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1.
Ground motion intensity parameters of past and potential earthquakes are required for a range of purposes including earthquake insurance practice. In regions with no or sparse earthquake recordings, most of the available methods generate only peak ground motion parameters. For cases where full ground motion time histories are required, simulations that consider fault rupture processes become necessary. In this study, a major novel use of simulated ground motions is presented in insurance premium calculations which also require ground motion intensity measures that are not always available through observations. For this purpose, potential earthquakes in Bursa are simulated using stochastic finite-fault simulation method with dynamic corner frequency model. To ensure simulations with reliable synthetic ground motions, input parameters are derived from regional data. Regional model parameters are verified by comparisons against the observations as well as ground motion prediction equations. Next, a potential large magnitude event in Bursa is simulated. Distribution of peak ground motion parameters and time histories at selected locations are obtained. From these parameters, the corresponding Modified Mercalli Intensities (MMI) are estimated. Later, these MMIs are used as the main ground motion parameter in damage probability matrices (DPM). Return period of the scenario earthquake is obtained from the previous regional seismic hazard studies. Finally, insurance rates for Bursa region are determined with implementation of two new approaches in the literature. The probability of the scenario event and the expected mean damage ratios (MDR) from the corresponding DPMs are used, and the results are compared to Turkish Catastrophe Insurance Pool (TCIP) rates. Results show that insurance premiums can be effectively computed using simulated ground motions in the absence of real data. 相似文献
2.
Earthquake ground motion model is an essential part of seismic hazard assessment. The model consists in several empirical ground motion prediction equations (GMPEs) that are considered to be applicable to the given region. When the recorded ground motion data are scarce, numerical modeling of ground motion based on available seismological information is widely used. We describe results of stochastic simulation of ground motion acceleration records for western Saudi Arabia. The simulation was performed using the finite fault model and considering peak ground acceleration and amplitudes of spectral acceleration at natural frequencies 0.2 and 1.0 s. Based on the parameters of the input seismological model that were accepted in similar previous studies, we analyze influence of variations in the source factor (stress drop) and in the local attenuation and amplification factors (kappa value, crustal amplification). These characteristics of the model are considered as the major contributors to the ground motion variability. The results of our work show that distribution of simulated ground motion parameters versus magnitude and distance reveals an agreement with the GMPEs recently used in seismic hazard assessment for the region. Collection of credible information about seismic source, propagation path, and site attenuation parameters using the regional ground motion database would allow constraining the seismological model and developing regional GMPEs. The stochastic simulation based on regional seismological model may be applied for generation of ground motion time histories used for development of analytical fragility curves for typical constructions in the region. 相似文献
3.
为研究近断层脉冲地震动中竖向加速度对砂土场地液化的影响,基于有限元平台OpenSees开发的边界面塑性本构模型,建立了动单剪单元试验模型和饱和砂土三维有限元模型。选取台湾Chi-Chi地震中10条具有速度脉冲特性的地震波,对比分析了水平双向脉冲波与三向脉冲波作用下土柱竖向位移、循环应力比、孔压比及等效循环周数的差异性,继而明确了脉冲地震动中竖向加速度对砂土液化的影响规律。研究表明,三向脉冲地震波中竖向加速度分量对场地永久位移值影响较小,但使永久位移的发展持时明显增大;土柱循环应力比受竖向地震动影响较小,因此分析脉冲地震动对场地剪切特性的影响时,可将三向脉冲地震动简化为水平双向地震动;考虑竖向地震动的三向脉冲地震波引起的孔压比变化幅度较大,孔压消散时间较长;三向脉冲地震波对应的等效循环周数较大,地震动发展持时长,可认为竖向加速度对场地液化有促进作用。 相似文献
4.
Kohiyama Masayuki Yamashita Norihiko Sato Tadanobu Hengjian Lu Maki Norio Tanaka Satoshi Hayashi Haruo 《Natural Hazards》2003,29(3):501-522
The Nishinomiya Built Environment Database, which can be used to analyze the disaster process of the 1995 Hanshin-Awaji Earthquake Disaster in Nishinomiya City, has been expanded with new data entries. The database contains the following very detailed datasets: (1) the urbanization area base map, (2) casualty data, (3) three sets of building damage data surveyed by the Nishinomiya City, the Architectural Institute of Japan and the City Planning Institute of Japan, and the Kobe University, (4) building property data based on the real estate tax roll, (5) photographs of the damaged buildings with the information on the place and orientation of the picture, and (6) the estimated distribution of the seismic ground motion. The seismic ground motion was simulated for the southern part of Nishinomiya City and two verification sites in Kobe City and Amagasaki City. In the simulation, the borehole data of public facilities were used to model the surface soils as one-dimensional layers, taking into consideration the fact that the spatial distribution of the sediment/basement interface forms a slope. The model of the fault rupture process simulated the characteristics of the seismic motion at basement level, and amplification effects of the surface layers were evaluated based on multiple reflection theory. The distribution of peak ground acceleration and peak ground velocity was estimated from acceleration response spectra at each borehole point. In addition, the relationship between simulated seismic ground motion and building damage was studied based on newly proposed band-passed spectrum intensity using the expanded database. This confirmed that detailed categorization is necessary in order to evaluate the fragility functions, especially for reinforced concrete structures. The database should provide fundamental information for identifying the relationship between the ground motions and the extent and pattern of building damage, or the pattern of the occurrence of casualties.Presently 相似文献
5.
时间域有限差分法(FDTD)对井中雷达的数值模拟 总被引：3，自引：4，他引：3
为了进一步认识雷达的探测性能，用数值模拟的方法来研究各种地质条件下雷达的信号反应。时间域的麦克斯韦差分方程可以用一系列的差分方程来表达，这个过程叫做时间域有限差分法(FDTD)。该方法可以有效地计算三维空间中电磁场的时间域信号。引入了可包含局部小网格的技术，计算精度和效率都得到了提高，同时，作为发射和接收的偶极子天线的模拟方法也得到了充分的考虑。计算了充水裂缝和一种矿体的井中雷达信号响应。结果表明，井中雷达可以用于探测地下充水裂缝和矿体。 相似文献
6.
微差爆破模拟天然地震的数值分析与效果评价 总被引：2，自引：0，他引：2
微差爆破可以创造出与天然地震相类似的振动环境。为了更好地对爆破模拟天然地震进行研究和评价,在LS-DYNA软件框架内,建立了适合于爆炸荷载作用下土体动力分析的实用模型,对原位土体场地爆破地震动试验进行了全尺寸数值模拟,并将模拟结果与现场实测数据进行比较分析,验证数值计算的准确性。计算结果表明,模拟得到的场地质点加速度-时程与实测数据比较吻合,因此,可以预先利用数值手段为试验方案设计提供指导;同时,数值模拟还总结了现场试验中未得到的场地压力变化规律和振动规律,分析了爆破地震动与天然地震的异同,丰富了爆破地震动的研究,表明利用爆破手段能够近似地模拟天然地震,为微差爆破模拟天然地震的研究工作提供了经济、简便而实用的方法。 相似文献
7.
Methods to simulate facies (or categorical) fields are numerous. However, calibration of simulated facies fields to large-scale or dynamic data still remains an important challenge due to the discrete nature of the fields, the non-linearity of the response with respect to the facies fields, and the non-derivability of the objective function used in calibration. A new gradual deformation method (GDM) is presented and tested for the calibration of facies realizations obtained by patch-multipoint simulation (MPS). The proposed method borrows ideas from pluriGaussian simulation, evolutionary algorithms, and GDM. Various test cases are considered: proportion maps, section of seismic amplitudes, inlet to outlet travel time along the shortest path, and water-cut curves obtained with a flow simulator. Both conditional/unconditional MPS simulations and 2D/3D problems are considered. In all studied test cases, the new GDM approach has provided excellent calibration to the target variables. The method is general as it can be used in conjunction with any facies simulator. 相似文献
8.
The semi-empirical approach for modeling of strong ground motion given by Midorikawa (Tectonophysics 218:287?C295, 1993) has been modified in the present paper for component wise simulation of strong ground motion. The modified approach uses seismic moment in place of attenuation relation for scaling of acceleration envelope. Various strong motion properties like directivity effect and dependence of peak ground acceleration with respect to surface projection of source model have been studied in detail in the present work. Recently, Sikkim earthquake of magnitude 6.9 (M w ) that occurred on September 18, 2011 has been recorded at various near-field and far-field strong motion stations. The modified semi-empirical technique has been used to confirm the location and parameters of rupture responsible for this earthquake. Strong motion record obtained from the iterative modeling of the rupture plane has been compared with available strong motion records from near as well as far-field stations in terms of root mean square error between observed and simulated records. Several possibilities of nucleation point, rupture velocity, and dip of rupture plane have been considered in the present work and records have been simulated at near-field stations. Final selection of model parameters is based on root mean square error of waveform comparison. Final model confirms southward propagating rupture. Simulations at three near-field and twelve far-field stations have been made using final model. Comparison of simulated and observed record has been made in terms of peak ground acceleration and response spectra at 5?% damping. Comparison of simulated and observed record suggests that the method is capable of simulating record which bears realistic appearance in terms of shape and strong motion parameters. Present work shows that this technique gives records which matches in a wide frequency range for Sikkim earthquake and that too from simple and easily accessible parameters of the rupture plane. 相似文献
9.
We present an overview of our recent results on utilizing small earthquakes in the earthquake engineering practice. Site-specific ground motion time-histories of large earthquakes can be successfully simulated using recordings of small earthquakes which are often referred to as 'empirical Green's functions' in seismology. Another important practical problem is whether and how these observations can be used in seismic risk studies which are based on empirical attenuation relations for ground motion parameters. We study a possibility of extrapolating attenuation relations for small earthquakes, to larger magnitudes using the data from the Garner Valley downhole array in Southern California. Finally we introduce efficient ground motion processing techniques in frequency- and time-domains and apply them to site response estimation. 相似文献
10.
针对基岩明显起伏、土层非均匀分布的典型河口盆地场地,考虑土体非线性特征,采用黏弹性人工边界模拟无限域对地震波动的影响,建立大尺度精细化二维有限元模型,分析了盆地地表地震动幅值、频谱、持时、传递函数特征,探讨了基岩起伏土层的地震动聚集效应及盆地边缘效应。结果表明：（1）盆地近地表土层表现出不同程度的地震动放大效应,且随土层深度增加呈非单调递减特征,基岩突变处地震动聚集效应明显,盆地两侧产生较为显著的边缘效应;场地中、长周期地震动的放大作用显著;（2）多遇地震、偶遇地震和罕遇地震水平时,场地卓越周期依次介于0.35～0.65 s、0.40～0.75 s和0.50～1.05 s之间;给出了盆地地表PGA（地表峰值加速度）、卓越周期均值等值线图及地表加速度反应谱放大因子建议值,地表设计地震动参数amax（地震影响系数）与Tg（特征周期）明显大于现行《建筑抗震设计规范》取值;（3）盆地特殊位置地表地震动持时得到不同幅度增长,且与输入地震动特性相关;（4）该盆地对0.5～2.0 Hz频段基岩地震动的放大效应比较显著,对小于0.2 Hz或大于2.5 Hz的基岩地震动,该盆地地震动放大效应不明显;（5）福州城区及其邻近区域地震动放大效应普遍较大。大尺度二维非线性分析一定程度上能合理反映微地形起伏、土层分布及土体非线性对地震波传播过程的影响。 相似文献
11.
多地貌单元复合场地非线性地震效应特征二维分析 总被引：2，自引：0，他引：2
针对由河漫滩、阶地、波状起伏的丘陵地带和残丘等组成的典型复合地形场地,基于ABAQUS软件的显式有限元并行计算集群平台,考虑土体的非线性特征,采用黏弹性人工边界模拟切除的无限域对地震波动的影响,建立了大尺度复合地形真实场地的二维有限元模型,并将基岩地震动视为SH波,分析了不同地貌单元复合场地地震效应特征。结果表明：地形差异引起地表各测点峰值加速度(PGA)及峰值位移(PGD)不同;在相同地震波入射下,河漫滩区地表PGA大于Ⅰ级阶地区域,但其PGD明显小于Ⅰ级阶地区域,且河漫滩区的峰值位移差动较小;场地地表水平加速度反应谱呈双峰及多峰现象,加速度在0.4～1.2 Hz频段放大较多,且加速度反应谱特性与输入地震动相关;特定频段（0.5～1.75 Hz）地震动放大效应与聚集效应比较明显,频率小于0.2 Hz及大于2 Hz时,场地地震动放大特征不显著。低丘区的敏感频率段宽于河漫滩区;观测点的位置影响相应的水平加速度持时大小,局部地形变化将引起地震动持时差异,且持时和输入地震动特性相关。 相似文献
12.
Modification in the semi-empirical technique for the simulation of strong ground motion has been introduced to incorporate the strong motion generation areas (SMGA) in the modeled rupture plane. Strong motion generation areas identified within the rupture plane of the Tohoku earthquake of March 11, 2011 (M w = 9.0), have been modeled using this modified technique. Two different source models having four and five SMGAs, respectively, are considered for modeling purpose. Strong motion records using modified semi-empirical technique have been simulated at two near-field stations located at epicentral distance of 137 and 140 km, respectively, using two different source models. Comparison of the observed and simulated acceleration waveforms is made in terms of root mean square error (RMSE) at both stations. Minimum root mean square error of the waveform comparison has been obtained at both the stations for source model having five SMGAs. Simulations from same rupture model have been made at other four stations lying at epicentral distance between 154 and 249 km. Comparison of observed and simulated records has been made in terms of RMSE in acceleration records, velocity records and response spectra at each six station. Simulations have been made at six other stations to obtain distribution of peak ground acceleration and peak ground velocity with hypocentral distance. Peak ground acceleration and velocity from simulated and observed records are compared at twelve stations surrounding the source of Tohoku earthquake. Comparison of waveforms and parameters extracted from observed and simulated strong motion records confirms the efficacy of the developed modified technique to model earthquake characterized by SMGAs. 相似文献
13.
Near-fault strong motion complexity of the 2000 Tottori earthquake (Japan) from a broadband source asperity model 总被引：1，自引：0，他引：1
The October 6/2000 Tottori earthquake that occurred in central Japan was an intermediate size strike-slip event that produced a very large number of near field strong motion recordings. The large amount of recorded data provides a unique opportunity for investigating a source asperity model of the Tottori earthquake that, combined with a hybrid strong motion simulation technique, is able to reproduce the observed broadband frequency near-fault ground motion.
We investigated the optimum source asperity parameters of the Tottori earthquake, by applying a Genetic Algorithm (GA) inversion scheme to optimise the fitting between simulated and observed response spectra and Peak Ground Acceleration (PGA) values. We constrained the initial model of our inversion by using the heterogeneous slip distribution obtained from a kinematic inversion of the source of previous studies. We used all the observed near-fault ground motions (−100 m) from the borehole strong motion network of Japan (KiK-Net), which are little affected by surficial geology (site effects).
The calculation of broadband frequency strong ground motion (0.1–10 Hz) is achieved by applying a hybrid technique that combines a deterministic simulation of the wave propagation for the low frequencies and a semi-stochastic modelling approach for the high frequencies. For the simulation of the high frequencies, we introduce a frequency-dependent radiation pattern model that efficiently removes the dependence of the pattern coefficient on the azimuth and take-off angle as the frequency increases. The good agreement between the observed and simulated broadband ground motions shows that our inversion procedure is successful in estimating the optimum asperity parameters of the Tottori earthquake and provides a good test for the strong ground motion simulation technique.
The ratio of background stress drop to average asperity stress drop from our inversion is nearly 50%, in agreement with the theoretical asperity model of Das and Kostrov [Das, S., Kostrov, B.V., 1986. Fracture of a single asperity on a finite fault: a model for weak earthquakes? Earthquake Source Mechanics, AGU, pp. 91–96.], and an empirical ratio of asperities to rupture area [Seismol. Res. Lett. 70 (1999) 59–80.].
The simulated radiation pattern is very complex for epicentral distances within half the fault length, but it approaches the radiation of a double-couple point source for larger distances.
The rupture velocity and rise time have a significant influence on the Peak Ground Velocity (PGV) distribution around the fault. An increase in rupture velocity produces a similar effect on the ground motion as a reduction in rise time. 相似文献
14.
Ground motion estimation at Guwahati city for an Mw 8.1 earthquake in the Shillong plateau 总被引：1，自引：0，他引：1
In this paper, the ground motion at Guwahati city for an 8.1 magnitude earthquake on Oldham fault in the Shillong plateau has been estimated by stochastic finite-fault simulation method. The corresponding acceleration time histories on rock level at several sites in the epicentral region have been computed. These results are validated by comparing them with the estimates obtained from Medvedev–Sponheuer–Karnik (MSK) intensity observations of 1897 Shillong earthquake. Using the local soil parameters, the simulated rock level acceleration time history at Guwahati city is further amplified up to the ground surface by nonlinear site response analysis. The results obtained are presented in the form of peak ground acceleration (PGA) contour map. The maximum amplification for PGA over Guwahati city is as high as 2.5. Based on the simulated PGA, the liquefaction susceptibility at several locations in the city has been estimated. The results are presented in the form of contours of factor of safety against liquefaction at different depths below the ground surface. It is observed that over a large part of the Guwahati city, the factor of safety against liquefaction is less than one, indicating that the city is highly vulnerable to liquefaction in the event of this earthquake. The contour maps obtained can be used in identifying vulnerable areas and disaster mitigation. 相似文献
15.
Scott Painter 《Mathematical Geology》1998,30(2):163-179
Stochastic simulations of subsurface heterogeneity require accurate statistical models for spatial fluctuations. Incremental values in subsurface properties were shown previously to be approximated accurately by Levy distributions in the center and in the start of the tails of the distribution. New simulation methods utilizing these observations have been developed. Multivariate Levy distributions are used to model the multipoint joint probability density. Explicit bounds on the simulated variables prevent nonphysical extreme values and introduce a cutoff in the tails of the distribution of increments. Long-range spatial dependence is introduced through off-diagonal terms in the Levy association matrix, which is decomposed to yield a maximum likelihood type estimate at unobserved locations. This procedure reduces to a known interpolation formula developed for Gaussian fractal fields in the situation of two control points. The conditional density is not univariate Levy and is not available in closed form, but can be constructed numerically. Sequential simulation algorithms utilizing the numerically constructed conditional density successfully reproduce the desired statistical properties in simulations. 相似文献
16.
G. Bourgault 《Mathematical Geology》1997,29(3):315-334
Parametric geostatistical simulations such as LU decomposition and sequential algorithms do not need Gaussian distributions.
It is shown that variogram model reproduction is obtained when Uniform or Dipole distributions are used instead of Gaussian
distributions for drawing i. i.d. random values in LU simulation, or for modeling the local conditional probability distributions
in sequential simulation. Both algorithms yield simulated values with a marginal normal distribution no matter if Gaussian,
Uniform, or Dipole distributions are used. The range of simulated values decreases as the entropy of the probability distribution
decreases. Using Gaussian distributions provides a larger range of simulated normal score values than using Uniform or Dipole
distributions. This feature has a negligible effect for reproduction of the normal scores variogram model but have a larger
impact on the reproduction of the original values variogram. The Uniform or Dipole distributions also produce lesser fluctuations
among the variograms of the simulated realizations. 相似文献
17.
地震动信号的小波分析 总被引：17，自引：0，他引：17
小波分析是一种新的数学方法,因具有良好的时频局部化性质而优于传统的傅立叶分析。地震动是由于地城引起的地面运动,其时间历程函数表现为具有突变特征的非平稳随机过程,因此更适于利用小波变换进行频谱分析。我们在总结小波分析基本原理和方法的基础上,首次利用小波变换分别对地震动加速度时程和速度时程进行了分解和重构,对地震动信号分解结果做了相应频谱分析,并对其小波分析的工程意义进行了初步探索。 相似文献
18.
For earthquake ground motion studies, the actual ground motion distribution should be reproduced as accurately as possible. For optimal estimation of ground motion, kriging has been shown to provide accurate estimates. Although kriging is accurate for this application, some estimates it provides are underestimates. This has dire consequences for subsequent design for earthquake resistance. Kriging does not provide enough information to allow an analysis of each estimate for underestimation. For such an application, disjunctive kriging is better applied. This advanced technique quantifies the probability that an estimate equals or exceeds particular levels of ground motion. Furthermore, disjunctive kriging can provide improved estimation accuracy when applied for local estimation of ground motion. 相似文献
19.
S. T. G. Raghu Kanth 《Journal of Earth System Science》2008,117(2):683-705
Success of earthquake resistant design practices critically depends on how accurately the future ground motion can be determined at a desired site. But very limited recorded data are available about ground motion in India for engineers to rely upon. To identify the needs of engineers, under such circumstances, in estimating ground motion time histories, this article presents a detailed review of literature on modeling and synthesis of strong ground motion data. In particular, modeling of seismic sources and earth medium, analytical and empirical Green’s functions approaches for ground motion simulation, stochastic models for strong motion and ground motion relations are covered. These models can be used to generate realistic near-field and far-field ground motion in regions lacking strong motion data. Numerical examples are shown for illustration by taking Kutch earthquake-2001 as a case study. 相似文献
20.
Steven B. Meyerhoff Reed M. Maxwell Wendy D. Graham John L. Williams III 《Hydrogeology Journal》2014,22(6):1329-1343
Subsurface heterogeneity is one of the largest sources of uncertainty associated with saturated hydraulic conductivity. Recent work has demonstrated that uncertainty in hydraulic conductivity can impart significant uncertainty in runoff generation processes and surface-water flow. Here, the role of site characterization in reducing hydrograph prediction bias and uncertainty is demonstrated. A fully integrated hydrologic model is used to conduct two sets of stochastic, transient simulation experiments comprising different overland flow mechanisms: Dunne and Hortonian. Conditioning hydraulic conductivity fields using values drawn from a simulated synthetic control case are shown to reduce both mean bias and variance in an ensemble of conditional hydrograph predictions when compared with the control case. The ensemble simulations show a greater reduction in uncertainty in the hydrographs for Hortonian flow. The conditional simulations predict surface ponding and surface pressure distributions with reduced mean error and reduced root mean square error compared with unconditional simulations. Uncertainty reduction in Hortonian and Dunne flow cases demonstrates different temporal signals, with more substantial reduction achieved for Hortonian flow. 相似文献