Unit:
Κατεύθυνση Εφαρμοσμένη Γεωλογία - ΓεωφυσικήLibrary of the School of Science
Author:
Gkosios Vasileios
Supervisors info:
Ιωάννης Αλεξόπουλος, Αναπλ. Καθηγητής, Γεωλογίας και Γεωπεριβάλλοντος, Ε.Κ.Π.Α.
Νικόλαος Βούλγαρης, Καθηγητής, Γεωλογίας και Γεωπεριβάλλοντος, Ε.Κ.Π.Α.
Κωνσταντίνος Σούκης, Επίκ. Καθηγητής, Γεωλογίας και Γεωπεριβάλλοντος, Ε.Κ.Π.Α.
Original Title:
Ανάπτυξη πειραματικών διατάξεων γεωσεισμικών και γεωηλεκτρικών τομογραφικών διασκοπικών τεχνικών για τη διερεύνηση σύνθετων γεωλογικών δομών
Translated title:
Development of experimental configurations for geoseismic and geoelectric tomographic imaging techniques, on the investigation of complex geological structure
Summary:
The main purpose of this thesis is to determine the optimal data acquisition and processing parameters of geoelectric and geoseismic tomographic imaging techniques for the investigation of the subsurface structure of complex geological environments.
To this end, two different study areas, characterized by a complex geological structure, were selected, where a detailed recognition of the geological environment and surface structures, geological mapping and applied surface geophysical survey were carried out.
These two areas are characterized by the presence of geological formations of sedimentary, igneous and metamorphic origin, but different geotectonic regimes that led to their present complex structure. In the case of the first study area of “Ano Doliana”, Arcadia, the main cause of the complex subsurface structure was tectonism. In the second study area of “Plaka Kerateas”, Attica, apart from tectonism, another factor leading to the development of the complex subsurface structure was an Upper Miocene granodiorite intrusion and the subsequent contact metamorphism of the surrounding formations.
The applied geophysical survey included the application of electrical resistivity tomography (ERT) and seismic refraction tomography (SRT) of longitudinal waves techniques. The geoelectrical measurements were taken with different arrays and electrode configurations along the same sections. Moreover, various types of seismic sources were used for the seismic measurements, at seventeen (17) shot locations along the geoseismic arrays. For the processing of geoelectrical data, clustered datasets were created resulting in complex geoelectrical plots, thus increasing the depth of investigation and the discriminatory capability. Regarding the seismic data, the processing included: (a) creation of synthetic models (based on the results of the geoelectrical method) and synthetic seismic records to determine the effectiveness and capabilities of the technique. (b) Spectral analysis of the seismic records to determine the optimal seismic source type in these environments and, (c) inversion of the field data to create representative subsurface velocity models.
The results of the two techniques confirmed and successfully delineated the complex subsurface structure that characterizes these two geological environments. The application of the electrical resistivity tomography technique, imposed as the primary geophysical imaging technique in such environments, which in combination with the seismic refraction tomography technique, are the two dominant, high resolution geophysical techniques for the elucidation of complex subsurface structures.
Main subject category:
Science
Keywords:
ERT, SRT, seismic sources, spectral analysis, modelling, Ano Doliana Arkadias, Plaka Kerateas
