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目前进行的地震危险性分析计算中, 潜在震源区范围和震级上限的确定过程中存在很大的不确定性。 采用二级划分和三级划分潜在震源区的方法, 对潜在震源区范围不确定性进行了研究; 用震级上限的单边正态分布模型代替固定的震级上限模型, 分析了这种改进对地震危险性分析结果的影响及其工程意义。 结果表明, 用三级划分潜源的方法代替二级划分潜在震源方法可降低局部地区的地震危险性, 对于在潜在震源区附近选址和降低工程成本有重要意义。 震级上限的改进, 使得地震危险性降低, 这对百年使用年限的工程更具有实用性。 相似文献
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潜在震源区震级上限不确定性研究 总被引：7，自引：1，他引：6
潜在震源区的震级上限（Mu）是指在该潜在震源区内可能发生的最大地震的震级．预期未来发生超过该震级地震的概率趋于0．本文运用误差分析及逻辑树等方法,并结合发震模型的数值模拟得到的大震合成目录等结果,系统分析并最终得到了不同途径给出的不同类型潜在震源区震级上限的不确定性．该结果可直接应用于包括地震区划在内的工程地震以及活动断裂危险性评价等工作中． 相似文献
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逻辑树方法可用于定量评定震级-频度关系,推断低震级地震年发生率时产生的不确定性．这些不确定性因素包括:震级-频度关系对自相似性的偏离;不同的拟合方法;确定年平均发生率的方法;拟合时的震级步长; 起算震级及震级误差等．本文以鲜水河震源区为例,研究强地震序列外推地震危险性评定所需要的4级以上地震年发生率时可能产生的不确定性．敏感性分析表明,同一种拟合方法中最敏感的因子是确定年发生率的方法,其次是震级步长和起算震级,震级误差影响相对较小．
逻辑树评定震级-频度关系不确定性的步骤为: ① 根据研究区已有资料和认识建立表述震级-频度关系不确定性的逻辑树;② 计算所有末端分支的震级-频度关系;③ 分析各不确定性因子的敏感性,修正逻辑树的结构和调整初始权重;④ 再计算末端分支的震级-频度关系,计算每一震级档的余累积分布函数; ⑤ 给定分位数,求得与此分位水准相应的地震年频数．
本文以80％和20％的分位水准,得到鲜水河震源区4级地震（不含余震）的年频数为0.643 0,而与分位数50％相应的年频数为0.631 8,两者十分接近． 相似文献
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一直以来,海啸波特征作为表征海啸潜在破坏性的参数指标得到了广泛应用,特别是针对近场极端海啸事件造成的灾害来说,这种表征具有较好的适用性.然而总结分析历史海啸事件造成的损失发现：在远场近岸及港湾系统中,海啸诱导的强流却是造成损失的主要原因.陆架或港湾振荡导致海啸波幅快速升降诱发强流,可能促使港工设施受到威胁及损害,进而对海啸预警服务及海事应急管理提出了新的挑战.因此,全面理解与评估海啸在港湾中诱发的灾害特征,探索港湾中海啸流的数值模拟方法,发展针对港湾尺度的海啸预警服务指导产品尤为迫切.受限于海啸流验证数据的缺乏及准确模拟海啸流技术方法的诸多不确定性,大部分海啸数值模拟研究工作主要是针对水位特征的研究及验证,可能导致对港湾中海啸灾害危险性认识的曲解与低估.本研究基于非线性浅水方程,针对夏威夷群岛三个典型港湾建立了精细化海啸数值模型（空间分辨率达到10 m）,并联合有限断层破裂模型计算分析了日本东北地震海啸在三个港湾及其邻近区域的海啸特征,波、流计算结果与实测结果吻合较好,精细化的海啸港湾模型模拟结果可信.模拟发现港湾中较小的波幅,同样可以产生强流.综合分析日本东北地震海啸波、流特征对输入条件不确定性的响应结果发现：港湾中海啸波-流能量的空间分布特征差异较大,这与港湾系统中海啸波的驻波特性相关;相比海啸波幅空间特征,海啸流特征具有更强的空间敏感性;海啸流时空分布特征对输入条件的不确定性响应比海啸波幅对这些不确定性的响应更强,海啸流的模拟与预报更有挑战性;不确定性对海啸流计算精度的影响会进一步传导放大港湾海啸流危险性的评估及对港工设施产生的应力作用的误差,合理的输入条件对海啸流的精确模拟至关重要.最后,希望通过本文的研究可以从海啸波-流特征角度更加全面认识近岸海啸灾害特征,拓展海啸预警服务的广度与深度,从而为灾害应急管理部门提供更加科学合理的辅助决策产品. 相似文献
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最大峰值加速度与有效峰值加速度的大小比例关系及影响因素探讨 总被引：1，自引：0，他引：1
分别以最大峰值加速度(以下简称PGA)和有效峰值加速度(以下简称EPA)为参数,对金沙江流域上12个工程场点进行了地震危险性分析,得到了各个场点在不同的年超越概率下的基岩PGA和EPA值。通过对PGA、EPA值比较分析认为:PGA与EPA值的大小比例关系主要受年超越概率大小的影响,当年超越概率较大时,表现为PGA>EPA;当年超越概率较小时,PGA与EPA的比例关系还与场点周围的潜源分布形式及潜源的震级上限的大小有关,不同的年超越概率、不同的潜源分布形式和震级上限,可使PGA>EPA,也可使PGA相似文献
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基于广义帕累托分布构建地震活动性模型,因其输入参数取值难以避免不确定性,导致依据该模型所得的地震危险性估计结果具有不确定性。鉴于此,本文选取青藏高原东北缘为研究区,提出了基于全域敏感性分析的地震危险性估计的不确定性分析流程和方法。首先,利用地震活动性广义帕累托模型,进行研究区地震危险性估计;然后,选取地震记录的起始时间和震级阈值作为地震活动性模型的输入参数,采用具有全域敏感性分析功能的E-FAST方法,对上述两个参数的不确定性以及两参数之间的相互作用对地震危险性估计不确定性的影响进行定量分析。结果表明:地震危险性估计结果（不同重现期的震级重现水平、震级上限及相应的置信区间）对两个输入参数中的震级阈值更为敏感;不同重现期的地震危险性估计结果对震级阈值的敏感程度不同;对不同的重现期而言,在影响地震危险性估计结果的不确定性上,两个输入参数之间存在非线性效应,且非线性效应程度不同。本文提出的不确定性分析流程和方法,可以推广应用于基于其它类型地震活动性模型的地震危险性估计不确定性分析。 相似文献
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潜在震源区不确定性因素分析 总被引：5，自引：1，他引：5
本文根据洪华生(Der Kiureghian-Ang)断层破裂模型,对不同尺度的潜在震源区及各种震源参数进行了地震危险性数值计算。分析了潜在震源区划分范围,震级上限M_u及β值等地震活动性参数的不确定性对地震危险性分析的影响,其结果可供地震区划及工程地震等工作者参考。 相似文献
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具有一定面波震级的海啸地震常常产生巨大的海啸，要想对海啸地震作出较早的，准确的海啸预报，尽早地确定其为可能引发海啸的事件是十分关键的。本文显示，利用P波脉冲宽度计算宽频带矩震级Mwp，可给出震源持续时间的精确估计，我们发现，结合Mwp和震源持续时间即可确定1992年的尼加拉瓜地震为一个可能的海啸地震。我们的结果显示，Mwp结合源持续时间可为海啸预报提供一种有效的工具，尤其是对于震源持续时间特别长的海地震。 相似文献
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Logic-tree Approach for Probabilistic Tsunami Hazard Analysis and its Applications to the Japanese Coasts 总被引：2，自引：0，他引：2
Tadashi Annaka Kenji Satake Tsutomu Sakakiyama Ken Yanagisawa Nobuo Shuto 《Pure and Applied Geophysics》2007,164(2-3):577-592
For Probabilistic Tsunami Hazard Analysis (PTHA), we propose a logic-tree approach to construct tsunami hazard curves (relationship
between tsunami height and probability of exceedance) and present some examples for Japan for the purpose of quantitative
assessments of tsunami risk for important coastal facilities. A hazard curve is obtained by integration over the aleatory
uncertainties, and numerous hazard curves are obtained for different branches of logic-tree representing epistemic uncertainty.
A PTHA consists of a tsunami source model and coastal tsunami height estimation. We developed the logic-tree models for local
tsunami sources around Japan and for distant tsunami sources along the South American subduction zones. Logic-trees were made
for tsunami source zones, size and frequency of tsunamigenic earthquakes, fault models, and standard error of estimated tsunami
heights. Numerical simulation rather than empirical relation was used for estimating the median tsunami heights. Weights of
discrete branches that represent alternative hypotheses and interpretations were determined by the questionnaire survey for
tsunami and earthquake experts, whereas those representing the error of estimated value were determined on the basis of historical
data. Examples of tsunami hazard curves were illustrated for the coastal sites, and uncertainty in the tsunami hazard was
displayed by 5-, 16-, 50-, 84- and 95-percentile and mean hazard curves. 相似文献
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Sensitivity of PSHA results to ground motion prediction relations and logic-tree weights 总被引：7，自引：0，他引：7
Fabio Sabetta Antonio Lucantoni Hilmar Bungum Julian J. Bommer 《Soil Dynamics and Earthquake Engineering》2005,25(4):317-329
Epistemic uncertainty in ground motion prediction relations is recognized as an important factor to be considered in probabilistic seismic hazard analysis (PSHA), together with the aleatory variability that is incorporated directly into the hazard calculations through integration across the log-normal scatter in the ground motion relations. The epistemic uncertainty, which is revealed by the differences in median values of ground motion parameters obtained from relations derived for different regions, is accounted for by the inclusion of two or more ground motion prediction relations in a logic-tree formalism. The sensitivity of the hazard results to the relative weights assigned to the branches of the logic-tree, is explored through hazard analyses for two sites in Europe, in areas of high and moderate seismicity, respectively. The analyses reveal a strong influence of the ground motion models on the results of PSHA, particularly for low annual exceedance frequencies (long return periods) and higher confidence levels. The results also show, however, that as soon as four or more relations are included in the logic-tree, the relative weights, unless strongly biased towards one or two relations, do not significantly affect the hazard. The selection of appropriate prediction relations to include in the analysis, therefore, has a greater impact than the expert judgment applied in assigning relative weights to the branches of the logic-tree. 相似文献
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采用球坐标系下非线性浅水波方程, 研究日本本州M9.0大地震引发的海啸对中国东南沿海的影响, 并计算了冲绳海槽构造带上3个不同段落可能发生潜在地震引发的海啸, 分析这些海啸与日本大海啸的浪高和走时关系. 结果表明, 日本地震海啸模拟结果与日本当地报道及中国东南沿海7个验潮站的报道结果相符. 冲绳海槽构造带中段可能发生的3次不同震级（M7.0, M7.5, M8.0）潜在地震引发的海啸到达中国东南沿海的时间比日本海啸提前约4个小时, 从震源区传播3个多小时即可到达华东沿海部分验潮站. 冲绳海槽M7.5潜在地震海啸在验潮站上计算的波高与日本海啸相当, 中冲绳海槽M8.0潜在地震海啸在大陈站的波高将超过0.9 m, 在坎门站波高将超过1.8 m. 北冲绳海槽的潜在地震海啸威胁主要集中在江苏盐城、 上海一带, 南冲绳海啸主要对台湾东北部和浙江沿海产生威胁. 本文对冲绳海槽构造带上潜在地震引发海啸的模拟结果, 可为中国东南沿海地区的防震减灾、 海啸预警提供有意义的参考. 相似文献
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Sinan Akkar Özkan Kale Ahmet Yakut Ulubey Çeken 《Bulletin of Earthquake Engineering》2018,16(8):3439-3463
This study describes the methodology implemented to establish the ground-motion logic-tree for national probabilistic seismic hazard map of Turkey for shallow active crustal regions. The presented procedure provides quantitative information to guide the hazard experts while establishing the logic tree to capture the epistemic uncertainty in ground-motion characterization. It uses non-data-driven and data-driven testing methods to identify and rank candidate ground-motion prediction equations (GMPEs) under a specific ground-motion database. The candidate GMPEs are subjected to visual inspection and are classified into center, body and range (CBR) spectral estimates for a proper consideration of epistemic uncertainty. The GMPEs classified into CBR are then used in a suite of seismic hazard sensitivity analysis to establish the most suitable GMPE logic-tree whose spectral estimates are not biased by any one of the GMPEs in the logic-tree structure. The sensitivity analysis considers normalized spectral ordinates and is not manipulated by the spectral amplitudes. The proposed procedure is inherited from the relevant studies of the Earthquake Model of the Middle East (EMME; www.efehr.org:8080/jetspeed/portal/emme.psml) regional seismic hazard project. This paper also highlights the similarities and differences in ground-motion characterization between EMME and our approach. 相似文献
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Stefano Parolai Gottfried Grünthal Rutger Wahlstrm 《Soil Dynamics and Earthquake Engineering》2007,27(1):49-59
Seismic noise was measured at some 20 sites in the Cologne area (Germany) aligned nearly perpendicular to a graben structure. The H/V spectral noise ratio for each site was used to derive realistic S-wave velocity profiles down to the bedrock by means of a genetic algorithm inversion. Numerical simulations were performed for different combinations of source and propagation path parameters: focal depth, epicentral distance, attenuation and fault mechanism. Synthetic seismograms were produced and converted to Fourier and response spectra. Finally, the site-specific values from response spectral ratios, with their uncertainties, were used to modify attenuation functions entering the logic-tree algorithm of the probabilistic seismic hazard assessment (PSHA). The site-specific response spectra show the significance of taking into account the local S-wave velocity structure in PSHA. 相似文献
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Probabilistic permanent fault displacement hazard via Monte Carlo simulation and its consideration for the probabilistic risk assessment of buried continuous steel pipelines 
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下载免费PDF全文 Permanent fault displacements (PFDs) because of fault ruptures emerging at the surface are critical for seismic design and risk assessment of continuous pipelines. They impose significant compressive and tensile strains to the pipe cross‐section at pipe‐fault crossings. The complexity of fault rupture, inaccurate mapping of fault location and uncertainties in fault‐pipe crossing geometries require probabilistic approaches for assessing the PFD hazard and mitigating pipeline failure risk against PFD. However, the probabilistic approaches are currently waived in seismic design of pipelines. Bearing on these facts, this paper first assesses the probabilistic PFD hazard by using Monte Carlo‐based stochastic simulations whose theory and implementation are given in detail. The computed hazard is then used in the probabilistic risk assessment approach to calculate the failure probability of continuous pipelines under different PFD levels as well as pipe cross‐section properties. Our probabilistic pipeline risk computations consider uncertainties arising from complex fault rupture and geomorphology that result in inaccurate mapping of fault location and fault‐pipe crossings. The results presented in this paper suggest the re‐evaluation of design provisions in current pipeline design guidelines to reduce the seismic risk of these geographically distributed structural systems. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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John McCloskey Andrea Antonioli Alessio Piatanesi Kerry Sieh Sandy Steacy Suleyman Nalbant Massimo Cocco Carlo Giunchi JianDong Huang Paul Dunlop 《Earth and Planetary Science Letters》2008,265(1-2):61-81
Several independent indicators imply a high probability of a great (M > 8) earthquake rupture of the subduction megathrust under the Mentawai Islands of West Sumatra. The human consequences of such an event depend crucially on its tsunamigenic potential, which in turn depends on unpredictable details of slip distribution on the megathrust and how resulting seafloor movements and the propagating tsunami waves interact with bathymetry. Here we address the forward problem by modelling about 1000 possible complex earthquake ruptures and calculating the seafloor displacements and tsunami wave height distributions that would result from the most likely 100 or so, as judged by reference to paleogeodetic data. Additionally we carry out a systematic study of the importance of the location of maximum slip with respect to the morphology of the fore-arc complex. Our results indicate a generally smaller regional tsunami hazard than was realised in Aceh during the December 2004 event, though more than 20% of simulations result in tsunami wave heights of more than 5 m for the southern Sumatran cities of Padang and Bengkulu. The extreme events in these simulations produce results which are consistent with recent deterministic studies. The study confirms the sensitivity of predicted wave heights to the distribution of slip even for events with similar moment and reproduces Plafker's rule of thumb. Additionally we show that the maximum wave height observed at a single location scales with the magnitude though data for all magnitudes exhibit extreme variability. Finally, we show that for any coastal location in the near field of the earthquake, despite the complexity of the earthquake rupture simulations and the large range of magnitudes modelled, the timing of inundation is constant to first order and the maximum height of the modelled waves is directly proportional to the vertical coseismic displacement experienced at that point. These results may assist in developing tsunami preparedness strategies around the Indian Ocean and in particular along the coasts of western Sumatra. 相似文献
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This study conducts coupled simulation of strong motion and tsunami using stochastically generated earthquake source models. It is focused upon the 2011 Tohoku, Japan earthquake. The ground motion time-histories are simulated using the multiple-event stochastic finite-fault method, which takes into account multiple local rupture processes in strong motion generation areas. For tsunami simulation, multiple realizations of wave profiles are generated by evaluating nonlinear shallow water equations with run-up. Key objectives of this research are: (i) to investigate the sensitivity of strong motion and tsunami hazard parameters to asperities and strong motion generation areas, and (ii) to quantify the spatial variability and dependency of strong motion and tsunami predictions due to common earthquake sources. The investigations provide valuable insights in understanding the temporal and spatial impact of cascading earthquake hazards. Importantly, the study also develops an integrated strong motion and tsunami simulator, which is capable of capturing earthquake source uncertainty. Such an advanced numerical tool is necessary for assessing the performance of buildings and infrastructure that are subjected to cascading earthquake–tsunami hazards. 相似文献