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针对微震事件易受噪声干扰等特点，本文将STA/LTA方法和基于方差的AIC方法（var-AIC）相结合，在震相到时初步拾取的基础上，使用台站的德洛内（Delaunay）三角剖分及台站间最大走时差约束来减少噪声干扰的影响. 利用到时进行地震定位之后，根据台站预测到时，在设定的时间窗内对地震震相进行更精细的分析. 特别是针对微震事件信噪比低的特点，设计了基于偏振分析的拾取函数，根据窗内STA/LTA方法和var-AIC方法的拾取结果自动选择合适的值作为震相到时. 最后，对西昌流动地震台阵2013年304个单事件波形数据的分析处理和检验结果表明，本文方法较传统方法具有更高的地震事件检测能力和更高的震相拾取精度. 相似文献
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In the list of ’repeating pairs’ or ’doublets’ of earthquakes in China identified by Schaff and Richards using tele-seismic waveform cross-correlation, there were 23 repeating pairs located in Liaoning Province. In this study the waveforms of these events were cross-correlated using records from Liaoning Regional Seismograph Network (LRSN), and the ’repeating events’ in the sense of regional waveform cross-correlation were obtained. The result was compared with that of Schaff and Richards and was used for the assessment of the seismic phase picking and event location practice of LRSN. The result shows that ’repeating events’ in the sense of teleseismic waveform cross-correlation and those in the sense of regional waveform cross-correlation have significant difference, al-though with some overlap. However, the overall assessment of the location accuracy and the phase pick errors of LRSN by using these two sets of ’repeating events’, respectively, provides similar results, while ’repeating events’ in the sense of regional waveform cross-correlation seem to be better performing in such an assessment. With the assumption that the separation between the ’repeaters’ be less than 1 km, the uncertainty in routine earthquake location of LRSN is estimated to be below 5 km, with the average of 2 km. In the observational bulletins of LRSN the time error in phase picking is estimated to be within ±1s for 94% Pg readings and for 88% Sg readings. 相似文献
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利用重庆数字地震台网2010年1月至2017年12月的地震波形资料和观测报告,选出5个研究区1 251个M_L≥1.5地震进行波形互相关计算,识别出358对同时被2个地震台站记录且各台波形互相关系数(cc)不小于0.8的重复地震对,涉及342个地震事件,约占地震总数的27%。将筛选出的重复地震对用于定量判断地震目录中震相拾取误差及评估台网定位精度,结果显示:重庆数字地震台网的垂直定位误差约为3 km,水平定位误差约为5 km,Pg、Sg震相拾取误差分别为0.5 s和0.7 s;其中武隆区地震定位和震相拾取精度最高,綦江区最低。 相似文献
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基于图像分析的双台面波相速度频散曲线快速提取方法 总被引：10，自引：1，他引：9
双台波形的互相关方法是面波相速度频散曲线提取的一种常用方法。传统的方法精度不高,效率较低。本文提出了一种基于图像分析的频散曲线快速提取方法,采用图像显示互相关振幅矩阵,且提出了快速追踪整条频散曲线的算法,并用Matlab编写了交互式的处理软件。基于这种方法编写的资料处理软件提高了双台相速度频散曲线提取的速度和精度,为大批量处理地震数据资料提供了坚实的软件基础。基于图像分析的方法可以更为清晰地展现出双台问的面波频散曲线的特征,对频散曲线的识别和分析也提供了更为有效的研究工具。 相似文献
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Seismic phase picking is the preliminary work of earthquake location and body-wave travel time tomography. Manual picking is considered as the most accurate way to access the arrival times but time consuming. Many automatic picking methods were proposed in the past decades, but their precisions are not as high as human experts especially for events with low ratio of signal to noise and later arrivals. As the increasing deployment of large seismic array, the existing methods can not meet the requirements of quick and accurate phase picking. In this study, we applied a phase picking algorithm developed on the base of deep convolutional neuron network (PickNet) to pick seismic phase arrivals in ChinArray-Phase III. The comparison of picking error of PickNet and the traditional method shows that PickNet is capable of picking more precise phases and can be applied in a large dense array. The raw picked travel-time data shows a large variation deviated from the traveltime curves. The absolute location residual is a key criteria for travel-time data selection. Besides, we proposed a flowchart to determine the accurate location of the single-station earthquake via dense seismic array and phase arrival picked by PickNet. This research expands the phase arrival dataset and improves the location accuracy of single-station earthquake. 相似文献
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根据１９８５年４月～１９８８年１０月３８次极远震资料，着重分析了乌鲁木齐台不同震中距极远震震相特征，提出了单台分析方法以及分析中应该注意的一些问题，对部分疑难震相进行了分析讨论。 相似文献
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岩石超声检测中最重要的一个环节是初至的拾取,然而该项工作往往费时费力,拾取精度受人为因素影响较大。为提高声波速度检测、声发射定位、以及超声层析成像的应用效率和精度,本研究将地震学中应用比较广泛的AIC初至自动提取技术引入到岩石超声检测中,并进行了适当改进。利用改进前后的AIC方法,自动拾取仿真信号和实际信号的初至,并利用长短时窗比方法(STA/LTA)和手动方法拾取了初至,同时分别与设定的实际初至进行对比。根据实验结果,对于信噪比较低的信号AIC方法要优于STA/LTA方法;改进前的AIC方法适用于起跳干脆、幅度变化大的信号,而改进后的AIC方法则适用于起跳较平缓的信号,且拾取到的初至与手动拾取的初至更加接近。 相似文献
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远震虚震源反射成像方法利用远震初至波在台网之下地表与地下界面间形成的反射波(PPdp震相)波形资料进行台网地区地震反射结构研究.此方法先用台网各台站的平均初至波形求取震源信号,再用该震源信号与各道地震记录作反褶积从而取得反射剖面.本文介绍了远震虚震源反射成像的基本原理和实现步骤,并以三峡地区的观测资料为例,得到三峡库首区上地壳的反射地震剖面.成像剖面中解释出的四川盆地和秭归盆地的底界面位置和形态与地表地质观测和大地构造背景吻合.为验证虚震源成像的能力,本文使用弹性波正演模拟合成地震数据,经过处理实际资料一样的步骤获得虚震源成像结果.正演模拟表明,叠加多个远震的反射地震剖面可以有效地改善成像的信噪比和连续性;虚震源成像需要选择特定的震源频率范围,以减轻高频噪音以及低频造成的成像问题.在研究上地壳结构时,建议在不适合主动源采集和缺乏低频信号的地区尝试远震虚震源方法. 相似文献
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本文讨论了用于微地震信号到时自动拾取的几种方法的原理及特点,包括长短时均值比(STA/LTA)方法、AIC方法、基于高阶统计量偏斜度和峰度的PAI-S/K方法等,提出了移动时窗峰度的快速算法和改进的峰度拾取初至方法.对我国西部某地观测到的13359个微地震记录,采用两种时窗进行了初至到时拾取,并与人工拾取的结果进行了对比.为使所研究的方法达到最佳效果,采用DE全局搜索方法,以人工拾取的初至作为参照,以时差在0.3 s以内的记录所占百分比作为目标函数,自动搜索最佳的拾取参数.结果显示,在拾取时窗选为P波初至前3 s至S波初至位置时,AIC方法的结果最佳,时差在0.3 s以内的记录占比达到93.6%;在拾取时窗选为包含S波到时的时窗时,改进的峰度法效果最佳,时差在0.3 s以内的记录占比83.8%. 相似文献
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分析了盐池台不同震中距极远震震相特征,提出了单台分析中应该注意的一些问题,这将有助于提高极远震的分析水平,对台站日常资料产出将起到积极作用。 相似文献
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地震P波震相到时与初动极性的精确读取是地震资料分析处理的重要步骤之一.本研究采用了一种新的高精度自动确定地震波P波震相到时与初动极性的概率分布的方法(POI方法,后同),在此基础上研究开发了一套自动化小震震源机制解的反演流程,并将其应用在云南小江断裂带周边区域的小震震源机制和构造应力场反演中.得到的震源机制与应力场反演结果与前人的研究一致,且与区域GPS观测结果和构造背景吻合度较好,显示该方法具有良好的应用前景,为高效分析密集台阵地震观测资料,开展小震震源参数测量与区域应力场反演提供了新的研究思路和技术手段. 相似文献
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地震P波震相到时与初动极性的精确读取是地震资料分析处理的重要步骤之一.本研究采用了一种新的高精度自动确定地震波P波震相到时与初动极性的概率分布的方法(POI方法,后同),在此基础上研究开发了一套自动化小震震源机制解的反演流程,并将其应用在云南小江断裂带周边区域的小震震源机制和构造应力场反演中.得到的震源机制与应力场反演结果与前人的研究一致,且与区域GPS观测结果和构造背景吻合度较好,显示该方法具有良好的应用前景,为高效分析密集台阵地震观测资料,开展小震震源参数测量与区域应力场反演提供了新的研究思路和技术手段. 相似文献
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羌塘盆地是我国最大的海相盆地.本文根据在羌塘盆地内布设的27个宽频带地震观测台站记录的远震波形数据,利用非线性复谱比反演算法得到各台站下方100 km深度范围内S波速度结构.结果表明.羌塘地区Moho深度较为平缓,平均深度为61 km;北羌塘地壳内低速层广泛分布;北羌塘具有两个较大的沉积盆地,龙尾错和白滩湖坳陷,沉积厚度分别有10 km和15 km.尽管北羌塘下地壳受到强烈的新生代火山岩作用改造,但是这种深部岩浆热作用会加速烃源岩中有机质的热演化历程.北羌塘两个盆地具有很好的油气前景.与北羌塘低速层分布相比,南羌塘下低速层更深,可能与班公怒江洋于中生代的俯冲消减及拉萨地体北向俯冲有关. 相似文献
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Xuanhui Yang Yu Jeffrey Gu Ping Shen Xiqiang Liu Zhizhen Zheng 《Pure and Applied Geophysics》2006,163(8):1515-1536
Signal extraction from overlapping seismic records is a common problem in geophysical data analysis. Identification and separation
of multiple seismic arrivals, analysis of large earthquakes as multiple point sources, and calculation of the true yield of
a large nuclear explosion from interfering small explosion, all hinge on our ability to effectively decouple two interfering
wave signals. This paper presents a method for signal separation based on an adaptive filtering technique. We apply a semi-deconvolution
algorithm to overlapping explosion records and S/SKS phase groups, and then perform noise reduction and signal decoupling
under different a priori conditions and assess the stabilities using a variance reduction approach. We demonstrate, through numerical experiments
and analysis of seismic station records, that the adaptive method can be both robust and practical for regional and teleseismic
applications. 相似文献
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以井—含水层系统潮汐理论为基础,利用Baytap-G潮汐分析程序计算鲁14井数字化水位的潮汐响应特征参数,提取井水位潮汐因子和相位差,分析远场大震前后井水位潮汐响应特征参数的变化情况,同时对固体潮和气压影响量进行分离,以期深入了解井水位微动态变化特征,为该井水位观测资料的动态评价和效能评估提供参考。结果表明：鲁14井潮汐地下水流类型以径向流为主,潮汐因子和相位差变化相对稳定,但受远场大震影响显著,其含水层渗透性随潮汐参数的增大（减小）而增大（减小）;地震波作用可使含水层渗透性发生变化,但并非导致含水层渗透性变化的主要因素。 相似文献
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Current deep neural networks (DNN) used for seismic phase picking are becoming more complex, which consumes much computing time without significant accuracy improvement. In this study, we introduce a cascaded classification and regression framework for seismic phase picking, named as the classification and regression phase net (CRPN), which contains two convolutional neural network (CNN) models with different complexity to meet the requirements of accuracy and efficiency. The first stage of the CRPN are shallow CNNs used for rapid detection of seismic phase and picking P and S arrival times for earthquakes with magnitude larger than 2.0, respectively. The second stage of CRPN is used for high precision classification and regression. The regression is designed to reduce the time difference between the probability maximum and the real arrival time. After being trained using 500,000 P and S phases, the CRPN can process 400 hours’ seismic data per second, whose sampling rate is 1 Hz and 25 Hz for the two stages, respectively, on a Nvidia K2200 GPU, and pick 93% P and 89% S phases with the error being reduced by 0.1s after regression correction. 相似文献
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基于时变窄带滤波技术提取可控震源扫频信号方法研究 总被引：1，自引：0，他引：1
精密主动地震监测为我们主动探测地下介质结构, 并监视其动态变化提供了一条可能的技术途径。 由于精密控制震源释放的能量强度小, 随着传播距离的增加, 信号的快速衰减, 在离震源较远处有用的震源信号被掩盖在很强的噪声中, 这对于震相的识别与走时的拾取精度有着很大的影响。 本文设计了一种时变窄带滤波器进行更为精细的滤波, 期望进一步提高观测数据信噪比, 再结合匹配滤波方法实现主动震源信号的检测与波形变换。 另外, 由于不同震相有一定的到时差, 使用时变窄带滤波器提取一个震相波形信息时, 将压制其他震相的波形信号, 从而实现了震相分离的技术。 仿真计算与实际资料处理显示了该方法在提高观测资料质量、 震相识别分辨率及震相分离方面具有一定的有效性与优越性。 通过对广东省新丰江库区精密可控震源试验数据进行时变窄带滤波方法的处理, 在震中距为200 km左右处的台站记录中检测到主动源信号, 体现了对远台弱信号的提取能力。 相似文献
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Earthquake detection in the Jiangsu region,China using graphics-processing-unit-based Match & Locate and rapid earthquake association and location* 
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下载免费PDF全文 Earthquake detection and location are essential in earthquake studies, which generally consists of two main classes: waveform-based and pick-based methods. To evaluate the ability of two different methods, a graphics-processing-unit-based Match & Locate (GPU-M&L) method and a rapid earthquake association and location (REAL) method are applied to continuous seismic data recorded by 24 digital seismic stations from Jiangsu Seismic Network during 2013 for comparison. GPU-M&L is one of waveform-based methods by waveform cross-correlations while REAL is one of pick-based method to associate arrivals of different seismic phases and locate events through counting the number of P and S picks and travel time residuals. Twenty-six templates are selected from the Jiangsu Seismic Network local catalog by using the GPU-M&L. The number of newly detected and located events is about 2.8 times more than those listed in the local catalog. We both utilize a deep-neural-network-based arrival-time picking method called PhaseNet and a short-term/long-term average (STA/LTA) trigger algorithm for seismic phase detection and picking by applying the REAL. We then refine seismic locations using a least-squares location method (VELEST) and a high-precision relative location method (hypoDD). By applying STA/LTA and PhaseNet, 1006 and 1893 events are associated and located, respectively. The newly detected events are mainly clustered and show steeply dipping fault planes. By analyzing the performance of these methods based on long-term continuous seismic data, the detected catalogs by the GPU-M&L and REAL show that the magnitudes of completeness are 1.4 and 0.8, respectively, which are smaller than 2.6 given by the local catalog. Although REAL provides improvement compared with GPU-M&L, REAL is highly dependent on phase detection and picking which is strongly affected by signal-noise ratio (SNR). Stations at southeast of the study region with low SNR may lead to few detections in the same area. 相似文献