共查询到19条相似文献，搜索用时 500 毫秒
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论述了断层地表永久位移概率地震危险性分析方法的发展过程和应用现状,指出了断层地表破裂预测模型研究的意义。根据我国最近的活动断层地表破裂震后调查结果,基于走滑型断层地表破裂数据,拟合了地表破裂预测模型。采用地震活动性模型和地表破裂预测模型,计算了则木河断裂地表迹线上的永久位移危险性曲线,对预测模型在工程场地地震危险性分析中的应用,提出了建议。 相似文献
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北京时间2022年1月8日,青海省门源县发生了MS6.9地震,震中位于冷龙岭断裂西端与托莱山断裂过渡区。地震发生后,文章利用亚米级分辨率的高分7号卫星影像对本次地震产生的地震破裂带进行详细解译,并与野外调查结果进行对比,获得此次地震地表破裂带分布及组合特征。结果显示,此次地震形成两条破裂带,长度分别约21 km和5 km,分别沿冷龙岭断裂西段和托莱山断裂东段展布。地震破裂带由一系列雁列式地震裂缝、挤压鼓包及拉张凹陷组成,破裂带组合特征反映出发震断裂明显的左旋走滑特征,但利用影像并未识别出同震位错等定量数据。在此基础上,文章对比冷龙岭断裂东段存在的历史地震破裂带,讨论了冷龙岭断裂未来地震危险性问题。 相似文献
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沿安宁河断裂带小相岭段发现了古地震的地表破裂遗迹。在两个场地开挖了横跨主断裂的探槽 ,以研究这里的晚全新世古地震。结果表明 ,在最近的大约 2 30 0a中 ,该断裂段至少发生过 4次伴有地表破裂的古地震事件 ,平均复发间隔为 6 0 0～ 70 0a。这里的最晚事件很可能发生在公元 15世纪 ,并且有可能发生在公元 14 80年。最晚事件沿地表断层产生了 3m的平均左旋位错 ,这相当于一次矩震级为 7 5± 0 3的走滑型大地震的同震平均位错量 相似文献
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为了解决采用Trimble GX 3D地面激光三维扫描仪分析互层胶结土中正断层地震地表破裂位错特征时,未有效模拟地表垂直和水平位移的基本特征,获取的地表破裂位错特征结果不准确的问题。提出新的互层胶结土中正断层地震地表破裂位错特征研究方法,先构建地震地表弹性位错模型,分析互层胶结土正断层的地表三维断裂特征,得到地表在受到走滑、逆冲和张开错动导致的地表错位变化情况;再通过正断层地震地表破裂离心机试验,获得互层胶结土中正断层地震地表破裂位错特征。试验结果说明,所提方法可有效分析互层胶结土中正断层地震地表破裂位错特征,且破裂点在土体模型中部和中下部的裂缝深度分别为22.4 m和33.4 m,裂缝上的破裂点处于土体模型的中下部时,裂缝的深度越深。 相似文献
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覆盖土层场地地震断裂反应分析方法 总被引：7，自引：1，他引：7
基于有限元和拟静力的根本原理，提出了一种基于断层位错的覆盖土层场地地震断裂反应弹塑性有限元分析方法，计算中考虑了土层厚度、断层种类和倾角、软弱夹层以及土的非线性等因素，通过编制的程序计算了地表断裂位移，模拟了土层的破裂过程。 相似文献
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云南中甸-大具断裂上新发现的地震地表破裂带 总被引：1，自引：0，他引：1
中甸-大具断裂是川滇菱形块体的西南边界,总体走向310°—320°。近年来我们对该断裂进行了1:50000条带状地质填图,发现了断裂活动的地质地貌证据。其中,在丽江大具盆地内（金沙江右岸）沿断裂新发现一处典型地震地表破裂带,长约600m,宽120m左右,主要表现为地表挤压鼓包、挤压垄脊、张裂缝、挤压阶区等,呈NW走向,与中甸-大具断裂走向基本一致。野外工作中,我们详细记录和测量了地表破裂的破裂样式、破裂规模和相关定量数据,利用旋翼无人机测绘了地表破裂带的形态和展布,获得了高精度DEM,分析了地表破裂表现出的运动性质。在已有资料的基础上讨论了地表破裂的形成时代、归属、震级大小,简要分析了其发震断层。新地震地表破裂带的发现为进一步研究中甸-大具断裂活动特征、古地震及地震危险性提供了基础资料。 相似文献
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Robert Graves Thomas H. Jordan Scott Callaghan Ewa Deelman Edward Field Gideon Juve Carl Kesselman Philip Maechling Gaurang Mehta Kevin Milner David Okaya Patrick Small Karan Vahi 《Pure and Applied Geophysics》2011,168(3-4):367-381
CyberShake, as part of the Southern California Earthquake Center??s (SCEC) Community Modeling Environment, is developing a methodology that explicitly incorporates deterministic source and wave propagation effects within seismic hazard calculations through the use of physics-based 3D ground motion simulations. To calculate a waveform-based seismic hazard estimate for a site of interest, we begin with Uniform California Earthquake Rupture Forecast, Version 2.0 (UCERF2.0) and identify all ruptures within 200?km of the site of interest. We convert the UCERF2.0 rupture definition into multiple rupture variations with differing hypocenter locations and slip distributions, resulting in about 415,000 rupture variations per site. Strain Green Tensors are calculated for the site of interest using the SCEC Community Velocity Model, Version 4 (CVM4), and then, using reciprocity, we calculate synthetic seismograms for each rupture variation. Peak intensity measures are then extracted from these synthetics and combined with the original rupture probabilities to produce probabilistic seismic hazard curves for the site. Being explicitly site-based, CyberShake directly samples the ground motion variability at that site over many earthquake cycles (i.e., rupture scenarios) and alleviates the need for the ergodic assumption that is implicitly included in traditional empirically based calculations. Thus far, we have simulated ruptures at over 200 sites in the Los Angeles region for ground shaking periods of 2?s and longer, providing the basis for the first generation CyberShake hazard maps. Our results indicate that the combination of rupture directivity and basin response effects can lead to an increase in the hazard level for some sites, relative to that given by a conventional Ground Motion Prediction Equation (GMPE). Additionally, and perhaps more importantly, we find that the physics-based hazard results are much more sensitive to the assumed magnitude-area relations and magnitude uncertainty estimates used in the definition of the ruptures than is found in the traditional GMPE approach. This reinforces the need for continued development of a better understanding of earthquake source characterization and the constitutive relations that govern the earthquake rupture process. 相似文献
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Potential sources are simplified as point sources or linear sources in current probabilistic seismic hazard analysis (PSHA) methods. Focus size of large earthquakes is considerable, and fault rupture attitudes may have great influ-ence upon the seismic hazard of a site which is near the source. Under this circumstance, it is unreasonable to use the simplified potential source models in the PSHA, so a potential rupture surface model is proposed in this paper. Adopting this model, we analyze the seismic hazard near the Chelungpu fault that generated the Chi-Chi (Jiji) earthquake with magnitude 7.6 and the following conclusions are reached. 1 This model is reasonable on the base of focal mechanism, especially for sites near potential earthquakes with large magnitude; 2 The attitudes of poten-tial rupture surfaces have great influence on the results of probabilistic seismic hazard analysis and seismic zoning. 相似文献
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计算机仿真模拟设定地震断层动态破裂传播和近断层强地表运动响应的结果表明, 对于特征地震而言,近断层附近的地表运动特征与断层破裂传播的方向性有着强烈的依赖关系. 当场地（观测点）至断层的距离给定时,正向于破裂传播方向的场地（场地A）的地表质点运动（位移、速度、加速度）,远远大于震中附近（场地B）和反向于破裂传播方向的场地（场地C）的地表质点运动,而且沿断层垂直分量所辐射的SH波的传播起到了主导作用. 对应于场地A,B和C,统计分析结果表明,峰值加速度的几何平均值之比为2.15:1.5:1, 而且各自的均方差分别为0.12, 0.11和0.13. 如果将所得的研究结果应用于概率地震危险性分析中,对于较低的年超越频度,近断层附近的地表峰值加速度的估算值可下降15%~30%. 因此,考虑到断层破裂传播方向性对地表运动的影响,区域衰减曲线的回归分析模型应该给予恰当的修正. 相似文献
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Seismic hazard assessment of Tehran,Iran with emphasis on near-fault rupture directivity effects 
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下载免费PDF全文 Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB,Probabilistic Seismic Hazard Analysis(PSHA) is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seismic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al.(1997) model with broadband approach and Shahi and Baker(2011) model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites. 相似文献
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Disaggregation of the seismic hazard has become a popular technique to convey information on the main sources contributing
to the hazard at a particular site. Recently published work adopts geographic disaggregation analysis of seismic hazard as
a tool to identify dominant rupture scenarios for municipalities in Mainland Portugal. The authors conclude that the seismic
hazard in South and Central Portugal is dominated by the seismicity that takes place offshore, around 70km WSW of Cape S.
Vicente, both for the return periods of 475 years and 975 years. Whilst recognizing the merits of the approach taken and the
utility of the tools developed, we take issue with this last conclusion. We consider that the proposed disaggregation returns
a picture of the biases in the hazard analysis, more than any real feature of the distribution of relevant seismogenic sources. 相似文献
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本文以二滩地区为例,介绍如何结合地震危险性分析的结果,采用理论模拟方法估计工作地区近场强地面运动情况,为工程抗震设计提供必需的地面运动动力学参数。 文中采用理论方法计算剪切位错点源的格林函数;根据断裂动力学模型、近场地面峰值加速度衰减曲线和场地附近的加速度谱来标定震源模型;计算了若在坝区附近发生Ms=6.2级地震时场地的综合地震图、加速度傅氏谱和反应谱等。由理论模拟计算的峰值加速度衰减曲线和观测结果符合较好。在震中距为20km处的加速度谱的截止频率fmax与观测值相吻合（约为8 Hz左右）,相应的峰值加速度为211cm/s2,振动持续时间为3.4秒。 相似文献
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本文研究了俯冲带潜在震源区离散化方法及考虑俯冲带高震级地震震源破裂面和震源深度的场点地震动计算方法,推导了俯冲带潜在震源区地震危险性计算公式,并使用中国海域及邻区地震危险性模型进行地震危险性试算.结果表明,本文建立的考虑俯冲带潜在震源区的地震危险性算法能够实现场点地震危险性计算时对俯冲带高震级地震震源破裂面和震源深度的... 相似文献
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The Mw 7.1 earthquake of November 12, 1999 severely damageda 2.5 km long viaduct on a stretch under construction of theIstanbul-Ankara motorway, 18 km W of Bolu. The fault rupture crossedthe viaduct with an observed offset close to 1.5 m; the viaduct decksuffered large permanent displacements but did not collapse.Seismic hazard at the site appears to be governed by characteristicearthquakes occurring every few hundred years both on the Düzce faultand on the main stretch of North Anatolian fault (NAF). Smaller activefaults near the site also contribute to the hazard.We investigate how a reliable design response spectrum of displacement canbe constructed for the viaduct site using both probabilistic and deterministictools. After checking the applicability of known attenuation relations againstrecorded data, we illustrate a hazard analysis that incorporates acharacteristic earthquake model for the relevant faults, and accounts forstatistical directivity effects on the Düzce fault. Constant-risk responsespectra up to 3 s are thus obtained for different return periods. Syntheticmotions at the site are generated next, using a known source model, inorder to explore the features of the displacement response spectrum atvibration periods in the range between 1s and 6 s, in which the dominantresponse of the viaduct deck, uncoupled from the piers, occurs. Adiscussion of results follows. 相似文献
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Resolving rupture processes of great earthquakes has fundamental importance to the study of earthquake physics,rupture dynamics, fault zone structure, and evolving processes. It also plays an essential role in earthquake hazard estimation,emergency response and seismic hazard mitigation. This paper reviews the major progress of the earthquake rupture process studies in the last decades, with an emphasize on the research directions of the department geophysics of Peking University including real-time response, back-projection techniques, geodetic data analysis, joint inversion and inversion in complex earth medium. We discussed the advantages and limitations of tradition methods; proposed a systematic and integrated approach from fast-response to detailed study. We also raised perspectives of using source models for ground motion prediction and the possibility of full-dynamic inversion. 相似文献