Monitoring time-dependent deformation patterns through geodetic techniques

Mandler, Eugenio (2023) Monitoring time-dependent deformation patterns through geodetic techniques, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Il futuro della terra, cambiamenti climatici e sfide sociali, 35 Ciclo. DOI 10.48676/unibo/amsdottorato/10786.
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In this thesis we focus on the analysis and interpretation of time dependent deformations recorded through different geodetic methods. Firstly, we apply a variational Bayesian Independent Component Analysis (vbICA) technique to GPS daily displacement solutions, to separate the postseismic deformation that followed the mainshocks of the 2016-2017 Central Italy seismic sequence from the other, hydrological, deformation sources. By interpreting the signal associated with the postseismic relaxation, we model an afterslip distribution on the faults involved by the mainshocks consistent with the co-seismic models available in literature. We find evidences of aseismic slip on the Paganica fault, responsible for the Mw 6.1 2009 L’Aquila earthquake, highlighting the importance of aseismic slip and static stress transfer to properly model the recurrence of earthquakes on nearby fault segments. We infer a possible viscoelastic relaxation of the lower crust as a contributing mechanism to the postseismic displacements. We highlight the importance of a proper separation of the hydrological signals for an accurate assessment of the tectonic processes, especially in cases of mm-scale deformations. Contextually, we provide a physical explanation to the ICs associated with the observed hydrological processes. In the second part of the thesis, we focus on strain data from Gladwin Tensor Strainmeters, working on the instruments deployed in Taiwan. We develop a novel approach, completely data driven, to calibrate these strainmeters. We carry out a joint analysis of geodetic (strainmeters, GPS and GRACE products) and hydrological (rain gauges and piezometers) data sets, to characterize the hydrological signals in Southern Taiwan. Lastly, we apply the calibration approach here proposed to the strainmeters recently installed in Central Italy. We provide, as an example, the detection of a storm that hit the Umbria-Marche regions (Italy), demonstrating the potential of strainmeters in following the dynamics of deformation processes with limited spatio-temporal signature

Tipologia del documento
Tesi di dottorato
Mandler, Eugenio
Dottorato di ricerca
Settore disciplinare
Settore concorsuale
Parole chiave
GNSS, strainmeter, borehole strainmeter, strainmeter calibration, aseismic deformations, post-seismic relaxation, independent component analysis, hydrological related deformations, transient deformations, slow deformations
Data di discussione
19 Giugno 2023

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