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  • 1
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    Strain rate relaxation of normal and thrust faults in Italy (2013)
    Oxford University Press
    Details
    Publication Date: 2013-10-09
    Description: We find that geodetic strain rate (SR) integrated with the knowledge of active faults points out that hazardous seismic areas are those with lower SR, where active faults are possibly approaching the end of seismic cycle. SR values estimated from GPS velocities at epicentral areas of large historical earthquakes in Italy decrease with increasing elapsed time, thus highlighting faults more prone to reactivation. We have modelled an exponential decrease relationship between SR and the time elapsed since the last largest earthquake, differencing historical earthquakes according to their fault rupture style. Then, we have estimated the characteristic times of relaxation by a non-linear inversion, showing that events with thrust mechanism exhibit a characteristic time (~ 990 yr) about three times larger than those with normal mechanism. Assuming standard rigidity and viscosity values we can infer an average recurrence time of about 600 yr for normal faults and about 2000 yr for thrust faults.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 2
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    Strain rate relaxation of normal and thrust faults in Italy (2013)
    Oxford University Press
    Details
    Publication Date: 2013-08-22
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Royal Astronomical Society.
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  • 3
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    The brittle-ductile transition as the switch of earthquakes: applications for seismic prediction (2012)
    Details
    Publication Date: 2021-01-27
    Description: The brittle-ductile transition (BDT) separates the lower crust where deformation occurs in steady-state regime, from the upper crust where it is rather dominated by stick-slip. The fault hangingwall above BDT accumulates elastic energy during the interseismic period, without significant evidence of surface strain rate Faults activate in areas of high strain rate gradients along the segments with lower strain rates Fluid discharge varies as a function of the tectonic setting The phenomenology gives insights for the parameters to be monitored in earthquake forecasting
    Description: Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC) within the INGV-DPC 2007-2009 agreement(project S1), Sapienza University and CNR-Eurocores-TopoEurope.
    Description: Unpublished
    Description: Brisbane Australia
    Description: 3.2. Tettonica attiva
    Description: open
    Keywords: brittle-ductile transition ; L' Aquila 2009 earthquake ; Emilia 2012 earthquake ; geodetic strain rate ; fault activation ; magnitude ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 4
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    Electromagnetic propagation features of ground-penetrating radars for the exploration of Martian subsurface (2007)
    European Association of Geoscientists & Engineers
    Details
    Publication Date: 2021-06-07
    Description: In this work, the effects of magnetic inclusions in a Mars-like soil are considered with reference to the electromagnetic propagation features of ground-penetrating radars (GPRs). Low-frequency and time-domain techniques, using L-C-R meters and TDR instruments, respectively, are implemented in laboratory experimental set-ups in order to evaluate complex permittivity and permeability and wave velocity for different scenarios of a dielectric background medium (silica) with magnetic inclusions (magnetite). Attenuation and maximum detection ranges have also been evaluated by taking into account a realistic GPR environment, which includes the transmitting/receiving antenna performance and the complex structure of the subsurface. The analysis and the interpretation of these results shed new light on the significant influence of magnetic inclusions on the performance of Martian orbiting and rover-driven GPRs.
    Description: Published
    Description: 5-11
    Description: reserved
    Keywords: ground-penetrating radars ; Martian subsurface ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Sumatra earthquake and Earth rotation (2006)
    Details
    Publication Date: 2017-04-04
    Description: The giant earthquake of December 26 2004 off the west coast of northern Sumatra is likely to have affected Earth rotational parameters. A preliminary analysis of data obtained by Satellite Laser Ranging technique evidenced a step discontinuity of (1.5±0.4) mas in the instantaneous pole path in correspondence with the earthquake occurrence. Since a step-like temporal dependence is not compatible with the action of an earthquake on the inertia tensor, we test the hypothesis that the effect isnít due to the excitation associated with the seismic rupture but instead to the water mass redistribution associated with the tsunami occurred after the earthquake. In order to quantify this effect, we used a synthetic numerical tsunami model to compute the excitation function associated with the tsunami wave propagation and therefore we compute the associated variation of the instantaneous pole path.
    Description: INGV
    Description: Unpublished
    Description: Vienna, Austria
    Description: open
    Keywords: Sumatra ; Tsunami ; Rotation ; 04. Solid Earth::04.03. Geodesy::04.03.02. Earth rotation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
    Format: 850832 bytes
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  • 6
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    Postseismic stress diffusion associated with Sumatra earthquake (2007)
    Details
    Publication Date: 2017-04-04
    Description: The giant megathrust occurred on 26th December 2004 off the west coast of northern Sumatra perturbated the stress field configuration over a wide area surrounding the event source. By means of a viscoelastic spherical model of global postseismic deformation and a new computational finite elements package (FEMSA) we perform an analysis of the stress diffusion following the earthquake near and far from the Sunda trench. We evaluated the stress changes due to the Sumatra earthquake by projecting the Coulomb stress over the sequence of aftershocks taken from various catalogues in a time window spanning about two years and then we considered the possibility that the Sumatra event could have affected subsequent events very far from the source.
    Description: Unpublished
    Description: Vienna - Austria
    Description: open
    Keywords: stress diffusion ; fault interaction ; finite elements ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
    Format: 5504639 bytes
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  • 7
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    Data Analysis of Permanent GPS networks in Italy (2009)
    Details
    Publication Date: 2017-04-04
    Description: Starting from 2004, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) set up a dense GPS network, called RING (Rete Integrata Nazionale GPS) in Italy in order to improve the knowledge of the geodynamics and tectonic processes. Due to the complexity of the tectonic behaviour in the area, the INGV also arranged the data analysis of all the permanent sites available in the Italian region. We will present time series and velocity fields obtained with two different processing software (GAMIT and BERNESE), analyzing the complete data set from 1998 to 2008 of over 300 sites. The processing is performed adopting a distributed session approach, with more than 10 clusters, sharing common stations, each of them consisting of about 40 stations. Daily loosely constrained solutions are routinely produced for each cluster and the velocity fields are obtained by stacking the daily normal equations rigorously. Residuals and differences between the two solutions will be presented and discussed. The comparison of the two geodetic solutions is an important tool to validate the results and to isolate systematic errors induced by the analysts and it is the first step to obtain a consensus solution of the Italian region.
    Description: Unpublished
    Description: Vienna - Austria
    Description: 1.9. Rete GPS nazionale
    Description: open
    Keywords: GPS ; Italian Permanent Networks ; RING ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 8
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    An algorithm for the search of homogeneous strain-rate fields (2009)
    Details
    Publication Date: 2017-04-04
    Description: The aim of this paper is to describe the theoretical fundamentals and the main features of a software suitably implemented to estimate the strain-rate tensor from continuous GPS data. Current softwares developed for geophysical applications generally estimate or compute bi-dimensional strain, since this is the most requested use. On the contrary, this software allows for a three-dimensional estimate of the strain-rate tensor. It accounts for all the significant GPS velocities and estimates the strain-rate components by the least squares method starting from the hypothesis of one homogeneous strain-rate field. An initial field has to be defined by at least 4 sites which pass the chi-squared test on the strain-rate homogeneity. The developed algorithm automatically searches for sites belonging to this initial homogeneous field, starting from the site nearest to the barycentre of the first 4 sites and proceeding until a user-defined limit distance. Each time a site is added, the homogeneity of the whole field is suitably tested by a number of statistic tests. In this work the algorithm has been also applied to some areas of geophysical interest.
    Description: Unpublished
    Description: Vienna - Austria
    Description: 1.9. Rete GPS nazionale
    Description: open
    Keywords: Strain-Rate ; GPS ; Statistical Tests ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Present day crustal deformation of the Italian peninsula observed by permanent GPS stations (2010)
    Details
    Publication Date: 2017-04-04
    Description: Italian penisula is a crucial area in the Mediterranean region to understand the active deformation processes along Nubia-Eurasia plate boundary. We present the velocity and strain rate fields of the Italian area derived from continuous GPS observations of more than 300 sites in the time span 1998-2009. The GPS networks were installed and managed by different institutions and for different purposes; altogether they cover the whole country with a mean inter-site distance of about 50 km and provide a valuable source of data to map the present day kinematics of the region. The data processing is performed by BERNESE software ver. 5.0, adopting a distributed session approach, with more than 10 clusters, sharing common stations, each of them consisting of about 40 stations. Daily loosely constrained solutions are routinely produced for each cluster and then combined into a network daily loose solution. Subsequently daily solutions are transformed on the chosen reference frame and the constrained time series are fitted using the complete covariance matrix, simultaneously estimating site velocities together with annual signals and sporadic offsets at epochs of instrumental changes. In this work we provide an updated detailed picture of the horizontal and vertical kinematics (velocity maps) and deformation pattern (strain rate maps) of the Italian area. The results show several crustal domains characterized by different velocity rates and styles of deformation.
    Description: Published
    Description: Vienna (Austria)
    Description: 1.9. Rete GPS nazionale
    Description: open
    Keywords: GPS permanent networks ; Italian area ; strain rate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Current geodetic deformation in the South Africa region (2009)
    Details
    Publication Date: 2017-04-04
    Description: We present a preliminary velocity field of the African continent derived from continuous GPS observations from 2004 to 2008. The aim of our work is to investigate the strain-rate pattern along the East Africa rift, in particular along the boundary of the two African plates (the Nubian and the Somalian) and in the South Africa region. We have processed GPS data in a time window spanning four years, i.e. from 2004 to 2008, involving IGS, TrigNet (a network of permanent GPS stations distributed throughout South Africa) and other sporadic sites. The GPS data have been processed by means of the Bernese software version 5.0 dividing the entire African network into two clusters. The combination of daily loosely constrained solutions provides the time series of about a hundred of permanent GPS sites mainly located in the African continent. Site velocities together with periodic signals, eventual steps, have been estimated simultaneously using the complete covariance matrices. Finally the velocity field has been expressed in the ITRF2005 reference frame. This investigation gives a preliminary idea of the velocity field and strain-rate pattern we can expect in the South-East Africa region, the observed deformations being barely measurable, below a few mm/year.
    Description: Unpublished
    Description: Vienna - Austria
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: open
    Keywords: GPS ; TrigNet Network ; South Africa ; Deformation ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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