Study on Lithosphere-Ionosphere Coupling:Investigation of Ionospheric Anomalies as seismic precursors based on GPS measurements acquired in the broader area of Patras Gulf and Ionian Islands

Doctoral Dissertation uoadl:1309012 719 Read counter

Unit:
Τομέας Γεωφυσικής - Γεωθερμίας
Library of the School of Science
Deposit date:
2016-06-28
Year:
2016
Author:
Βλάχου Κωνσταντίνα
Dissertation committee:
Καθηγητής Ευάγγελος Λάγιος (Επιβλέπων), Καθηγητής Παναγιώτης Παπαδημητρίου, Αναπληρωτής Καθηγητής Ανδρέας Τζάνης
Original Title:
Μελέτη Αλληλεπίδρασης Συστήματος Λιθόσφαιρα-Ιονόσφαιρα:Διερεύνηση Ιονοσφαιρικών Ανωμαλιών ως Πρόδρομων Σεισμικών Φαινομένων βάσει GPS μετρήσεων με εφαρμογή στην ευρύτερη περιοχή του Πατραϊκού Κόλπου και Ιονίων Νήσων
Languages:
Greek
Translated title:
Study on Lithosphere-Ionosphere Coupling:Investigation of Ionospheric Anomalies as seismic precursors based on GPS measurements acquired in the broader area of Patras Gulf and Ionian Islands
Summary:
The present thesis aims on observing intense ionospheric variations prior to
strong earthquakes (M 5.8) recently occurred in the seismically active area of
Greece. On one hand, data from permanent CGPS stations, operating continuously
at a frequency of 1 Hz in the broader research area, both inside and outside
each earthquake preparation zone, were used to estimate the vertical component
of Total Electron Content (TEC) in the F2 layer of the Ionosphere. The applied
methodology was based on an algorithm deduced by Electromagnetic Wave
Propagation and Plasma Theory. A statistical analysis of VTEC values, as
estimated over each CGPS station, was additionally carried out during a 15-day
period before and after the occurrence of each seismic event in order to detect
ionospheric disturbances through positive or negative deviations of the
observed VTEC values from the upper or lower limits of their normal rates.
Furthermore, the effect of solar activity on Ionosphere was also considered to
identify whether the observed by CGPS ionospheric variations are associated
with intense solar activity or the occurrence of a large earthquake. For this
reason, the geomagnetic indices (Kp, Ap & Dst) were estimated to determine the
geomagnetic conditions before earthquakes occurred and consequently to ensure
the quiet geomagnetic regime that is favorable for the detection of
seismo-ionospheric effects.
On the other hand, research was focused on studying the geodynamic regime of
the most seismically active zones in Greece. For this purpose, Differential GPS
data from in situ campaign measurements have been acquired and were processed
along with CGPS data to study the crustal deformation patterns of the areas
where strong seismic activity has been occurred during the last decade, such as
the broader area of Patras Gulf and Central Ionian Islands. In addition,
seismological data were used to deduce the seismicity regime of the research
areas.
Consideration of the above aspects have indicated that the 2014 Cephalonia
earthquakes (Mw=6.1 & 5.9) as long as the May 24th 2014 (Mw=6.8) North Aegean
earthquake consist of important cases that need to be further investigated in
order to evaluate the relationship between strong earthquakes and ionospheric
anomalies. Serious seismo-ionospheric indications were also found a few days
prior to the June 8th 2008 NW Peloponnese earthquake (Mw=6.4) and the March
25th 2007 Cephalonia earthquake (Mw= 5.6). While, less obvious
seismo-ionospheric effects were detected on i) the January 6th 2008 Leonidio
earthquake (Mw= 6.0), ii) the July 15th 2008 SSW Rodeos earthquake (Mw= 6.3),
iii) the June 2013 earthquakes (Mw=6.1 & 5.8) to the south of Crete.
Furthermore, regarding the above mentioned seismic events, strong ground
deformation mainly on the horizontal components was detected at the nearest to
each earthquake epicenter area CGPS stations, indicating that the extent of
earthquake preparation zone in the Lithosphere is of the same order of
magnitude with the disturbed due to seismic activity ionospheric area.
Keywords:
Ionospheric Anomalies, Lithosphere-Ionosphere Coupling, Seismo-Ionospheric Precursors, Total Electron Content (TEC), GPS Measurements
Index:
No
Number of index pages:
0
Contains images:
Yes
Number of references:
357
Number of pages:
657
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