Browsing by Author "Üner, S."

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Determination of Dynamic Soil Properties of Van Yuzuncu Yil University Campus for the Preparation of Microzonation Map
(TMMOB - Jeoloji Muhendisleri Odasi, 2015) Akin, M.K.; Akin, M.; Akkaya, İ.; Özvan, A.; Üner, S.; Selçuk, L.; Tapan, M.
One of the most important factors causing loss of life and property during earthquakes is the soil conditions that the structure is built on. Determination of the soil engineering properties for understanding the behavior of ground under dynamic loads and/or minimizing the losses that may occur is quite crucial. The earthquakes occured in our country especially in 1999 and later on, and the resulting loss of life and property once more emphasized the importance of the social and economic dimensions of the impact created by the earthquake. Dynamic soil properties must be studied in accordance with the principles of microzonation considering the natural disasters such as earthquake. For this aim, the dynamic soil properties of Van Yuzuncu Yil University campus area are determined. Liquefaction, soil amplification and the like for the campus area are investigated through field studies conducted in order to reveal the ground conditions, and consequently the suitability for settlement is evaluated to guide the future planning of the campus. © 2015, TMMOB - Jeoloji Muhendisleri Odasi. All Rights Reserved.
Earthquake Induced Soft Sediment Deformation Structures (Seismites): Van Gölü Basin, Eastern Anatolia
(Hacettepe Universitesi Yerbilmleri, 2010) Üner, S.; Yeşilova, C.; Yakupoǧlu, T.; Üner, T.
The Van Gölü Basin is one of the basins located on the Eastern Anatolia Plateau and it includes Van Gölü, which is the largest sodic lake in the world, within its boundaries. The basin was formed in the Late Pliocene and attained its final shape with Quaternary volcanic activity. Deformation structures are found in Quaternary aged sandy and silty lacustrine sediments in the Van Gölü Basin. These soft sediment deformation structures formed by liquefaction or fluidization of the unconsolidated sediments are classified in three groups, being those of contorted structures (simple and complex convolute bedding and ball-pillow structures), water escape structures (dish and pillar structures), and load structures (flame structures). Deformation structures may occur by overpressure, waves that originated in storms, sudden changes in groundwater movements and seismic shaking. Based on the field observations, regional tectonic and sedimentological data and previous studies, it is concluded that these deformation structures have been developed and may be called seismites. The existence of seismites in different levels of lacustrine sediments in the Van Gölü Basin is an indicator of a Quaternary tectonic activity in the region as well as an indicator of frequent occurrences of earthquakes with magnitudes of 5 or greater.
The Effect of Tectonism on Deltaic Wetland Migration: a Case Study From Bendimahi River Delta System (Lake Van-Eastern Turkey)
(International Association of Great Lakes Research, 2019) Üner, S.
Coastal wetlands are in decline globally because of climatic and/or hydrological changes, and anthropogenic activities. Deltaic wetlands are complex environments formed by different water sources, particularly when ionically rich soda water and freshwater and converge and influence the presence and diversity of biological activity. Lake Van is a terminal lake, 1650 meters above the sea level, surrounded by high mountains. Because of its alkaline water, vegetation and biological activity are generally rich in the deltaic areas. In this study, geological evolution of Bendimahi River Delta System, located on northeastern part of the Lake Van, is assessed as to constructive and destructive temporal factors, determined with satellite images and field studies. Bendimahi river channel is significantly deformed by regional tectonic activity and this deformation has caused migration of deltaic wetland. That migration process has resulted in abandoned deltaic area and a new delta formation. Hydrological and biological results of the migration of the Bendimahi River Delta System clearly indicate the importance of wetlands on coastal ecology, especially alkaline lakes. © 2019
Geomorphological Properties and Tectonic Activity of Alaköy Fault (Lake Van Basin- Eastern Anatolia)
(Hacettepe Universitesi Yerbilmleri, 2013) Okuldaş, C.; Üner, S.
The Lake Van Basin, formed in the Late Pliocene, is located on the north of Bitlis-Zagros Suture Belt and attained its final shape with Quaternary volcanic activity. Young structures created by N-S compressional neotectonic period are observed in lacustrine deposits of Lake Van. Nearly E-W trending Alaköy Thrust Fault is one of these structures which is 20 km far from Van city center. The most damaged areas due to the 23 October 2011 earthquakes (7.1 and 5.6 Mw) and the intense aftershocks are situated on this fault zone which can be followed along 25 km by geomorphologic indicators. The fault cuts off the Quaternary coastal lacustrine deposits and juxtaposes them with basement rocks of the basin in patches. The activity of the fault can be detected by unpaired terraces near the channel, interrupted drainages, fans formed on the fault and topographic slope breaks. In this study the fault plane measurements of Alaköy Fault are presented for the first time. The purpose of this study is to discuss the recent activity of Alaköy Fault within a regional content with the help of structural and geomorphologic data.
Late Miocene Evolution of Kargı Fan Delta (Aksu Basin, Antalya)
(Hacettepe Universitesi Yerbilmleri, 2011) Üner, S.; Dirik, K.; Çiner, A.
Miocene Aksu Basin is a foreland basin, located on the southern part of the Anatolian peninsula in Africa-Eurasia subduction zone. The basin fill is composed of shallow marine clastics and carbonates and coarse grained fan delta deposits. In this study, structural and sedimentological evolution of Tortonian Kargi{dotless} Fan Delta developed in the western part of the basin is examined in the context of tectonism and sea level changes. Facies, depositional processes and sub-environments (e.g. alluvial fan, lagoon, fan delta front) of this coarse grained fan delta sequence, indicate both regressive and transgressive periods. Alternations of continental red beds with shallow marine conglomerates containing patch reefs are very typical. Changes in the depositional characteristics of fan delta can be explained by regional tectonism and related sea level changes together with the amount of sediments carried into the basin. Kargi{dotless} Fan Delta is a key sedimentary sequence in the understanding of the evolution of the Aksu Basin.
Natural and Anthropogenic Driving Forces on Holocene Coastline Evolution of Lake Van (Eastern Anatolia): a Geological Approach
(Hacettepe Universitesi Yerbilmleri, 2022) Üner, S.
Coastal areas along the lakes are sensitive to climatic, hydrologic, and anthropogenic changes. These areas also reveal the interaction between natural driving forces and anthropogenic factors. Lake Van coastal region is a dynamic area heavily affected by natural processes and human activities. The present study focuses on Lake Van’s coastline evolution and the associated driving forces. Natural driving forces influencing the changes in the coastline were determined as rock type, water-level fluctuations, wave and current action, tectonics, and fluvial-based processes. The lake’s eastern coast is the most intensive region for erosion and deposition in terms of natural factors. Most residents prefer to live in Lake Van’s coastal areas, likely a large percentage of the world's population choice. Coastal settlements and their coastal protection structures such as embankments and harbours negatively affect the natural processes such as erosion, sediment transportation, and deposition. Dams and river reclamation channels build on rivers indirectly affect the coastal evolution by reducing the sediment input into the lake. These anthropogenic stressors on coastal evolution completely change the natural balance. Understanding all these environmental factors is an indicator of the existing circumstances of the Lake Van coastal area and provides a broader perspective to assess protection and management of this area. © 2022, Hacettepe Universitesi Yerbilmleri. All rights reserved.
Seismogenic Structures in Quaternary Lacustrine Deposits of Lake Van (Eastern Turkey)
(De Gruyter Open Ltd, 2014) Üner, S.
Soft-sediment deformation structures formed by liquefaction and/or fluidisation of unconsolidated sediments due to seismic shocks are frequent in the Quaternary sandy, silty and clayey deposits of Lake Van. They are present in both marginal and deep lacustrine facies. Their morphology and interpreted genesis imply that they should be considered as fluid-escape structures (dish and pillar structures, flame structures and sand volcanoes), contorted structures (simple and complex convolutions and ball-and-pillow structures) and other structures (disturbed layers and slump structures). The most recently formed structures are related to the October 23rd, 2011 Van-Tabanlý (Mw 7.2) earthquake. The existence of seismites at various stratigraphic levels in the lacustrine deposits is indicative of tectonic activity that frequently triggered earthquakes with magnitudes of 5 or more, affecting the Lake Van Basin.
Structural and Sedimentological Properties of Lacustrine Deposits in Pliocene Dorutay Basin (özalp-Van)
(Hacettepe Universitesi Yerbilmleri, 2015) Üner, S.; Okuldaş, C.; Yilmaz, A.V.
The collision between the Arabian and Eurasian plates caused to the formation of intramontane basins around Lake Van during and after Miocene. Pliocene Dorutay Basin (Özalp-Van) is one of these basins. Plio-Quaternary lacustrine deposits in the basin, uncomformably overlie the basement rocks composing of Carboniferous aged metamorphic rocks and Cretaceous ophiolites, indicate the existance of a widespread lake in the region at that time. This paleolake was around 2060 meter above the sea level and occupied in 150 km2 area. The boundaries of the paleolake can be determined using shore facies of lacustrine deposits. Sedimentary facies were investigated for understanding the depositional subenvironments and depositional processes of basin fill. Eight sedimentary facies and two facies associations representing to shallow lacustrine and shore subenvironment were recognized. Dorutay Basin is located on a seismically active region. Faults on boundaries of the basin and the basin fill play an important role on geological evolution of the basin. Especially the activity of Çırakköy Fault named with this study is the main reason of the changing from closed basin condition to open basin. Earthquake records and geomorphological data are showing the recent tectonnic activity of the basin. © 2015 Pushpa Publishing House. All Rights Reserved.