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衰减、场地响应等地震波传播信息综合研究 总被引：1，自引：0，他引：1
地震激发的波,经过传播路径、仪器、场地等因素的调制作用成为台站地震记录,即台站记录是震源、路径、仪器、场地等多种因素的耦合,而基于地震记录研究震源信息、路径衰减、场地响应等则是逆向的解耦过程。基于地震学理论、通过各种计算技术,从地震波形资料中解析出关于地震震源力学参数、地震波传播介质及台站场地响应信息是地震研究的重要内容,也是认识地震孕育、发生、发展过程,了解地震孕育背景构造特征等的有效途径。本文在地震学前沿理论方法的基础上使用最新计算机技术开展了以下3个方面的工作。 相似文献
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简要介绍当前国内外关于天然地震与爆破、塌陷等非天然地震特征研究及事件类型识别的进展。对各类事件的定义及主要波形特征进行简要综述,重点介绍了事件类型判定的各类识别方法。与自然界天然地震不同,非天然地震由人工干预或人类活动间接引发。爆破是炸药在爆炸瞬间能量迅速释放,部分能量以地震波形式向外传播,引起地表振动而产生破坏效应的一种地震;塌陷是由于岩层崩塌陷落而形成的地震。虽然在地震台网记录到的天然地震与爆破、塌陷的波形存在一定的共性特征,但由于震源类型、波的传播路径、震源深度等不同,各类事件的波形记录在P波初动、P波与S波最大振幅比、持续时间、震相、短周期面波发育情况、发震时刻、空间位置分布以及频谱特征等方面差异明显。目前主要有两类方法来识别地震与爆破、塌陷等非天然事件。一类为直接基于波形在信号、数据方面的特征,通过定性分析来进行事件类型判定,如波形时频分析对比法、小波变换、相关系数等;另一类为统计学领域诸如模式识别等算法,利用统计算法综合考虑多个事件特征判据的定量判定阀值来实现地震与爆破、塌陷事件类型的识别,如最小距离法、改进的连续亨明方法、Fisher方法、逐步代价最小决策法、支持向量机、前馈神经网络等。两类方法本质上均为提取有效特征判据,即对数据进行降维使用,未将事件记录的全部信息用于事件判定。因此,有必要使用一种可从全部事件记录中自动提取各类信息并可组合底层特征的算法来对各类事件进行判断识别。 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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地震波衰减性质的研究是地震学研究的重要课题.地震台站(地震仪)记录到的地震波,包含了地震震源效应、地震波的传播路径效应、台站场地响应及仪器响应.在使用地震波资料研究震源性质时,必须要扣除地震波传播路径效应、台站场地响应及仪器响应的影响.地震波传播的路径效应(地震波衰减),除了随距离存在几何衰减外,还有一个重要的影响因素--即介质的非弹性衰减,用介质品质因子Q值来度量.Q值是地球介质的基本物理参数之一,是对地震进行定量和研究震源性质(如震源参数的测定等)所必需的重要参数,在震源物理和工程地震研究中具有重要应用价值. 相似文献
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《地震地磁观测与研究》2015,(5)
2009年6月5日下午15时许,重庆市武隆县铁矿乡鸡尾山山体发生一次特大型岩质滑坡,能量相当于ML 2.7地震,与该市辖区内构造地震、爆破、岩溶塌陷等波形进行对比,得到不同类型地震事件的波形特征和频谱特征,此次滑坡波形特点为:波形初动不清晰,在滑坡过程中波形振幅变化不大;由于地表吸收,高频衰减快;0—4 Hz低频段近台波形丰富,优势频率为0.6 Hz。 相似文献
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场地条件对地震动具有较大影响, 研究不同场地条件下的地震动特征对地震动的校正具有重要意义。 本文以九寨沟地震为例, 收集了66个台站的198条三分量强震观测记录和SRTM(Shuttle Radar Topography Mission)公里格网的DEM(Digital Elevation Model)数据, 从多个角度对场地特征进行分析。 首先根据坡度法使用DEM数据对九寨沟特征进行了场地分类, 然后讨论了不同场地类型下的加速度时程、 加速度反应谱、 地震动衰减等地震动特征。 研究表明, 缺少实测资料的情况下, 地形坡度可以作为Vs30(地表以下30 m范围的平均剪切波速度)的一种替代指标, 利用坡度法可以较快速地对场地进行分类; 利用强震观测记录能够从多角度对台站的场地特征进行分析, 不同场地类型对地震动影响不同, 其中, 土层对地震动具有明显的放大效应。 该结论可以为地震动结果的校正提供依据。 相似文献
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《地震学报》2010,(3)
研究了如何从天然地震和人工爆破事件的波形记录中提取出有效、适用的波形特征,以用于对爆破事件的识别.首先对波形记录进行了4层小波包变换;然后对变换得到的最后一层小波包系数提取3种波形特征:能量比特征、香农熵特征及对数能量熵特征;最后利用v-SVC支持向量分类机对这3种特征的分类能力进行了外推检验.通过选用不同地区、不同台站、不同震级的天然地震与人工爆破的波形记录,力求提取的特征量能尽可能地反映天然地震与人工爆破波形的本质区别,尽量弱化震中距、震级等因素对识别效果的影响.结果表明,上述3种特征中以香农熵特征的识别效果最好,能反映天然地震与人工爆破的本质区别,可作为识别天然地震与人工爆破的一个有效判据. 相似文献
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爆破地震动效应的数值模拟分析 总被引：13，自引：0，他引：13
爆破设计中,场地条件复杂时经验公式的应用受到一定限制。本文采用波动有限元分析方法,研究复杂场地条件下工程爆破时场地的地震动效应,研究爆破地震动特征及衰减规律。根据某重点工程场地岩土参数的原位测试和试验结果,用自行研制的软件包进行场地爆破地震动效应的数值模拟分析,为工程爆破设计及施工前建筑物、仪器设备的加固提供了依据。施工试爆实测结果与本文数值模拟分析给出的结果一致,说明本文方法是可行的,对其它工程也有借鉴作用。 相似文献
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J. L. Bonner D. C. Pearson W. S. Phillips S. R. Taylor 《Pure and Applied Geophysics》2001,158(11):2017-2039
—?During 1997 and 1998, twelve chemical explosions were detonated in boreholes at the former Soviet nuclear test site near the Shagan River (STS) in Kazakhstan. The depths of these explosions ranged from 2.5 to 550 m, while the explosive yield varied from 2 to 25 tons. The purpose of these explosions was for closure of the unused boreholes at STS, and each explosion was recorded at local distances by a network of seismometers operated by Los Alamos National Laboratory and the Institute of Geophysics for the National Nuclear Center (NNC). Short-period, fundamental-mode Rayleigh waves (Rg) were generated by these explosions and recorded at the local stations, resultingly the waves exhibited normal dispersion between 0.2 and 3 seconds. Dispersion curves were generated for each propagation path using the Multiple Filter Analysis and Phase Match Filtering techniques. Tomographic maps of Rg group velocity were constructed and show a zone of relatively high velocities for the southwestern (SW) region of the test site and slow propagation for the northeastern (NE) region. For 0.5?sec Rg, the regions are separated by the 2.1?km/sec contour, as propagation in the SW is greater than 2.1?km/sec and less in the NE region. At 1.0 sec period, the 2.3?km/sec contour separates the two regions. Finally, for 1.5 and 2.0 sec, the separation between the two regions is less distinct as velocities in the NE section begin to approach the SW except for a low velocity region (<2.1?km/sec) near the center of the test site. Local geologic structure may explain the different regions as the SW region is composed predominantly of crystalline intrusive rocks, while the NE region consists of alluvium, tuff deposits, and Paleozoic sedimentary rocks. Low velocities are also observed along the Shagan River as it passes through the SW region of the test site for shorter period Rg (0.5–1.0?sec). Iterative, least-squares inversions of the Rg group velocity dispersion curves show shear-wave velocities for the southwestern section that are on average 0.4?km/sec higher than the NE region. At depths greater than 1.5?km the statistical difference between the models is no longer significant. The observed group velocities and different velocity structures correlate with P-wave complexity and with spatial patterns of magnitude residuals observed from nuclear explosions at STS, and may help to evaluate the mechanisms behind those observations. 相似文献
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对琼北地区确定性井下人工爆破和天然地震事件波形特征进行梳理,分析人工爆破与天然地震波不同判据特征。结果表明:P波初动方向、振幅比是识别人工爆破和天然地震的2个主要判据;尾波持续时间、S波最大振幅与持续时间比可作为识别人工爆破和天然地震的一般判据;发震时间可根据事件的强度、规律性,并结合其他判据,仅作为识别过程中的参考因素。 相似文献
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—?Spectral modulation is used as a criterion for discriminating multiple mining explosions from earthquakes and single blasts. Features in the spectra of regional arrivals from quarry blasts may be explained by the spatio-temporal configuration of shot patterns and are explored via a model based on spatial waveform decorrelation and propagation delay (directivity) effects. The phenomenon of decreasing modulation with decreasing average phase velocities of the seismic wave arrivals can be attributed to a trend of decreasing similarities of waveforms with increasing distance between individual explosions making up the shot pattern for the respective arrivals. Rescaling of the modulation patterns with respect to frequency can be explained by the Doppler effect.¶The postulated relationship between shot pattern layouts and sizes, together with their firing sequences, on one hand, and the similarities and differences in modulation characteristics among the various regional arrivals, on the other hand, can be used to derive information about the mining practices in a region that is otherwise not accessible. Moreover, such analyses could be utilized for detecting unusual activities in the CTBT monitoring system. 相似文献
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对太原基准地震台记录的核爆及天然地震波形进行对比分析,结果显示：①与天然地震相比,核爆震相特征相对独特;②地震优势频率较窄,而核爆优势频率则较宽,即对于震中距相近、当量不同的核爆波形,太原台记录的时频变化特征相似;③对于震中距相近的天然地震与核爆波形,太原台记录的时频特征差异明显。 相似文献
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We relocate 81 large nuclear explosions that were detonated at the Balapan and Degelen Mountain subregions of the Semipalatinsk test site in Kazakhstan during the years 1978 to 1989. The absolute locations of these explosions are available, as well as very accurate estimates of their origin times. This ground truth information allows us to perform a detailed analysis of location capability. We use a sparse network of stations with highly accurate first arrival picks measured using a waveform cross-correlation method. These high quality data facilitate very accurate location estimates with only a few phases per event. We contrast two different approaches: 1) a calibration-based approach, where we achieve improved locations by using path corrections, and 2) a model-based approach, where we achieve improved locations by relocating in a recently published global 3-D P-velocity model. Both methods result in large improvements in accuracy of the obtained absolute locations, compared to locations obtained in a 1-D reference earth model (ak135). The calibration-based approach gives superior results for this test site, in particular when arrival times from regional stations are included. Estimated locations remain well within a 1000 km2 region surrounding the ground truth locations when the path corrections for the Balapan and Degelen Mountain subregions are interchanged, but even for the short separation between these two regions, we find variations in the path corrections that cause systematic mislocations. The model-based approach also results in substantially reduced mislocation distances and has the distinct advantage that it is, in principle, transportable to other source regions around the world. 相似文献
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利用天津地震台网23个短周期地震仪记录到的2015年8月12日天津港爆炸事件波形数据,对事件进行初步分析和研究。分别使用能量包络线法和波形匹配法,共识别出4次爆炸事件,并结合波形互相关的主事件定位法对爆炸事件进行定位。分析结果表明:第一次爆炸发生的时间为2015年8月12日23时34分4秒,1.77s后发生了规模更大的二号爆炸事件;34.11s后又发生了最强的三号爆炸事件;86.33s再一次发生了能量较弱的四号爆炸事件,其中二号与三号爆炸事件相距65~70m,二号与四号事件相距160~170m。此外,通过选用爆破、矿塌、核爆和天然地震等不同类型事件的波形数据,从时间域和频率域分别对这些事件进行对比分析,发现其震相特征表现出明显差异。 相似文献
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The presence of man-made explosions in a seismic catalogue leads to errors in statistical analyses of seismicity. Recently, the need to monitor man-made explosions used for mining, road excavating, and other constructional applications has been become a demanding challenge for the seismologists. In this way, we gain new insight into the cross-correlation technique and conduct this approach to discriminate explosions from seismic datasets. Following this, improved P-wave arrival times are used for more precise relocation. In this study, the waveform cross-correlation technique provides a reliable means for discriminating explosions which have cross-correlation coefficients (CC) of 0.6 or greater with their own corresponding stacked waveforms. The results illustrate that approximately 80 % of seismicity of southeast of Tehran, recorded by the Iranian Seismological Center (IRSC), includes events which have cross-correlation coefficients of ≥0.6 with their corresponding stacked waveforms. Furthermore, with improved P-wave arrival time, there is a better chance to relocate explosions precisely in the region under study. 相似文献
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J. R. Murphy I. O. Kitov B. W. Barker D. D. Sultanov 《Pure and Applied Geophysics》2001,158(11):2077-2101
—?During the period 1965 to 1988, the former Soviet Union (FSU) conducted over 120 peaceful nuclear explosions (PNE) at locations widely dispersed throughout the territories of the FSU. These explosions sample a much wider range of source conditions than do the historical explosions at the known nuclear test sites and, therefore, seismic data recorded from these PNE tests provide a unique resource for use in deriving improved quantitative bounds on the ranges of seismic signal characteristics which may require consideration in global monitoring of the Comprehensive Test-Ban Treaty (CTBT). In this paper we summarize the results of a detailed statistical analysis of broadband seismic data recorded at the Borovoye Geophysical Observatory from 21 of these PNE tests at regional distances extending from about 7 to 19 degrees, as well as the results of theoretical waveform simulation analyses of near-regional (Δ?相似文献