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1.
本文介绍了特征地震的对数正态分布模型、 正态分布模型和布朗过程时间模型, 提出了使用地震破裂面源模型的特征地震含时间的概率地震危险性分析理论和方法. 通过具体算例对不同的特征地震模型进行了比较, 并对特征地震危险性分析方法进行了系统探索. 研究结果表明, 特征地震含时间模型在复发周期早期的地震危险性低于不含时间模型, 而在后期其地震危险性则高于不含时间模型. 特征地震复发周期的对数正态分布模型与布朗过程时间模型计算得出的地震危险性差别不大. 在未到期望复发时间时, 正态分布模型与前两种模型计算的地震危险性差别不大; 而接近期望复发时间及之后时段, 正态分布模型计算的地震危险性则迅速增大. 相似文献
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采用了分布式地震活动性模型. 该模型无需潜在震源区划分,同时简化了地震危险性概率分析方法. 根据破坏性地震目录建立了3个地震活动性模型,利用高斯光滑函数获得了华北区域内的a值分布特征,使用3种典型的衰减模型,分别计算了50年内超越概率10%, 5%和2%的地震动峰值加速度分布. 其分析结果显示了峰值加速度分布特征与我国第四代区划图大体一致,特定地震活动区（太原、 石家庄等地区）的峰值加速度略高于第四代区划图的结果,而这种峰值加速度分布特征与该地区较高的地震活动性特征是一致的. 概率危险性曲线结果表明,唐山、太原和北京等地区的潜在地震危险性比华北区域内其它城市高. 相似文献
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交城断裂为太原盆地西界的主控边界断裂,为查明交城断裂在这一地区的确切位置和地裂缝与交城断裂的关系,采用地震地质调查和人工地震勘探对在此范围内交城断裂的具体位置和地层错断情况进行了详细研究。结果表明,交城断裂交城县城段并不是位于基岩隆起区与盆地倾斜平原的分界处,而是位于距该分界东南约200 m处。交城县城西北侧的地裂缝与地震勘探在这一带所探查到的交城断裂的位置相当吻合,由此可以推断地裂缝的产生与交城断裂有关,属构造地裂缝。指出,在进行活动断裂附近的城市规划或重大工程建设时应对“山根”的倒退现象予以高度重视。 相似文献
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鄂尔多斯块体周缘历史上多次发生大地震,同时该地区人口稠密,城市群集中,有必要分析该地区未来30年的大地震危险性,为该地区的应急备灾工作提供参考.本文利用块体周缘活动断层的滑动速率、历史地震古地震等资料,建立了考虑大地震发生率的时间非平稳性质和大地震危险性近断层分布特征的地震危险性模型.计算了块体周缘未来30年Ⅷ度地震动的超越概率分布图,并同《中国地震动参数区划图》的地震危险性模型进行了比较.本文研究认为,由断层滑动速率估算的断层地震活动性与基于地震目录统计的地震活动性总体差别不大,但断层源的地震危险性在沿断层破裂面地区增大明显.结果认为,鄂尔多斯块体周缘未来30年地震危险性最高的地区在块体西南缘,六盘山东麓断裂和会宁—义岗断裂及周边地区是未来30年地震危险性较高的地区. 相似文献
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交城断裂带北段最大潜在地震发震概率评估1 总被引：1，自引：1，他引：0
基于太原市目标区交城断裂带的定量研究,特别是对活动断裂上的古地震资料进行的系统、详细的分析与总结,建立了反映该断裂地震地质特点和运动学属性的复发模式和概率模型.引入震级-地表破裂长度、震级-震源破裂长度、震级-断层破裂面积以及震级-地震矩的经验关系进行震级估计,最后进行综合评估以确定交城断裂带北段潜在地震的最大震级.复发模式的建立兼顾了泊松和准周期两种模式,利用专家意见法组合相应的Poisson模型和BPT模型,计算活动断裂最大潜在地震的复发概率.结果表明,交城断裂带北段潜在地震最大震级为Ms7.2级,而未来50a、100a、200a发生Ms7.2级地震的概率分别为2.1％、4.0％和7.9％. 相似文献
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本文采用了空间光滑地震活动性模型,该模型无需潜在震源区划分,同时发展了概率地震危险性分析新方法。根据三种地震目录资料建立了三种地震活动性模型,利用高斯光滑函数获得了湖南区域内的比值分布特征,使用了两种典型的衰减模型,计算了50年内超越概率10％的地震动峰值加速度（PGA）分布。其分析结果显示PGA分布特征与中国地震动参数区划图大体一致,部分区域PGA提高,PGA达0．05g的区域显著扩大,其中包括邵阳、湘潭、吉首、怀化等重要城市,而这种PGA分布特征与该地区地震活动性特征是一致的。概率危险性曲线的结果表明常德等地区的潜在地震危险性比湖南区域内其他城市高。表明此模型用于地震危险性计算中是简便易行的,且具有较高的精度。尤其对于地质和地震构造信息缺乏的弱震区和中强震区,该方法作为替代方法并有着广泛的应用价值。 相似文献
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利用华北地区地震活动性资料,建立了地震危险性计算的一致性模型.在此模型的基础上,得出了北京、天津、唐山和济南等7个城市未来2500年内地震的时空强度分布,并计算了2500年回复周期的地震动峰值加速度(PGA).结果表明,唐山和太原的PGA最大(>0.2g),石家庄和北京次之(≈0.17g).对华北地区2500年地震记录的正演计算结果表明,太原和唐山地区的潜在地震危险最有可能来源于震级在6.0～7.0、震中距离在12～15km的地震活动;而北京、天津和石家庄地区则可能来源于震级在5.5～6.0、震中距离在10km左右的地震活动.采用IBC(International Building Code)方法计算后的结果显示,太原、唐山等地区的PGA与2001年我国地震动峰值加速度值基本一致,与此地区的较高地震活动性特征相符.利用随机震源模型,还给出了影响此7个城市的最大地震记录的加速度、速度及位移时程曲线,这对本区工程建筑的抗震性设计以及对救援设施的选址等有重要作用. 相似文献
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根据华北地区的地震目录,建立了4个空间光滑的地震活动性模型,并以这些模型为空间分布函数,将华北地震区每个地震带的地震年发生率分配到空间格点中,计算这一地区的地震危险性．结果表明,采用仪器记录地震计算得到的地震活动性模型和地震危险性结果能够反映华北地区现今的地震活动水平和地震危险性水平,符合人们对现今华北地区地震危险性的认识;采用历史破坏性地震（Mge;4.7）计算的地震活动性模型和地震危险性结果,较好地反映了华北地区中强地震活动区的地震危险性水平;以地震应变计算地震活动率,并根据点椭圆模型和线椭圆模型计算得到的地震活动性模型,能够较好地反映大地震的活动水平和空间构造特征．将根据4个模型计算得到的50年超越概率10%峰值加速度（PGA）分布加权平均,得到综合的华北地区PGA分布,并将该PGA分布与根据《中国地震动参数区划图》中综合潜源方案计算得到的50年超越概率10%的PGA分布做了比较,发现二者无本质差别,均能反映华北地震区的地震危险性水平．当然,二者也具有一定的差异:前者计算得到的符合PGAge;100 cm/s2条件的区域面积明显要比后者的大,而符合PGAge;250 cm/s2条件的区域面积则比后者的要小. 这主要是由于潜在震源区类型和空间分布函数不同造成的． 相似文献
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Aykut Deniz Kasim Armagan Korkmaz Ayhan Irfanoglu 《Pure and Applied Geophysics》2010,167(12):1475-1484
Izmir, the third largest city and one of the major economic centers in Turkey, has more than three million residents and one-half million buildings. The city, located in a seismically active region in western Anatolia, was a subject of the 1997 RADIUS (Risk Assessment Tools for Diagnosis of Urban Areas against Seismic Disaster) project. In this paper, the seismic hazard of Izmir is investigated through probabilistic seismic hazard assessment. First, the seismic setting of Izmir is presented. Considering the statistics of earthquakes that took place in the region during the period 1900–2005, a simple seismic hazard model is used to facilitate the assessment. To account for modeling uncertainties associated with the values of seismicity parameters, a logic tree procedure is employed in carrying out the seismic hazard computations. The resulting weighted average seismic hazard, presented in terms of peak ground acceleration and associated probability of exceedence, could be considered the “best estimate” of seismic hazard for Izmir. Accordingly, for a return period of 475 years, for rock sites, a PGA value of 0.34 g is calculated. This PGA hazard estimate is close to the current code-recommended design acceleration level for Izmir. 相似文献
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The first step in any seismic hazard study is the definition of seismogenic sources and the estimation of magnitude-frequency relationships for each source. There is as yet no standard methodology for source modeling and many researchers have worked on this topic. This study is an effort to define linear and area seismic sources for Northern Iran. The linear or fault sources are developed based on tectonic features and characteristic earthquakes while the area sources are developed based on spatial distribution of small to moderate earthquakes. Time-dependent recurrence relationships are developed for fault sources using renewal approach while time-independent frequency-magnitude relationships are proposed for area sources based on Poisson process. GIS functionalities are used in this study to introduce and incorporate spatial-temporal and geostatistical indices in delineating area seismic sources. The proposed methodology is used to model seismic sources for an area of about 500 by 400 square kilometers around Tehran. Previous researches and reports are studied to compile an earthquake/fault catalog that is as complete as possible. All events are transformed to uniform magnitude scale; duplicate events and dependent shocks are removed. Completeness and time distribution of the compiled catalog is taken into account. The proposed area and linear seismic sources in conjunction with defined recurrence relationships can be used to develop time-dependent probabilistic seismic hazard analysis of Northern Iran. 相似文献
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本文以天水地区为研究区,结合地震潜在震源区模型和Newmark位移预测方程,采用概率地震危险性分析方法,计算了该地区50年超越概率10%水平下的Newmark位移。同时,根据天水地区50年超越概率10%下的阿里亚斯烈度,并结合Newmark位移与阿里亚斯烈度的关系式,计算了天水地区在遭受50年超越概率10%下的阿里亚斯烈度影响时,潜在滑坡体产生的Newmark位移分布。通过比较上述两种方法得到的天水地区不同Newmark位移的分布特征,本文认为二者虽然存在较大差异,但其空间分布特征均能反映天水地区每个场点处的相对滑坡危险性。对滑坡危险性水平进行分区的结果显示,天水地区60%以上的区域具有高地震滑坡危险性,50%以上的区域具有甚高地震滑坡危险性。本文的研究结果可以作为天水地区地震危险性及风险评估的参考资料,也可以作为天水地区城市规划、土地使用规划、地震应急准备以及其它公共政策制定的参考资料。 相似文献
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本文利用晋冀蒙交界地区1500年以来记录较完整的MS5.0及以上历史地震烈度资料和2000年以来的地震活动资料，分别进行地震灾害危险性和地震活动性分析。首先，利用ArcGIS将历史地震烈度资料数字化，没有等震线记录的地震用烈度衰减关系计算烈度圈半径。将研究区划分成0.1°×0.1°的网格，将烈度资料分配到与之相交的每个网格，并用烈度-频度关系计算每个网格的烈度a、b值。基于地震发生遵从泊松分布的假定，估算未来50年内晋冀蒙交界区遭受某一地震烈度的超越概率。同时，计算50年超越概率10%对应的地震烈度，计算结果表明张家口蔚县、阳原和山西广灵县周边地区的地震危险性较高。最后，采用中小地震能量密度值计算方法，对2000年以来的现今地震活动进行定量分析，与历史地震烈度资料分析结果进行对比，发现中小地震活动圈定的危险区与历史地震烈度资料评估计算的概率高值区相对应，因此，这两种方法可为晋冀蒙交界地区的地震活动性和危险性评价提供参考。 相似文献
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M. Boccaletti G. Corti P. Gasperini L. Piccardi G. Vannucci S. Clemente 《Pure and Applied Geophysics》2001,158(12):2313-2332
—?The city of Florence possesses a concentration of cultural and artistic treasures which is unique in the world. In this sense it has a particularly high seismic exposure and a potentially high vulnerability. In order to better evaluate its seismic hazard and risk, we analyzed the seismic response of the urban area of Florence by performing a multidisciplinary study on the effects of earthquakes on the city. By a computer aided methodology we re-evaluated the seismic intensity reports of the May 18 and June 6, 1895 earthquakes in different parts of the city and compared these data with recent studies on surface geology, active tectonics and actual fault movements in the Florence basin. We concluded that more detailed studies of soil response are needed to form a basis for public policy. 相似文献
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隧道围岩受地震荷载作用影响产生开裂变形,给交通、安全与经济带来极大影响,为提升隧道安全稳定性能,以某市隧道为对象,研究地震作用下深埋隧道围岩形变的数值模拟。综合考虑地震动作用与地震波扩散特性,利用FLAC软件构建三维动力模型;通过边界设置解决地震波反射问题,基于物理力学参数与地震荷载条件,通过相对变形法研究地震条件下深埋隧道围岩变形特性、能量聚集特性与安全性能。研究结果显示:深埋隧道围岩受地震荷载作用影响,形成挤让、椭圆化的变形走向;变形达到最高值时,应变能量密度高于2350 J/m^3的区域集中在隧道Ⅰ洞左侧围岩边墙和中夹岩柱上;各监测点安全系数呈非对称性,隧道右侧下角区域安全系数低于国家相关标准,计算结果与实际测量结果一致。 相似文献
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In this paper, we have proposed an alternative seismic hazard modeling by using distributed seismicites. The distributed seismicity model does not need delineation of seismic source zones, and simplify the methodology of probabilistic seismic hazard analysis. Based on the devastating earthquake catalogue, we established three seismi- city model, derived the distribution of a-value in northern China by using Gaussian smoothing function, and cal-culated peak ground acceleration distributions for this area with 2%, 5% and 10% probability of exceedance in a 50-year period by using three attenuation models, respectively. In general, the peak ground motion distribution patterns are consistent with current seismic hazard map of China, but in some specific seismic zones which in-clude Shanxi Province and Shijiazhuang areas, our results indicated a little bit higher peak ground motions and zonation characters which are in agreement with seismicity distribution patterns in these areas. The hazard curves have been developed for Beijing, Tianjin, Taiyuan, Tangshan, and Ji’nan, the metropolitan cities in the northern China. The results showed that Tangshan, Taiyuan, Beijing has a higher seismic hazard than that of other cities mentioned above. 相似文献
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-- We investigate the impact of different rupture and attenuation models for the Cascadia subduction zone by simulating seismic hazard models for the Pacific Northwest of the U.S. at 2% probability of exceedance in 50 years. We calculate the sensitivity of hazard (probabilistic ground motions) to the source parameters and the attenuation relations for both intraslab and interface earthquakes and present these in the framework of the standard USGS hazard model that includes crustal earthquakes. Our results indicate that allowing the deep intraslab earthquakes to occur anywhere along the subduction zone increases the peak ground acceleration hazard near Portland, Oregon by about 20%. Alternative attenuation relations for deep earthquakes can result in ground motions that differ by a factor of two. The hazard uncertainty for the plate interface and intraslab earthquakes is analyzed through a Monte-Carlo logic tree approach and indicates a seismic hazard exceeding 1 g (0.2 s spectral acceleration) consistent with the U.S. National Seismic Hazard Maps in western Washington, Oregon, and California and an overall coefficient of variation that ranges from 0.1 to 0.4. Sensitivity studies indicate that the paleoseismic chronology and the magnitude of great plate interface earthquakes contribute significantly to the hazard uncertainty estimates for this region. Paleoseismic data indicate that the mean earthquake recurrence interval for great earthquakes is about 500 years and that it has been 300 years since the last great earthquake. We calculate the probability of such a great earthquake along the Cascadia plate interface to be about 14% when considering a time-dependent model and about 10% when considering a time-independent Poisson model during the next 50-year interval. 相似文献
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山西断陷带位于鄂尔多斯与华北地块交汇处,是我国著名的历史强震活动带之一,尤其是断陷盆地中部区域,6级以上地震频发.本研究旨在揭示忻定盆地中南部、太原盆地及临汾盆地中北部交汇处的深部结构特征,分析盆地的形成和演化,探讨该区域孕震环境.利用山西地震台网观测数据以及固定地震台站融合流动台站得到的地震数据,共7455个地震事件,采用双差层析成像方法,反演得到了太原盆地及周边地区的三维P波速度结构及精定位结果.层析成像结果显示,忻定盆地、太原盆地的中上地壳为明显的低速异常,被高速的石岭关隆起隔开,深部结构特征相对简单.太原盆地、临汾盆地及灵石隆起之间的深部结构特征较为复杂,反映了两个盆地演化过程的复杂性.穿过忻定盆地的速度剖面显示,在中地壳存在明显的低速异常体,且大部分地震都发生在该低速体上方;穿过太原盆地北部的剖面显示,该区域在20~25 km深度范围内有较密集的地震分布,并勾画出交城断裂呈犁形的断层特征;穿过太原盆地中部的剖面显示,太原盆地自西向东沉积层逐渐减薄;穿过临汾盆地的剖面揭示,汾东断裂在浅部倾角较陡,随深度增加倾角逐渐变小,倾向向东. 相似文献
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The occurrence of the Algiers earthquake (M 6.8) of May 21, 2003, has motivated the necessity to reassess the probabilistic seismic hazard of northern Algeria. The fact that this destructive earthquake took place in an area where there was no evidence of previous significant earthquakes, neither instrumental nor historical, strongly encourages us to review the seismic hazard map of this region. Recently, the probabilistic seismic hazard of northern Algeria was computed using the spatially smoothed seismicity methodology. The catalog used in the previous computation was updated for this review, and not only includes information until June 2003, but also considers a recent re-evaluation of several historical earthquakes. In this paper, the same methodology and seismicity models are utilized in an effort to compare this methodology against an improved and updated seismic catalog. The largest mean peak ground acceleration (PGA) values are obtained in northernmost Algeria, specifically in the central area of the Tell Atlas. These values are of the order of 0.48 g for a return period of 475 years. In the City of Algiers, the capital of Algeria, and approximately 50 km from the reported epicenter of this latest destructive earthquake, a new mean PGA value of 0.23 g is obtained for the same return period. This value is 0.07 g greater than that obtained in the previous computation. In general, we receive greater seismic hazard results in the surrounding area of Algiers, especially to the southwest. The main reason is not this recent earthquake by itself, but the significant increase in the mmax magnitude in the seismic source where the city and the epicenter are included. 相似文献