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1.
Strong motion uncertainty determined from observed records by dense network in Japan 总被引：2，自引：1，他引：1
Nobuyuki Morikawa Tatsuo Kanno Akira Narita Hiroyuki Fujiwara Toshihiko Okumura Yoshimitsu Fukushima Aybars Guerpinar 《Journal of Seismology》2008,12(4):529-546
The variation of ground motions at specific stations from events in six narrow areas was inspected by using K-NET and KiK-net
records. A source-area factor for individual observation stations was calculated by averaging ratios between observed values
for horizontal peak acceleration and velocity, as well as acceleration response spectra for 5% damping, and predicted values
using a ground-motion model (usually known as an attenuation relation) by Kanno et al. (Bull Seismol Soc Am, 96:879–897, 2006). Standard deviations between observed and predicted amplitudes after the correction factor are less than 0.2 on the logarithmic
scale and decrease down to around 0.15 in the short-period range. Intra-event standard deviation clearly increases with decreasing
distance due to differing paths around near source area. Standard deviations may increase with amplitude or decrease with
magnitude; however, both amplitude and magnitude of the data are strongly correlated with distance. The standard deviation
calculated in this study is obviously much smaller than that of the original ground-motion model, as epistemic uncertainties
are minimized by grouping ground motions at specific stations. This result indicates that the accuracy of strong ground motion
prediction could be improved if ground-motion models for specified region are determined individually. For this to be possible,
it is necessary to have dense strong-motion networks in high-seismicity regions, such as K-NET and KiK-net. 相似文献
2.
John Douglas Didier Bertil Agathe Roullé Pascal Dominique Philippe Jousset 《Journal of Seismology》2006,10(3):271-299
Strong-motion networks have been operating in the Caribbean region since the 1970s, however, until the mid-1990s only a few analogue stations were operational and the quantity of data recorded was very low. Since the mid-1990s, digital accelerometric networks have been established on islands within the region. At present there are thought to be about 160 stations operating in this region with a handful on Cuba, 65 on the French Antilles (mainly Guadeloupe and Martinique), eight on Jamaica, 78 on Puerto Rico (plus others on adjacent islands) and four on Trinidad.After briefly summarising the available data from the Caribbean islands, this article is mainly concerned with analysing the data that has been recorded by the networks operating on the French Antilles in terms of their distribution with respect to magnitude, source-to-site distance, focal depth and event type; site effects at certain stations; and also with respect to their predictability by ground motion estimation equations developed using data from different regions of the world. More than 300 good quality triaxial acceleration time-histories have been recorded on Guadeloupe and Martinique at a large number of stations from earthquakes with magnitudes larger than 4.8, however, most of the records are from considerable source-to-site distances. From the data available it is found that many of the commonly-used ground motion estimation equations for shallow crustal earthquakes poorly estimate the observed ground motions on the two islands; ground motions on Guadeloupe and Martinique have smaller amplitudes and are more variable than expected. This difference could be due to regional dependence of ground motions because of, for example, differing tectonics or crustal structures or because the ground motions so far recorded are, in general, from smaller earthquakes and greater distances than the range of applicability of the investigated equations. 相似文献
3.
One approach to model the high-frequency attenuation of spectral amplitudes of S-waves is to express the observed exponential decay in terms of Kappa (κ) factor [1]. Kappa is a significant parameter used for identifying the high-frequency attenuation behavior of ground motions as well as one of the key parameters for stochastic strong ground motion simulation method. As of now, there is not a systematic investigation of the Kappa parameter based on the recently-compiled Turkish ground motions. In this study, we examine a strong ground motion dataset from Northwestern Turkey with varying source properties, site classes and epicentral distances. We manually compute κ from the S-wave portion of each record and study both horizontal and vertical kappa values. We use traditional regression techniques to describe the (potential) relationships between kappa and selected independent variables such as the site class, distance from the source or magnitude of the event. A linear effect of magnitude on kappa is not found statistically significant for the database studied herein. We express the initial findings of a regional κ model for Northwestern Turkey as a function of site class and epicentral distances. Single station analyses at selected sites confirm the regional model. Finally, we present stochastic strong motion simulations of past events in the region using the proposed kappa model. Regardless of the magnitude, source-to-site distance and local site conditions at the stations, the high-frequency spectral decay is simulated effectively at all stations considered. 相似文献
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6.
As part of the effort to assess the seismic hazards of Singapore and the Malay Peninsula, representative ground motion prediction models have to be established. Seven existing attenuation relationships developed for shallow crustal earthquakes in stable continent and active tectonic regions are examined, and they are found to consistently over‐predict the ground motions of Sumatran‐fault earthquakes recently recorded in Singapore. This may be attributed to the differences in the regional crustal structures and distance ranges considered. Since the number of recorded ground motions in the region is very limited, a new set of attenuation relationships is derived based on synthetic seismograms. The uncertainties in rupture parameters, such as stress drop, focal depth, dip and rake angles, are defined according to the regional geological and tectonic settings as well as the ruptures of previous earthquakes. Ground motions are simulated for earthquakes with Mw ranging from 4.0 to 8.0, within a distance range from 174 to 1379km. Besides magnitude and distance, source‐to‐station azimuth is found to influence the amplitudes of the ground motions simulated. Thus, the azimuth is taken as an independent variable in the derived ground motion attenuation relationships. The Sumatran‐fault segments that have the potential to generate a specified level of response spectral accelerations in Singapore and Kuala Lumpur are identified based on the newly derived ground motion models. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
7.
本文通过格林函数反褶积方法，由台湾峡谷附近的记录资料预测峡谷区的强地面运动的时程曲线．峡谷区的理论格林函数应用２．５维ＳＨ混合方法求解．通过格林函数反褶积方法得到的峡谷区费丛１及费丛２台的位移、速度、加速度和实际资料对比，取得了满意结果．计算结果表明，峡谷底部的峰值加速度相对峡谷边缘为最小；在靠近震中的一侧，峡谷的加速度的最大振幅相对比另一侧大．还给出了其余３个台的预测结果，研究了它们的加速度傅里叶谱和反应谱． 相似文献
8.
Testing the Validity of Simulated Strong Ground Motion from the Dynamic Rupture of a Finite Fault, by Using Empirical Equations 总被引：1，自引：0，他引：1
This paper is concerned with testing the validity of the ground motions estimated by combining a boundary integral equation method to simulate dynamic rupture along finite faults with a finite difference method to compute the subsequent wave propagation. The validation exercise is conducted by comparing the calculated ground motions at about 100 hypothetical stations surrounding the pure strike-slip and pure reverse faults with those estimated by recent ground motion estimation equations derived by regression analysis of observed strong-motion data. The validity of the ground motions with respect to their amplitude, frequency content and duration is examined. It is found that the numerical simulation method adopted leads to ground motions that are mainly compatible with the magnitude and distance dependence modelled by empirical equations but that the choice of a low stress drop leads to ground motions that are smaller than generally observed. In addition, the scatter in the simulated ground motions, for which a laterally homogeneous crust and standard rock site were used, is of the same order as the scatter in observed motions therefore, close to the fault, variations in source propagation likely contribute a significant proportion of the scatter in observed motions in comparison with travel-path and site effects. 相似文献
9.
The 2003 Bam, Iran, earthquake caused catastrophic damage to the city of Bam and neighboring villages. Given its magnitude (M w ) of 6.5, the damage was remarkably large. Large-amplitude ground motions were recorded at the Bam accelerograph station in the center of Bam city by the Building and Housing Research Center (BHRC) of Iran. We simulated the Bam earthquake acceleration records at three BHRC strong-motion stations—Bam, Abaraq, and Mohammad-Abad—by the empirical Green’s function method. Three aftershocks were used as empirical Green’s functions. The frequency range of the empirical Green’s function simulations was 0.5–10 Hz. The size of the strong motion generation area of the mainshock was estimated to be 11 km in length by 7 km in width. To estimate the parameters of the strong motion generation area, we used 1D and 2D velocity structures across the fault and a combined source model. The empirical Green’s function method using a combination of aftershocks produced a source model that reproduced ground motions with the best fit to the observed waveforms. This may be attributed to the existence of two distinct rupture mechanisms in the strong motion generation area. We found that the rupture starting point for which the simulated waveforms best fit the observed ones was near the center of the strong motion generation area, which reproduced near-source ground motions in a broadband frequency range. The estimated strong motion generation area could explain the observed damaging ground motion at the Bam station. This suggests that estimating the source characteristics of the Bam earthquake is very important in understanding the causes of the earthquake damage. 相似文献
10.
目前基于海底实测记录的分析发现海底与陆地地震动特性存在明显差异,但难以进一步确定海底地震动特性的影响因素。在以往研究的基础上对比同次地震中相邻海底台站间地震动特性的差异,并分析造成差异的原因。以日本K-NET地震台网中6个海底强震台站及其相邻不同场地条件陆地台站监测的8次强震记录为研究对象,通过分析强震记录的峰值加速度、水平放大系数谱、竖向与水平反应谱的比谱等,对比分析不同海底台站地震动的特性,以及海底台站与相邻不同场地条件陆地台站地震动特性的差别。研究发现：（1）海底与陆地竖向地震动存在明显差异;（2）不同海底台站间地震动特性亦存在较大差异和明显的规律性,海底场地条件、地形等场地因素对海底地震动特性的影响较大;（3）海底水平向地震动反应谱的特征周期较大,谱特性介于陆地中硬土与软土场地间。 相似文献
11.
Serious damage due to soil liquefaction occurred in a wide area of the Tohoku and the Kanto regions in Japan during 2011 off the Pacific coast of Tohoku Earthquake (MW 9.0). The farthest liquefied site from the epicenter of the 2011 main shock is Ikenouchi, Minamiboso City, whose epicentral distance is approximately 440 km. Evaluation of strong ground motions at Ikenouchi is very important to understand why liquefaction was observed in such a far site. For this purpose, in-situ geotechnical investigations including aftershock observation were carried out at Ikenouchi. Then, the ground motions at Ikenouchi during the 2011 main shock was estimated based on the site-effect substitution method considering the microtremor H/V spectral ratios and the aftershock observation results. Finally, 3-D effective stress analyses were carried out using a FEM code ‘FLIP’ to understand how site-specific characteristics of strong ground motions affected the behavior of the ground including liquefaction. A striking feature of the estimated waveforms at the target site is that the waveforms include a much larger number of cycles compared to the records at permanent observation stations around the target site. Such a site-specific feature of strong ground motions was one of the main causes of the occurrence of liquefaction 440 km away from the epicenter. The result suggests the importance of taking into account not only soil properties but also site-specific characteristics of strong ground motions for a rational assessment of liquefaction for future large earthquakes. 相似文献
12.
《地震工程与工程振动(英文版)》2015,(2)
Near-field strong ground motions are useful for engineering seismology studies and seismic design, but dense observation networks of damaging earthquakes are still rare. In this study, based on the strong-motion data from the M w 6.6 Lushan earthquake, the ground motion parameters in different spatial regions are systematically analyzed, and the contributions from different effects, like the hanging-wall effect, directivity effect, and attenuation effect are separated to the extent possible. Different engineering parameters from the observed ground motions are compared with the local design response spectra and a new attenuation relation of Western China. General results indicate that the high frequency ground motion, like the peak ground acceleration, on two sides of the fault plane is sensitive to the hanging-wall effect, whereas the low frequency ground motion, like the long period spectral acceleration, in the rupture propagation direction is affected by the directivity effect. Moreover, although the M w 6.6 Lushan earthquake is not a large magnitude event, the spatial difference of ground motion is still obvious; thus, for a thrust faulting earthquake, in addition to the hanging effect, the directivity effect should also be considered. 相似文献
13.
根据日本强震布设的经验,在地震震级越小时,要得到对应烈度,要求观测记录强震台站布置网格间距越小。根据上海市地貌类型及地层特点,基于现有强震台分布,提出新增强震台站布设构想,为今后上海市强震观测点合理布设提供参考。 相似文献
14.
Strong ground motions are estimated for the Pacific Northwest assuming that large shallow earthquakes, similar to those experienced in southern Chile, southwestern Japan, and Colombia, may also occur on the Cascadia subduction zone. Fifty-six strong motion recordings for twenty-five subduction earthquakes ofM
s7.0 are used to estimate the response spectra that may result from earthquakesM
w<81/4. Large variations in observed ground motion levels are noted for a given site distance and earthquake magnitude. When compared with motions that have been observed in the western United States, large subduction zone earthquakes produce relatively large ground motions at surprisingly large distances. An earthquake similar to the 22 May 1960 Chilean earthquake (M
w 9.5) is the largest event that is considered to be plausible for the Cascadia subduction zone. This event has a moment which is two orders of magnitude larger than the largest earthquake for which we have strong motion records. The empirical Green's function technique is used to synthesize strong ground motions for such giant earthquakes. Observed teleseismicP-waveforms from giant earthquakes are also modeled using the empirical Green's function technique in order to constrain model parameters. The teleseismic modeling in the period range of 1.0 to 50 sec strongly suggests that fewer Green's functions should be randomly summed than is required to match the long-period moments of giant earthquakes. It appears that a large portion of the moment associated with giant earthquakes occurs at very long periods that are outside the frequency band of interest for strong ground motions. Nevertheless, the occurrence of a giant earthquake in the Pacific Northwest may produce quite strong shaking over a very large region. 相似文献
15.
基于芦山7.0级地震中断层距小于100 km自由场台站的强震动记录观测数据,研究此次地震近断层地震动的方向性特性,并探讨方向性特性与震源破裂机制、断层距离和空间方位的关系.研究结果表明：（1）与距断层较远记录不同,近断层地震动在不同的观测方向上表现出显著的强度差异,存在明显的极大和极小作用方向.在不同的方向上,最大加速度反应可达最小值的4倍以上;（2）这种方向性差异在T=1.0 s以上的长周期段更为明显,在T=0.1 s以下的短周期段,地震动随方向变化的差异较小.地震动强度随方向变化的差异随周期增大而增大,不同方向上的加速度反应谱值的最大值与最小值之比从周期T=0.01 s时的约1.7增大到周期T=10 s时的约2.4;（3）在距离断层约35 km以内,地震动具有明显方向性,地震动卓越方向具有垂直断层走向的特征,随断层距的增大,这种方向性不明显.从不同方向上地震动强度的差异来看,随断层距增大,地震动强度在不同方向上的差异在减小,表现为各个周期的最大值/中值和最大值/最小值比值均随断层距离增大缓慢减小;（4）近断层地震动的方向性特性主要受断层上、下盘的相对运动所控制,其在长周期的卓越方向与水平同震位移方向一致,且该卓越方向上的地震动强度绝对大小与地震破裂造成的静态位移明显相关,表现为地震动强度随水平同震位移的增大而增大. 相似文献
16.
Near-field strong ground motions are useful for engineering seismology studies and seismic design, but dense observation networks of damaging earthquakes are still rare. In this study, based on the strong-motion data from the M w 6.6 Lushan earthquake, the ground motion parameters in different spatial regions are systematically analyzed, and the contributions from different effects, like the hanging-wall effect, directivity effect, and attenuation effect are separated to the extent possible. Different engineering parameters from the observed ground motions are compared with the local design response spectra and a new attenuation relation of Western China. General results indicate that the high frequency ground motion, like the peak ground acceleration, on two sides of the fault plane is sensitive to the hanging-wall effect, whereas the low frequency ground motion, like the long period spectral acceleration, in the rupture propagation direction is affected by the directivity effect. Moreover, although the M w 6.6 Lushan earthquake is not a large magnitude event, the spatial difference of ground motion is still obvious; thus, for a thrust faulting earthquake, in addition to the hanging effect, the directivity effect should also be considered. 相似文献
17.
This article has two purposes. Firstly, a validation exercise of the modal summation technique for the computation of synthetic
strong-motion records is performed for two regions of Europe (Umbria-Marche and south Iceland), using a variety of region
specific crustal structure models, by comparing the predicted ground motion amplitudes with observed motions. It is found
that the rate of decay of ground motions is well predicted by the theoretical decay curves but that the absolute size of the
ground motions is underpredicted by the synthetic time-histories. This is thought to be due to the presence of low-velocity
surface layers that amplify the ground motions but are not included in the crustal structure models used to compute the synthetic
time-histories.
Secondly, a new distance metric based on the computed theoretical decay curves is introduced which should have the ability
to model the complex decay of strong ground motions. The ability of this new distance metric to reduce the associated scatter
in empirically derived equations for the estimation of strong ground motions is tested. It is found that it does not lead
to a reduction in the scatter but this is thought to be due to the use of crustal structure models that are not accurate or
detailed enough for the regions studied.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
A methodology for the investigation of the spatial variation of seismic ground motions is presented; data recorded at the SMART-1 dense instrument array in Lotung, Taiwan, during Events 5 and 39 are used in the analysis. The seismic motions are modeled as superpositions of sinusoidal functions, described by their amplitude, frequency, wavenumber and phase. For each event and direction (horizontal or vertical) analysed, the approach identifies a coherent, common component in the seismic motions at all recording stations, and variabilities in amplitudes and phases around the common component sinusoidal characteristics, that are particular for each recording station. It is shown that the variations in both the amplitudes and the phases of the motions at the station locations around the common component characteristics contribute significantly to the spatially variable nature of the motions, and, furthermore, they are correlated: increase in the variability of the amplitudes of the motions recorded at individual stations around the common amplitude implies increase in the variability of the phases around the common phase. The dispersion range of the amplitude and phase variability around their corresponding common components appear also to be associated with physical parameters. The spatially variable arrival time delays of the waveforms at the stations due to their upward travelling through the site topography, in addition to the wave passage delays identified from signal processing techniques, constitute another important cause for the spatial variation of the motions; their consideration in the approach facilitates also the identification of the correlation patterns in the amplitudes and phases. © 1997 by John Wiley & Sons, Ltd. 相似文献
19.
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
20.
运用经验格林函数法模拟了2008年5月12日汶川8.0级大地震的近场强地面运动.拟合过程中,首先参考其他学者反演结果给出的滑动量分布的特征,确定强震动生成区的大致范围;然后利用Somerville等(1999)提出的地震矩与凹凸体面积间的经验关系式确定强震动生成区(SMGA)细小划分的初值,继而利用遗传优化算法确定以上两者的最优值及其他震源参数.数值模拟波形同实际地震观测记录在时间域和频率域分别进行了比较,结果显示,在所选取的18个观测台中,多数台站的数值模拟结果同实际观测结果符合得很好,特别是大于1 Hz的高频部分.我们发现断层面上有5个强震动生成区,其中两个的位置与其他学者反演的滑动量集中分布区相一致,但强震动生成区规模和上升时间比Somerville等(1999)获得的定标率外延的估计值要小. 相似文献