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1.
地震通常在时空上是丛集的。传统的地震危险性分析所考虑的只是每个地震丛集中最大震级的事件——主震,并用所考虑场地地震动强度量值的超越率来表示（Cornell,1968）。这种地震危险性概率分析（PSHA）用于长期的结构设计或评估。近来,出于对短期风险的管理,已采用一种类似的方法来进行余震地震危险性概率分析（APSHA）,其与主震的发生相关（Yeoand Cornell,2009）。地震危险性概率分析通常用一种均匀泊松过程来描述事件的发生,而余震地震危险性概率分析则通过有条件的非均匀泊松过程来模拟余震的发生,其概率值取决于触发余震序列的主震震级。另外,由主震和后续余震组成的每个地震丛集,可以看成以相同主震概率发生的单一事件。这就可以用相对简单的方式在危险性分析中考虑余震,这个方法首先由Toro和Silva（2001）论证,并由Boyd（2012）进一步研究。实际上,这篇短文中心探讨概率方面,说明地震危险性概率分析和余震地震危险性概率分析的联合结果以得到一种考虑主震一余震序列的地震危险性整体解析解的可行性,而前面提到的研究中这些仍然缺乏。这种方法应用的结果,说明有助于依据导致超越某一加速度阈值同时也考虑余震的地震事件发生率（如对于结构设计）,初步评估地震危险性的增加。因而这从地震工程长远来看是切合实际的方向。 相似文献
2.
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
3.
本文介绍了余震危险性概率分析的概念,完整列出其相关公式的解析表达式并阐述了余震危险性概率分析的具体方法。以2017年九寨沟MS7.0地震为例,首先,求得该地震余震序列的相关参数,结果显示:九寨沟MS7.0地震余震序列理论最大余震震级约为ML5.3;b值约为0.784 1,明显低于中国西南地区同类型的其它地震,表明九寨沟地震余震区应力水平相对较高;p值约为1.109 7,明显高于中国西南地区同类型的其它地震,表明九寨沟地震余震序列随时间衰减较快。其次,计算此次地震余震与主震释放能量的比例关系,结果显示:在九寨沟MS7.0地震事件中,截止到10月22日约99.69%的能量为主震所释放,0.31%的能量为余震所释放。最后,利用九寨沟MS7.0余震序列参数结果并结合衰减关系,分别计算了主震后0—1天、1—10天、10—30天和90—100天内不同断层距内不同水平的峰值加速度和峰值速度的超越概率,结果显示:随着断层距增加,在相同时间间隔内超越概率的值呈下降趋势;在震后第一天内余震危险性最高,随着震后时间增加,相应的超越概率值呈现出明显下降趋势,表明九寨沟MS7.0地震余震危险性主要来自早期余震。本文的相关成果可以为震后地震危险性分析提供参考,并为短时间内应急救援及灾后重建提供辅助决策意见。 相似文献
4.
《地震工程与工程振动》2017,(2)
本文划分了西宝高速公路研究区域地震区带和潜在震源区,采用历史地震资料计算了地震活动性参数,在PGA衰减关系、地震危险性概率计算方法和场地地震动影响分析的基础上,计算了西宝高速公路未来50年超越概率2%、10%和63%的PGA分布,基于Arc GIS绘制了西宝高速公路地震危险性分区图;从设计地震危险性和实际地震危险性2方面总结了公路结构物地震危险性评价方法,开展了漆水河大桥、千河大桥、沣河大桥和渭河大桥等典型结构物的地震危险性评价。研究结果表明:西宝高速公路PGA跨越Ⅶ度和Ⅷ度基本烈度区,评价结果略高于我国第四代地震区划图,这是与渭河断陷盆地地震活跃的现实一致的;漆水河大桥和千河大桥的地震危险性是可控的,沣河大桥和渭河大桥的地震危险性不可控,应采取工程措施进行抗震加固。 相似文献
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6.
基于OpenSEES平台,以某近海刚构桥桥墩为例,选取符合场地类型的地震波,并根据地震记录构造主余震序列。运用"能力需求比"分析方法建立不同服役时间节点桥墩控制截面在不同损伤状态条件下的地震易损性曲线,研究氯离子侵蚀和主余震序列对桥墩抗震性能的影响。结果表明:同一损伤状态的超越概率随着服役时间延长和PGA增大而不断变大,且随着损伤状态等级提高,超越概率逐渐降低。轻微损伤状态下,主余震序列对桥墩易损性影响较小;中等损伤、严重破坏和完全倒塌状态下,同一服役期,考虑主余震序列作用下桥墩的超越概率相比于仅考虑主震作用明显增大。 相似文献
7.
鉴于我国砌体结构抗震面临的严峻形势,以及主余震序列作用下砌体结构易损性研究存在的不足,以汶川地震中1栋典型砌体房屋为依托,开展考虑主余震序列作用的砌体结构易损性研究。首先,建立了结构的三维有限元模型,并从结构动力特性与损伤等方面验证了模型的合理性; 其次,选取整体损伤耗能作为结构性能参数,并给出了对应不同破坏等级的结构整体损伤耗能界限值; 最后,基于IDA方法对结构进行了不同主余震序列作用下的易损性分析。结果表明:相对于层间位移角,整体损伤耗能更适用于描述余震对结构的累积损伤效应; 随着结构主震损伤程度的加深,余震对结构造成的影响越明显,且主余震序列作用下结构呈现出比主震单独作用下高一个破坏等级的趋势; 当ΔPGA小于0.6时,结构的极限状态超越概率最大增幅不超过10%,此时余震的影响较小; 当ΔPGA大于0.6时,结构的极限状态超越概率最大增幅可达到33.1%,此时余震的影响较大。 相似文献
8.
该文首先将汶川余震序列分成西南、 东北两段, 用加卸载响应比方法分别进行分析, 结果表明震后两段的响应比值都比较低, 明显小于1, 这可判断汶川地震属于主余震型地震; 且地震序列中的强余震(M≥5.0)发生前加卸载响应比值出现明显异常, 大都是加卸载响应比出现峰值, 之后发生强余震。 考虑到主震后余震的时空丛集现象, 结合ETAS模型对原有的加卸载响应比计算式进行改造, 并分析了主震之后15天的改造后响应比值, 发现改造后的响应比在一定程度上消除了丛集的影响, 并展示了对紧随主震发生的强余震的预测能力。 相似文献
9.
尽管缺少可信的确定性地震前兆,但地震学家通过对地震丛集属性日渐精确的理解,已经获得了地震活动的重要的预测信息。在过去的15年间和较大的地震序列期间,公众可以近实时地得到基于一般短期丛集模型并与时间有关的地震概率。这些预报描述一个给定震级主震之后可能发生地震事件的平均概率和数目,但并不适合于当前特定的序列和不包含可能的余震位置信息。我们的模型在两方面依赖于一般的预测模型的基本原则：它以强地面震动概率表述预测,并将一个现有的基于断层数据和历史地震并与时间无关的发震模型,和描述与时间有关的区域地震丛集的渐增的复杂模型结合起来,得到一个在加州任何地方未来24小时强震动概率随时间变化的地图。我们的地震危险性建模方法可以帮助大家较好地理解随时间变化的地震危险性,并增加它对公众、应急决策者和媒体的实用性。 相似文献
10.
应用地震动衰减关系计算了1966年邢台地震以来中国大陆及近海发生的21次MSge;7地震序列的主震和强余震产生的有效峰值加速度，并对计算结果进行了比较分析， 发现76.2%地震序列的强余震产生的有效峰值加速度超过主震，其中50%多的强余震产生的有效峰值加速度在大范围内大幅度地超过主震. 本研究表明在强余震震中区附近，强余震往往会造成比主震更严重的破坏， 因此在地震危险性分析中要充分考虑强余震的影响场，才能为抗震设防提供科学、安全、可靠的依据. 相似文献
11.
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
12.
Probabilistic seismic hazard analysis in Nepal 总被引：3，自引：0，他引：3
The seismic ground motion hazard for Nepal has been estimated using a probabilistic approach. A catalogue of earthquakes has been compiled for Nepal and the surrounding region （latitude 26% N and 31.7% N and longitude 79° E and 90° E） from 1255 to 2011. The distribution of catalogued earthquakes, together with available geological and tectonic information were used to delineate twenty-three seismic source seismic source information and probabilistic earthquake hazard prediction relationship, peak ground accelerations （PGAs） have zones in Nepal and the surrounding region. By using the parameters in conjunction with a selected ground motion been calculated at bedrock level with 63%, 10%, and 2% probability of exceedance in 50 years. The estimated PGA values are in the range of 0.07-0.16 g, 0.21 0.62 g, and 0.38-1.1 g for 63%, 10%, and 2% probability of exceedance in 50 years, respectively. The resulting ground motion maps show different characteristics of PGA distribution, i.e., high hazard in the far-western and eastern sections, and low hazard in southern Nepal. The quantified PGA values at bedrock level provide information for microzonation studies in different parts of the country. 相似文献
13.
地震危险性概率分析(PSHA)是目前最广泛应用于地震灾害与风险性评估的方法。然而它在计算中却存在着一个错误:把强地面运动衰减关系(一个函数)的条件超越概率等同于强地面运动误差(一个变量)的超越概率。这个错误导致了运用强地面运动误差(空间分布特征)去外推强地面运动的发生(时间分布特征)或称之为遍历性假设,同时也造成了对PSHA理解和应用上的困难。本文推导出新的灾害计算方法(称之为KY-PSHA)来纠正这种错误。 相似文献
14.
ShahidA．Khan M．AliShah M．Qaisar 《地震学报》2003,25(4):361-373
通过确定性和概率性方法，对发展迅速的巴基斯坦沿海地区进行了地震危险性评估．根据该地区的地震构造和地质条件，确定了5个地震区域的11个断层作为该地区的潜在震源，计算了每个潜在震源的最大可能震级．根据与之相关震源的最大可信震级，计算了7个沿海城市的峰值加速度（PGA）．瓜达尔（Gwadar）和奥尔马腊（Ormara）的峰值加速度分别为0.21和0.25 g，处于地震危险性水平较高的地区；杜尔伯德（Turbat）和卡拉奇（Karachi）位于地震危险性水平较低的地区，峰值加速度小于0.1 g．同时，分别绘制了50年和100年超越概率为10％的PGA区划图，区划图的分区间隔为0.05 g． 相似文献
15.
In this paper, a new probabilistic seismic hazard assessment (PSHA) is presented for Peninsular India. The PSHA has been performed using three different recurrence models: a classical seismic zonation model, a fault model, and a grid model. The development of a grid model based on a non-parameterized recurrence model using an adaptation of the Kernel-based method that has not been applied to this region before. The results obtained from the three models have been combined in a logic tree structure in order to investigate the impact of different weights of the models. Three suitable attenuation relations have been considered in terms of spectral acceleration for the stable continental crust as well as for the active crust within the Gujarat region. While Peninsular India has experienced large earthquakes, e.g., Latur and Jabalpur, it represents in general a stable continental region with little earthquake activity, as also confirmed in our hazard results. On the other hand, our study demonstrates that both the Gujarat and the Koyna regions are exposed to a high seismic hazard. The peak ground acceleration for 10 % exceedance in 50 years observed in Koyna is 0.4 g and in the Kutch region of Gujarat up to 0.3 g. With respect to spectral acceleration at 1 Hz, estimated ground motion amplitudes are higher in Gujarat than in the Koyna region due to the higher frequency of occurrence of larger earthquakes. We discuss the higher PGA levels for Koyna compared Gujarat and do not accept them uncritically. 相似文献
16.
Mine Betül Demircioğlu Karin Şeşetyan Tamer Y. Duman Tolga Çan Senem Tekin Semih Ergintav 《Bulletin of Earthquake Engineering》2018,16(8):3399-3438
Over the years, several local and regional seismic hazard studies have been conducted for the estimation of the seismic hazard in Turkey using different statistical processing tools for instrumental and historical earthquake data and modeling the geologic and tectonic characteristics of the region. Recently developed techniques, increased knowledge and improved databases brought the necessity to review the national active fault database and the compiled earthquake catalogue for the development of a national earthquake hazard map. A national earthquake strategy and action plan were conceived and accordingly with the collaboration of the several institutions and expert researchers, the Revision of Turkish Seismic Hazard Map Project (UDAP-Ç-13-06) was initiated, and finalized at the end of 2014. The scope of the project was confined to the revision of current national seismic hazard map, using the state of the art technologies and knowledge of the active fault, earthquake database, and ground motion prediction equations. The following two seismic source zonation models are developed for the probabilistic earthquake hazard analysis: (1) Area source model, (2) Fault and spatial smoothing seismic source model (FSBCK). In this study, we focus on the development and the characterization of the Fault Source model, the background spatially smoothed seismicity model and intrinsic uncertainty on the earthquake occurrence-rates-estimation. Finally, PSHA results obtained from the fault and spatial smoothed seismic source model are presented for 43, 72, 475 and 2475 years return periods (corresponding to 69, 50, 10, and 2% probability of exceedance in 50 years) for PGA and 5% damped spectral accelerations at 0.2 and 1.0 s. 相似文献
17.
Behrooz Tavakoli 《Journal of Seismology》2002,6(4):525-545
The sensitivity and overall uncertainty in peak ground acceleration (PGA)estimates have been calculated for the city of Tabriz, northwestern Iran byusing a specific randomized blocks design. Eight seismic hazard models andparameters with randomly selected uncertainties at two levels have beenconsidered and then a linear model between predicted PGA at a givenprobability level and the uncertainties has been performed. The inputmodels and parameters are those related to the attenuation, magnituderupture-length and recurrence relationships with their uncertainties.Application of this procedure to the studied area indicates that effects ofthe simultaneous variation of all eight input models and parameters on thesensitivity of the seismic hazard can be investigated with a decreasingnumber of computations for all possible combinations at a fixed annualprobability. The results show that the choice of a mathematical model ofthe source mechanism, attenuation relationships and the definition ofseismic parameters are most critical in estimating the sensitivity of seismichazard evaluation, in particular at low levels of probability of exceedance.The overall uncertainty in the expected PGA for an annual probability of0.0021 (10% exceedence in 50 yr) is expressed by a coefficient ofvariation (CV) of about 34% at 68% confidence level for a distance ofabout 5km from the field of the major faults. The CV will decrease withincreasing site-source distance and remains constant, CV = 15%, fordistances larger than 15 km. Finally, treating alternative models on theoverall uncertainty are investigated by additional outliers in input decision. 相似文献
18.
In the process of updating existing PSHA maps in Central Asia, a first step is the evaluation of the seismic hazard in terms of macroseismic intensity by applying a data driven method. Following the Site Approach to Seismic Hazard Assessment (SASHA) [11], the evaluation of the probability of exceedance of any given intensity value over a fixed exposure time, is mainly based on the seismic histories available at different locations without requiring any a-priori assumption about seismic zonation. The effects of earthquakes not included in the seismic history can be accounted by propagating the epicentral information through a Intensity Prediction Equation developed for the analyzed area. In order to comply with existing building codes in the region that use macroseismic intensity instead of PGA, we evaluated the seismic hazard at 2911 localities using a macroseismic catalog composed by 5322 intensity data points relevant to 75 earthquakes in the magnitude range 4.6–8.3. The results show that for most of the investigated area the intensity having a probability of at least 10% to be exceeded in 50 years is VIII. The intensity rises to IX for some area struck by strong earthquakes in the past, like the Chou-Kemin-Chilik fault zone in northern Tien-Shan, between Kyrgyzstan and Kazakhstan, or in Gissar range between Tajikistan and Uzbekistan. These values are about one intensity unit less than those evaluated in the Global Seismic Hazard Assessment Program (GSHAP; Ulomov, The GSHAP Region 7 working group [29]). Moreover, hazard curves have been extracted for the main towns of Central Asia and the results compared with the estimates previously obtained. A good agreement has been found for Bishkek (Kyrgyzstan) and Dushanbe (Tajikistan), while a lower probability of occurrence of I=VIII has been obtained for Tashkent (Uzbekistan) and a larger one for I=IX in Almaty (Kazakhstan). 相似文献
19.
Conventional method of probabilistic seismic hazard analysis (PSHA) using the Cornell–McGuire approach requires identification of homogeneous source zones as the first step. This criterion brings along many issues and, hence, several alternative methods to hazard estimation have come up in the last few years. Methods such as zoneless or zone-free methods, modelling of earth’s crust using numerical methods with finite element analysis, have been proposed. Delineating a homogeneous source zone in regions of distributed seismicity and/or diffused seismicity is rather a difficult task. In this study, the zone-free method using the adaptive kernel technique to hazard estimation is explored for regions having distributed and diffused seismicity. Chennai city is in such a region with low to moderate seismicity so it has been used as a case study. The adaptive kernel technique is statistically superior to the fixed kernel technique primarily because the bandwidth of the kernel is varied spatially depending on the clustering or sparseness of the epicentres. Although the fixed kernel technique has proven to work well in general density estimation cases, it fails to perform in the case of multimodal and long tail distributions. In such situations, the adaptive kernel technique serves the purpose and is more relevant in earthquake engineering as the activity rate probability density surface is multimodal in nature. The peak ground acceleration (PGA) obtained from all the three approaches (i.e., the Cornell–McGuire approach, fixed kernel and adaptive kernel techniques) for 10% probability of exceedance in 50?years is around 0.087?g. The uniform hazard spectra (UHS) are also provided for different structural periods. 相似文献