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1.
Within the framework of the performance based earthquake engineering, site specific earthquake spectra for Van province has been obtained. It is noteworthy that, in probabilistic seismic hazard assessment, as a first stage data from geological studies and records from the instrumental period were compiled to make a seismic source characterization for the study region. The probabilistic seismic hazard curves were developed based on selected appropriate attenuation relationships, at rock sites, with a probability of exceedance 2, 10 and 50% in 50 yrs period. The obtained results are compared with the spectral responses proposed for seismic evaluation and retrofit of building structure in Turkish Earthquake Code (2007), section 7. The acceleration response spectrums obtained from probabilistic seismic hazard analysis are matched to adjust earthquake accelerograms recorded during the 2011 Van earthquakes by using SeismoMatch v2.0 software. The aim of this procedure is to obtain a set of reasonable earthquake input motions for the seismic evaluation of existing buildings. 相似文献
2.
Repeated earthquakes (EQs) are clear indication of alarming seismicity which can be witnessed across Indian subcontinent. Increase in population density with inappropriate construction practice repeatedly rise alarm that in comparison to damage scenarios experienced during previous major to great EQs in India, future catastrophes would be manifold. Performing regional seismic hazard as well as site response studies can possibly help in accurate estimation of probable future seismic scenario. Site class (SC) of EQ recording stations is an important part of both seismic hazard as well as site response analyses. In seismic hazard analysis, suitable attenuation relations are often selected based on comparison of recorded ground motion with proposed ground motion as per selected attenuation relation for the same SC. Thus, unless SC of recorded ground motions is known, suitability of selected attenuation relation cannot be validated. In addition, recent studies suggest that for same soil column, ground motion may amplify at the surface from minimal to very high depending upon input motion characteristics. Thus again, unless SC of recording station is not known, recorded ground motion cannot be considered with confidence as outcrop or base motion for region specific site response studies. In the present work, SC of eight recording stations located in Tarai region of Uttarakhand, India located adjacent to the Himalayan belt and which are part of PESMOS database, are established by three different methods namely; equivalent linear ground response analysis, generalized inversion technique and horizontal to vertical spectral ratio method. Collectively all these three methods suggest same SC for each of the eight recording stations including Roorkee, Rishikesh, Dehradun etc. Further, obtained SC based on the present study is considerably different from available SC as per PESMOS database. However, present findings are matching with recent published work. Obtained results can be very helpful in developing surface seismic hazard using regional ground motion records towards minimizing future EQ induced damages. 相似文献
3.
《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2013,7(3-4):173-185
The most important seismic hazard parameters required to demarcate seismic zones are the peak horizontal acceleration (PHA) and spectral acceleration (SA). The two approaches for evaluation of seismic hazard are the probabilistic seismic hazard analysis and the deterministic seismic hazard analysis (DSHA). The present study evaluates the seismic hazard of the South Indian Peninsular region based on the DSHA methodology. In order to consider the epistemic uncertainties in a better manner, a logic tree approach was adopted in the evaluation of seismic hazard. Two types of seismic sources and three different attenuation relations were used in the analysis. The spatial variation of PHA (mean and 84th percentile values) and SA values for 1 Hz and 10 Hz at bedrock level (84th percentile values) for the entire study area were evaluated and the results are presented here. The surface level peak ground acceleration (PGA) values will be different from that of the bedrock level values due to the local site conditions. The PGA values at ground surface level were evaluated for four different National Earthquake Hazard Reduction Program site classes by considering the non-linear site response of different soil types. The response spectra for important cities in South India were also prepared using the deterministic approach and the results are presented in this paper. 相似文献
4.
China is prone to highly frequent earthquakes due to specific geographical location, which could cause significant losses to society and economy. The task of seismic hazard analysis is to estimate the potential level of ground motion parameters that would be produced by future earthquakes. In this paper, a novel method based on fuzzy logic techniques and probabilistic approach is proposed for seismic hazard analysis (FPSHA). In FPSHA, we employ fuzzy sets for quantification of earthquake magnitude and source-to-site distance, and fuzzy inference rules for ground motion attenuation relationships. The membership functions for earthquake magnitude and source-to-site distance are provided based on expert judgments, and the construction of fuzzy rules for peak ground acceleration relationships is also based on expert judgment. This methodology enables to include aleatory and epistemic uncertainty in the process of seismic hazard analysis. The advantage of the proposed method is in its efficiency, reliability, practicability, and precision. A case study is investigated for seismic hazard analysis of Kunming city in Yunnan Province, People’s Republic of China. The results of the proposed fuzzy logic-based model are compared to other models, which confirms the accuracy in predicting the probability of exceeding a certain level of the peak ground acceleration. Further, the results can provide a sound basis for decision making of disaster reduction and prevention in Yunnan province. 相似文献
5.
Generally the seismic hazard of an area of interest is considered independent of time. However, its seismic risk or vulnerability, respectively, increases with the population and developing state of economy of the area. Therefore, many areas of moderate seismic hazard gain increasing importance with respect to seismic hazard and risk analysis. However, these areas mostly have a weak earthquake database, i.e., they are characterised by relative low seismicity and uncertain information concerning historical earthquakes. In a case study for Eastern Thuringia (Germany), acting as example for similar places in the world, seismic hazard is estimated using the probabilistic approach. Because of the lack of earthquakes occurring in the recent past, mainly historical earthquakes have to be used. But for these the actual earthquake sources or active faults, needed for the analysis, are imprecisely known. Therefore, the earthquake locations are represented by areal sources, a common practice. The definition of these sources is performed carefully, because their geometrical shape and size (apart from the earthquake occurrence model) influence the results significantly. Using analysis tools such as density maps of earthquake epicentres, seismic strain and energy release support this. Oversizing of areal sources leads to underestimation of seismic hazard and should therefore be avoided. Large location errors of historical earthquakes on the other hand are represented by several alternative areal sources with final superimposition of the different results. In a very similar way information known from macroseismic observations interpreted as source rather than as site effects are taken into account in order to achieve a seismic hazard assessment as realistic as possible. In very local cases the meaning of source effects exceeds those of site effects very likely. The influence of attenuation parameter variations on the result of estimated local seismic hazard is relatively low. Generally, the results obtained by the seismic hazard assessment coincide well with macroseismic observations from the thoroughly investigated largest earthquake in the region. 相似文献
6.
Nuclear power plants are designed to prevent the hazardous effects of the earthquakes and any external events to keep the safety of the plant. Ninety-one shallow seismic refraction profiles were performed to determine shear wave velocity of the engineering layers at the site of El Dabaa area that is situated to the northern coastline of Egypt for seismic hazard microzonation evaluation according to hazard index values. A microzonation is a procedure of delineating an area into individual zones having different ranks of numerous seismic hazards. This will aid in classifying areas of high seismic risk which is vigorous for industrial design of nuclear structures. The site response analysis requires the characterization of subsurface materials considering local subsurface profiles of the site. Site classification of the area under investigation was undertaken using P- and S-waves and available borehole data. The studied nuclear power plant site has been characterized as per NEHRP site classification using an average velocity of transverse wave (V s 30 ) of depth 30 m which acquired from seismic survey. This site was categorized into two site classes: the major one is “site class B,” and the minor one is “site class A.” The attenuation coefficient, the damping ratio and the liquefaction potential are geotechnical parameters which were derived from P- and S-waves, and have their major effects on the seismic hazard contribution. 1D ground response analysis was carried out in the places of seismic profiles inside the site for estimating the amount of ground quaking using peak ground acceleration (PGA), site amplification, predominant frequency and spectral accelerations on the surface of ground by the DEEPSOIL software package. Seven factors (criteria) deliberated to assess the earthquake hazard index map are: (1) the peak ground acceleration at the bedrock, (2) the amplification of the site, (3) the liquefaction potential, (4) the main frequency of the earthquake signal, (5) the average V s of the first 30 m from the ground surface, (6) the depth to the groundwater and (7) the depth to the bedrock. These features were exemplified in normalized maps after uniting them to 0–1 scores according to some criteria by the minimum and maximum values as linear scaling points. Multi-criteria evaluation is an application of multi-criteria decision analysis theory that used for developing a seismic hazard index map for a nuclear power plant site at El Dabaa area in ArcGIS 10.1 software. Two models of decision making were used in this work for seismic hazard microzonation. The analytic hierarchy process model was applied to conduct the relative weights of the criteria by pairwise comparison using Expert Choice Software. An earthquake hazard index map was combined using Weighted Linear Combination model of the raster weighted overlay tool of ArcGIS 10.1. The results indicated that most of the study site of the nuclear power plant is a region of low to moderate hazard; its values are ranging between 0.2 and 0.4. 相似文献
7.
This paper deals with the probabilistic seismic hazard analysis carried out in the Oran region, situated in the Northwest of Algeria. This part of Algeriawas historically struck by strong earthquakes. It was particularly affected during theOctober 9, 1790 Oran earthquake of intensity X. The main purpose of this work is to assessseismic hazard on rocks in order to provide engineers and planners with a basic tool for seismicrisk mitigation. The probabilistic approach is used in order to take into account uncertaintiesin seismic hazard assessment. Seismic sources are defined in the light of the most recentresults obtained from seismotectonics analyses carried out in North Algeria.Source parameters such as b-values, slip rate and maximum magnitude are assessed for eachseismic source. The attenuation of ground shaking motion with distance is estimated byusing attenuation relationships developed elsewhere throughout the world (Sadigh et al., 1993; Ambraseys and Bommer, 1991). The two relationships agree well with the local data. Differentchoices of source parameter values and attenuation relationships are assigned weights in alogic tree model. Results are presented as relationships between values of peak groundacceleration (PGA) and annual frequency of exceedance, and maps of hazard for returnperiods of 200 years and 500 years. A maximum peak ground acceleration of 0.42 g is obtainedfor the Oran site for a return period of 500 years. 相似文献
8.
In this paper we apply a probabilistic methodology to map specific seismic hazard induced by the Vrancea Seismogenic Zone, which represents the uttermost earthquake danger to Romania as well as its surroundings. The procedure is especially suitable for the estimation of seismic hazard at an individual site, and seismic hazard maps can be created by applying it repeatedly to grid points covering larger areas. It allows the use of earthquake catalogues with incompletely reported historical and complete instrumental parts. When applying themethodology, special attention was given to the effect of hypocentral depth and the variation of attenuation according to azimuth. Hazard maps specifying a 10% chance of exceedance of the given peak ground acceleration value for an exposure time of 50 years were prepared for three different characteristic depths of earthquakes in the Vrancea area. These maps represent a new realistic contribution to the mitigation of the earthquake risk caused by the Vrancea Seismogenic Zone in terms of: (1) input data (consistent, reliable, and the most complete earthquake catalogue), (2) appropriate and specific attenuation relationships (considering both azimuthal and depth effects); and (3) a new and versatile methodology. 相似文献
9.
The use of logic trees in probabilistic seismic hazard analyses often involves a large number of branches that reflect the uncertainty in the selection of different models and in the selection of the parameter values of each model. The sensitivity analysis, as proposed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796–817], is an efficient tool that allows the construction of logic trees focusing attention on the parameters that have greater impact on the hazard.In this paper the sensitivity analysis is performed in order to identify the parameters that have the largest influence on the Western Liguria (North Western Italy) seismic hazard. The analysis is conducted for six strategic sites following the multi-parameter approach developed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796–817] and accounts for both mean hazard values and hazard values corresponding to different percentiles (e.g., 16%-ile and 84%-ile). The results are assessed in terms of the expected PGA with a 10% probability of exceedance in 50 years for rock conditions and account for both the contribution from specific source zones using the Cornell approach [Cornell, C.A., 1968. Engineering seismic risk analysis. Bull. Seismol. Soc. Am. 58, 1583–1606] and the spatially smoothed seismicity [Frankel, A., 1995. Mapping seismic hazard in the Central and Eastern United States. Seismol. Res. Lett. 66, 8–21]. The influence of different procedures for calculating seismic hazard, seismic catalogues (epicentral parameters), source zone models, frequency–magnitude parameters, maximum earthquake magnitude values and attenuation relationships is considered. As a result, the sensitivity analysis allows us to identify the parameters with higher influence on the hazard. Only these parameters should be subjected to careful discussion or further research in order to reduce the uncertainty in the hazard while those with little or no effect can be excluded from subsequent logic-tree-based seismic hazard analyses. 相似文献
10.
Seismic Hazard for Selected Sites in Greece: A Bayesian Estimate of Seismic Peak Ground Acceleration 总被引：1，自引：1，他引：1
A procedure for estimating maximum values of seismic peak ground accelerationat the examined site and quantiles of its probabilistic distribution in a future timeinterval of a given length is considered. The input information for the method areseismic catalog and regression relation between peak seismic acceleration at a givenpoint and magnitude and distance from the site to epicenter (seismic attenuation law).The method is based on Bayesian approach, which simply accounts for influenceof uncertainties of seismic acceleration values. The main assumptions for the method are Poissonian character of seismic events flow and distribution law of Gutenberg-Richter's type. The method is applied to seismic hazard estimation in six selected sitesin Greece. 相似文献
11.
The preparation of the preliminary seismic hazard maps of the territory of Slovenia has been based on an expansion of the basic approach laid out by Cornell in 1968. Three seismic source models were prepared. Two of them are based mainly on the earthquake catalogue using the Poissonian probability model. A map of seismic energy release and a map of earthquake epicenter density are used to delineate seismic sources in these models. The geometry of the third model which is based on a rough estimate of seismotectonic setting is taken from the probabilistic seismic hazard analysis of a nuclear power plant in Slovenia. Published ground motion attenuation models based on strong motion records of recent strong earthquakes in Italy are used. Test maps for variable and uniform b-values are presented. The computer program, Seisrisk III, developed by the U.S. Geological Survey is used. 相似文献
12.
Seismically triggered landslides can cause great damage to the road construction in mountainous areas. The permanent displacement analysis based on Newmark sliding-block model can evaluate risk of these landslides from the perspective of deformation damage and overall failure probability of slopes. However, the sliding-block model does not consider the attenuation effect of the shear strength on the sliding surface during earthquake, causing the calculated value of Jibson method to be less than the actual value. Therefore, the Newmark model was modified by adding attenuation coefficients to the effective internal friction angle and the effective cohesion of geologic units. The landslide areal density was proposed for hazard zoning with the Wenchuan earthquake data. The results showed that the predicted values agreed well with the real distribution of the landslides triggered by the Lushan earthquake. The proposed hazard zoning method in this paper can predict the severity of seismic landslides in consideration of the environmental changes in mountainous regions after the earthquake and provide support for the site selection in highly seismic areas.
相似文献13.
A Probabilistic method is used to evaluate the seismic hazard of nineteen embankment dam sites in Jordan. A line source model developed by McGuire (1978) is used in this study. An updated earthquake catalogue covering the period from 1 A.D. to 1991 A.D. is used for this purpose. This catalogue includes all earthquakes that occurred in Jordan and adjacent areas, more specifically between latitudes 27.0°–35.5° N and longitudes 32.0°–39.0° E.Nine distinct seismic sources of potential seismic activities are identified. The seismic hazard parameters are determined using the method suggested by Kijko and Sellevoll (1989).The Peak Ground Acceleration (PGA) is selected as a measure of ground motion severity. Esteva (1974) attenuation relationship is used in evaluating PGA values at each dam site. Analysis is carried out for 50%, 90%, and 95% probability that is not being exceeded in a life time of 50, 100, and 200 years.Results of analysis indicate that PGA values are higher for dam sites closer to the Dead Sea Fault. This fault is believed to be responsible for most earthquake activities in Jordan and vicinity. The highest PGA value is found to be for Al-Karama dam site. 相似文献
14.
A probabilistic assessment of the seismic hazard in Turkey 总被引：1，自引：0，他引：1
15.
沙牌坝址基岩场地地震动输入参数研究 总被引：2，自引：0，他引：2
重大水利水电工程地震动输入参数必须根据专门的地震危险性分析结果来确定。目前由地震危险性分析得到的一致概率反应谱具有包络的意义,不能反映实际地震的频谱特性,输入“一致概率反应谱”可能导致地震作用偏大;拟合设计反应谱人工生成地震动加速度时程的频率非平稳性也没有得到很好解决。为了解决这些问题,得到与坝址地震危险性一致、具体地震的输入参数,结合沙牌大坝提出了一套适用于重大水利水电工程基岩场地地震动输入参数确定方法：通过以有效峰值加速度为参数的概率地震危险性计算分析,确定坝址不同超越概率下的有效峰值加速度及对坝址贡献最大的潜在震源区;在最大贡献潜在震源内利用震级空间联合分布概率最大法确定坝址设定地震,依据加速度反应谱衰减关系确定与坝址设定地震对应的设计反应谱;根据设定地震结果和时变功率谱模型参数衰减关系确定时变功率谱,将时变功率谱和最小相位谱按三角级数叠加法进行强度和频率非平稳地震加速度时程合成。在对沙牌坝址区域的地震活动性及地震构造环境分析评价的基础上,采用上述方法,得到了坝址基岩场地不同超越概率下的有效峰值加速度、设计反应谱、强度和频率非平稳地震加速度时程等地震动输入参数。 相似文献
16.
In the present study, the seismic hazard in the city of Patras, central Greece, is estimated. The computations are based on a slightly modified version of the method proposed by Cornell, allowing the introduction of individual attenuation laws for each seismic source. The obtained results emphasize the dependence of hazard on attenuation and the importance of the use of local attenuation laws in seismic hazard assessment. 相似文献
17.
Amit Shiuly 《Journal of the Geological Society of India》2018,92(1):54-58
Peak Ground Acceleration (PGA) is a very important ground motion parameter which is used to define the degree of ground shaking during an earthquake. It is also very helpful for designing earthquake resistant structure. The PGA can be estimated by attenuation relationships using magnitude, distance, source type etc of a ground motion. In the past, several researchers have developed over 450 attenuation relationships for predicting PGA for a specific region. In the present study an attempt has been made to develop an attenuation relationship on the basis of these available previous relationships in rock site which will be applicable for any region of the world. In the present study, PGA has been expressed as a function of moment magnitude and hypo-central distance in rock site. Chi-square test have also been performed with available earthquake data in American and Indian region for verifying the accuracy of the generated attenuation relationship. Using multiple regression and Genetic Algorithm (GA) the attenuation relationship equations have also been generated. These equations will be very helpful for performing seismic hazard analysis and predicting earthquake force in any region of the world. 相似文献
18.
Guatemala is one of the Central American countries that for some years now have been participating in a regional program for natural hazard assessment and disaster reduction, funded by the Nordic countries and coordinated by a regional institution (CEPREDENAC). Recent work related to seismic hazard has included the standardization, reporting and processing of seismicity data across the borders, followed by regional hazard modeling. The work presented here for Guatemala City represents a step from a regional to a more local level, based on reevaluation of historical seismicity, geological data related to active faults, and attenuation relations recently derived from analysis of strong motion records from the region. The site specific hazard calculations indicate that expected values of peak ground acceleration are ranging from less than 2 to more than 6 m s–2, corresponding to annual exceedence probabilities ranging from 0.1 to 0.001, respectively.
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19.
The assessment of seismic hazard at five selected sites in the Sannio-Matese region is based on the computer program SRAMSC. Owing to the extensive historical data base for the output parameter, the MSK intensiy is chosen. The seismicity model is made up of five narrow area seismic sources. Circular or elliptical macroseismic fields are assigned to individual sources. A generalized Kövesligethy equation is used for this purpose as the attenuation relationship. The study reveals similar and a rather high hazard at the sites at Benevento, Boiano, and Melfi, which are located in the zone of highest seismic activity. At the Pomigliano and Lucera sites, the assessed hazard is much lower. 相似文献
20.
A method based on Bayesian techniques has been applied to evaluate the seismic hazard in the two test areas selected by the participants in the ESC/SC8-TERESA project: Sannio-Matese in Italy and the northern Rhine region (BGN). A prior site occurrence model (prior SOM) is obtain from a seismicity distribution modeled in wide seismic sources. The posterior occurrence model (posterior SOM) is calculated after a Bayesian correction which, basically, recovers the spatial information of the epicenter distribution and considers attenuation and location errors, not using source zones. The uncertainties of the occurrence probabilities are evaluated in both models.The results are displayed in terms of probability and variation coefficient contour maps for a chosen intensity level, and with plots of mean return period versus intensity in selected test sites, including the 90% probability intervals.It turns out that the posterior SOM gives a better resolution in the probability estimate, decreasing its uncertainty, especially in low seismic activity regions. 相似文献