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Oya Pamukçu Tolga Gönenç Osman Uyanik Hasan Sözbilir Olcay Çakmak 《Acta Geophysica》2014,62(4):849-871
Western Anatolia has an extensional tectonic regime and the characteristics of the deformation in the continental crust observed in Aegean Region have a very complex structure. In our study area, the ?zmir city, Turkey, which is located within this active region, the general geological setting is also rather complex. This first microgravity study in ?zmir and its surroundings is related to the determination of active fault zones. It was conducted in the south of ?zmir, with the aim to investigate this complex structure in detail through microgravity data collected from six profiles throughout the survey area. The variation in Bouguer values was profoundly investigated along Profile P1 in N-S direction that was delineated to intersect all the tectonic elements. For this reason, Profile P1 was modeled in this study as 2D. As a result, the created gravity model was investigated together with geology, earthquake focal depths, and isostasy. 相似文献
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A geohazard reconnaissance study based on geoscientific information for development needs of the western region of Istanbul (Turkey) 总被引：1，自引：0，他引：1
Tamer Y. Duman Tolga Can Reşat Ulusay Mustafa Keçer Omer Emre Serafettin Ateş Ibrahim Gedik 《Environmental Geology》2005,48(7):871-888
The role of geoenvironmental information is becoming increasingly important as legislative changes have forced developers
and planning authorities to consider more implications and impact on the environment of large-scale development initiatives.
Therefore, integration of surface and subsurface geoscientific information for development needs has prime importance and
provides a means of identifying potential problems and opportunities at an early stage in any planned development. However,
from the experience of recent natural disasters, it is evident that this was not case the taken into consideration in many
countries. In addition to thousands of casualties, many urbanized areas, industrial districts and large-scale engineering
structures suffered severe damages from the natural hazards due to many reasons including the lack of preliminary engineering
geological maps and zoning maps of the settlement areas. Turkey is one of the countries which is exposed to natural hazards
such as earthquakes, landslides and floods. In particular, the devastating 1999 Kocaeli earthquake, which affected the Marmara
Region of Turkey, focused the attention on densely urbanized and industrialized metropolitan areas such as Istanbul. The rapid
growth of Istanbul, particularly towards west with minimal geoscientific information resulted in an overwhelming pressure
on the natural environment. In addition, a large earthquake, which is expected to occur in the Marmara Sea within the next
30 years, also pose a threat to the city and its surroundings. In this study, on the basis of the geological, geomorphological
and geophysical reconnaissance study, an integrated geoscientific data were collected from the western region of Istanbul
and evaluated for geohazards. The paper focuses on the geological and geomorphological aspects that control the occurrence
of some geohazards such as earthquake-induced liquefaction, landslides and flooding. In this context, the geological map of
the region was revised and Quaternary deposits were classified into 11 units, in detail. Liquefaction-prone areas were evaluated
by using geomorphological criteria based on field investigation, by the examination of the available records from 88 boreholes
drilled on recent deposits and by the data from resistivity profiles. The landslides within the region were classified according
to their type, relative depth and activity. In addition, fluvial and marine flood-prone areas were also delimited within the
region. Finally, a series of maps such as landslide inventory maps, and maps showing liquefaction- and flood-prone areas were
produced with the aid of Geographic Information Systems (GIS) to assist in designing further detailed site investigations
and to reduce costs by ensuring a more focused approach to strategic planning and site selection. 相似文献
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In this study, we report results concerning the accumulation of heavy metals in seawater from Izmit Bay. The bay was divided into the three parts: the eastern, the central and the western basins. The goal of this study was to determine levels of heavy metals at various depths in the bay between April 2008 and May 2010. Liquid–liquid extractions were performed on seawater samples. An atomic absorption spectrophotometer was used to measure levels of six metals: lead, cadmium, chromium, iron, manganese and zinc. We applied our results to evaluate the status of pollution in the Gulf of Izmit. Significant seasonal differences in metal concentrations and higher concentrations of many metals in water near the shore are evidence for uncontrolled release of pollutants in the water. 相似文献
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Susceptibility assessments of shallow earthflows triggered by heavy rainfall at three catchments by logistic regression analyses 总被引：11，自引：3，他引：11
Tolga Can Hakan A. Nefeslioglu Candan Gokceoglu Harun Sonmez Tamer Y. Duman 《Geomorphology》2005,72(1-4):250-271
Sometimes regional meteorological anomalies trigger different types of mass movements. In May 1998, the western Black Sea region of Turkey experienced such a meteorological anomaly. Numerous residential and agricultural areas and engineering lifelines were buried under the flood waters. Besides the reactivation of many previously delineated landslides, thousands of small-scale landslides (mostly the earthflow type) occurred all over the region. The earthflows were mainly developed in flysch-type units, which have already presented high landslide concentrations. In this study, three different catchments — namely Agustu, Egerci, and Kelemen — were selected because they have the most landslide-prone geological units of the region. The purposes of the present study are to put forward the spatial distributions of the shallow earthflows triggered, to describe the possible factors conditioning the earthflows, and to produce the shallow earthflow susceptibility maps of the three catchments. The unique condition units (UCU) were employed during the production of susceptibility maps and during statistical analyses. The unique condition units numbered 4052 for the Agustu catchment, 13,241 for the Egerci catchment and 12,314 for the Kelemen catchment. The earthflow intensity is the highest in the Agustu catchment (0.038 flow/UCU) and lowest in the Egerci catchment (0.0035 flow/UCU). Logistic regression analyses were also employed. However, during the analyses, some difficulties were encountered. To overcome the difficulties, a series of sensitivity analyses were performed based on some decision rules introduced in the present study. Considering the decision rules, the proper ratios of UCU free from earthflow (0) / UCU including the earthflow (1) for the Agustu, Egerci and Kelemen catchments were obtained as 3, 6, and 5, respectively. Also, a chart for the proper ratio selection was developed. The regression equations from the selected ratios were then applied to the entire catchment and the earthflow susceptibility maps were produced. The landslide susceptibility maps revealed that 15% of the Agustu catchment, 8% of the Egerci catchment, and 7% of the Kelemen catchment have very high earthflow susceptibility; and most of the earthflows triggered by the May 1998 meteorological event were found in the very high susceptibility zones. 相似文献
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