Radar Interferometry for Monitoring Crustal Deformation. Geodetic Applications in Greece

Παπουτσής, Ιωάννης Ε.

dc.contributor.author	Παπουτσής, Ιωάννης Ε.	el
dc.date.accessioned	2014-10-21T08:31:45Z
dc.date.available	2014-10-21T08:31:45Z
dc.date.issued	2014-10-21
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/39261
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.1204
dc.rights	Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by-nc-nd/3.0/gr/	*
dc.subject	Ραντάς	el
dc.subject	Διαφορική Συμβολομετρία	el
dc.subject	Σαντορίνη	el
dc.subject	Τεκτονική	el
dc.subject	Σεισμός Αθήνας	el
dc.subject	Εδαφική Παραμόρφωση	el
dc.subject	Radar Interferometry	en
dc.subject	Santorini	en
dc.subject	Crustal Deformation	en
dc.subject	Athens earthquake	en
dc.subject	Tectonics	en
dc.subject	Volcano	en
dc.title	Radar Interferometry for Monitoring Crustal Deformation. Geodetic Applications in Greece	en
heal.type	doctoralThesis
heal.secondaryTitle	Διαφορική συμβολομετρία ρανταρ για την παρακολούθηση της γήινης παραμόρφωσης. Γεωδαιτικές εφαρμογές στην Ελλάδα.	el
heal.classification	ΧΑΡΤΟΓΡΑΦΗΣΗ	el
heal.language	en
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2014-01-22
heal.abstract	The onset of the new Millennium found remote sensing scientists, geophysicists, geodesists, and engineers equipped with powerful new tools for measuring crustal deformation via Earth Observation. The growing flow of satellite data, along with the development of innovative algorithms and processing chains, have allowed the systematic mapping of surface deformation, pertinent to earthquakes, volcanic eruptions, landslides, and ground subsidence due to manmade activities, leading to the enhancement of our understanding of the manifestation of several geophysical phenomena and the processes that govern them. This dissertation focuses on the use of radar interferometry geodetic techniques for mapping ground displacement in a geophysically active country, Greece. Greece has unique geomorphology, is plagued by frequent earthquakes and contains several active volcanic centers along the Hellenic Arc. Moreover, the capital of Greece, Athens, is a heavily urbanised metropolis in which heavy construction activities have taken place in the last two decades, including works for accommodating the 2004 Olympic Games. Firstly, the catastrophic earthquake (Mw 5.9) which struck Athens on September 7, 1999 is studied. Interferometric stacking is applied to derive the displacement field in Thriasio Pedio, showing significant deformation with the maximum line-of-sight (LOS) subsidence being approximately 6 cm. Then, the deformation pattern is validated using as reference an external data source provided by terrestrial surveying along the Mornos river open aqueduct. It is found that the deviation of the InSAR and leveling subsidence profiles along Mornos, fall entirely within the confidence interval defined for the leveling data. The 2008 Movri earthquake (Mw 6.4) which hit north-west Peloponnese is subsequently investigated with satellite interferometry. DInSAR stacking analysis detects co-seismic motion only in Kato Achaia where the interferogram fringe pattern shows vertical displacement ranging from 3 to 6 cm. Combining this information with in-situ observations from engineers and geologists who visited the area, a dislocation model and historical seismicity records, it is argued by geophysicists that the causal association between ground displacement and increased earthquake damage in the hanging wall of the motion becomes possible not only for pure dip-slip earthquakes but also for strike-slip earthquakes with a small dip-slip component. The thesis also tackles a problem of a purely geodetic nature, the generation of accurate digital elevation models using the state-of-the-art crossinterferometry methodology, by coherently combining ERS and Envisat data on a Tandem mission. The available perpendicular baselines used are not ideal, however DEM reconstruction is successful for two sites in Attica prefecture, exhibiting signi cantly lower local height variations compared to an existing DEM, but with reduced spatial coverage. Additionally, it is confirmed that cross-interferometric coherence increases in agricultural areas with rolling topography, whereas surface and volume decorrelation kick in for mountainous and urban areas respectively. The core part of this research work is the application of multi-interferogram techniques (PSI & SBAS) for the accurate mapping of surface deformation in the wider Athens metropolitan area from 1992 until 2010. Two descending and one ascending ERS and Envisat tracks are processed, generating for the first time LOS ground velocity maps that depict local displacement patterns in the area, with unprecedented accuracy and spatial coverage, even in non-urban areas. These interferometric measurements can serve as a benchmark for future regional geodetic surveys. Furthermore, the multi-track LOS displacement rate fields allows the decomposition of the velocity vectors to their vertical and horizontal components. Results of the time-series analysis indicate that a large area containing the Kifisia municipality was subsidizing in the period 1992-1999 (~ 8 mm/yr) and has been uplifting since 2002 (~ 4 mm/yr). This is attributed to water extraction activities that took place up until late 1995. Since then, Kifisia is on a restoration phase. More importantly, a zoom at Thriasio Pedio shows that there were no subtle vertical crustal deformation signals with noteworthy magnitude prior to the 1999 Athens earthquake. The revealing outcome, however, is the identification of clear zones of horizontal displacement with opposite signs close to the earthquake epicenter. Finally, the surface deformation associated with the recent unrest in the Santorini Volcanic Complex, spanning from January 2011 to February 2012, is presented and discussed. PSI and SBAS are again used producing dense LOS ground deformation maps and the displacement field is compared with GPS observations from ten continuous sites installed on Santorini. Results show a clear and large inflation signal, up to 150 mm/yr in the LOS direction, with a radial pattern outward from the center of the caldera. The deformation inferred from GPS and InSAR is modeled using a Mogi source located north of the Nea Kameni island, at a depth between 3.3 km and 6.3 km and with a volume change rate in the range of 12 million m3 to 24 million m3 per year. The depth and volume change rate characteristics of the best fit Mogi model, along with the declaration of the end of the episode using GPS and InSAR data (estimated to have occurred in late February 2012), leads to the conclusion that Santorini has entered a new era of relative stability, decreasing the probability of an imminent volcanic eruption.	en
heal.abstract	Η διατριβή εστιάζει στη χρήση γεωδαιτικών τεχνικών συμβολομετρίας ραντάρ για τη χαρτογράφηση της μετατόπισης του εδάφους στη βάση πρωτοποριακών ερευνητικών κατευθύνσεων: (1) Η πρώτη κατεύθυνση αφορά στη χρήση και ολοκλήρωση δεδομένων από πολλούς δορυφορικούς αισθητήρες SAR διαφορετικής χρονικής, χωρικής και φασματικής ανάλυσης και διαφορετικών γεωμετριών απεικόνισης. (2) Επεξεργασία δεδομένων SAR χρησιμοποιώντας διάφορες μεθόδους αιχμής, όπως είναι οι τεχνικές σώρευσης χρονοσειρών διαφορικών συμβολογραμμάτων, ενσωματώνοντας και βρίσκοντας συνέργειες ανάμεσα σε συμβατικές μεθόδους διαφορικής συμβολομετρίας και αλγόριμους στοίβαξης συμβολογραμμάτων και μεθοδολογίες σταθερών σκεδαστών. (3) Σε ορισμένες περιοχές μελέτης, οι δορυφορικές γεωδαιτκές μετρήσεις από SAR επιβεβαιώθηκαν με επίγειες παρατηρήσεις από σταθερούς σταθμούς GPS και χωροσταθμίσεις. (4) Έλαβε χώρα επεξεργασία πρωτοφανούς όγκου δεδομένων SAR, δημιουργώντας μια μοναδική γεωβάση με διαχρονικές γεωδαιτικές παρατηρήσεις σε κρίσιμες γεωφυσικά περιοχές. Οι παραπάνω καινοτόμες μέθοδοι εφαρμόστηκαν σε διάφορες περιοχές γεωφυσικού ενδιαφέροντος στην Ελλάδα. Συγκεκριμένα μελετήθηκαν οι σεισμοί της Αθήνας το 1999 και της Μόβρης το 2008, έγινε παραγωγή ψηφιακών μοντέλων εδάφους υψηλής υψομετρικής ακρίβειας με συνδυαστική χρήση δεδομένων ERS και Envisat, χαρτογραφήθηκε η εδαφική παραμόρφωση την Αττική για το διάστημα 1992 - 2010 και τέλος ανιχνεύθηκε και ποσοτικοποιήθηκε η επιφανειακή παραμόρφωση στο ηφαίστειο της Σαντορίνης κατά την πρόσφατη γεωφυσική του αναταραχή το 2011.	el
heal.sponsor	ΕΜΠ	el
heal.advisorName	Παραδείσης, Δημήτριος	el
heal.committeeMemberName	Κοντοές, Χαράλαμπος	el
heal.committeeMemberName	Φράγκος, Παναγιώτης	el
heal.committeeMemberName	Παναγόπουλος, Αθανάσιος	el
heal.committeeMemberName	Γκίκας, Βασίλειος	el
heal.committeeMemberName	Δρακάτος, Γεώργιος	el
heal.committeeMemberName	Παρχαρίδης, Ισαάκ	el
heal.academicPublisher	Σχολή Αγρονόμων και Τοπογράφων Μηχανικών.	el
heal.academicPublisherID	ntua
heal.numberOfPages	255 σ.
heal.fullTextAvailability	true