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  • 1
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    FEM inversion of DInSAR data of the 2009 L’Aquila Earthquake (Italy) (2011)
    Details
    Publication Date: 2017-04-04
    Description: Slip distribution on fault planes is usually retrieved by geodetic data assuming the local crust as an elastic, homogeneous and isotropic half-space. However, realistic complexities such as non-homogeneous elastic structure and topographic relief can be handled only by numerical methods. Such elaborated models are computationally expensive and are usually implemented for forward modelling rather than for inversion purposes. On the other hand, spatially dense geodetic data (e.g. DInSAR displacement maps) often reveal complex patterns of coseismic deformation, pointing out the oversimplification of the analytical models. We develop a procedure to perform inversion of geodetic data based on Finite Element (FE) method, accounting for a more realistic description of the Earth crust, e.g. medium heterogeneity, anisotropy, topographic relief. FE computed Green functions are implemented in an inversion framework to constrain the fault slip distribution in complex media. The method is applied to the 2009 L’Aquila earthquake (Mw 6.3). The fault geometry is constrained by three DInSAR maps of coseismic displacement from ENVISAT and COSMO-Skymed satellites. In addition to these re-computed images, we use near-field GPS data. The fault dip is fixed at 50°, in accordance to recently relocated aftershocks of the L’Aquila earthquake. We build a FE model including the fault geometry previously determined and the heterogeneities of the local crust. A linear inversion is performed to constrain the slip distribution in the heterogeneous medium. Results from inversions highlight the non-negligible influence of the medium structure: homogeneous and heterogeneous models show discrepancies in the fault slip distribution values up to 20%.
    Description: Published
    Description: Wien
    Description: 3.1. Fisica dei terremoti
    Description: open
    Keywords: earthquake ; finite element
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 2
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    The Mw 7.9Wenchuan (China) Earthquake: exploring the role of crustal heterogeneities from finite element analysis of DInSAR coseismic deformation (2011)
    Details
    Publication Date: 2017-04-04
    Description: A destructive (Mw 7.9) earthquake struck the Sichuan province (China) on May 12, 2008. The seismic event, the largest in China in more than three decades and referred as the Wenchuan earthquake, ruptured approximately 280 km of the Yingxiu-Beichuan fault and about 70 km of the Guanxian-Anxian fault. Surface effects were suffered over a wide epicentral area (about 300 km E-W and 250 km N-S). The huge earthquake took place within the context of long term uplift of the Longmen Shan range in eastern Tibet. The Longmen Shan fault zone is the main tectonic boundary between the Sichuan basin and eastern Tibet and is characterized by a large topographic relief (from 500m a.s.l. to more than 4000m) and large variations in rheological properties. The coseismic deformation is imaged by a set of ALOS-PALSAR L-band SAR interferograms. We use an unprecedented high number of data (25 frames from 6 adjacent tracks) to encompass the entire coseismic area. The resulting mosaic of differential interferograms covers an overall area of about 340 km E-W and 240 km N-S. The complex geophysical context of Longmen Shan and the variations of the fault geometry along its length can be better handled by means of numerical methods. The fault geometry is constrained by inversions of geodetic data and by taking into account the geological features of eastern Tibet and Sichuan basin. As a result, we build a Finite Element (FE) model consisting of two non planar faults embedded in a non-homogeneous medium with real topography of the area. We develop a procedure to perform inversions of DInSAR data based on FE computed Green functions of the surface displacement field. We retrieve a complex slip distribution on the fault segments in a heterogeneous medium with realistic surface topography.
    Description: Published
    Description: Wien
    Description: 3.1. Fisica dei terremoti
    Description: open
    Keywords: earthquake ; finite element ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 3
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    The 2021 Greece Central Crete ML 5.8 Earthquake: An Example of Coalescent Fault Segments Reconstructed from InSAR and GNSS Data (2022)
    MDPI
    Details
    Publication Date: 2022-11-21
    Description: The ML 5.8 earthquake that hit the island of Crete on 27 September 2021 is analysed with InSAR (Interferometry from Synthetic Aperture Radar) and GNSS (Global Navigation Satellite System) data. The purpose of this work is to create a model with sufficient detail for the geophysical processes that take place in several kilometres below the earth’s surface and improve our ability to observe active tectonic processes using geodetic and seismic data. InSAR coseismic displacements maps show negative values along the LOS of ~18 cm for the ascending orbit and ~20 cm for the descending one. Similarly, the GNSS data of three permanent stations were used in PPK (Post Processing Kinematic) mode to (i) estimate the coseismic shifts, highlighting the same range of values as the InSAR, (ii) model the deformation of the ground associated with the main shock, and (iii) validate InSAR results by combining GNSS and InSAR data. This allowed us to constrain the geometric characteristics of the seismogenic fault and the slip distribution on it. Our model, which stands on a joint inversion of the InSAR and GNSS data, highlights a major rupture surface striking 214◦, dipping 50◦ NW and extending at depth from 2.5 km down to 12 km. The kinematics is almost dip-slip normal (rake −106◦), while a maximum slip of ~1.0 m occurred at a depth of ca. 6 km. The crucial though indirect role of inherited tectonic structures affecting the seismogenic crustal volume is also discussed suggesting their influence on the surrounding stress field and their capacity to dynamically merge distinct fault segments.
    Description: Published
    Description: 5783
    Description: 2T. Deformazione crostale attiva
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: SAR ; GNSS ; interferometry ; source modelling ; 27 September 2021 earthquake ; Crete system faults ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Coupling Flank Collapse and Magma Dynamics on Stratovolcanoes: The Mt. Etna Example from InSAR and GNSS Observations (2024)
    MDPI
    Details
    Publication Date: 2024-01-23
    Description: Volcano ground deformation is a tricky puzzle in which different phenomena contribute to the surface displacements with different spatial–temporal patterns. We documented some high variable deformation patterns in response to the different volcanic and seismic activities occurring at Mt. Etna through the January 2015–March 2021 period by exploiting an extensive dataset of GNSS and InSAR observations. The most spectacular pattern is the superfast seaward motion of the eastern flank. We also observed that rare flank motion reversal indicates that the short‐term contraction of the volcano occasionally overcomes the gravity‐controlled sliding of the eastern flank. Conversely, fast dike intrusion led to the acceleration of the sliding flank, which could potentially evolve into sudden collapses, fault creep, and seismic release, increasing the hazard. A better comprehension of these interactions can be of relevance for addressing short‐term scenarios, yielding a tentative forecasting of the quantity of magma accumulating within the plumbing system.
    Description: Published
    Description: 847
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Keywords: Etna Volcano ; SAR interferometry ; GNSS ; flank collapse ; magma intrusion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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