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Piersanti, Antonio
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Piersanti, Antonio
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antonio.piersanti@ingv.it
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76 results
Now showing 1 - 10 of 76
- PublicationOpen AccessThe 2009 L’Aquila earthquake coseismic rupture: open issues and new insights from 3D finite element inversion of GPS, InSAR and strong motion data(2015-05-15)
; ; ; ; ; ; ; We present a Finite Element inverse analysis of the static deformation field for the Mw= 6.3, 2009 L’Aquila earthquake, in order to infer the rupture slip distribution on the fault plane. An univocal solution for the rupture slip distribution has not been reached yet with negative impact for reliable hazard scenarios in a densely populated area. In this study, Finite Element computed Green’s functions were implemented in a linear joint inversion scheme of geodetic (GPS and InSAR) and seismological (strong motion) coseismic deformation data. In order to fully exploit the informative power of our dense dataset and to honor the complexities of the real Earth, we implemented an optimized source model, represented by a fault plane subdivided in variable size patches, embedded in a high-resolution realistic three-dimensional model of the Apenninic seismo-tectonic setting, accounting for topographic reliefs and rheological heterogeneities deduced from local tomography. We infer that the investigated inversion domain contains two minima configurations in the solution space, i.e. a single- and a double-patch slip distribution, which are almost equivalent, so that the available datasets and numerical models are not able to univocally discriminate between them. Nevertheless our findings suggest that a two high-slip patch pattern is slightly favoured.305 140 - PublicationOpen AccessA relationship between giant earthquakes and core flow instabilities?(2008-12)
; ; ; ; ; ;Cannelli, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Melini, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Piersanti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; Giant earthquakes of exceptional energy release induce large coseismic deformation field, with measured offsets of the order of millimeter recorded by GPS stations at distances of thousand kilometers from the epicenter. The recorded deformation field is just the surface expression of a volume deformation affecting the whole Earth. According to theoretical models of global coseismic deformation, the 2004 Sumatra-Andaman earthquake, which was the second-greatest occurred in the instrumental age, is expected to have affected the core-mantle boundary with static deformations of the order of millimeter over a large area. At the same time, high-resolution core magnetic-field models based on satellite observations evidenced a short-timescale geostrophic fluid acceleration at the top of the core. These anomalies are located in a region corresponding to the Indian ocean and occur in a time window containing the earthquake occurrence. More interestingly, the acceleration pattern is close to the modeled displacement due to earthquake coseismic effects. These evidences suggest us the possible existence of a relationship between giant earthquakes and rapid perturbations in the Earth core dynamics.191 126 - PublicationOpen AccessBreaking the Adriatic Plate: Adjoint 3D Tomography for the Italian Lithosphere(2021-12-13)
; ; ; ; ; ; ; ; ; ; ; ; ;; ; ;; ; ;The evolution and state of geological structure at Earth’s surface is best understood with an accurate characterization of the subsurface. We present high-resolution seismic tomographic images of tectonic and geological structures of the Italian lithosphere. Enhanced accuracy is enabled by state-of-the-art methods, including three-dimensional wavefield simulations in combination with an adjoint-state method. The procedure iteratively improves an initial 3D traveltime tomography model of the region using full waveforms from 163 earthquakes recorded by 412 stations. Model Im25, resulting from 25 iterations, characterizes the subsurface structure in terms of compressional and shear wavespeeds at a resolution corresponding to a minimum period ~10 s. We discuss three primary findings of Im25 model: a) images of the lithospheric structure in Central Italy highlight the role of fluids and gas (CO2) and their correlation with seismicity, b) images of Southern Italy illuminates the plumbing system of Mt. Etna volcano, c) images of the Adriatic plate explore its complex lithosphere and tectonic evolution.82 20 - PublicationOpen AccessItalian Radon mOnitoring Network (IRON): A permanent network for near real-time monitoring of soil radon emission in Italy(2018)
; ; ; ; ; ; ; We introduce the Italian Radon mOnitoring Network (IRON): a new nationwide permanent network for near real-time measurements of soil radon emissions in Italy. Deployed over the last 9 years, presently IRON consists of 26 stations mainly concentrated in the Central- Southern Apennines, but marginally covering the whole Italian peninsula. At present, most IRON stations have recorded radon concen- tration time-series for more than 4-5 years. With a standard sampling interval of about two hours, the whole IRON dataset consists of nearly 440,000 single radon concentration measurements. Here we present the network in terms of sites, installations types and collected time series. The amount of data, together with the systematic methods of measurements, allowed us to evaluate some significant aspects related both to the measurement methodology and to the complex dynamics of soil radon emanations. Two case studies show, respec- tively, how different observational setups impact on the features of the recorded signal, and how observed fluctuations in radon con- centration may be ascribed to geophysical processes taking place at depth in the crust. We discuss the potential suitability of IRON, in order to study the relation between radon variability and the preparation processes of strong earthquakes.500 168 - PublicationOpen AccessImplementing soil radon detectors for long term continuous monitoring(2019-07-14)
; ; ; ; ; ; ; The employment of different instruments for radon continuous measurements within the Italian Radon mOnitoring Network (IRON), mostly INGV, Algade AER and Airthings Corentium instruments, requires a uniform characterization and calibration protocol for the results to be comparable in a rigorous way. A 56 L stainless steel radon chamber with a sensitivity of 0.95 ± 0.01 Bq m-3 per pulse h-1 has been used and validation of Algade AER, Airthings Corentium and Durridge RAD7 radon monitors equipped with solid-state detectors operated at different absolute humidity values has been performed, extending their operative range. Robustness to atmospheric electromagnetic phenomena of INGV and Algade AER instruments has been investigated and, for the former instrument, improved.365 41 - PublicationRestrictedCUBIT and seismic wave propagation based upon the Spectral-Element Method: An advanced unstructured mesher for complex 3D geological media(2008)
; ; ; ; ; ; ;Casarotti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Stupazzini, M.; Department of Earth- and Environmental Sciences, Ludwig-Maximilians-Universitat, Munich, Germany ;Lee, S. J.; Institute of Earth Science, Academia Sinica. Taipei, Taiwan ;Komatitsch, D.; Laboratoire de Modlisation et d’Imagerie en Gosciences UMR 5212, Universit de Pau et des Pays de l’Adour., Pau, France ;Piersanti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Tromp, J.; Seismological Laboratory, California Institute of Technology, Pasadena, California, USA; ; ; ; ; ; ; ; ;Brewer, M. L.Marcum, D.Unstructured hexahedral mesh generation is a critical part of the model- ing process in the Spectral-Element Method (SEM). We present some ex- amples of seismic wave propagation in complex geological models, automati- cally meshed on a parallel machine based upon CUBIT (Sandia Laboratory, cubit.sandia.gov), an advanced 3D unstructured hexahedral mesh genera- tor that offers new opportunities for seismologist to design, assess, and improve the quality of a mesh in terms of both geometrical and numerical accuracy. The main goal is to provide useful tools for understanding seismic phenomena due to surface topography and subsurface structures such as low wave-speed sedimentary basins. Our examples cover several typical geophysical problems: 1) “layer-cake” volumes with high-resolution topography and complex solid- solid interfaces (such as the Campi Flegrei Caldera Area in Italy), and 2) models with an embedded sedimentary basin (such as the Taipei basin in Taiwan or the Grenoble Valley in France).236 31 - PublicationOpen AccessFinite Element Modeling of the Static and Quasi-static Deformation associated with the 2004 Sumatra Earthquake(2007-06-25)
; ; ; ;Volpe, Manuela; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Casarotti, Emanuele; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Piersanti, Antonio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; The great Sumatra-Andaman earthquake of December 26, 2004 was one of the largest earthquakes ever recorded since 1900. The earthquake resulted from complex slip on the fault along the subduction zone where the oceanic portion of the Indian Plate slides under the Eurasian Plate, by the Indonesian island of Sumatra. The direction of convergence of the subducting plate relative to the overriding plate is oriented oblique to the trench axis and the rupture occurred for 1200 km along the interplate megathrust. In the present work we use a new computational FEM strategy to model the co- and post-seismic deformation field associated with the Sumatra earthquake. We are able to study the joint effects of sphericity and 3D geometrical and reological heterogeneities on the investigated observables. The comparison between our synthetic results and the available deformation data will allow us to ascertain if complexities in the physical properties of the medium could play an important role in assessing the deformation field besides source properties.139 355 - PublicationOpen AccessTrade-off between seismic source detail and crustal heterogeneities in spherical 3D finite element modeling: a 2004 Sumatra earthquake case study(2011)
; ; ; ;Volpe, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Melini, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Piersanti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; Finite-element methods are a powerful numerical simulation tool for modeling seismic events, as they allow three-dimensional complex models to be solved. We used a three-dimensional finite-element approach to evaluate the co-seismic displacement field produced by the devastating 2004 Sumatra–Andaman earthquake, which caused permanent deformations that were recorded by continuously operating GPS networks in a region of unprecedented area. Previous analysis of the static displacement fields have focused on the heterogeneous distribution of moment release on the fault plane; our intention here is to investigate how much the presence of crustal heterogeneities trades-off seismic source details. To achieve this aim, we adopted a quite simple source model in modeling the event. The key feature of our analysis is the generation of a complex three-dimensional spherical domain. Moreover, we also carried out an accurate analysis concerning the boundary conditions, which are crucial for finite-element simulations.277 115 - PublicationOpen AccessFEMSA: A finite element simulation tool for quasi-static seismic deformation(2006-12-11)
; ; ; ;Volpe, M.; Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, I-00143 Rome, Italy ;Melini, D.; Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, I-00143 Rome, Italy ;Piersanti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, I-00143 Rome, Italy; ; Modeling postseismic deformation is an increasingly valuable tool in earthquake seismology. In particular, the Finite Element (FE) numerical method allows accurate modeling of complex faulting geometry, inhomogeneous materials and realistic viscous flow, appearing an excellent tool to investigate a lot of specific phenomena related with earthquakes.159 536 - PublicationOpen AccessThe Pollino 2012 seismic sequence: clues from continuous radon monitoring(2016)
; ; ; ; ; The 2012 Pollino (Calabria, Italy) seismic sequence, culminating in the Mw 5.2 earthquake of 25 October 2012, is investigated, exploiting data collected during a long-term continuous radon monitoring experiment performed in the epicentral area from late 2011 to the end of 2014. We analyse data collected both using a phenomenological approach based on quantitative evidence and a purely numerical analysis including the following: (i) correlation and cross-correlation investigations; (ii) an original approach aimed at limiting the impact of meteorological parameters variations on the interpretation of measured radon levels; (iii) a change point analysis; (iv) the implementation of an original detection algorithm aimed at highlighting the connections between radon emission variations and major seismic events occurrence. Results from both approaches suggest that radon monitoring stations can be subject to massive site effects, especially regarding rainfall, making data interpretation harder. The availability of long-term continuous measurements is crucial to precisely assess those effects. Nevertheless, statistical analysis shows a viable approach for quantitatively relating radon emanation variations to seismic energy release. Although much work is still needed to make radon time series analysis a robust complement to traditional seismological tools, this work has identified a characteristic variation in radon exhalation during the preparation process of large earthquakes.238 54