Morphotectonic analysis of the East Anatolian fault zone (E. Turkey) using remote sensing techniques

The transform Arabian/Anatolian plate boundary is at the origin of active tectonic structure elements that initiate large and destructive earthquakes. The aim of this thesis is to improve our knowledge and understanding of the fault behavior and deformation remarks by analyzing surface deformation along the East Anatolian Fault (EAF) that is a morphologically very distinct and seismically active left-lateral strike-slip fault that extends for ~400 km forming the Arabian/Anatolian plate boundary in southeastern Turkey. Together with its conjugate the North Anatolian Fault (NAF), the EAF helps accommodate westward escape of the Anatolian plate from the Arabian/Eurasian collision zone. In this thesis, we study morphotectonics and tectonic activity of the EAF and its splay Adıyman Fault (AdF) using the most important tectonic geomorphology indexes and analyzing different satellite images within the Arabian/Anatolian plates deformation zone. The core parts of the thesis focus on the study of morphotectonic indexes along the EAF, examining the geological offsets along the Erkenek Segment of the EAF through analyzing ASTER satellite images, relative tectonic activity assessment of the AdF, and geological and tectonic mapping along the AdF using Landsat 8 satellite images. The methods used in this thesis work are divided into two parts; the first part describes the importance of the tectonic geomorphology applications as a very useful tool to examine the interplay between tectonic and surface processes that shape the landscape in regions of active deformation and at time scales ranging from days to millions of years. It also presents a review of the most effective morphotectonic indexes (e.g., Mountain front Sinuosity; valley-floor with to valley floor-height; Hypsometric analysis) that are used to evaluate the tectonic activity along the study region. The second section gives a brief view about the application of remote sensing techniques in geology and tectonics and how the techniques have a great power to assess the different tectonic features and trace the structural elements along any active zone. Also, it presents the characteristics of the different satellite data (ASTER and Landsat 8 (OLI)) with the revision of the different method that we used in this study (e.g. Band Ratio Composite and Minimum Noise Fraction Analysis). The morphotectonic features along the East Anatolian Fault (EAF) are examined for the first time to provide insights into the nature of landscape development and better understanding of variations in tectonic activity and fault evolution. Several geomorphic indices, namely mountain front sinuosity, valley-width to valley-height ratio, stream length-gradient index, basin asymmetry factor, drainage density, and hypsometric analysis are obtained from digital elevation models. We show that mountain front sinuosity varies from 1.01 to 1.46 on five segments. The mean ratio of valley-width to valley-height along the five segments ranges from 0.11 to 1.32, which is well correlated with the mountain front sinuosity values. The stream length-gradient index values are between from 50 and 350 along the studied segments. Analysis of the basin asymmetry factor of 18 catchments gives values from 1.88 to 26.25 are examined along the study fault zone and we present the basin asymmetry factor with values from 1.88 to 26.25. The drainage density values of the studied catchments range from 3.5 to 5.6. Finally, the hypsometric analysis index of the 18 catchments records high, intermediate, and low relative tectonic activity. The results show that all geomorphic indices are remarkably uniform along the entire fault length, thus implying that its development was essentially coeval along its length, and supporting the view that the present-day Arabian/Anatolian plate boundary (delimited by the EAF) jumped eastwards from the Malatya-Ovacik Fault Zone at ~3 Ma. This is in a good agreement with the nearly uniform geological offsets and the present-day slip rate of ~10 mm/yr along the entire fault as determined by GPS measurements. The Erkenek Segment is one of the most active and prominent splays of the East Anatolian Fault. To reveal any potential geological offset geology along the AdF is refined by remote sensing techniques. This is because, mapping the geology at high spatial resolution along this segment with conventional mapping techniques is highly challenging due to the complex tectonics and the abundant number of different lithological units of varying spatial extent. Therefore, in this study, we applied image spectral rationing techniques by using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data along the Erkenek Segment. Images created with band ratios with 1/3-1/9-3/9, 7/3-1/7-3/5 and 9/5-5/3-3/1 are found to be remarkably useful for detailed lithological mapping and hence detecting the geological offsets along this section of the fault. Thus, these ASTER band-ratio images can be used for the lithological mapping along the whole EAF and on other regions in the world with similar lithological and geomorphological conditions. Geomorphic indices that include mountain-front sinuosity, valley floor width-to-valley height ratio, catchment asymmetry factor, hypsometric integrals and curves, and drainage density are calculated to evaluate the relative tectonic activity along the Adıyaman fault. Each geomorphic index is classified into three classes and averaged to define an index for relative tectonic activity (RTA) to allow the Adıyaman Fault to be divided into categories of low, intermediate and high RTA. The results confirm that the Adıyaman Fault is an active fault with intermediate Quaternary tectonic activity, suggesting that it is of minor importance in accommodating plate boundary deformation, consistent with recent crustal motions determined by GPS studies. Nevertheless, it is worthwhile to note that the Adıyaman Fault still poses a significant seismic hazard for the region despite its relatively lower tectonic activity. Independent Component Analysis (PCA and ICA) and Minimum Noise Fraction Analysis (MNFA) techniques of the Landsat 8 are applied to study the Adıyaman Fault. It is shown that the lithologic units, fault patterns, and morphological and structural features can be mapped highly accurately by using spectral-matching techniques in regions where rocks are well exposed. Inspection of all possible band combinations indicates that PCA 134 and 231, and ICA 132 band combinations give the best false-color composite images for identifying the rock units and contacts. Analysis of MNFA band combinations shows that MNFA 521 band combination also is robust for discriminating the rock units particularly Quaternary clastic units (colluvium/alluvium). MNFA band 1 alone provides the best image to trace the tectonic and structural elements in the study area. The new up-to-date lithologic map of the Adıyaman Fault that we produce upon to the interpretation of processed OLI images reveals several river channels offset and beheaded by the Adıyaman Fault, verifying its Quaternary activity. This study demonstrates that, when used with the OLI data, the PCA, ICA, and MNFA are very powerful for lithological and structural mapping in actively deforming tectonic zones, and hence can be applied to other regions elsewhere in the world where the climate is arid to semi-arid, and the vegetation cover is scarce. In generally this study presents the help of the tectonic geomorphology and remote sensing applications to evaluate the tectonic activities of a major plate boundary fault and a minor fault within the Arabian/Anatolian deformation zone. Improving our tectonic understanding of the active regions requires accurate tectonic measurements and data analysis. It so important to link the morphotectonic analysis with the different surface displacements, slip rates, and major seismic events in order to create a complete scenario about the deformation story of the active regions. Also, the new developed remote sensing methods with high-resolution images are required to go deep and gain the most benefits of applying these techniques for geology and tectonics purposes.