Vedat Toprak

Vent distribution and its relation to regional tectonics, Cappadocian Volcanics, Turkey

Abstract The distribution of polygenetic and monogenetic volcanoes of the Neogene-Quaternary Cappadocian Volcanic Province (CVP) is analyzed to investigate the relationship between vent location and regional tectonic lineaments. Two fault systems exist in the province. One system (Miocene-Quaternary Tuzgolu–Ecemis system) is oblique, whereas the other system (late Miocene–Pliocene CVP system) is parallel to the long axis of the CVP. The polygenetic volcanoes are aligned parallel to the second system but concentrate around the major faults of the first system. Regional offsets are proposed along the first fault system based on the distribution of the polygenetic volcanoes. The monogenetic volcanoes group into five geographically distinct clusters. In the western part of the CVP, the monogenetic cones are aligned parallel to the CVP system, whereas in the central part the cones are fed by dikes injected along the recent fractures of the Tuzgolu–Ecemis system. In the eastern part, the monogenetic cones form along the radial fractures of the Erciyes composite volcano.

Neotectonic and volcanic characteristics of the Karasu fault zone (Anatolia, Turkey): The transition zone between the Dead Sea transform and the East Anatolian fault zone

AbstractThe Karasu Rift (Antakya province, SE Turkey) has developed between east-dipping, NNE-striking faults of the Karasu fault zone, which define the western margin of the rift and westdipping, N-S to N20°-30°E-striking faults of Dead Sea Transform fault zone (DST) in the central part and eastern margin of the rift. The strand of the Karasu fault zone that bounds the basin from west forms a linkage zone between the DST and the East Anatolian fault zone (EAFZ). The greater vertical offset on the western margin faults relative to the eastern ones indicates asymmetrical evolution of the rift as implied by the higher escarpments and accumulation of extensive, thick alluvial fans on the western margins of the rift. The thickness of the Quaternary sedimentary fill is more than 465 m, with clastic sediments intercalated with basaltic lavas. The Quaternary alkali basaltic volcanism accompanied fluvial to lacustrine sedimentation between 1.57 ± 0.08 and 0.05 ± 0.03 Ma. The faults are left-lateral oblique-slip f...

Plio-Quaternary evolution of the Küçük Menderes Graben Southwestern Anatolia, Turkey

The Küçük Menderes Graben (KMG) is part of the horst-graben system of southwestern Anatolia (Turkey), bounded by the Bozdağ horst in the north and the Aydın horst in the south. The Plio-Quaternary evolution of the KMG has been evaluated using the nature of the Miocene-Quaternary fill sediments and palaeostress analysis of slip data measured in different parts of the graben. The graben is composed of five subbasins—the Kiraz, Ödemiş, Bayındır, Dağkızılca-Torbalı and Selçuk—that are connected to each other through narrow Quaternary troughs. The Dağkızılca, Kiraz and Selçuk basins bear Miocene and younger sequences whereas the other subbasins are largely filled by Quaternary sediments. The maximum thickness of the Quaternary fill reaches about 270 m in the Ödemiş and Bayındır subbasins. The calculated slip results indicate multidirectional extension, three successive deformational periods, and possible counterclockwise rotation in the KMG during the post-Miocene period. The first phase was a strike-slip regime under N-S compression, followed by a second phase of deformation which resulted in ENE-WSW extension with strike-slip components. The final phase of deformation was NE-SW extension which constituted the final evolution of the KMG. The graben gained its present morphological configuration via the onset of E-W-trending, high-angle normal faulting imposed on the regionwide synformal structure during the Plio-Quaternary. The KMG evolved as a result of rifting during the Plio-Quaternary which followed Late Miocene unroofing of the Menderes Massif and the evolution of the Büyük Menderes and Gediz grabens.

Microzonation for earthquake hazards: Yenisehir settlement, Bursa, Turkey

Abstract Detailed geological, hydrogeological and geotechnical studies were performed for the assessment of the foundation conditions of the present and future settlement areas of Yenisehir. Yenisehir is located 50 km east of Bursa, Turkey, within an east–west trending elliptical sedimentary basin. The present and future development areas of Yenisehir cover 10 km 2 . The topography of the settled area is quite smooth and the slopes are generally less than 10°. Yenisehir is located within a First-Degree Earthquake Zone of Turkey according to the seismic design code. The seismicity of the town is mainly controlled by the Geyve-Iznik and Bursa fault zones. The study also involves trial pitting, drilling, in situ testing and laboratory testing. Borehole logs, index properties of soils, standard penetration test results and groundwater level measurements were used for activity and liquefaction assessments of the foundation material. Based on the evaluation of the data, two geotechnical zones were distinguished. The northern part of the area is characterized by cohesive soils of high expansion behaviour and the southern part by alternation of cohesive and non-cohesive soils showing high liquefaction potential.

Structure of the Galatean Volcanic Province, Turkey

The Galatean volcanic province (GVP), located in northwestern Anatolia, is an ENE-WSW-oriented belt. The province as a whole corresponds to a depression filled with volcanic and sedimentary rocks. The northern margin of the GVP is truncated by the North Anatolian fault, whereas it is surrounded by a continental sedimentary pile interfingering with volcanics on the south. Field and aerial photographic studies reveal that the GVP consists of several volcanic complexes scattered throughout the province. Nine of these complexes are recognized, each covering an area of hundreds of km2 of circular or ellipsoidal form, with moderately to well-preserved morphology. They include calderas, stratovolcanoes characterized by central vent (s), and radial flows of both lava and volcaniclastics. Several continental basins are disposed between the major volcanic complexes. These basins are isolated from one another or are partly connected and may differ in age and lithology. Available radiometric and paleontologic age det...

Object-based classification of landforms based on their local geometry and geomorphometric context

Terrain as a continuum can be categorized into landform units that exhibit common physical and morphological characteristics of land surface which may serve as a boundary condition for a wide range of application domains. However, heterogeneous views, definitions, and applications on landforms yield incompatible nomenclature that lacks interoperability. Yet, there is still room for developing methods for classification of land surface into landforms that can provide different disciplines with a basis of landscape description that is also commonsense to human insight. This study proposes a method of landform classification that reveals general geomorphometry of the landscape. A set of landform classes that are commonsense to human insight and relevant to various disciplines is adopted to generate landforms at the landscape scale. The proposed classification method is based on local geometry of the surface and the geomorphometric context in a higher level framework. A set of digital terrain models (DTMs) at relevant scale is utilized where local geometry is represented with morphometric DTMs, and the geomorphometric context is incorporated through ‘relative terrain position’ and ‘terrain network.’ ‘Object-based image analysis’ tools that have the ability to segment and classify DTMs into representative terrain objects and connect those objects in a multi-level hierarchy is utilized. Ambiguities in landforms both in attribute and geographical space are represented via fuzzy classification. The proposed method is applied to two different case areas to evaluate the efficiency and stability of the outcomes. Results reveal a reasonable amount of consistency where landform classes can be utilized as general or multi-purpose regarding some ambiguity that is already inherent in landforms.

A new straight line reconstruction methodology from multi-spectral stereo aerial images

In this study, a new methodology for the reconstruction of line features from multispectral stereo aerial images is presented. We take full advantage of the existing multispectral information in aerial images all over the steps of pre-processing and edge detection. To accurately describe the straight line segments, a principal component analysis technique is adapted. The line to line correspondences between the stereo images are established using a new pair-wise stereo matching approach. The approach involves new constraints, and the redundancy inherent in pair relations gives us a possibility to reduce the number of false matches in a probabilistic manner. The methodology is tested over three different urban test sites and provided good results for line matching and reconstruction.

Activity level of tectonic basins, western section of the North Anatolian Fault Zone, Turkey

We employed quantitative techniques to investigate tectonic activity levels and development stages of the Bolu, Yenicaga, Dortdivan, Cerkes, Ilgaz, and Tosya structural basins along the western portions of the main trace of the North Anatolian Fault Zone (NAFZ). Our methodology incorporates six morphometric indices: basin shape (basin elongation and compactness), hypsometric integral, mountain-front sinuosity, stream length gradient index, valley floor width-to-height ratio, and asymmetry factor, obtained from the digital elevation model of the region generated from 1/25,000-scale topographic maps. These indices are integrated within the framework of an analytical hierarchy process to provide relative activity level values of the individual basins. The new analyses indicate that the basins have contrasting tectonic activity characteristics. Judging from the applied indices, the relative increasing order of the tectonic basin activity is Dortdivan, Cerkes, Yenicaga, Ilgaz, Tosya, and Bolu. Among the basins located to the north of the NAFZ, the activity decreases eastwards, whereas to the south of this profound fault zone, it decreases towards the west.

Comprehensive Strip Based Lineament Detection Method (COSBALID) from point-like features: a GIS approach

Abstract Comprehensive Strip Based Lineament Detection (COSBALID) is a new method that detects lineaments from point-like features. It is based on the strip concept and composed of various steps, which apply filtering techniques in order to increase the accuracy and linearity of detected lineaments. The structure of the method is so robust that its parameters and variables are partially data driven giving the user great flexibility to adopt and modify them dynamically, in the course of processing, and impose new parameters at any step without altering the main structure of the method. The main steps of the method are as follows: (1) creation of a database using a GIS medium, (2) configuration of strips (polygons) (3) creation of an initial (strip) database by rotating the strips incrementally, (4) detection of unrefined alignments, (5) distance filtering, (6) linearity check, (7) repetition and redundancy check, and (8) further analysis based on various properties of the point like features. The method is applied to 94 volcanic cones within the Cappadocian Volcanic Province. The initial number of alignments is 2485 which gradually decreases to 25 after performing above-mentioned test and filters. The advantage of COSBALID method, over existing models is that it detects the exact geographical position of the end members of the lineaments. In addition, the method considers additional properties of point-like features such as type and shape.

Accurate matching and reconstruction of line features from ultra high resolution stereo aerial images

In this study, a new reconstruction approach is proposed for the line segments that are nearly-aligned (≤ 10o) with the epipolar line. The method manipulates the redundancy inherent in line pair-relations to generate artificial 3D point entities and utilize those entities during the estimation process to improve the height values of the reconstructed line segments. The best point entities for the reconstruction are selected based on a newly proposed weight function. To test the performance of the proposed approach, we selected three test patches over a built up area of the city of Vaihingen–Germany. Based on the results, the proposed approach produced highly promising reconstruction results for the line segments that are nearly-aligned with the epipolar line. 1. INTRODUCTION & MOTIVATION The matching and reconstruction of line segments in ultra high resolution stereo aerial images is a very challenging task due to various reasons; substantial change in viewpoints, inconsistency of line endpoint locations, the limitations of the line geometric constraints imposed, lack of rich textures in line local neighbourhood, repetitive patterns etc. Up to now, a significant number of research papers have been devoted to stereo line matching (ex: Schmid and Zisserman, 1997; Baillard and Dissard, 2000; Scholze et. al., 2000; Zhang and Baltsavias, 2000; Suveg and Vosselman, 2004; Herbert et. al., 2005; Wang et. al., 2009; Ok et. al., 2010a, b); however, the ambiguity of line matching is an issue that remains unsolved. Moreover, in addition to the problems of matching, the reconstruction of the matched line segments under stereo geometry is also a challenging issue and the final accuracy of the reconstructed line segments is still limited to certain imaging conditions. So far, the general attempt to solve line matching problems in stereo geometry has relied on various descriptors specialized for one to one line matching in which the relations between the line features are not effectively taken into account. However, the integration of the line to line relations during matching not only exposes new constraints to improve the performance of matching (Ok et. al., 2010a, b), but also provides new opportunities for better estimation of the height values of the line endpoints during the reconstruction stage. In a recent work, we presented a novel approach for the pair-wise matching of line segments from stereo aerial images (Ok et. al., 2010a), and later we further developed and extended the approach to deal with repetitive linear patterns problem (Ok et. al., 2010b). In this paper, our motivation and contribution is mainly on the height estimation of the matched segments. Although the method of direct construction gives satisfactory reconstruction results for the lines that are not aligned with the epipolar line, a dramatic decrease in terms of height accuracy for the lines that are nearly or exactly aligned (≤ 10 o) with the epipolar line is inevitable (Fig. 1). This is due to the reason that if the angles of lines in image space get closer to the epipolar direction, the two projection planes generated from line segments become similar and in the worst case (exact alignment) they turn out to be the same plane. For those cases, the direct construction of 3D lines from the intersection of planes is highly problematic in terms of final height accuracy and may be even some cases the intersection (or the reconstruction) may not be possible. Therefore, in this paper, we propose a new reconstruction method which also relies on line to line relations developed in the pair-wise approach. The main idea is to manipulate the redundancy inherent in pair-relations to generate artificial 3D point entities (Xi) from available pair matches and utilize those points during the estimation process to improve the height estimation of the matched segments. However, since we do not exactly know whether the two lines in a pair really intersect on the Earth surface or not, before the estimation process, we select the proper point entities by means of a new weight function which is composed of mainly three terms computed in a pairwise manner; Euclidean distance, epipolar constraint and intersection angle in image space. For each problematic matching case (≤ 10o), we automatically select the appropriate artificial 3D point entities and integrate each selected entity during the estimation process along with the projection planes of the problematic line segments. Thus, at the end of this joint estimation, we have a possibility to reconstruct those problematic line segments with promising final accuracies.