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1.
使用单键群方法研究了2011年3月11日日本本州东北部海域9.0级地震前地震空间相关长度变化。结果表明,在本次地震发生前约两年,5级以上地震的空间相关长度开始出现明显增长,变化趋势可以用幂次率进行很好的拟合。用没有7级以上强震发生的时段内的地震目录,采用相同方法进行了计算,没有发现明显的幂次率增长现象,说明强震前5级以上地震的空间相关长度的幂次率增长是地震孕育过程中震源区的物理性质特征的表现之一。 相似文献
2.
利用可大范围获取的空间参数给出区域土壤液化的评估方法,可预估震前各地区土壤液化可能性,可快速评估震后震区土壤液化情况,对预防减轻地震灾害以及地震快速响应救援都具有重要意义的.本文以我国1976唐山大地震液化调查资料为背景,提出了区域土壤液化预测的四参数简化评估方法,并用2011年新西兰基督城地震进行了检验.选取场地平均剪切波速V s30、复合地形指数CTI、场地到河流的距离DR以及地面峰值加速度PGA,分别代表土壤密实程度、饱水状态、地质年代和遭遇的地震作用大小,并基于我国唐山地震液化区域调查资料生成的样本,运用经典二元Logistic回归方法,建立了区域土壤液化预测模型和评估公式,回归检验结果良好,整体回判成功率为77%,非液化和液化区域成功率分别为73%和78%.将公式应用于评估2011年新西兰基督城地震液化情况,区域液化和非液化成功率分别为82%和88%,总体成功率为84%.以上结果表明本文模型可靠,方法正确,可用于区域土壤液化震前预估以及土壤液化震后快速评估. 相似文献
3.
在PEER地震动数据库(PGMD)的基础上, 结合近几年国内外特大地震的地面运动记录, 建立了地面运动数据库, 同时根据日本MW9.0特大地震获得的141组记录进行统计回归建立加速度反应谱衰减关系, 并采用条件均值反应谱法, 即设定地震与结构概率需求结合的方法选择地面运动. 选波实例表明, 当设定地震为特大地震时, 基于条件均值反应谱法选取地面运动记录时, 扩展数据库中大震记录并建立符合大震记录加速度反应谱的衰减关系是十分必要与迫切的. 该思路为进一步研究结构动态时程分析中地面运动记录选取问题及所选记录提供了依据. 相似文献
4.
本文把地震矩和地面加速度之间的理论关系与地震烈度和该加速度之间的经验关系结合起来,导出了使用Ⅵ度等震线平均半径估算我国历史大地震矩震级的公式。 我们使用这一公式给出了53个大地震的矩震级,并对其它震源参数作了计算和讨论。从本文的结果来看,板内地震的矩震级不大于9.0。 相似文献
5.
Yan-Guo Zhou Kai Liu Dao-Sheng Ling Tao Shen Yun-Min Chen 《Bulletin of Earthquake Engineering》2018,16(11):5151-5170
Estimating the possible region of liquefaction occurrence during a strong earthquake is highly valuable for economy loss estimation, reconnaissance efforts and site investigations after the event. This study identified and compiled a large amount of liquefaction case histories from the 2008 Wenchuan earthquake, China, to investigate the relationship between the attenuation of seismic wave energy and liquefaction distance limit during this earthquake. Firstly, we introduced the concept of energy absorption ratio, which is defined as the absorbed energy of soil divided by the imparted energy of seismic waves at a given site, and the relationship between the energy absorption ratio and the material damping ratio was established based on shear stress–strain loop of soil element and the seismic wave propagation process from the source to the site. Secondly, the threshold imparted seismic energy of liquefaction was obtained based on existing researches of absorbed energy required to trigger liquefaction of sandy soils and the ground motion attenuation characteristics of the 2008 Wenchuan earthquake, and the liquefaction distance limit of this earthquake was estimated according to the proposed magnitude–energy–distance relationship. Finally, the field liquefaction database of 209 sites of the 2008 Wenchuan earthquake was used to validate such an estimation, and the field observed threshold imparted seismic energy to cause liquefaction in recent major earthquakes worldwide was back-analyzed to check the predictability of the present method, and several possible mechanisms were discussed to explain the discrepancy between the field observations and the theoretical predictions. This study indicates that seismic energy attenuation and liquefaction distance limit are regional specific and earthquake dependent, and 382 J/m3 is the average level of threshold imparted seismic energy to cause liquefaction for loose saturated sandy soils, and the corresponding liquefaction distance limit is approximately 87.4 km in fault distance for a Mw?=?7.9 event in the Chengdu Plain. The proposed regional energy attenuation model and threshold imparted seismic energy may be considered as an approximate tool in evaluating the liquefaction hazard during potential earthquakes in this area. 相似文献
6.
A methodology for the performance‐based seismic risk assessment of classical columns is presented. Despite their apparent instability, classical columns are, in general, earthquake resistant, as proven from the fact that many classical monuments have survived many strong earthquakes over the centuries. Nevertheless, the quantitative assessment of their reliability and the understanding of their dynamic behavior are not easy, because of the fundamental nonlinear character and the sensitivity of their response. In this paper, a seismic risk assessment is performed for a multidrum column using Monte Carlo simulation with synthetic ground motions. The ground motions adopted contain a high‐ and low‐frequency component, combining the stochastic method, and a simple analytical pulse model to simulate the directivity pulse contained in near source ground motions. The deterministic model for the numerical analysis of the system is three‐dimensional and is based on the Discrete Element Method. Fragility curves are produced conditional on magnitude and distance from the fault and also on scalar intensity measures for two engineering demand parameters, one concerning the intensity of the response during the ground shaking and the other the residual deformation of the column. Three performance levels are assigned to each engineering demand parameter. Fragility analysis demonstrated some of the salient features of these spinal systems under near‐fault seismic excitations, as for example, their decreased vulnerability for very strong earthquakes of magnitude 7 or larger. The analysis provides useful results regarding the seismic reliability of classical monuments and decision making during restoration process. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
7.
震级转换关系及其对地震活动性参数的影响研究 总被引：11，自引：3，他引：8
本文根据1990-2007年《中国地震年报》中同时给出Ms和ML、且震源深度〈70km的6577个浅源地震资料,经统计回归得到了全国和各地震区Ms与ML之间的经验关系。新的震级转换关系接近于Ms=ML,本文建议在需要进行震级标度转换时,对于没有测定Ms的低震级地震可直接使用Ms=ML进行转换。与目前广泛使用的震级转换关系相比,采用本文建议的震级转换方法后,全国各地震区5级以上地震的数量基本没有变化,但5级以下地震的数量有明显增加,导致由此统计得到的各地震区震级．频度关系中的b值有不同程度的增大。此外,用地震数量直接得到的4级以上地震的年平均发生率V4有明显增高,且部分地震区甚至增加了50％以上。在高震级地震发生率不变的情况下,地震活动性参数的上述变化反映了对地震区地震活动水平的估计有提高,可能导致概率地震危险性分析结果的提高,对地震区划和工程场地地震安全性评价有重要意义。 相似文献
8.
In this study, a total of 115,246 ground motions recorded during earthquakes of Moment magnitudes ranging from M_w 5.0 to M_w 9.0 are analyzed statistically. A total of 21 ground motion parameters characterising the recorded acceleration time histories are used in the analysis. Classification of these parameters through statistical correlation is reported and a parameter called "distance from zero-amplitude axis," or dZ-A, is formulated in the principal component space. The ability for dZ-A to rate the damage potentials of strong motion records is evaluated through correlation of dZ-A with Japan Meteorological Agency(JMA) instrumental seismic intensities. This parameter can be used to rate damage potential of any strong motion record irrespective of the magnitude and location of the earthquake. It can also be used in selecting ground motion records of appropriate damage potential in seismic design and probabilistic analysis. 相似文献
9.
根据最近几次的近断层地震观测记录研究显示,在现行结构抗震设计规范中很少考虑近断层效应的影响,对于缺乏近断层强震观测资料地区,抗震设计规范的改进方法及近断层效应的设计参数还没有统一结论. 本文基于UBC97近断层因子设计理念, 在收集世界范围内近断层观测记录的基础上,按场地和震级进行分类,建立了中长周期关键点处的加速度谱需求的衰减关系式,推导给出了缺乏近断层观测资料地区近断层影响因子的震级和断层距的关系式. 并以我国现行的建筑抗震设计规范为基础,建议了近断层影响因子的参考取值和修正后的反应谱曲线,为我国结构抗震设计提供了参考. 相似文献
10.
2022年3月16日在日本福岛县东部海域发生7.4级地震,本文基于近实时震害评估系统RED-ACT对此次地震进行了快速评估,包括强震动记录分析、区域地震破坏力震害评估结果和典型桥梁破坏,并结合实际震害对比了该系统评估结果以及其他主要震害快速评估系统的分析结果,结果表明：(1)此次地震造成的地面运动强度较大,多数台站记录PGA较2021年福岛7.3级地震更强,反应谱在0.5～1.3s区间呈现远高于2021年福岛地震的趋势。(2)RED-ACT的震害评估结果相较于日本NIED-CRS系统和美国USGS-PAGER系统与实际震害更为接近,在强震动记录较为密集的地区,开展基于强震动时程和建筑非线性分析的震害评估能够得到更为准确的震害评估结果。(3)此次地震对白石市附近桥梁造成了一定的破坏,桥梁破坏附近处的强震动会对典型桥梁结构造成一定程度的破坏。 相似文献
11.
Lianyang Zhang 《Soil Dynamics and Earthquake Engineering》1998,17(4):219-226
The feasibility of using the optimum seeking method to assess the seismic liquefaction potential of sands has been investigated. Optimization theory is a very important branch of applied mathematics and has a wide application in the practical world. Using the available field sand liquefaction data, the influence of various factors is quantified using the optimum seeking method. The factors considered are: the earthquake magnitude M, the distance of the site from the source of the earthquake L, the depth of the water table Dw, the depth of the sand deposit Ds, and the standard penetration test (SPT) blow count N. The most important factors have been identified as the earthquake magnitude and the SPT blow count. Prediction results show that the proposed method is effective and feasible. Since neither normalization of the SPT blow count nor calculation of the seismic shear-stress ratio are required, the proposed method is simpler and more direct than the conventional methods of evaluating liquefaction potential. 相似文献
12.
文中简要介绍了判别细粒土地震液化分析方法的发展历程,指出了工程建设中考虑细粒土地震液化问题的必要性。基于已有研究成果,阐述了可用于工程设计的软弱粉质粘土地震液化简化判别方法,并对建筑抗震设计新规范中增加的相关条款进行了说明解释。 相似文献
13.
Empirical attenuation relationship for Arias Intensity 总被引：1，自引：0，他引：1
Arias Intensity is a ground motion parameter that captures the potential destructiveness of an earthquake as the integral of the square of the acceleration–time history. It correlates well with several commonly used demand measures of structural performance, liquefaction, and seismic slope stability. A new empirical relationship is developed to estimate Arias Intensity as a function of magnitude, distance, fault mechanism, and site category based on 1208 recorded ground motion data from 75 earthquakes in active plate‐margins. Its functional form is derived from the point‐source model, and the coefficients are determined through non‐linear regression analyses using a random‐effects model. The results show that for large magnitude earthquakes (M > 7) Arias Intensity was significantly overestimated by previous relationships while it was underestimated for smaller magnitude events (M ? 6). The average horizontal Arias Intensity is not significantly affected by forward rupture directivity in the near‐fault region. The aleatory variability associated with Arias Intensity is larger than that of most other ground motion parameters such as spectral acceleration. However, it may be useful in assessing the potential seismic performance of stiff engineering systems whose response is dominated by the short‐period characteristics of ground motions. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
14.
福建水口水库诱发地震最大震级预测 总被引：3，自引：0，他引：3
许振栋 《地震地磁观测与研究》2004,25(3):58-62
福建水口水库于1993年3月下闸蓄水,同年5月23日发生首次诱发地震,迄今已超过1400次,其中最大地震为1996年4月21日ML4．1地震。水口水库能诱发多大震级的地震一直是人们关心的话题。本文根据国内外已发生水库诱发地震震例资料,结合水口库区的具体情况,应用概率预测法、综合影响参数预测法、两级模糊评判法、古登堡—里克特公式外推预测法、发育断裂长度预测震级法、历史地震最高震级预测法等方法,对水口水库可能诱发的最大震级进行预测研究。综合结果认为：水口水库有可能诱发最大5．0级地震。 相似文献
15.
天津市及邻区地震烈度衰减关系研究 总被引：2，自引：1，他引：1
本研究立足于地震应急领域,选用天津市及邻区34个震例的72条烈度等震线数据,利用最小二乘法拟合得到该地区的地震烈度衰减关系。依据椭圆模型的适用性,将震级上限定为6.5级。考虑到地震应急工作需求和邻区地震对天津辖区造成破坏的可能性,以及辖区内有感地震对社会生产、群众情绪产生的影响,研究将数据限定为天津市周边400km范围内的烈度外包线,震级下限为3.6级。通过与已有衰减关系对比,本研究结果对于5级以下地震应酌情降低烈度值,对于5级以上地震结果更合理。 相似文献
16.
Mario Rodriguez 《地震工程与结构动力学》1994,23(6):627-643
Even though a number of parameters have been proposed in the literature for measuring the capacity of earthquake ground motions to damage structures, most of them are not consistent with building damage observed during earthquakes. In this study, a parameter for measuring seismic damage capacity is proposed. It uses the energy dissipated by a structure in inelastic deformations and a structural overall drift, and it is evaluated for three typical ground motions recorded in severe earthquakes. By using this parameter, consistent results with building damage observed in these earthquakes are obtained, which indicate the importance of displacement control for minimizing seismic damage. 相似文献
17.
Cvetan Sinadinovski Lazo Pekevski Dragi Dojcinovski Dragana Cernih 《Journal of Seismology》2018,22(6):1451-1467
During the months of June–July 2017, the Lake Ohrid area in the southwestern Macedonia experienced a series of small to intermediate earthquakes. More than a thousand earthquakes occurred in that period, all in the epicentral area about 10 km east-northeast from Ohrid city center. The earthquakes showed characteristics of a swarm with 50 of them having magnitudes of 3 or greater and the strongest reaching magnitude M5.0. The earthquakes caused concern among the people in Ohrid and neighboring cities and villages and prompted the installation of two networks of temporary stations. One network was deployed in the epicentral area to determine in more detail the earthquakes’ depth and source parameters. The other urban network of instruments was installed to monitor the influence of the ground on the amplification of shaking and the dynamics of structures in the city of Ohrid. In this study, a selection of the urban network strong motion (SM) records was analyzed for the first time. Accelerograph records from a magnitude M3.1 earthquake recorded at eight places in the city and from the two earthquakes with magnitudes M4.2 and M5.0 recorded at the permanent seismological station Ohrid (code OHR) were used. The results of the behavior of the instrumented building were also compared with the findings of previous experiments. The differences in the spectral values on the SM records from the stations were investigated in respect to the ground conditions and location where the instruments were installed, i.e., bedrock and sediments at the sites. The power spectra and the H/V ratio of the earthquake records from the 2017 seismic sequence in the Ohrid area were also viewed in respect to the Eurocode-8. In addition to being used as part of standard engineering practice, this information about the local soil conditions can be of interest to geophysicists in seismic and geotechnical investigations, as well as in seismic risk-assessment applications. 相似文献
18.
本文基于Lomnitz提出的MRI理论,用"累积地震矩(CSM)"算法对全球1900—1999年7级以上的地震进行了处理,试图通过分析大震前CSM图像的变化,来判断地震发生的可能性。对不同地区的6个地震震前CSM图像的分析表明:7级以上地震的CSM图像在震前5到10年内会改变,大部分地震发生在CSM的高值区或次高值区。通过实际运算发现:在不同的地区应使用不同的值可获得较好的结果,用于计算的地震数越多,获得的结果越好。有些大地震前CSM异常区域不是唯一的,往往会出现几个,这可能与研究区域的地震活动性有关。因此,笔者认为:若要获得可靠的CSM图像,除应当考虑不同地区的小震活动水平外,还应考虑地震断层对震后能量分布影响。统计结果表明:在目标地震发生后,下一次地震在空间上发生在原地及2度距离范围内的概率较大,在3度以外区域发生的概率相差不大;在时间上,发生在原地区震后1年内的概率最高,这可能与余震活动有关;在5年的时间里,下一次地震发生的次数占到全部地震的70%以上。因此,要注意大地震后,目标地震附近有地震能量进一步释放的危险性。 相似文献
19.
The combination of well-documented liquefaction response during the Darfield and Christchurch, New Zealand, earthquakes, densely-recorded ground motions for the events, and detailed subsurface characterization provides an unprecedented opportunity to investigate the significance of the spatial variation of magnitude scaling factors (MSF) on liquefaction triggering. Towards this end, MSF were computed at 15 SMS sites across Christchurch and its surroundings using two established approaches. Trends in the spatial variation of the MSF computed using number of equivalent cycles (neq) from both approaches were similar, with the spatial variation being more significant for the Christchurch earthquake than the Darfield earthquake. However, there was no consistent trend for regions with lower computed MSF having experienced more severe or widespread liquefaction. Additionally, there is a general correlation between MSF and amax, but because amax ranges more widely than MSF it has a greater influence on the resulting seismic demand imposed on the soil than MSF does. Nevertheless, the spatial variation of the MSF is deemed significant enough that it warrants being considered for incorporation into future variants of simplified liquefaction evaluation procedures. 相似文献
20.
基于钻孔应变地震波记录确定地震面波应变震级 总被引：1，自引：0，他引：1
近年发展的高采样率的钻孔应变仪可以记录到地震波造成的水平应变,是动态库仑应力研究的重要手段.利用钻孔应变仪记录的应变地震波确定地震震级,是一个重要的科学课题.本文收集了我国10个应变台站四分量钻孔应变仪2020年1—3月记录的10 Hz采样应变地震波资料,共选出震级M≥4.0的浅源地震68个,用最小二乘法求得应变震级公式为Mε=lg E max+1.65 lg(Δ)+1.43.对于6.5级以下的地震,计算得到的应变震级ε与中国地震台网中心公布的震级M CENC基本一致:M CENC=1.03ε-0.23,但本研究中的两个7级地震,应变震级出现了震级饱和现象.本文的基本结论是:应变定震级是可行的,但对于两个7级地震的饱和现象需要进一步深入研究,因为它们不但涉及震级确定,而且涉及远震动态库仑应力触发地震的研究.今后要对更多的大震钻孔应变波形记录进行分析. 相似文献