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We performed a probabilistic analysis of earthquake hazard input parameters, NW Turkey covers Gelibolu and Biga Peninsulas, and its vicinity based on four seismic sub-zones. The number of earthquakes with magnitude M ≥ 3.0 occurred in this region for the period between 1912 and 2007 is around 5130. Four seismic source sub-zones were defined with respect to seismotectonic framework, seismicity and fault geometry. The hazard perceptibility characterization was examined for each seismic source zone and for the whole region. The probabilities of earthquake recurrences were obtained by using Poisson statistical distribution models. In order to determine the source zones where strong and destructive earthquakes may occur, distribution maps for a, b and a/b values were calculated. The hazard scaling parameters (generally known as a and b values) in the computed magnitude–frequency relations vary in the intervals 4.28–6.58 and 0.59–1.13, respectively, with a RMS error percentage below 10 %. The lowest b value is computed for sub-zone three indicating the predominance of large earthquakes mostly at Gelibolu (Gallipoli) and north of Biga Peninsula (southern Marmara region), and the highest b value is computed for sub-zone two Edremit Bay (SW Marmara region). According to the analysis of each seismic sub-zone, the greatest risk of earthquake occurrence is determined for the triangle of Gelibolu–Tekirda? western part of Marmara Sea. Earthquake occurrence of the largest magnitude with 7.3 within a 100-year period was determined to be 46 % according to the Poisson distribution, and the estimated recurrence period of years for this region is 50 ± 12. The seismic hazard is pronounced high in the region extending in a NW–SE direction, north of Edremit Bay, west of Saros Bay and Yenice Gönen (southern Marmara region) in the south. High b values are generally calculated at depths of 5–20 km that can be expressed as low seismic energy release and evaluated as the seismogenic zone. 相似文献
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Investigation of the relationship of seismic intensity measures and the accumulation of damage on concrete gravity dams using incremental dynamic analysis 
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下载免费PDF全文 Nonlinear analysis tools are gaining prominence for the design and evaluation of concrete gravity dams. The performance limits of concrete gravity dams within the framework of performance based design are challenging to determine in comparison to those used for the assessments based on linear elastic analyses. The uncertainty in quantifying the behavior of these systems and the strong dependence of the behavior on the ground motion play an important role. The purpose of the study is to quantify the damage levels on a representative monolith using incremental dynamic analysis (IDA). For this purpose, the constitutive model utilized was calibrated first to the existing experimental results to verify the ability of the utilized cracking model to simulate the crack propagation process. Next, the relation between the damage levels on the monolith and the ground motion characteristics was investigated. The results of the conducted IDA showed that the engineering demand parameters (EDP) such as the crest displacement and acceleration showed weak correlation with the damage states. The spectral velocity and the peak ground acceleration were determined to be better predictors for the damage on the monolith. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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In order to investigate crustal structure beneath the eastern Marmara region, a seismic refraction survey was conducted across
the North Anatolian Fault (NAF) zone in north west Turkey. Two reversed profiles across two strands of the NAF zone were recorded
in the Armutlu Highland where a tectonically active region was formed by different continents. We used land explosions in
boreholes and quarry blasts as seismic sources. A reliable crustal velocity and depth model is obtained from the inversion
of first arrival travel times. The velocity-depth model will improve the positioning of the earthquake activities in this
active portion of the NAF. A high velocity anomaly (5.6–5.8 km s−1) in the central highland of Armutlu block and the low velocity (4.90 km s−1) pattern north of Iznik Lake are the two dominant features. The crustal thickness is about 26 ± 2 km in the north and increases
to about 32 ± 2 km beneath the central Armutlu block in the south. P-wave velocities are about 3.95 km s−1 to 4.70 km s−1 for the depth range between about 1 km and 5 km in the upper crust. The eastern Marmara region has different units of upper
crust with velocities varying with depth to almost 8 km. The high upper crust velocities are associated with Armutlu metamorphic
rocks, while the low velocity anomalies are due to unconsolidated sedimentary sequences. The western side of Armutlu block
has complex tectonics and is well known for geothermal sources. If these sources are continuous throughout the portions of
the crust, it may be associated with a granitic intrusion and deformation along the NAF zone. That is, the geothermal sources
associated with the low velocity may be due to the occurrence of widespread shear heating, even shear melting. The presence
of shear melting may indicate the presence of crustal fluid imposed by two blocks of the NAF system. 相似文献
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Gündüz Horasan Aysun Boztepe Güney Ayşegül Küsmezer Feyza Bekler Zafer Öğütçü Nebiye Musaoğlu 《Journal of Asian Earth Sciences》2009,34(1):90-99
Scientists have proposed two fault systems of different ages in the Sea of Marmara: the Thrace-Eski?ehir Fault Zone of Early Miocene–Early Pliocene age and the North Anatolian Fault Zone of Late Pliocene–Recent age. Different seismicity rates and extensions of these faults onto land near ?stanbul have been suggested. One of the reasons for these differences is the contamination of seismicity catalogs by seismic events from quarries operated in ?stanbul and its vicinity, including Gaziosmanpa?a (Cebeci and Kemerburgaz), Çatalca, Ömerli, Gebze, and Hereke.In this study, we investigated waveforms of 179 seismic events (1.8 < Md < 3.0) from the KOERI, NEMC digital database. We determined differences between earthquakes and quarry blasts based on time- and frequency-domain analyses of their seismograms (amplitude peak ratio, power ratio, and spectral amplitude ratio) and used these differences as discriminants. The results of this study indicate that 15% and 85% of the investigated seismic events are earthquakes and quarry blasts, respectively. 相似文献
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Doğan Kalafat Kıvanç Kekovalı Feyza Akkoyunlu Zafer Ögütçü 《Journal of Seismology》2014,18(3):371-384
On 23 October 2011 at 1341 local time, a strong earthquake (Mw?=?7.1) occurred east of Lake Van (KOERI; Kandilli Observatory and Earthquake Research Institute). The focal parameters of the main shock and 29 aftershocks with M?≥?4.0 were obtained from regional broadband seismic data from KOERI network by using Regional Moment Tensor Inversion Code (Dreger 2002). It is confirmed that the main shock had thrust faulting mechanism. The stress tensor analysis was completed using the focal mechanism solutions and the software developed by (Gephart Comp Geosci 16: 953-989, 1990). The maximum principal stress (P compressional) of the main shock is aligned in a N-S (NNW/SSE) direction and the tensional axis (T dilatation) is aligned in an E-W (ENE-WSW) direction. The b value is calculated as 0.96 using the maximum likelihood method (Utsu 1999). 相似文献
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S. Feyza Cinicioglu Ilknur Bozbey Sadik Oztoprak M. Kubilay Kelesoglu 《Engineering Geology》2007,94(3-4):145-165
This paper presents an integrated, earthquake-damage assessment that standardizes and quantifies methods of analysis. The proposed methodology evaluates all damage-causing phenomena, both individually and in combination. This approach inherently relates to soil-structure interactions by quantifying site-specific geotechnical and structural properties. Specifically considered is ground shaking, the primary damage-causing phenomenon. Also evaluated are the collateral effects of liquefaction, degradation of seismic-bearing capacity and slope failure (landslides). The methodology incorporates a literature-derived probabilistic assessment of damage-causation, and is interpreted and presented as single numbers deemed “Damage Grades.” These damage grades integrate the initial probabilistic evaluation with professional experience and judgment in order to determine potential damage to a particular structure at a particular location. This methodology was applied, with success, to two different locations in Istanbul, Turkey. It should be tested by engineering geologists and geotechnical engineers, for it may be applicable to earthquake-prone areas elsewhere. 相似文献
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