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1.
Directionality of ground motions has been discussed in near-source groundmotion study. This is interesting from the point of structural response.Dominance of the fault normal (FN) component has been reported inrelation to fault rupture direction based on the observation recordsobtained in the source area (e.g.. Somerville et al., 1996). The authorsperformed the damage survey of the two Turkey earthquakes in 1999, theKocaeli and the Düzce earthquake, and realized that minaret is a goodtarget to investigate the ground motion directionality, because a minaret isa simple cantilever structure without structural directionality. This paperdescribes the ground motion directionality based on the survey of minaretdamages during the two earthquakes in Turkey. From the damage survey,it is found that the fault normal direction was dominant with a certaindistance from the fault, say, less than 1km. While, at the region withshorter distances, the damage direction was not fault normal but about40° from the fault strike. Discussion is addressed for the specificdamage direction inferred from the minaret damage near the fault. 相似文献
2.
Turkey was struck by two major events on August 17th and November 12th, 1999. Named Kocaeli (Mw=7.4) and Düzce (Mw=7.2) earthquakes, respectively, the two earthquakes provided the most extensive strong ground motion data set ever recorded in Turkey. The strong motion stations operated by the General Directorate of Disaster Affairs, the Kandilli Observatory and Earthquake Research Institute of Bogazici University and Istanbul Technical University have produced at least 27 strong motion records for the Kocaeli earthquake within 200 km of the fault. Kocaeli earthquake has generated six motions within 20 km of the fault adding significantly to the near-field database of ground motions for Mw>=7.0 strike–slip earthquakes. The paper discusses available strong motion data, studies their attenuation characteristics, analyses time domain, as well as spectral properties such as spectral accelerations with special emphasis on fault normal and fault parallel components and the elastic attenuation parameter, kappa. A simulation of the Kocaeli earthquake using code FINSIM is also presented. 相似文献
3.
The devastating zmit and Düzce earthquakes were followed by theOrta intra-plate earthquake (MS = 6.1) occurred in the central Anatolianblock on June 6, 2000. The focal mechanism, aftershock distribution andthe field studies (Emre et al., 2000) suggest a movement on a 21-km longDodurga fault striking nearly N-S where the sense of motion is left-lateralstrike-slip with considerable amount of normal component. We applied theconstrained linear finite-fault inversion method of Hartzell and Heaton(1983) to the teleseismic P and SH waveforms to derive a coseismic slipdistribution model for the earthquake. Time windows approach is appliedallowing variable rise times and rupture velocities. The source-rise timefunction is discretized into consecutive time intervals that stand for slipcontribution of individual subfaults. Although no clear surface ruptureswere associated with the earthquake, the resulting slip model suggestscoseismic slip in the order of several tens of centimetres. Our coseismicslip distribution model identifies two slip patches with the followingmaximum slip values: (1) the larger one (42 cm) is located to the southof the hypocenter at depth range of 4–8 km and (2) the smaller one(31 cm) is located just above and north of the hypocenter. Theslip-model yield a seismic moment of 1.0 × 1018 Nm, most of whichis released from the rupture over the depth of 8 km. 相似文献
4.
The paper focuses on the study of the dynamic response of a wind turbine installed close to seismic fault in an earthquake prone region of Greece. The investigation of the seismic behavior of the turbine is performed with response spectrum analysis using the elastic acceleration spectrum provided by the Greek National Aseismic Code for the project area, increased by 25% due to proximity to seismic fault, as recommended by the Code. Also, dynamic analysis is performed using the spectrum obtained from the assessment of seismic hazard at the site of the project (Local), for two typical cases of earthquakes of magnitudes Ms=5.8 and Ms=7.3 with epicentral distances of 1 km and 11 km from the test position, respectively. Finally, a time-history analysis is carried out using an artificial accelerogram obtained from the local spectrum envelope, for the site of the project, considering 1% damping ratio. The direct comparison of the response spectrum analysis results with the corresponding ones obtained from the dynamic and time-history analyses indicates that the implementation of the elastic acceleration spectrum is insufficient, although increased, and therefore it could be deduced that the current recommendation of the Greek National Aseismic Code to consider an increment of 25% on the elastic acceleration spectrum in regions close to seismic faults, requires review and further improvement. 相似文献
5.
6.
Haluk Sucuoğlu 《Journal of Seismology》2002,6(3):347-355
The purpose of this paper is to summarize the strong motion data from thenearest stations to the fault ruptures of the August 17, 1999 Kocaeli andNovember 12, 1999 Düzce earthquakes and to document informationthat will be significant for its interpretation. Significant engineeringcharacteristics of the near-field strong motions are discussed, with particularemphasis on the site conditions, rupture directivity effects and transversecomponent orientations relative to the fault. In the course of this study,the most significant strong motion stations and adjacent parts of the faultare visited. All locations are verified using a hand-held GPS receiver. Thusinstrument housing characteristics, preliminary impression on siteconditions, and relatively precise relationship of the stations to the nearestfaulting can be reported. 相似文献
7.
S. W. Park H. Ghasemi J. Shen P. G. Somerville W. P. Yen M. Yashinsky 《地震工程与结构动力学》2004,33(13):1249-1270
The seismic performance of the Bolu Viaduct in the Duzce, Turkey, earthquake of November 1999 was studied via a non‐linear, time‐history analysis of a multi‐degree of freedom model. The viaduct had a seismic isolation system consisting of yielding‐steel energy dissipation units and sliding pot bearings. The Duzce earthquake caused a surface rupture across the viaduct, which resulted in excessive superstructure movement and widespread failure of the seismic isolation system. The effect of the rupture was modeled by a static, differential ground displacement in the fault‐parallel direction across the rupture. The ground motions used in the analysis contain common near‐fault features including a directivity pulse in the fault‐normal direction and a fling step in the fault‐parallel direction. The analysis used a finite element package capable of modeling the mechanical behavior of the seismic isolation system and focused on the structural response of a 10‐span module of the viaduct. This analysis showed that the displacement of the superstructure relative to the piers exceeded the capacity of the bearings at an early stage of the earthquake, causing damage to the bearings as well as to the energy dissipation units. The analysis also indicated that shear keys, both longitudinal and transverse, played a critical role in preventing collapse of the deck spans. Published in 2004 by John Wiley & Sons, Ltd. 相似文献
8.
The objective of this study is to evaluate the seismic hazard in Eastern Marmara Region using an improved probabilistic seismic hazard assessment methodology. Two significant improvements over the previous seismic hazard assessment practices are accomplished in this study: advanced seismic source characterization models in terms of source geometry and recurrence relationships are developed, and improved global ground motion models (NGA-W1 models) are employed to represent the ground motion variability. Planar fault segments are defined and a composite magnitude distribution model is used for all seismic sources in the region to properly represent the characteristic behavior of the North Anatolian Fault without the need for an additional background zone. Multi-segment ruptures are considered using the rupture model proposed by the Working Group on California Earthquake Probabilities (2003). Events in the earthquake catalogue are attributed to the fault zones and scenario weights are determined by releasing the accumulated seismic energy. The uniform hazard spectra at 10 % probability of exceedance in 50 years hazard level for different soil conditions (soil and rock) are revealed for specific locations in the region (Adapazar?, Düzce, Gemlik, Izmit, Iznik and Sapanca). Hazard maps of the region for rock site conditions at the selected hazard levels are provided to allow the readers perform site-specific hazard assessment and develop site-specific design spectrum for local site conditions. 相似文献
9.
A representative attenuation relationship is one of the key components required in seismic hazard assessment of a region of interest. Attenuation relationships for peak ground acceleration, peak ground velocity and response spectral accelerations for Sumatran megathrust earthquakes, covering Mw up to 9.0, are derived based on synthetic seismograms obtained from a finite‐fault kinematic model. The relationships derived are for very hard rock site condition and for a long‐distance range between 200 and 1500 km. They are then validated with recorded data from giant earthquakes on the Sumatran megathrust occurring since year 2000. A close examination of the recorded data also shows that spectral shapes predicted by most of the existing attenuation relationships and that specified in the IBC code are not particularly suitable for sites where potential seismic hazard is dominated by large‐magnitude, distant, earthquakes. Ground motions at a remote site are typically signified by the dominance of long‐period components with periods longer than 1 s, whereas the predominant periods from most of the existing attenuation relationships and the IBC code are shorter than 0.6 s. The shifting of response spectrum towards longer period range for distant earthquakes should be carefully taken into account in the formulation of future seismic codes for Southeast Asia, where many metropolises are located far from active seismic sources. The attenuation relationship derived in the present study can properly reproduce the spectral shape from distant subduction earthquakes, and could hopefully give insights into the formulation of future seismic codes. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
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
11.
On July 20, 1995, an earthquake of M
L=4.1 occurred in Huailai basin, northwest of Beijing, with epicenter coordinates 40.326°N, 115.448°E and focal depth 5.5 km.
Following the main shock, seismicity sharply increased in the basin. This earthquake sequence was recorded by Sino-European
Cooperative Huailai Digital Seismograph Network (HDSN) and the hypocentres were precisely located. About 2 hours after the
occurrence of the main shock, a smaller event of M
L=2.0 took place at 40.323°N, 115.447°E with a focal depth of 5.0 km, which is very close to the main shock. Using the M
L=2.0 earthquake as an empirical Green’s function, a regularization method was applied to retrieve the far-field source-time
function (STF) of the main shock. Considering the records of HDSN are the type of velocity, to depress high frequency noise,
we removed instrument response from the records of the two events, then integrated them to get displacement seismogram before
applying the regularization method. From the 5 field stations, P phases in vertical direction which mostly are about 0.5 s
in length were used. The STFs obtained from each seismic phases are in good agreement, showing that the M
L=4.1 earthquake consisted of two events. STFs from each station demonstrate an obvious “seismic Doppler effect”. Assuming
the nodal plane striking 37° and dipping 40°, determined by using P wave first motion data and aftershock distribution, is
the fault plane, through a trial and error method, the following results were drawn: Both of the events lasted about 0.1 s,
the rupture length of the first one is 0.5 km, longer than the second one which is 0.3 km, and the rupture velocity of the
first event is 5.0 km/s, larger than that of the second one which is about 3.0 km/s; the second event took place 0.06 s later
than the first one; on the fault plane, the first event ruptured in the direction γ=140° measured clockwise from the strike
of the fault, while the second event ruptured at γ=80°, the initial point of the second one locates at γ=−100° and 0.52 km
from the beginning point of the first one. Using far-field ground displacement spectrum measurement method, the following
source parameters about the M
L=4.1 earthquake were also reached: the scalar earthquake moment is 3.3×1013 N·m, stress drop 4.6 MPa, rupture radius 0.16 km.
Contribution No. 99FE2022, Institute of Geophysics, China Seismological Bureau.
This study is supported by the Chinese Joint Seismological Science Foundation (95-07-411). 相似文献
12.
Empirical equations are presented for the prediction of displacement response ordinates for damping ratios of 2, 5, 10, 20 and 30% of critical and for response periods up to 4s, using 532 accelerograms from the strong‐motion databank from Europe and the Middle East. The records were all re‐processed and only employed for regressions at periods within the usable range, defined as a fraction of the filter cut‐off and depending on the instrument type (digital or analogue), earthquake magnitude and site class. The equations can be applied to predict the geometric mean displacement and pseudo‐acceleration spectra for earthquakes with moment magnitudes ( M ) between 5 and 7.6, and for distances up to 100km. The equations also include style‐of‐faulting and site class as explanatory variables. The predictions obtained from these new equations suggest that earlier European equations for spectral displacements underestimate the ordinates at longer periods as a result of severe filtering and the use of the spectral ordinates at periods too close to the filter cut‐off. The results also confirm that the period defining the start of the constant displacement plateau in the Eurocode 8 (EC8) spectrum is excessively short at 2s. The results not only show that the scaling factor defined in EC8 for estimating the spectral ordinates at damping ratios different from 5% of critical are a good general approximation, but also that this scaling varies with magnitude and distance (reflecting the influence of duration) and also displays a mild dependence on response period. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
13.
选取分布在北川-映秀中央断裂两侧断层距120 km以内的40个强震动台站的记录,对汶川地震近断层地震动竖向和水平向加速度峰值、速度峰值、竖向和水平向加速度反应谱及谱比值进行了统计分析.研究表明:(1)地震动加速度峰值有显著的上盘效应,经验衰减模型的结果表明,在距地表破裂3~60 km的范围内,龙门山发震断层上盘一侧竖向与水平向的加速度峰值要比衰减模型得到的平均值大30%~40%.上盘的加速度峰值残差大部分是正值,而断层下盘残差大部分为负;水平地震动的东西分量幅值总体要大于南北分量,东西分量衰减相对较慢.(2)地震动长周期成分较弱,加速度反应谱值随周期增大而迅速减小,在周期1.0 s 时,即使在靠近中央断裂的最大加速度反应谱值也只有0.5 g;地震动加速度反应谱谱比值(竖向/水平向)沿龙门山断层周围的分布,在较长周期(T=0.2 s, 0.5 s, 1.0 s)与短周期(T=0.05 s, 0.1 s)有明显的不同.(3)近断层竖向地震动显著,地震动加速度峰值比在(竖向/水平向)可达1.4.在龙门山发震断层的上盘,地震动加速度峰值比整体上比下盘要大,竖向地震动尤为剧烈.部分近断层记录的地震动谱比值(竖向/水平向)在短周期(< 0.1 s)甚至超过1.5,统计分析还表明谱比值在短周期段(< 0.1 s)随断层距的增大而减小. 相似文献
14.
选取了1999年9月21日台湾集集7.6级地震主震中68组断层距在20km以内的近断层台站记录和46组断层距在40~70km的东部台站记录,按台站的上下盘位置、场地条件和断层距分组,对其竖向和水平加速度反应谱比值V/H进行了统计分析。研究表明:1)断层的滑动方向和断层破裂的传播方向对断层距在3km以内的台站上的地面运动谱比值V/H有一定影响,且主要体现在中短周期范围内,例如平行断层方向的谱比值要比垂直断层方向的谱比值大。在下盘断层距3~20km的范围内,场地条件对V/H基本没有影响。2)在集集地震中长周期(>3s)部分的谱比值通常>32,且有一个较高的峰值,表明其竖向运动加速度中的长周期分量大于其它地震。3)对于下盘的台站,地面运动在短周期(<0.2s)段的谱比值不随断层距的增加而减少。与中远(>40km)距离的台站相比较,近断层台站的V/H在工程界关心的周期范围内普遍较大。4)场地条件对谱比值V/H的影响在近断层处不显著。在远离断层的东部台站上,硬土场地谱比值V/H在长周期段大于软土场地 相似文献
15.
Seismic site coefficients (F s ) for Imphal city have been estimated based on 700 synthetically generated earthquake time histories through stochastic finite fault method, considering various combinations of magnitudes and fault distances that may affect Imphal city. Seismic hazard curves and Uniform Hazard Response Spectra (UHRS) are presented for Imphal city. F s have been estimated based on site response analyses through SHAKE-91 for a period range of engineering interest (PGA to 3.0 s), for 5% damping. F s were multiplied by UHRS values to obtain surface level spectral acceleration with 2 and 10% probability of exceedance in 50 year (～2500 and ～500 year) return period. Comparison between predicted mean surface level response spectra and IS-1893 code shows that spectral acceleration value is higher for longer periods (i.e., >1.0 s), for ～500 year return period, and lower for periods shorter than 0.2 s for ～2500 year return period. 相似文献
16.
中国青海省门源县于2022年1月8日发生6.9级地震。依据该地震震源断层信息设置4种不同的位错分布模式,基于Okada提出的地表位移解析解分别计算4种模式下地表同震位移场,结合现场观测数据,探讨发震断层的滑动形式及其对周边地表产生的影响。结果表明,此次地震发震断裂初步判断主要为冷龙岭断裂西侧延伸至托莱山断裂,以左旋走滑断层为主,断层面上最大位错量达到4 m左右;震中西南侧向NE方向运动,东南侧向SE方向运动,西北侧和东北侧分别向NW以及SW方向运动;震中附近小范围区域产生了超过1.5 m的地表水平位移,破裂带上存在竖向地表位移超过0.5 m的区域;现场监测到局部产生最大约2.1～2.3 m的水平位错,以及部分区段垂直位错量最大达到0.7 m;以震中位置为中心,断层引起的地表位移影响范围达到约30 km×36 km,此范围内产生的地表位移大于0.1m。研究为此次地震的震后恢复工作以及此区域后续的工程设防等提供参考。 相似文献
17.
选取断层距小于200 km的64组强震记录数据,基于小波方法分析汶川地震近断层速度脉冲的地震动特性,并将此次地震中获取到的速度脉冲周期和幅值参数与Chi-Chi 地震和Northridge地震进行了比较,统计分析地震震级、距离对速度脉冲的周期和幅值参数的影响.研究表明:(1)汶川地震近断层速度脉冲具有周期长、幅值小的特点.速度脉冲周期主要分布在6~14 s之间,其中51MZQ台沿平行断层的分量脉冲周期最大为14.2 s,速度脉冲幅值与Chi-Chi 地震和Northridge地震相比明显偏小.(2) 速度脉冲记录出现在沿着地震断层破裂传播的方向上,且与地表断裂的距离都在30 km以内,这些长周期速度脉冲的形成可能主要由破裂传播的向前方向性效应引起.(3)速度脉冲的周期随矩震级呈对数线性增大,且随断层距增大有减小趋势.在矩震级小于Mw7.5时,观测到的地震动脉冲幅值为50~150 cm/s之间,与100 cm/s的典型断层滑动速率非常接近;而震级大于Mw7.5时,断层距10km范围内脉冲的幅值已经超过100 cm/s,个别记录的脉冲幅值甚至达到200 cm/s,远超过前人给出的饱和值,这可能与大的永久形变或该处土层介质条件有关. 相似文献
18.
Introduction The 1303 Shanxi Hongtong M=8 earthquake is the earliest M=8 event determined in histori-cal records in China and the largest recorded in Shanxi fault-depression system in history. Some researchers have discussed the tectonic environment of this earthquake (DENG, et al, 1973; DENG, 1984; DENG, XU, 1994, 1995; Seismo-geological Brigade, State Seismological Bureau, Depart-ment of Geology and Geography, Peking University, 1979; LIU, XIAO, 1982; ZHANG, JIA, 1986; SU, … 相似文献
19.
利用精河M_W6.3地震有限断层破裂模型,计算了精河地震产生的位移场、应力场、周围主要断层上的静态库仑应力变化以及主震对余震的触发作用。结果表明:(1)精河地震产生的地表隆升最大值约为6.6cm,沉降最大值约为1.8cm;水平位移方向呈现震中南北侧向震中汇聚、震中东西侧向外"流出"的特点。(2)精河地震产生的水平面应力场展布南北侧物质主要受到指向震中的拉张力作用,东西两侧物质主要受到因震中过剩物质东西向排出而导致的东西向挤压力作用。(3)震中西侧距震中约20km的库松木契克山前断裂中段和震中东北部距震中约50km的四棵树-古尔图南断裂西段的库仑应力加载均大于0.01MPa,即2处为地震危险区。(4)在震源深度为8~12km的余震事件中,约有85.5%处于库仑应力加载区,即受到主震的的触发作用;在深度为4~8km的余震事件中,约有87%受到主震的应力触发作用。 相似文献
20.
Pulse-like ground motion observed during the 6 February 2023 MW7.8 Pazarcık Earthquake (Kahramanmaraş, SE Türkiye) 
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下载免费PDF全文 Fan Wu Junju Xie Zhao An Chenghao Lyu Tuncay Taymaz Tahir Serkan Irmak Xiaojun Li Zengping Wen Baofeng Zhou 《地震科学（英文版）》2023,36(4):328-339
In this study, we analyzed 100 three-component strong ground motion records observed within 200 km of the causative fault of the 6 February 2023 MW7.8 Pazarcık (Kahramanmaraş) Earthquake in SE Türkiye. The wavelet method was utilized to identify and analyze the characteristics of pulse-like ground motions in the near-fault region, while considering the uncertainty of the pulse orientation during the analysis. Our investigation focused on the effects of the focal mechanism and rupture process on the spatial distribution, pulse orientation, and maximum pulse direction of the observed pulse-like ground motion. We also analyzed the amplitude and period of the observed ground pulses and the effect of long-period amplification on the ground motion response spectra. Our results indicated the following: (1) A total of 21 typical ground velocity pulses were observed during this earthquake, exhibiting complex characteristics due to the influence of the strike-slip mechanism and rupture directivity. Most ground pulses (17 out of 21) were recorded within 20 km of the fault, in a wide range of orientations, including normal and parallel to the fault direction. The waveforms exhibited unidirectional features, indicating the effects of left-lateral fault slip. Distinct pulses observed more than 20 km from the fault were mainly oriented normal to the fault. The waveforms were bidirectional with double- or multi-round trips as a result of rupture directivity. (2) The amplitudes of the observed pulses ranged from 30.5 to 220.0 cm/s, with the largest peak velocity of 220.0 cm/s observed at Station 3138. The pulse periods ranged from 2.3 to 14.5 s, with the longest pulse period of 14.5 s observed at Station 3116. The amplitude and period of the pulses observed during this earthquake were comparable to those of similar-magnitude global earthquakes. The amplitude of the pulses decreased significantly with increasing fault distance, whereas the pulse period was not significantly affected by the fault distance. (3) Compared with non-pulse records, the velocity pulse records had a pronounced amplification effect on the acceleration response spectra near the pulse period, with factors ranging from 2.1 to 5.8. The larger velocity pulses also significantly amplified the velocity response spectra, particularly over the long periods. This significant amplification effect of the pulses on the response spectra leads to empirical models underestimating the long-period earthquake ground motion. 相似文献