorithm INGV CSFI08 to postseismic rebound models

Wed, 30 Apr 2008 22:00:00 GMT

Title: Application of the Post-Widder Laplace inversion algorithm INGV CSFI08 to postseismic rebound models Authors: Cannelli, Valentina; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Melini, Daniele; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Piersanti, Antonio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Spada, Giorgio; Insitute of Physics, University of Urbino, Italy Abstract: The analytic solution of postseismic and postglacial rebound models with Maxwell viscoelastic rheology is usually done in the Laplace domain because the governing equations become formally identical to the elastic case and can be solved with standard linear propagation techniques.

Postseismic deformation modeling of the Aquila earthquake

Mon, 27 Apr 2009 22:00:00 GMT

Title: Postseismic deformation modeling of the Aquila earthquake Authors: Cannelli, Valentina; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Melini, Daniele; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: A model for the postseismic deformation following the 6th Aquila 2009 earthquake.

Impact of Sumatra earthquake on CMB topography and core ellipticity

Tue, 31 Oct 2006 23:00:00 GMT

Title: Impact of Sumatra earthquake on CMB topography and core ellipticity Authors: Cannelli, Valentina; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Melini, Daniele; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Piersanti, Antonio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: Characterization of the global impact of 2004 Sumatra earthquake event through the investigation of its effects on core-mantle boundary (CMB) shape and on the elliptical part of the gravity field (J2)

Distensional Mediterranean and World Orogens

Sat, 31 Dec 2011 23:00:00 GMT

Title: Distensional Mediterranean and World Orogens Authors: Scalera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Editors: Scalera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Cwojdzinski, S. 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.

How do volcanic rift zones relate to flank instability? Evidence from collapsing rifts at Etna

Tue, 18 Sep 2012 22:00:00 GMT

Title: How do volcanic rift zones relate to flank instability? Evidence from collapsing rifts at Etna Authors: Ruch, J.; Dipartimento Scienze Geologiche, Università Roma Tre, Roma, Italy; Pepe, S.; National Research Council (CNR), Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA), Napoli, Italy; Casu, F.; National Research Council (CNR), Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA), Napoli, Italy; Acocella, V.; Dipartimento Scienze Geologiche, Università Roma Tre, Roma, Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Solaro, G.; National Research Council (CNR), Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA), Napoli, Italy; Sansosti, E.; National Research Council (CNR), Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA), Napoli, Italy Abstract: Volcanic rift zones, characterized by repeated dike emplacements, are expected to delimit the upper portion of unstable flanks at basaltic edifices. We use nearly two decades of InSAR observations excluding wintertime acquisitions, to analyze the relationships between rift zones, dike emplacement and flank instability at Etna. The results highlight a general eastward shift of the volcano summit, including the northeast and south rifts. This steadystate eastward movement (1-2 cm/yr) is interrupted or even reversed during transient dike injections. Detailed analysis of the northeast rift shows that only during phases of dike injection, as in 2002, does the rift transiently becomes the upper border of the unstable flank. The flank's steady-state eastward movement is inferred to result from the interplay between magmatic activity, asymmetric topographic unbuttressing, and east-dipping detachment geometry at its base. This study documents the first evidence of steady-state volcano rift instability interrupted by transient dike injection at basaltic edifices.

A pilot GIS database of active faults of Mt. Etna (Sicily): A tool for integrated hazard evaluation

Mon, 31 Dec 2012 23:00:00 GMT

Title: A pilot GIS database of active faults of Mt. Etna (Sicily): A tool for integrated hazard evaluation Authors: Barreca, G.; Università degli Studi di Catania, Dipartimento di Scienze Biologiche, Geologiche ed Ambientali, Sez. Scienze della Terra, Italy; Bonforte, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: A pilot GIS-based system has been implemented for the assessment and analysis of hazard related to active faults affecting the eastern and southern flanks of Mt. Etna. The system structure was developed in ArcGis® environment and consists of different thematic datasets that include spatially-referenced arc-features and associated database. Arc-type features, georeferenced into WGS84 Ellipsoid UTM zone 33 Projection, represent the five main fault systems that develop in the analysed region. The backbone of the GIS-based system is constituted by the large amount of information which was collected from the literature and then stored and properly geocoded in a digital database. This consists of thirty five alpha-numeric fields which include all fault parameters available from literature such us location, kinematics, landform, slip rate, etc. Although the system has been implemented according to the most common procedures used by GIS developer, the architecture and content of the database represent a pilot backbone for digital storing of fault parameters, providing a powerful tool in modelling hazard related to the active tectonics of Mt. Etna. The database collects, organises and shares all scientific currently available information about the active faults of the volcano. Furthermore, thanks to the strong effort spent on defining the fields of the database, the structure proposed in this paper is open to the collection of further data coming from future improvements in the knowledge of the fault systems. By layering additional user-specific geographic information and managing the proposed database (topological querying) a great diversity of hazard and vulnerability maps can be produced by the user. This is a proposal of a backbone for a comprehensive geographical database of fault systems, universally applicable to other sites.