1,721,199 research outputs found
Space–time evolution of crustal deformation related to the Mw 6.3, 2009 L'Aquila earthquake (central Italy) from principal component analysis inversion of GPS position time-series
No full textIn this work, we present a study of the coseismic and post-seismic crustal deformation associated to the Mw 6.3, 2009 April 6 L'Aquila earthquake from the analysis of GPS displacement time-series. We use a principal component decomposition-based inversion method to study the space- and time-dependent evolution of slip on faults without any a priori assumption on the model used to characterize the temporal evolution of crustal deformation. The method adopted allows us to account for the initial post-seismic deformation in estimating the coseismic displacements, in a consistent manner for the whole GPS network. We use elastic dislocation theory and a least-squares procedure to invert for the slip distribution on the mainshock fault (Paganica fault) and a second fault (Campotosto fault), where a Mw 5.2 aftershock occurred on April 9. The geometries for these faults are obtained from a singular value decomposition of precisely relocated aftershocks. We find that the use of complex fault geometries is not justified by the GPS observations available. An inversion that accounts for post-seismic slip to occur on both the Paganica and Campotosto faults provides a better fit to the GPS time-series observations, than using only the Paganica fault segment, at a 95 per cent confidence level. Within our resolution, afterslip regions do not migrate over time and are localized on fault patches that are approximately complementary to those of coseismic slip. We find that the position of some relevant afterslip patches is different if the inversion is performed assuming a fixed rake or not. We estimate the parameter a – b of rate- and state-dependent friction on those fault regions accommodating afterslip that are robustly characterized in our inversions. We find values of the order of 10−3, which is near the transition from potentially unstable to nominally stable friction. These results are in agreement with laboratory measurements performed on typical rocks of the L'Aquila region
The coseismic ground deformations of the 1997 Umbria-Marche earthquakes: a lesson for the development of new GPS networks.
No full textAfter the occurrence of the two main shocks Mw=5.7 (00.33 GMT) and Mw=6.0 (09:40 GMT) on September
26, 1997, which caused severe damage and ground cracks in a wide area of the Umbria Marche region, the Istituto
Nazionale di Geofisica in cooperation with the Istituto Geografico Militare Italiano set out to detect the coseismic
ground deformation and reoccupied the available geodetic monuments placed across the epicentral area,
belonging to the first order Italian GPS network IGM95 and to the Tyrgeonet network.
The comparison between the pre and post-earthquakes coordinate set, the latter obtained from the surveys performed
in the early days of October 1997 in the Umbria Marche earthquake area, showed maximum displacements
values at the closest stations to the epicentres, up to 14.0±1.8 and 24.0±3.0 cm in the horizontal and vertical
components, respectively. The availability of the IGM95 stations allowed geodetic data to be translated into
relevant geophysical results. For the first time in Italy, the evaluation of post-earthquake coordinates at 13 vertices
provided, the estimation of a significant deformation field associated with a seismic sequence.
Unfortunately, the same actions could not be applied to the October 14, 1997, Mw=5.6 Sellano earthquake,
whose epicentre was located a few tens of km south of the previous ones, due to a lack of available geodetic vertices
of Tyrgeonet and IGM95 networks in the surroundings of the epicentral zone. This fact, which prevented
the estimation of coseismic deformation and seismic source modelling for this earthquake, clarified the need to
set up tailor made GPS networks devoted to geophysical applications, able to capture a possible coseismic signal,
but also interseismic and post-seismic signals, at the surface of the Earth’s crust at the scale of the expected
magnitudes and fault length. Here we show and discuss the development of the Discrete GPS and Continuous
GPS (CGPS) networks in the Italian region started since the early 1990s, which greatly increased after the
1997 Umbria Marche earthquakes, and the insights gained from this action which can be also integrated as Global
Observing Strategy to monitor our Environment from Earth and Space
Coastal retreat and marine flooding scenario for 2100: A case study along the coast of Maddalena peninsula (southeastern Sicily)
No full textANZIDEI M., SCICCHITANO G., TARASCIO S., DE GUIDI G., MONACO C., BARRECA G., MAZZA G., SERPELLONI E. & VECCHIO A., Coastal retreat and marine flooding scenario for 2100: a case study along the coast of Maddalena Peninsula (southeastern Sicily). (IT ISSN 0391-9838, 2018). The coastal area of southeastern Sicily (Italy) is undergoing weak land subsidence, heavy coastal retreat, land flooding and exposed to severe storms associated with high-waves, also in consequence of the global sea level rise, which is expected to raise even more that 1 m by 2100 AD depending on different estimates. This value will be even larger in subsiding coasts, entailing widespread environmental changes, coastal retreat, marine flooding and loss of land, which will be subtracted to human activities. To understand the impact of rising sea level on the coast of Maddalena Peninsula, near the town of Siracusa, we realized a very high resolution Digital Terrain Model (DTM) through aerial photogrammetric surveys, obtained by Unmanned Aerial Vehicles (UAV) on which we projected the expected coastline for 2100 AD. Here we show a detailed marine flooding scenario for 2100, as generated from: i) high resolution DTM, ii) rate of land subsidence from GPS data and iii) predicted sea level projections from the IPCC AR5 reports (RCP2.6 and RCP8.5). Our analysis estimates a maximum relative sea level rise at 0.20 m and 0.65 m for 2050 AD and 2100 AD, respectively for AR 8.5 scenario. The increased sea levels will cause relevant morphological changes to the investigated coast with a maximum beach retreat of 27 m and a loss of land of 7400 m2, affecting building integrity and people safety
Assetto organizzativo e forme di gestione per progetti
No full textSi propone non solo quale manuale di aggiornamento teorico sui modelli più avanzati di project management ma anche come strumento di lavoro immediatamente utile per quanti vogliano implementare nelle organizzazioni dell'healthcare nuovi processi di eccellenza fondati su metodologie rigorose ed "evidenze di efficacia" in grado di rispondere alla domanda di cura di una società sempre più complessa e dinamica
Microplate kinematics, strain accumulation and geodetic fault slip rates along the Sicily-Calabria segment (southern Italy) of the Nubia-Eurasia plate boundary from the analysis and modeling of dense GPS networks.
No full textMicroplate kinematics, strain accumulation and geodetic fault slip rates along the Sicily-Calabria segment (southern Italy) of the Nubia-Eurasia plate boundary from the analysis and modeling of dense GPS networks
Crustal Velocity and Strain-Rate fields in Italy and Surrounding Regions: New Results From the Analysis of Permanent and Non- Permanent GPS Networks.
No full textA new geodetic velocity solution for Italy and surrounding areas, obtained from the analysis of continuous and survey-mode Global Positioning System observations collected between 1991 and 2002, is presented
Data analysis of permanent GPS networks in Italy and surrounding regions:application of a distributed processing approach
No full textThe procedures used to combine into a uniform velocity solution the observations of more than 80
continuous GPS stations operating in the central Mediterranean in the 1998-2004 time interval. are describe
ACTIVE FAULTS IN THE INNER NORTHERN APENNINES: A MULTIDISCIPLINARY REAPPRAISAL
Full text linkThe recent seismic events in Garfagnana (January 2013 Mw 4.8) and Lunigiana (June 2013 Mw 5.1) have drawn new attention by the geological community on the seismotectonic problems of the internal segment of the northern Apennines, its seismogenic sources and related surface expressions, i.e. active faults. The long term to recent geological evolution of the Apennines has been characterized by contractional tectonics in the foreland, accompanied by extensional structures in the internal domain (Elter et al., 1975; Meletti et al., 2000; Carminati and Doglioni, 2012). This kinematic setting is still active today as documented by the crustal deformation given by GPS analysis (Bennett et al., 2012; Faccenna et al., 2014) and seismological data (INGV).
Within this tectonic frame our work focuses on a revision of geological, geomorphological, geodetic, and seismological (instrumental and historical) data, with the aim to present a reappraisal of active faults of the internal Apennines North of the Arno river. We present a revision of the structural and morphological characteristics of the active fault systems, as well as the kinematics and strain rate estimates. They represent a new frame for an improvement of the current Ithaca (ISPRA) as well as DISS (INGV) catalogues with some utilities for the MS local projects. Finally, this work allows a better understanding of the seismotectonics of a region which in 1920 hosted the Fivizzano EQ, with an estimated Mw 6.5 similar to the main shock of the 2016 Central Italy seismic sequence
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