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Ohne Zusammenfassung 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
327.
Physical and chemical characterization of spent oil shale (OS) from El-Lajjun area has been carried out and compared with
the original OS. The spent shale (SS) is subjected to leaching tests to detect the possibilities of heavy metals released
from it into the environment. Standard column leaching experiments have revealed no detectable release of heavy metals to
the percolating water. The effectiveness of the SS in removing Pb2+ from wastewater has been investigated. The SS is very efficient in removing most of Pb2+ where 1 m3 of SS has an efficiency to remove from 64 to 94% of Pb2+ from about 1,300 m3 wastewater sample containing 50 ppm Pb2+. The efficiency decreases substantially with increasing Pb2+ concentration in the wastewater. In real situations, where Pb2+ concentration is very low (i.e., less than 5 ppm), the efficiency of the SS is expected to be 100%. 相似文献
328.
Siwa oasis is located in the extreme western part of the Egyptian western desert. There are several archaeological sites in
the oasis; the most distinct ones are Alexander the Great temple at Aghormi hill and the Gebel El Mota tomb excavations. They
have suffered due to deterioration and cracks of different kinds and some parts are getting worse as rock falls occur. From
field inspection and lab analysis, it is clear that lithology plays an important role on the extent of damage. Alexander the
Great temple was built over the northern edge of Aghormi hill, which consists of two distinct beds—an upper limestone bed
and a lower shale one. From field survey and laboratory analysis, the shale is considered as a high expanded bed and weak
in its bearing capacity, as its clay content (mainly smectite) experienced swelling due to wetting from the ground water spring
underneath. Consequently, the upper limestone bed suffered from map cracking associated with rock falls due to the differential
settlement of the swelled lower shale one. The temple was threatened by slope instability and had experienced many cracks.
At Gabal El Mota tomb excavations, it was noticed that a comparison of tombs of the same opening size revealed that those
that excavated on shale beds had cracked much more than those that excavated on limestone. This may be attributed to the low
bearing capacity of excavated shale walls. The remedial measures suggested to overcome the stability problems on these archaeological
sites are grouting or construction of retaining walls. 相似文献
329.
D.W. Simpson R.M. Kebeasy C. Nicholson M. Maamoun R.N.H. Albert E.M. Ibrahim A. Megahed A. Gharib A. Hussain 《Journal of Geodynamics》1987,7(3-4)
A telemetered network of 8 short-period seismograph stations was installed at Aswan Reservoir in July 1982 to monitor induced seismicity near the site of a magnitude 5
earthquake which occurred in November 1981. A continuous monitor of the seismicity is provided by pen and ink recording of 4 stations. An event detector is used to identify events of interest, for which all of the stations are recorded on magnetic tape. Approximate displacement magnifications are 40, 000 at 1 hz with a maximum of 500, 000 at 20 hz. 相似文献
330.
S.J. Gibowicz Z. Droste R.M. Kebeasy E.M. Ibrahim R.N.H. Albert 《Engineering Geology》1983,19(2):95-109
From the middle of January to the middle of March, 1981 a microearthquake survey was conducted jointly by Polish and Egyptian seismologists in the Abu-Simbel area, about 230 km upstream from the Aswan High Dam. A small seismic array composed of six stations and a magnetic-tape digital recording system was operated during the survey. Altogether 63 microearthquakes at epicentral distances of up to 50 km and 12 local earthquakes at distances of up to 200 km were recorded, but only 16 microearthquakes could be properly located. All of them originated either directly under the High Dam Reservoir or close to its shores, thus implying their association with its water level fluctuations.It was deduced that under the Abu-Simbel array a deep fracture zone or deep fault extending in the NNE—SSW direction, 1–3 km wide and several kilometers deep, must be present to explain the observed effects of heavy attenuation and scattering of seismic waves under the array. This fracture zone might be a deep expression of the western edge of the Nile Valley in the Abu-Simbel area. 相似文献