共查询到19条相似文献，搜索用时 140 毫秒
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场地响应是精确测定震源参数和稳健估计出高精度地壳介质衰减变化的关键影响因素之一,采用H/V尾波谱比法,对祁连山主动源观测台网中40个短周期观测台站的场地响应进行了分析。结果表明,祁连山主动源观测台网中40个短周期观测台站均存在不同程度的放大（衰减）作用,根据40个台站观测波形的尾波场地响应曲线特征,可将其分为平坦类、放大类、高频衰减类,在1~20 Hz频段内部分台站场地响应曲线呈现平坦,场地响应值为1~2倍;而大部分台站在不同频段有明显放大（衰减）作用,场地响应值为0.3~9倍。台站台基岩性可能是决定场地响应曲线特征和大小的主要因素,且与台基介质密度具有反相关性。 相似文献
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利用2016年云南测震台网记录到的地脉动数据,运用H/V谱比法计算分析了47个测震台站在0.1～20.0Hz频段内的场地响应。选取2012～2016年期间云南测震台网记录到的ML≥2.5地震做单台震级偏差统计分析,挑出受场地放大作用而出现单台震级大于台网平均震级的台站做去场地放大校正,然后重新统计单台震级偏差情况。计算结果显示云南测震台网的台站受台基条件和所处位置等地质构造因素影响,均存在一定程度的场地放大作用,大部分台站场地响应的卓越频率为1～6Hz,放大倍数为2～4倍。受场地放大作用的影响,大姚、芒市等19个台站的单台ML震级大于台网平均震级。在去除场地放大作用后,台站单台震级与台网平均震级的偏差有所减小。 相似文献
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山东数字地震台站场地响应估算 总被引：1，自引：0，他引：1
为了建立山东省数字地震台站场地响应数据库,选取山东区域数字地震台网自2009年4月至2012年1月记录的ML≥2.5地震事件,通过信噪比方法挑选出质量较高的86次地震,采用互相衔接的三段几何衰减模型,基于遗传算法,利用Moya等方法对山东省36个地震台站进行场地响应测算.其中35个台站未显示明显的放大作用,聊城台场地响应变化起伏较大,高频部分放大明显,烟台、招远、即墨、五连、菏泽台场地响应总体表现出一定衰减作用. 相似文献
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华北中北部地区震源参数和场地响应的联合反演 总被引：9，自引：2，他引：9
利用遗传算法反演华北中北部地区27个地震震源谱的低频水平、拐角频率和25个台站的场地响应。具体方法是利用研究区的平均衰减模型对记录谱进行路径校正，然后假定每一个地震的ω^2模型，调整低频水平和拐角频率使所有台站场地响应的标准偏差最小，最后给出参与计算的每个台站的场地响应。结果表明，17个基岩台中11个台的场地响应在1～20Hz范围内接近1，6个基岩台的场地响应部分频段放大或缩小3倍以上。8个井下摆台站的场地响应形态相同，表现为低频放大，高频部分迅速衰减。地震矩与震级的关系为logM0=17．1 1．13ML，地震矩与震源半径的关系为logM0=19．4 0．0052r。 相似文献
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《地震研究》2020,(1)
准确的衰减特征及台站响应对于定量确定地震台网观测环境和分析其构造机制具有重要意义。选取2008—2017年辽宁数字地震台网地震波形资料,利用Lg波谱比与台站场地响应联合反演方法,获得了1～7 Hz Lg波三分向(UD,NS,EW)衰减关系,参与评估的32个台站的场地响应幅值曲线较为平滑,各频段衰减效应存在差异。大多数台站的场地效应幅值在1～8,少数台在低频或高频段上呈现放大效应,最大的幅值近16。结果表明:辽宁地区为低Q0(对应频率1 Hz)和低频率依赖性的构造活跃区,场地响应特征与浅层结构及地质构造有密切关系。不同场地类型的场地响应特征差异明显:井下场地类型的场地响应在低频段内(1～2 Hz)有明显的放大效应;地表较山洞场地类型的场地响应幅值在径向和垂向上都有抬升;相同场地类型中,场地响应放大效应在径向上比垂向上大的多,可能与台基岩性特征有关,而岩性差异对场地响应特征的影响不明显。 相似文献
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不同标度震级关系和台基影响问题探讨 总被引：2，自引：1，他引：2
利用近年中国数字地震台网观测报告中的中国及邻区地震目录资料,取能够同时计算面波震级MS和近震震级ML的地震,拟合出2种震级之间的关系,发现与过去使用30余年的换算公式存在系统差别。考虑现代化地震数字观测系统有动态范围大、频带宽、台站多、覆盖区域广、测定精度高的特点,由此拟合的关系应当更可靠。考虑不同误差因素统计面波震级MS和近震震级ML的关系表明,2种震级之间换算和不换算的差别并不大,因此建议MS和ML震级之间不换算为宜。分析地震台站的场地响应发现:一些基岩台的放大因子在1附近,场地响应不随频率变化;处于沉积土层的台站,放大因子在低频段大于1,高频段小于1;还有一些台站在某个频段范围大于1,或者小于1。另外,沉积土层台站的单台震级和台网平均震级差也随周期增大,呈现由负到正的增长趋势。看来并不存在固定的台站校正系数,因此不能把台站校正作为提高震级测定精度的方法。 相似文献
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采用分布于鄂尔多斯地块及其周缘的32个地震台站记录到的19次地震事件共487条数字化波形记录, 利用遗传算法反演得到了整个鄂尔多斯地块地壳内S波的三段几何扩散参数、S波非弹性衰减Q值随频率变化的关系式、32个台站的场地响应以及19次地震的震源参数. 计算结果表明, 鄂尔多斯地块地壳内S波非弹性衰减在1 Hz处的Q值比地质构造活跃地区的结果要大得多. 32个地震台站的场地响应在高频部分除个别台站外基本没有表现出明显的放大效应,但在低频区间部分台站之间有一定的差异. 19次地震事件的地震矩对数值与震级ML有很好的线性关系. 相似文献
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《地震工程学报》2016,(Z2)
利用河北测震数字台网2009年1月-2015年5月记录到的169个ML≥2.5地震(含山区和平原)4 180条波形资料,将河北(含北京、天津)及邻近地区作为研究区域,根据地形及地质构造将研究区域分为山区和平原两个区,采用三段几何衰减模型,用Atkinson(1992)方法计算各自的Q值,得到山区和平原的非弹性衰减Q随频率变化的关系式分别为:Q(f)=474.8f0.3589,Q(f)=294.5f0.5193,并与已有的结果进行对比。在此基础上,利用Moya(2000)方法进行震源谱和场地响应的联合反演,得到了93个基岩台、58个井下台的场地响应,基岩台的场地响应随频率的变化较为复杂。不同类型的基岩台场地响应绝大多数无明显的一致性特征;井下台站的场地响应随频率变化的形态基本一致,在低频段(1~7 Hz)表现为放大作用,在高频段(7~20 Hz)表现为衰减效应。 相似文献
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2012年5月28日河北省唐山市古冶区与滦县交界发生4.8级地震, 国家强震动台网中心在河北、 天津和北京的94个强震动台站记录到了本次地震的加速度。 本文给出了获取记录的强震动台站分布及强震动记录结果, 统计了强震动记录数量随震中距的变化, 给出了3个较小震中距台站记录到的加速度时程; 绘制了空间地震动峰值加速度等值线图及周期0.2 s、 2.0 s加速度反应谱值的等值线, 发现峰值加速度等值线与长周期加速度反应谱等值线极值分布具有明显地域差异, 分析认为是由于厚沉积层对长周期地震动具有放大作用造成的。 通过强震动记录与适用于本区的三个衰减关系对比, 分析了此次地震的峰值加速度衰减特征, 同时研究了周期0.2 s、 2.0 s加速度反应谱值的衰减特征, 周期2.0 s反应谱值随震中距的衰减与衰减关系能较好地对应, 然而在震中距100～130 km沉积层较厚的集中地区, 表现出了实际记录较衰减关系值偏大的现象, 认为同样是由于厚沉积层对地震动加速度反应谱长周期的放大作用导致的。 研究了震中距差别不大的情况下, 场地类型与沉积层厚度对反应谱特征周期的影响, 对比基岩台站与软弱地基土层台站的强震动记录反应谱, 发现软弱土层台站的土层对地震动有一定的放大作用, 导致中长周期地震动被放大, 对比位于沉积层较薄的隆起区台站与位于沉积层较厚的凹陷区台站强震动记录反应谱, 发现厚的沉积层不仅对反应谱长周期有放大的作用, 同时也会使得反应谱特征周期值变大。 相似文献
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2008年汶川MS8.0地震获得了大量的强震动记录, 为研究反应谱特征参数衰减特性提供了重要的基础资料. 本文对已知场地条件的174个台站的记录进行研究, 计算其加速度反应谱并按照最小二乘分段拟合方法进行标定, 进而拟合了反应谱平台值的衰减关系;对比分析了水平方向与竖直方向反应谱平台值的衰减特性, 提出用“平台值的场地衰减影响系数”来定量研究不同场地类型对反应谱平台值的影响, 用“衰减曲线下降速率”来定量分析不同衰减曲线的衰减速率. 通过计算得出水平向Ⅰ, Ⅱ, Ⅲ类场地的平台值场地衰减影响系数平均值分别为0.5358, 1和1.579, 且Ⅲ类场地的加速度平台值衰减曲线的衰减速率最小. 相似文献
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DISCUSSION ON ATTENUATION CHARACTERISTICS,SITE RESPONSE AND MAGNITUDE DETERMINATION IN SICHUAN 
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下载免费PDF全文 The attenuation characteristics and site response are calculated respectively for each individual tectonic unit in Sichuan (Sichuan Basin,west Sichuan plateau and Panzhihua-Xichang area),using digital waveform data recorded by regional seismic networks and relevant seismic phase data collected from China Seismograph Network.The frequency dependent Q(f) is obtained by the iterative grid-search technique described by Atkinson and Mereu based on trilinear geometrical spreading model.The source spectra are determined by the model of Brune and the site responses of seismic stations are derived by Moya's method using genetic algorithms.Comparison to conventional ML estimates shows that the network local magnitude bias is quite significant at low and intermediate magnitudes.The bias at the jth station for the ith event is defined as ΔMij=Mij-Mi, where ΔMij is the station magnitude and Mi the network-average value.For comparison,we mapped the spatial distribution of biases by digital seismograms recorded from 10535 earthquakes of magnitude 2.5≤ML≤4.9 that occurred in Sichuan from January 1,2009 to June 30,2015.Based on the above data,the attenuation characteristics,site response and their effects on magnitude determination in Sichuan are analyzed.Our results demonstrate that the associated model for regional quality factor for frequencies can be expressed as Q1(f)=450.6f0.513 4 for Sichuan Basin,Q2(f)=136.6f0.581 3 for west Sichuan Plateau and Q3(f)=101.9f0.666 3 for Panzhihua-Xichang area.Site response results indicate that different stations show different amplifications.Maps of biases appear to be different,but with similar dominant spatial distribution.For stations in Sichuan Basin,their greater magnitudes are functions of low attenuation in structure and amplification effects of both seismic stations and basin effects.For stations in west Sichuan Plateau,the possible causes of these lower magnitudes are severe dependence upon source region due to extreme lateral variations in either structure or path effect attenuation.For stations in Panzhihua-Xichang area,broken medium caused by strong tectonic activity or large earthquakes and heat flow up-welling along active faults may be the main reasons of low magnitude values when earthquakes occur in western Sichuan and eastern Tibetan region.And the greater magnitudes for earthquakes along the Longmen Mountains appear to be well correlated with edge effect of sedimentary basin on strong ground motion.In our study,stations magnitude biases appear to be extremely correlated with tectonic structures and different regions when seismic rays passing through,magnitudes are affected significantly by lateral variations in attenuation characters rather than site responses. 相似文献
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Based on spectral ratio method, a joint inversion method was used to obtain parameters of Lg wave attenuation and site response. The inversion method allows simple and direct (two-parameter) determination of Lg wave attenua- tion and site response from sparse spectral data, which are not affected by radiation pattern factor and different response of same instrument after geometrical spreading. The method was used successfully for estimating site re- sponse of stations of Zhejiang Seismic Network and measuring Lg wave attenuation. The study is based on 20 earth- quakes occurred in northeast of Taiwan with magnitude MS5.0~6.7 and 960 seismic wave records from 16 stations in Zhejiang area from 2002 to 2005. The parameters of site response and Lg attenuation were calculated with a fre- quency interval of 0.2 Hz in the range of 0.5 Hz to 10 Hz. Lg wave attenuation coefficient corresponding to U-D, E-W and N-S components are γ ( f )=0.00175 f 0.43485, γ ( f )=0.00145f 0.48467 and γ ( f )=0.0021f 0.41241, respectively. It is found that the site response is component-independent. It is also found that the site response of QIY station is significant above the frequency of 1.5 Hz, and that the site response of NIB station is low for most frequency 相似文献
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根据山西数字地震台网14个地震台的310条波形资料，研究了山西地区的非弹性衰减系数；采用Atkinson和Moya方法，研究了各台的场地响应和几种震源参数，并对这两种方法的反演结果进行了对比分析. 得到山西地区非弹性衰减Q值随频率f的关系为Q(f)=323.2f 0.506；得到的14个台站的场地响应均没有显示出明显的放大效应，这与山西台站均处于岩石地基相符；得到了拐角频率与地震矩、地震矩与应力降、震源半径与应力降之间存在依赖关系. 相似文献
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为了研究2021年5月22日玛多MS 7.4地震地震动特征,收集16个强震台的峰值加速度和其中9个台的强震波形数据,利用峰值加速度衰减及反应谱等分析玛多MS 7.4地震强震动特征。结果表明,多数台站的PGA值都随震中距的增大而平稳下降,PGA的衰减特征与青藏区衰减关系间有较好的一致性;土层台与基岩台的加速度反应谱明显不同,震中距越小,短周期高频成分越多,衰减越快,震中距越大,长周期高频成分越少,衰减越慢;加速度反应谱的水平向与竖向比值曲线在4 s内呈现两峰一谷的现象,初步认为,距发震断层较近的野马滩1号大桥所受到的破坏及水泥路面的明显错断受水平向地震动作用的影响更大。 相似文献
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WANG Heng-zhi YU Yan-xiang HE Bin PENG Xiao-bo ZHAN Xiao-yan ZHU Sheng-chu 《地震地质》2018,40(6):1349-1361
An M4.9 earthquake occurred at the junction of Gaoyou and Baoying on July 20, 2012. In this paper, 43 sets of strong motion records of the main shock are analyzed. With these data, we analyzed the characteristics of the peak ground motion value, attenuation relation, duration and acceleration response spectrum. We draw the peak acceleration contour map of the region near the epicenter. The contour line is smooth and the trend of long axis is northwest-southeast. Distribution of peak acceleration of the observed records is basically consistent with the real intensity distribution. Compared with the predicted result based on the seismic attenuation relation proposed by Yu Yanxiang and Wang Suyunon for eastern China and the Fifth-generation ground motion zonation map, the horizontal PGA and PGV of Gaoyou-Baoying earthquake are higher than the predicted results that are based on the model of Fifth-generation ground motion zonation map, while the PGV is similar with the predicted results which are based on Yu Yanxiang and Wang Suyun's model. We regressively analyzed the spatial-temporal change curves of the two types of relative ground motion durations. Compared with the predicted results proposed by Bommer et al. (2009) based on the NGA strong motion records, the durations of all the three components of this earthquake are higher. 10 typical recordings' acceleration response spectra with 5% damping are calculated, their peak periods are around 0.1~0.3s. The acceleration response spectrum of the station 32BYT, which has the largest amplitude, is considerably larger than the Chinese code design spectra, while it becomes notably smaller when the period is larger than 0.4s. Compared with the horizontal bedrock acceleration response spectrum predicted by the attenuation relationship for the eastern part of China, the observed response spectrum shape is similar with the predicted ones, while almost all the observed response spectrum values (except station 32YCT)are smaller than the predicted bedrock acceleration response spectrum. These phenomena suggest that this earthquake has a weak impact on the seismic fortification standards in this area. Using H/V single-station spectral ratio method, amplitude and site amplification effect of the two typical stations are calculated, and the results show the H/V values are obviously larger than that of ground microtremor. This suggests that the site of the station has obvious amplification effect on ground motion. 相似文献