共查询到20条相似文献，搜索用时 15 毫秒
1.
2.
3.
选取乌兰浩特地震台记录到的典型天然地震事件及爆破事件,根据断裂带分布及波形记录特征,分析地震及爆破事件的震相特征。结果表明,研究区域近震波形Pn、Pg、Sn、Sg震相及Sm面波较清晰,Pg、Sg波走时差一般不大于23 s,与中国地震台网中心发布的MS震级间的偏差一般小于0.6级;远震P、S、pP、sP震相可较清晰识别,Pm、L面波记录较明显,P、S波走时差一般不小于25 s,震级偏差一般小于0.4级,且通过震相特征及实地考察发现,爆破多为霍林郭勒区域爆破事件。 相似文献
4.
选取乌兰浩特地震台记录到的典型天然地震事件及爆破事件,根据断裂带分布及波形记录特征,分析地震及爆破事件的震相特征.结果表明,研究区域近震波形Pn、Pg、Sn、Sg震相及Sm面波较清晰,Pg、Sg波走时差一般不大于23 s,与中国地震台网中心发布的MS震级间的偏差一般小于0.6级;远震P、S、pP、sP震相可较清晰识别,Pm、L面波记录较明显,P、S波走时差一般不小于25 s,震级偏差一般小于0.4级,且通过震相特征及实地考察发现,爆破多为霍林郭勒区域爆破事件. 相似文献
5.
常规Vibroseis可控震源Chirp扫描的地震响应存在明显的旁瓣效应,二元m-序列伪随机扫描的解码地震剖面中存在严重的相关噪声,而基于伪随机编码的匹配扫描方法可有效压制解码地震剖面中的相关噪声,提高了地震记录的信噪比.为了将匹配伪随机编码方法应用到冲击式震源中,提出了基于脉冲编码震源的匹配冲击技术.以匹配扫描方法为理论基础给出了匹配冲击信号的编码与解码过程,以有限元差分法对匹配冲击技术和常规线性扫描冲击技术进行了地震数值模拟.结果表明,匹配冲击的综合解码地震剖面中,不存在线性扫描冲击解码地震剖面中能量较强的相关噪声干扰,剖面具有很高的信噪比和分辨率.地震波激发采集对比实验验证了匹配冲击技术在压制相关噪声及远偏移距地震道随机噪声方面相比线性扫描冲击技术所具有的优势. 相似文献
6.
地震子波估计是地震资料处理和解释中的一个关键问题,子波估计的可靠性会直接影响反褶积和反演的准确度.现有的子波估计方法分为确定型和统计型两种类型,本文通过结合这两类方法,利用确定型的谱分析法和统计型的偏度最大化方法,分别提取时变子波的振幅和相位信息,得到估计的时变子波.这种方法不需要对子波进行任何时不变或相位等的假设,具有对时变相位的估计能力.进而利用估计时变子波进行非稳态反褶积,提高地震记录的保真度,为精细储层预测和描述提供高质量的剖面.理论模型试算验证了方法的可行性,通过实际地震资料的处理应用,表明该方法能有效地提取出子波时变信息. 相似文献
7.
The last decade or so has seen the development of refined performance-based earthquake engineering (PBEE) approaches that now provide a framework for estimation of a range of important decision variables, such as repair costs, repair time and number of casualties. This paper reviews current tools for PBEE, including the PACT software, and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore, proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed, highlighting needs for future research. To illustrate the potential of the methodology, performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the PEER performance-based earthquake engineering framework, applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations. 相似文献
8.
The last decade or so has seen the development of refined performance-based earthquake engineering(PBEE) approaches that now provide a framework for estimation of a range of important decision variables,such as repair costs,repair time and number of casualties. This paper reviews current tools for PBEE,including the PACT software,and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore,proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed,highlighting needs for future research. To illustrate the potential of the methodology,performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the PEER performance-based earthquake engineering framework,applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations. 相似文献
9.
考虑双向水平地震作用的结构设计问题研究 总被引：1，自引：0，他引：1
分析了抗震设计中考虑双向水平地震作用的必要性,指出了研究双向地震作用的必要性,通过国内外规范相关条文的对比指出目前研究有待完善的关键问题和方向,结合近期研究成果对其中几个值得注意的问题提出建议。 相似文献
10.
Basic reasons for different kinds of failures of record synchronization of the independent seismic stations, operating as elements both of domestic and foreign seismic arrays, are established. Proceeding from it, software and hardware are proposed for ensuring reliable and precise synchronization of stations. Their operation is based on periodic fine tuning of the station’s analog-to-digital converter (ADC) sampling cycle by an exact time signal obtained from the GPS receiver. This procedure is executed with minimum or even no additional load on the controller of the seismic recorder. Such an approach allows not only matching each ADC sample to astronomical time, but also to provide simultaneous ADC sampling of all stations in the seismic array with an accuracy of 10 μs, which is especially important for solving a number of geophysical problems. Experimental researches and trial operation of the created equipment are carried out. High reliability of the equipment and compliance of technical characteristics to the purposes of the development are confirmed. 相似文献
11.
D. G. Levchenko I. P. Kuzin M. V. Safonov V. N. Sychikov I. V. Ulomov B. V. Kholopov 《Seismic Instruments》2010,46(3):250-264
Development and application of broadband seismic sensors, namely velocimeters of electrochemical type (chemotrons), are considered.
The principle of operation and design of modern electrochemical (molecular-electronic) converters of seismic signals for linear
and rotary motions are described. The data on metrological certification and prolonged trials of these seismic sensors on
test benches are presented. Their advantages as compared to stationary broadband seismic sensors of electrodynamic type lie
in impact immunity, high power supply efficiency, operability at large inclinations and in a wide temperature range. Comparative
analysis of records of the Sichuan Earthquake (China, May 12, 2008) obtained in Moscow on a test bench at the Institute of
Physics of the Earth of the Russian Academy of Sciences with help of an electrodynamic seismic sensor and on a test bench
at the Design Bureau of Oceanological Equipment of the Russian Academy of Sciences with the help of an electrochemical sensor
is presented in conclusion. 相似文献
12.
针对山地地震勘探数据低信噪比问题,近地表散射波分离意义显得尤为突出,地震干涉测量法为此提供了一种技术手段.本文将地震干涉测量理论和散射理论结合起来,导出了近地表散射波地震干涉测量表达式,分为互相关型和褶积型表达式,它们由实际波场和背景波场干涉测量构成.根据近地表散射波分离理论,结合陆上地震勘探实际观测系统,采用褶积和反褶积混合型地震干涉测量配置,用实际地震资料展示了近地表散射波分离技术的应用效果.经过理论分析和砾石区实际资料试验,表明地震干涉测量不仅能分离测线上散射源产生的散射波,而且能分离部分侧面散射波.该技术的优点在于它适应于起伏地形和不均匀近地表结构,并且不需要起伏地形和近地表速度信息.为了从实际资料中消除近地表散射波,本文采用多道匹配滤波自适应减法,在砾石区见到较好效果. 相似文献
13.
建筑物震害预测模糊震害指数法 总被引：6，自引：3，他引：6
建筑物震害预测是城市防震减灾的基础工作之一。本文在分析现有震害预测方法的基础上，提出了一种新的震害预测方法－模糊震害指数法。模糊震害指数法以现有震害预测资料为基础，采用模糊数学方法实现。本文详细阐述了模糊震害指数法的理论模型，推导了其数学公式，最后给出了实例分析。 相似文献
14.
Georgios N. Stavrakakis 《Pure and Applied Geophysics》1988,127(1):21-31
Seismic hazard analysis requires the estimation of the probabilities that earthquakes will take place within a region of interest, and the expected level of ground motion which will be received at a site during the nextt years. The earthquake magnitude has been used as a basic parameter, because it is available, under the assumption that the earthquake occurrence is a compound Poisson process with exponential or multinomial distribution of magnitude.For improving the hazard prediction, we used the seismic moment as a basic parameter to estimate the mean rate, , of occurrence of earthquakes in a function of seismic moment rate and slip rate released in a seismogenic region.As an illustration of the model, the seismic hazard analysis at different sites in and around the Gulf of Corinth, central Greece, is presented on the basis of the earthquake magnitude and the seismic moment. Comparison of the results shows that determination of the mean rate of earthquake occurrence, using the conventional Gutenberg-Richter recurrence model, underestimates the seismic hazard at a site. 相似文献
15.
复地震道分析又称三瞬分析,该分析方法可将反映地震信号局部变化情况的地震波的瞬时振幅、瞬时相位和瞬时频率等信息分离开.本文应用Hilbert变换求解虚地震记录,用复地震道分析方法求取"三瞬"信息,并用该方法计算了理论合成地震记录的瞬时振幅、瞬时相位和瞬时频率,获得了较好的效果.同时,本文也利用该方法对某区块实际地震资料进行了处理,结果表明,复地震道分析方法获得的"三瞬"信息可反映地震信号的局部变化,有助于进行地震薄互层分析,并能提高数据的解释精度. 相似文献
16.
Based on previous observations of the phenomenon of precursory seismic quiescence before crustal main shocks and recent results that indicate an increase in the occurrence of main shocks in the next years, we focus this study on the detection of the seismic quiescence situation in Greece in the beginning of 1999. We use the declustered seismicity catalogue of the Institute of Geodynamics, National Observatory of Athens (NOA) from 1968–1998, to investigate the significance of seismic quiescence for the region 19°–29°E and 34°–42°N. We searched for seismicity rate changes at every node of the grid by a moving time window and we present the results for the beginning of 1999. The results map four (4) areas having a quiescence which duration ranges from 3.8 to6 years in the beginning of 1999. Three of these areas have been devestated by catastrophic earthquakes 17–21 years ago and significant quiescence also preceded those main shocks. Based on these results, an estimate of the future seismic hazard of these areas is made. 相似文献
17.
18.
The concept of fractals is used here for the identification of seismic reflectors with special emphasis on thin‐bed delineation, which is generally overlooked during standard data processing. A new fractal analysis scheme is applied to both synthetic and real field seismic data. The fractal dimensions of the three seismic attributes – amplitude, phase, and instantaneous frequency – have been analysed and evaluated. A change in fractal dimension is found to occur whenever there is a reflection. However, the resolution in the delineation of reflectors varies, depending on the attribute under consideration and the method of fractal dimension estimation used. Fractal analysis is performed on both noise‐free and noisy synthetic data to establish the noise tolerance limit for both the ‘divider method’ and the ‘Hurst method’. It is then tested with different peak frequencies of the source wavelet to establish the criteria for using the divider method and the Hurst method. The divider method is found to be suitable for high peak frequency source wavelets (> 25 Hz), while the Hurst method is best suited for low peak frequency source wavelets (< 25 Hz). Finally, when applied to the digitally processed and migrated field seismic data, it could even delineate reflectors which otherwise went undetected on the migrated time section. 相似文献
19.
A total of 235 potential seismic sources in Iran and neighboring regions are delineated based on available geological, geophysical, tectonic and earthquake data for seismic hazard assessment of the country. In practice, two key assumptions are considered; first, the assumption of earthquake repeatedness, implying that major earthquakes occur preferentially near the sites of previous earthquakes; second, the assumption of tectonic analogy, which implies that structures of analogous tectonic setting are capable of generating same size earthquakes. A two-step procedure is applied for delineation of seismic sources: first, demarcation of seismotectonic provinces; second, determination of potential seismic sources. Preferentially, potential seismic sources are modeled as area sources, in which the configuration of each source zone is controlled, mainly, by the extent of active faults, the mechanism of earthquake faultings and the seismogenic part of the crust. 相似文献
20.
四维地震(4D seimic)主要是指利用重复三维地震测量资料进行油藏动态监测。在油田开发过程中,由于储层特性变化所引起的地震振幅异常、频率变化以及反射同相轴下拖现象等均可作为注蒸汽波及范围四维地震监测的良好识别标志。由于叠后地震资料中常常存在动校正速度不准、动校正拉伸畸变、剩余静校正误差、以及CDP道集中各道波形的差异性等多方面的问题,这会对叠后地震资料所反映出的四维地震异常特性产生影响,造成解释结果的差异性和不确定性。为此,本文尝试开展叠前地震属性反演研究,利用瞬时频率、瞬时频率梯度、能量衰减85%时的频率、最大振幅频率、最大振幅、总能量等多种衰减属性的叠前剖面及其差值剖面来定性解释四维地震实验区的注入蒸汽在剖面上的反映。 相似文献