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    Geomorphological investigation of the excavation-induced Dundar landslide, Bursa, Turkey
    (Taylor & Francis Ltd, 2008) Erginal, Ahmet Evren; Turkes, Murat; Ertek, T. Ahmet; Baba, Alper; Bayrakdar, Cihan
    This paper discusses the occurrence and development of the excavation-induce deep-seated landslide, which took place near Dundar village, located west of Orhaneli town in northwestern Turkey. The event occurred in the Bursa-Orhaneli lignite field, which has been actively operating since 1979. Due to undermining of a gently inclined slope (10 degrees) to extract a coal seam, primary tension cracks, which were precursors of the movement, were first observed in the northern head area in mid- to late October 2003. This movement happened simultaneously with precipitation that was significantly above long-term average measured at a nearby climatology station (Keles). This precipitation amount is characterized statistically by a significant standardized anomaly of 1.6. The majority of the monthly precipitation total in October 2003, which mainly consisted of rain showers and thunderstorms, occurred in the last week of the month. By April 2004, rotational failure continued intermittently. After a relatively wet (rainy and snowy) period from January 2004 to April 2004, the main rotational slump occurred in late April 2004, causing the entire destruction of Dundar village's cemetery. Daily climatic and synoptic meteorological data have proved that heavy showers in late April may had triggered the last slump by producing rain showers of 19.3 mm and 19.9 mm daily total on 27 and 28 April 2004, respectively. Field observations carried out along the main head scarp have shown that the slope failure was facilitated by a pre-existing normal fault with an east- west direction and 80 degrees dip. Grain-size analysis showed that the failure occurred on clayey silt, which forms 55% of the slip surface material. Based on the evidence from X-ray fluorescence and energy dispersive X-ray spectroscopy results, smectite-type clay - a product of the chemical weathering of tuff - was the main constituent of the slip surface material. The landslide occurred over an area of 600 m x 650 m with a total volume of 8775 000 m(3). Approximately 28 hectares of farm land were entirely destroyed and the excavated coal seam was buried. The mining operation was moved to 100 m north of the landslide area near Gumuspinar village. From morphological evidence, it is concluded that excavation activities caused the failure to extend in more than one direction as an enlarging sliding mechanism; this produced a high landslide risk for Gumuspinar village, where the most significant normal fault with a 75 m vertical displacement in a coal-bearing sequence is found in the lignite field.
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    Öğe
    The formation of beachrock on the North Cyprus coast
    (2008) Ertek, T. Ahmet; Erginal, A. Evren; Bozcu, Mustafa; Türker, Gülen
    Kıbrıs adasının kuzey kıyılarında yalıtaşı oluşumları tespit edildi. Yalıtaşların petrografik bileşimi ve çimentolanma özellikleri detaylı arazi çalışmaları, ince kesit yorumlamaları ve ICP-AES analizlerine dayalı olarak gerçekleştirildi. Mevcut bulgular yalıtaşlarının genellikle geride kıyı kumulları ve denizel taraçalarla sınırlandırılan plajlarda, istisna olarak da tektonikle yükselmiş dalga aşınım düzlükleri üzerinde geliştiğini göstermektedir. Yalıtaşları özellikle Troodos masifi ve Girne dağlarından gelen kum ve çakıllarca zengindir. Çimentolaşma tuzlu su-tatlı su karışım zonunda gelişmiştir.
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    Öğe
    Using caesium-137 measurements to investigate soil erosion rates in western Istanbul (NW Turkey)
    (2005) Haciyakupoglu, Sevilay; Ertek, T. Ahmet; Walling, Des E.; Ozturk, Z. Fatih; Karahan, Gursel; Erginal, A. Evren; Celebi, Nilgun
    Buyukcekmece Reservoir, located in the western outskirts of Istanbul, is one of the major water resources of Istanbul, and supplies drinking water to about 4 million people. Erosion in the catchment of the reservoir is an important problem in terms of its longer-term sustainability for water supply. There is an urgent need to obtain reliable quantitative data regarding erosion and deposition rates within the catchment to assess the magnitude of the problem and to plan catchment management strategies. In the absence of existing data, attention has focussed on the potential for using 137Cs measurements to provide retrospective estimates of medium-term soil erosion rates within the catchment over the past ca. 40 years. To date, the 137Cs approach has not been used to document soil redistribution rates in Turkey and this contribution reports an attempt to confirm the viability of the approach and the results of a preliminary investigation of rates of soil loss from uncultivated areas within the catchment. The soil redistribution rates estimated using the profile distribution conversion model varied from - 16.11 (erosion) to 4.59 (deposition) t/ha/year. © 2005 Elsevier B.V. All rights reserved.