华北中北部地区震源参数和场地响应的联合反演

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。     

场地响应、震源参数与介质衰减的同时反演

采用Ω平方模型来约束中小地震的震源位移振幅谱,从而实现对震源参数、介质的几何扩散特征、介质的非弹性衰减以及场地响应等参数的同时反演,数值模拟结果表明该方法是可靠的。江苏省苏南地区的几何扩散较好地符合三段衰减统计模型,该地区的品质因子与频率的依赖关系以频率3．0Hz为界分为低频、高频二部分．且均符合指数衰减关系,而全部频率点的品质因子频率依赖关系似乎与四元素流变模型的Q值理论频率特征曲线比较一致。该地区中小地震地震矩对数值与震级ML具有较好的线性关系;地震矩与拐角频率呈现出良好的双对数关系,且该地区的地震应力降与震源半径之间的关系在震源半径小于300m时与圆盘静态破裂模式理论关系较吻合。     

内蒙古中西部地区震源参数和场地响应反演

采用Atkinson方法,基于遗传算法,利用呼和浩特数字地震台网7个子台记录的9次质量较高的地震事件资料,计算了内蒙古中西部地区的品质因子Q值和非弹性衰减系数c（f）。在所研究的频率范围内,前者和频率．厂有很好的线形关系：Q（f）=116．8f^1.000后者与频率．厂的变化关系不明显。在此基础上采用Moya方法反演了7个地震台的场地响应和地震的震源参数,并对它们之间的相互关系进行了讨论。结果显示在所研究的频率域内7个基岩台站的场地均不同程度的存在放大作用,其次震源参数间具有较好的线性关系。本文还详细介绍了Atkinson方法和Moya方法的原理和计算步骤。     

山东中西部及邻近地区震源参数和场地响应的反演

利用山东数字地震台网10个地震台自2004年6月至2007年8月记录的数字波形资料,采用Atkinson（1992）方法反演了山东中西部及邻近地区的非弹性衰减,得到该地区Q值与频率的关系是Q（f）=382．2·f^0.443。运用Moya（2000）方法反演了10个台站的场地响应,得到了26个地震的震源参数,并对所得结果进行了初步讨论。     

利用遗传算法反演非弹性衰减系数、震源参数和场地响应

随着数字化地震台网在全国陆续建设完成,利用数字化台网记录的大量地震波形资料提取地震的震源参数,如地震矩、破裂尺度、应力降等,更好地为地震预测和地震危险性分析服务,逐渐成为当前的一项日常工作(Hough et al.,1999;Bindi et al.,2001).虽然     

利用数字地震台网资料联合反演福建地区Q值、场地响应和震源参数

文中利用福建数字地震台网1998年建网以来记录的2.5级以上地震的波形资料,采用Atkinson等提出的方法计算了福建地区地震波非弹性衰减系数、几何扩散系数和台站场地响应。考虑到该方法在计算台站场地响应时得到的结果是相对场地响应,利用Moya等提出的方法对台站场地响应进行重新计算,对震源谱的低频水平和拐角频率进行联合反演,并计算了参与反演的地震的新参数(地震矩、应力降和破裂半径),同时讨论了它们之间的关系。反演结果表明福建地区地壳平均Q值与频率的关系为Q=504.1×f0.332,而场地响应均表现为与频率相关并基本在1附近波动,这与福建数字地震台站基本建立在基岩之上的实际情况相符合。震源参数的计算结果表明,地震矩与震级以及震源谱拐角频率的相关性较好,而地震矩与应力降以及应力降与震源半径之间的依赖关系不很明确,这可能与参与计算的地震数量以及震级范围有关     

利用数字化地震波形资料研究山西中南部地区的非弹性衰减系数、震源参数和场地响应

利用遗传算法反演山西中南部地区14个地震震源谱的低频水平、拐角频率和7个台站的场地响应。结果表明,Q(f)与频率的关系是:Q(f)=299.4f0.563;7个基岩台中岢岚、东山、阳城台在3 Hz~6 Hz附近有6~8倍的放大、离石台在2 Hz~10 Hz有2~3倍的放大。标量地震矩M。与ML震级线性相关较好,震源半径在230 m~508 m之间;拐角频率和地震矩之间的关系表现为拐角频率随地震矩的减小而增大;应力降和地震矩之间存在着应力降随地震矩的增大而增大的关系。     

应用Moya方法反演浙江地区震源参数和台站场地响应

根据浙江数字地震台网记录的发生在浙江省及其附近海域的中小地震的波形资料,采用Moya方法[1],反演浙江地区震源参数和场地响应特征。     

四川地区震源参数和台站场地响应初步研究

利用成都遥测数字地震台网数字地震波形数据资料,采用Atkinson方法得到四川地区的品质因子Q值与频率,的关系为：Q（f）=203．1f0.834。采用Moya方法反演得到了地震的场地响应,采用Moya方法与Atldnson方法分别得到了相应地震的震源谱参数,两种方法的结果保持了很好的一致性。得到的震源参数结果表明：地震矩与震级的关系为：logM0=17．27＋1．18Mt,地震矩与拐角频率关系,即随着地震矩的增大,拐角频率减小,这些地震的应力降在10-400巴之间,应力降与地震矩之间没有明显的依赖关系。     

利用井下数字地震记录反演非弹性衰减系数震源参数和场地响应

利用天津地区近场井下数字地震波形记录,基于遗传算法,采用Atkinson方法得到了天津地区的品质因子Q值与频率的关系为Q(f)=97.0f0.98.采用Moya方法反演了地震的震源参数和台站的场地响应.     

山西地区非弹性衰减系数、场地响应和震源参数的初步研究

利用山西数字测震台网“十五”数字化之后34次 ML2.5～ML5.2级地震波形资料,采用Atkinson方法反演出非弹性衰减Q值随频率f的关系为Q( f)=469.5df0.3141;采用Moya方法反演得出41个台站的场地响应,结果显示出仪器安置在山洞且地处外界干扰小的台站没有明显的放大效应,而其它台站尽管都是基岩台...     

三维多层介质重力-地震同步联合反演

联合反演是地球物理勘探的重要解释手段,能够提高模型参数的反演精度.本文在归纳和分析重力与地震资料联合反演的研究和应用现状的基础上,利用三维多层介质模型的地震走时和重力正演公式,推导了地震走时和重力异常对界面深度的雅可比矩阵,实现了三维重力-地震同步联合反演界面成像.最后进行了数值理论模型模拟和实例计算,结果表明地震走时和重力同步联合反演很好的重建了三维多层介质界面.     

Seismic Ground Motion Zoning Maps of the Pangxi Region

The seismotectonic environment and seismic activity in Southwest China region were studied based on new data and new results obtained during the Eighth and Ninth Five-Year Plans,the seismic areas and zones and potential seismic source zones were determined.and the relation between seismic activity parameters and ground motion attenuation was determined.Finally the seismic gound motion zoning maps of the Pangxi region was compiled by using the multi-parameter and multi-scheme method.     

Seismic Zonation of the Delhi Region for Bedrock Ground Motion

An endeavor is made to compute peak ground horizontal accelerations at bedrock level in the Delhi region due to the seismogenic sources present around Delhi. The entire area is divided into six seismogenic sources for which seismic hazard analysis is carried out using the complete and extreme part of the seismicity data. Maximum likelihood estimates of hazard parameters viz., seismic activity rate , b value and maximum probable earthquake M _max are made for each zone. The return periods and the probabilities of occurrence of various magnitudes for return periods of 50, 100 and 1000 years are also computed for each zone. The peak ground acceleration (PGA) values for 20% exceedance in 50 years are then computed for the Delhi region from each zone. The maximum PGA value considering all the zones is 0.34 g, which is due to the Mathura fault zone. The seismogenic zones V and VI, i.e., Mathura fault zone and the Sohna fault zone are observed to be contributing maximum PGA values in the Delhi region governing the isoacceleration contours computed for the region. The seismic zonation map for the PGA values at the bedrock level is obtained for the Delhi region. This can be used directly as input for the microzonation of ground motion at the surface by incorporating the local site conditions.     

Joint Inversion of Body-Wave Arrival Times and Surface-Wave Dispersion for Three-Dimensional Seismic Structure Around SAFOD

We incorporate body-wave arrival time and surface-wave dispersion data into a joint inversion for three-dimensional P-wave and S-wave velocity structure of the crust surrounding the site of the San Andreas Fault Observatory at Depth. The contributions of the two data types to the inversion are controlled by the relative weighting of the respective equations. We find that the trade-off between fitting the two data types, controlled by the weighting, defines a clear optimal solution. Varying the weighting away from the optimal point leads to sharp increases in misfit for one data type with only modest reduction in misfit for the other data type. All the acceptable solutions yield structures with similar primary features, but the smaller-scale features change substantially. When there is a lower relative weight on the surface-wave data, it appears that the solution over-fits the body-wave data, leading to a relatively rough V _s model, whereas for the optimal weighting, we obtain a relatively smooth model that is able to fit both the body-wave and surface-wave observations adequately.     

Analysis of the Impact of Source Region Structures on Seismological Parameter Scanning

By taking moderate-strong earthquakes in South,North and West China as the research subjects and taking into consideration the fault strikes in these regions,this paper selects 8 kinds of seismology indexes with clear physical significance and strong independence to carry out spatial scanning of the parallel,vertical and oblique slip of fault along the fault strike.Based on the size of correlation coefficients between the scanning curve and source region curve we quantitatively analyze the difference between scan results among different slip modes and study the impact of fault strike in different tectonic divisions on scanning results and variation rules of seismological parameters.The results show that not only does the change of spatial parameters have a great influence on seismological parameter scanning,but so does the fault strike in the source region.This paper presents the optimum condition parameters with least spatial influencing scanning scope for different magnitude seismology indexes and analyzes the possible influence of fault strike on seismological parameter scanning results.