Alessandra Borghi

Alessandra Borghi
National Institute of Geophysics and Volcanology | INGV · Sezione di Bologna

PhD

About

68
Publications
8,871
Reads
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856
Citations
Additional affiliations
February 2021 - March 2021
University of Bologna
Position
  • Instructor
Description
  • Instructor of the course "Fundamental Physics of the Solid Earth" (Satellite Geodesy part) of the 2nd level Master Space missions science, design and applications (SPICES).
November 2018 - present
National Institute of Geophysics and Volcanology
Position
  • Researcher
May 2014 - October 2018
Università Telematica "E-Campus"
Position
  • Research Associate

Publications

Publications (68)
Article
Full-text available
In this work we present and discuss new geodetic velocity and strain-rate fields for the Euro-Mediterranean region obtained from the analysis of continuous GNSS stations. We describe the procedures and methods adopted to analyze raw GPS observations from >4000 stations operating in the Euro-Mediterranean, Eurasian and African regions. The goal of t...
Article
The 2019–2020 Southwest Puerto Rico earthquake sequence ruptured multiple faults with several moderate magnitude earthquakes. Here, we investigate the seismotectonics of this fault system using high-precision hypocenter relocation and inversion of the near-field strong motions of the five largest events in the sequence (5.6≤Mw≤6.4) for kinematic ru...
Article
Full-text available
Plain Language Summary We use a nonstandard method for the detection of microseismicity at depth augmenting the available catalog. The enhanced seismicity distribution is coupled with the observable deformation on a geodetic network of continuous GPS to infer a better comprehension of the earthquake behavior. The earthquake patterns in Central Apen...
Thesis
In the present work, we have carried out the synthetic test to investigate the BSS (Blind Source Separation) methods for the research of GPS time-series. We prepared simulations of residual time series using the Gaussian-white noise and heavy-side step function to represent the discontinuity that is often found and described in the scientific liter...
Article
Full-text available
In 2014, the Jeddah Municipality made a call for an estimate of a centimetric precision geoid model to be used for engineering and surveying applications, because the regional geoid model available at that time did not reach a sufficient precision. A project was set up to this end and dedicated sets of gravity and Global Positioning System (GPS)/le...
Conference Paper
Full-text available
Central Italy magnitude 6+ earthquake sequences in Umbria-Marche 1997, L’Aquila 2009 and Amatrice 2016 highlighted two faulting geometries: high angle normal faulting moderate and shallow seismicity and subhorizontal shear zone with lower magnitude and deeper seismicity. Using waveform matching of foreshocks and aftershocks of the 2009 and 2016 seq...
Chapter
Nowadays, Building Information Modeling (BIM) is a common design approach to support the life cycle of projects in the field of Architecture Engineering Construction (AEC). New constructions’ projects require a BIM modeling to provide digital information within a 3D digital mockup. The main target is to reduce time and cost related to the elaborati...
Article
Full-text available
The analysis of Global Positioning System (GPS) coordinates time series is a valuable tool in quantifying crustal deformations. The longer continuous GPS time series allow estimation of nonlinear signatures. As a matter of fact, besides the linear and periodic behaviors, other relevant signals are present in such time series as the so-called transi...
Poster
Full-text available
The laterally heterogeneous structure of the Antarctic continental lithosphere affects the response to the time-varying cryospheric loads at the surface, and mantle dynamics at depth. So far, knowledge of these complex interactions has been quite sketchy: glacial isostatic adjustment is generally studied by means of layered rheological models, intr...
Article
Full-text available
This paper compares three different methods capable of estimating the deflection of the vertical (DoV): one is based on the joint use of high precision spirit leveling and Global Navigation Satellite Systems (GNSS), a second uses astro-geodetic measurements and the third gravimetric geoid models. The working data sets refer to the geodetic Internat...
Article
Slow-slip events (SSEs) are common at subduction zone faults where large mega earthquakes occur. We report here that one of the best-recorded moderate size continental earthquake, the 2009 April 6 moment magnitude (Mw) 6.3 L'Aquila (Italy) earthquake, was preceded by a 5.9 Mw SSE that originated from the decollement beneath the reactivated normal f...
Article
Full-text available
The world’s most geologically complex Himalayan arc is well known for its tectonic and seismic activities due to the collision of Indian and Eurasian plates. Based on these elements [global positioning system (GPS) deformation measurements, scaling exponent (D) of the tectonic elements and past seismicity] studied here can contribute to better unde...
Poster
Full-text available
I terremoti locali e regionali registrati dalla Rete Accelerometrica Nazionale della DPC e dalle reti OGS ed INGV dal 2008 al 2014 per M > 3 vengono utilizzati per migliorare le conoscenze sulla struttura crostale della Pianura Padana mediante l’analisi delle onde di super cie per periodi compresi tra 4 e 20 s. Il numero di misure di dispersione e...
Conference Paper
Full-text available
In order to properly localise earthquakes and define, especially in tectonically active areas, the seismic risk, there is the necessity to have reliable earth models. Unfortunately, conventional geophysical tomographic methods face the problem of irregular data coverage over the surface of the studied volume, which can produce irregular image resol...
Chapter
Collocation approach has been applied to get a global Moho model in spherical approximation based on a GOCE geopotential model. A simple single layer model, with known density contrast, has been considered and a linearized relationship between the spherical harmonic coefficients of the anomalous potential and those of the Moho depth has been derive...
Article
Full-text available
When the results of geophysical models are compared with data, the uncertainties of the model are typically disregarded. This paper proposes a method for defining the uncertainty of a geophysical model based on a numerical procedure that estimates the empirical auto- and cross-covariances of model-estimated quantities. These empirical values are th...
Article
A local earthquake tomography recently performed down to 300 km depth in the Calabrian Arc region evidenced that the Ionian subducting slab is in-depth continuous beneath the central part of the Arc while detachment of the deep portion of the subducting structure already occurred beneath the edges of the Arc itself. In the present study, seismic to...
Conference Paper
Since the past decade, geodetic techniques are widely used to gain important information for the monitoring and modeling of the deformation of the Earth at different length and time scales. Although the GNSS derived estimates of the Earth crust velocity are becoming more and more reliable, advanced data analysis techniques are needed to recognize g...
Article
DInSAR and GPS data are nowadays currently used in geophysical investigation, e.g. for estimating slip rate over the fault plane in seismogenic areas. This analysis is usually done by mapping the surface deformation rates as estimated by GPS and DInSAR over the fault plane using suitable geophysical models (e.g. the Okada model). Usually, DInSAR ve...
Article
The estimate of the Moho surface in the Italian area has been performed to refine a global Moho model. In fact, at regional scale, the gravity based Moho estimate can benefit from the availability of such a global model. This information can be usefully exploited to remove low frequencies from local gravity data allowing a better detection and inve...
Article
We propose a way to combine GPS and GRACE data for regional scale cross check and validation especially of the most commonly used PREM (Preliminary Earth Reference Model). In form of h and k Love numbers, global PREM is very often used to simulate elastic rebound due to present-day ice mass loss, to derive the mass distribution produced by the obse...
Article
In order to validate the results of geophysical models a common procedure is to compare model predictions with observations by means of statistical tests. A limit of this approach is the lack of a covariance matrix associated to model results, that may frustrate the achievement of a confident statistical significance of the results. Trying to overc...
Presentation
The aim of this study is to estimate a global Moho depth using the GOCE global gravity model GO_CONS_GFC_2_SPW_R2. A simple two-layers model, with known density contrast, has been considered and a linearized relationship between the spherical harmonic coefficient of the anomalous potential Tnm and those of the Moho depth has been derived. In this w...
Article
Full-text available
An innovative approach to seismic hazard assessment is illustrated that, based on the available knowledge of the physical properties of the Earth structure and of seismic sources, on geodetic observations, as well as on the geophysical forward modeling, allows for a time-dependent definition of the seismic input. According to the proposed approach,...
Article
A finite-element thermomechanical model is used to analyse present-day crustal deformation in the surroundings of the Calabrian Arc. The major structural complexities of the Tyrrhenian area are taken into account, along with the rheological properties of the rocks resulting from a thermal analysis. A comparison between the results obtained from a m...
Article
P>A key issue in our understanding of the earthquake cycle and seismic hazard is the behaviour of an active fault during the interseismic phase. Locked and creeping faults represent two end-members of mechanical behaviours that are given two extreme rupturing hazard levels, that is, high and low, respectively. Geophysical and space geodetic analyse...
Conference Paper
Previous works (Agnew, 1992; Langbein et al., 1997; Zhang et al., 1997; Mao et al., 1999; Williams, 2003; Williams et al., 2004; Amiri-Simkoeii et al., 2007) have proved that the daily GPS time series are characterized by coloured noise. The Power Law Noise Process (PLNP) method has been generally adopted to describe the noise of continuous GPS obs...
Article
A key issue in our understanding of the earthquake cycle and seismic hazard is the behaviour of active faults during their interseismic phase, with locked and creeping faults representing two end-members of mechanical behaviours and two extreme rupturing hazard level, i.e. high and low, respectively. Geophysical and space geodetic analyses, within...
Article
We describe a success story at the junction between South-Eastern Alps and external Dinarides that has led to an early deployment of GPS stations prior to the predicted July 12th 2004 moderate size Slovenia Krn Mountain earthquake. The success story consisted in a straightforward integration between a long-lasting lithosphere-scale rock mechanics e...
Article
Full-text available
Airborne gravimetry is a valuable method for measuring gravity over large un-surveyed areas. This technology has been widely applied in Canada, Antarctica and Greenland to map the gravity field of these regions. In 2005, two tests in the Italian area have been performed by ENI in co-operation with the Politecnico di Milano and the Danish National S...
Article
One objective of the ALPS-GPSQUAKENET project was the installation of a permanent GPS array in the Alpine Space. The GPS network - also known as the Geodetic Alpine Integrated Network (GAIN) - was funded by the EU Community Initiative INTERREG IIIB Alpine Space Programme. It consists today of roughly 40 permanent GPS stations covering large parts o...
Article
Airborne gravimetry is an important method for measuring gravity over large unsurveyed areas. This technology has been widely applied in Canada, Antarctica and Greenland to map the gravity fields of these regions and in recent years, in the oil industry. In 2005, two tests in the Italian area were performed by ENI in cooperation with the Politecnic...
Article
The thermomechanic evolution of the lithosphere–upper mantle system during Calabrian subduction is analysed using a 2-D finite element approach, in which the lithosphere is compositionally stratified into crust and mantle. Gravity and topography predictions are cross-checked with observed gravity and topography patterns of the Calabrian region. Mod...
Article
An up to date determination of a high-resolution geoid requires the use of best available databases concerning digital terrain model (DTM), bathymetry, global geopotential model and gravity field. The occasion to revisit methods to validate and merge different data sets has been created by a new project for the determination of a new European Geoid...
Article
Full-text available
This paper presents the results of a blind experiment that is performed using two pairs of dihedral reflectors. The aim of the experiment was to demonstrate that interferometric synthetic aperture radar (InSAR) measurements can indeed allow a displacement time series estimation with submillimeter accuracy (both in horizontal and vertical directions...
Article
We combine Global Positioning System (GPS) measurements with forward modelling of viscoelastic relaxation and after-slip to study the post-seismic deformation of the 1997 Umbria-Marche (Central Apennines) moderate shallow earthquake sequence. Campaign GPS measurements spanning the time period 1999–2003 are depicting a clear post-seismic deformation...
Article
Full-text available
In this paper the latest Italian quasi-geoid estimation in presented. Comparing to the previous version of the quasi-geoid, ITALGEO99, in thus computation new data have been taken into account, relating to gravity and the terrain and sea bed altimetric description. In particular an up-to-date DTM has been realised on the basis of the NASA SRTM 3″ p...
Chapter
In this work we analysed the time series of daily solutions of 4 Italian GPS permanent stations with the aim of investigating the presence of temporal correlations and their impact on the estimation of weekly solution and velocity field precisions. We found that precisions are remarkably lower when temporal correlations are considered; in particula...
Article
Full-text available
[1] We combine aftershock strain mapping, GPS measurements and leveling profiles with forward modeling of viscoelastic relaxation to study the postseismic deformation of the 1997 Umbria-Marche (Central Apennines) earthquake sequence. We explore the feasibility of GPS monitoring of postseismic transients, for the first time in Italy, generated by sh...
Article
Full-text available
The correct estimation of coordinate and velocity precisions is of fundamental importance when GPS permanent stations are used to realize and maintain a reference system and to infer geodynamical interpretations. In particular, using the least squares estimation principle, the reliability of adjustment results is strictly linked to the adopted stoc...
Article
Full-text available
Working Group on Measurements and Methods of Hight Precision Space Geodesy - ASI Research (1998-1999-2000)
Article
Full-text available
The ITALGEO99 quasi-geoid estimate is presented. This gravimetric quasi-geoid has been computed in the area 36° ≤ φ ≤ 47°, 6° ≤ λ ≤ 19° on a 2′ × 2′ regular geographical grid. With respect to the previous ITALGEO95 estimate, new gravity data have been included in the gravity data base (Slovenia area) and a completely revised DTM has been used for t...
Conference Paper
Full-text available
The least-squares collocation method, used to predict or filter a signal, is based on the estimation of the empirical covariance function and the fitting of the empirical values with a proper model function. Generally, with the standard methods on the sphere, we reach a good fitting only up to the first zero of the empirical function. In this work...
Conference Paper
Full-text available
A report on quasi-geoid computations in South America, based on the existing gravity data base collected in the framework of the South America Gravity Project (SAGP) is presented. Two estimation methods will be described. One of these is the standard "remove-restore" technique. The gridding of the residual gravity values (i.e. free air gravity anom...
Article
The collocation method can be fruitfully applied in SST estimation on repeated mission tracks. Some applications have been carried out in the western Mediterranean Sea using ERS1-ERM and TOPEX/POSEIDON data. In this work some refinements of the method are analyzed to obtain improvements in the estimates of the stationary component of the SST in the...

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Projects

Projects (6)
Project
https://zcyphygeodesy.com/en/ Self-developed, Fully Open, and Forever Free! A large Windows package for scientific computing of geophysical geodetic monitoring. Which adopts the scientific uniform numerical standards and analytic compatible geophysical algorithms accurately to compute various tidal and non-tidal effects on various geodetic quantities outside the solid Earth, approach global-reginal load deformation field and temporal Earth’s gravity field, and then quantitatively monitor surface hydrology environment, ground stability variations and geological disasters, in order to promote the collaborative monitoring of multi-geodetic technologies and deep fusion of multi-source heterogeneous geodetic data.
Project
Local gravity geoid computation. Theoretical problems related to the least-squares collocation method applied to the geoid undulation computation.
Project
Gravity data inversion for the knowledge of the depth of the Moho and the definition of 3D models of crustal density.