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准实时中小地震震源机制波形自动反演系统的构建及在首都圈地区的应用 总被引：1，自引：0，他引：1
基于Cut And Paste(CAP)全波形拟合反演震源机制解方法, 依托中国地震局地震预测研究所准实时地震波形数据服务系统, 通过接收区域实时连续波形数据, 构建了首都圈地区准实时准自动波形反演系统, 使系统实现当地震大于3.5级时, 可自动、 迅速反演得到震源机制解。 同时考虑到一些台站的地震波形质量或信噪比等因素, 系统也可通过人为干预方式重新反演求得相关结果。 文中详细阐述了震源机制解波形反演系统的运行流程及该系统的基本构建思路, 并对实例进行对比分析, 表明该系统具有较好的实用性。 相似文献
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利用中小震作为经验格林函数,选取0.2~2.0 Hz频段的强震数据进行波形反演,获得了2021年福岛县冲地震的破裂过程。结果表明:该地震的破裂主要集中在断层面距离震源约25 km的区域内,沿震源向东北延伸约5 km,向西南延伸约20 km;在该区域内,识别出两个滑动量集中的区域,均分布在距离震源约15 km西南侧,主要滑动量集中区域最大滑动量约3.2 m,深度基本与震源一致;次要滑动量集中区域略比主要滑动量集中区域浅约18 km。该震源模型对应矩震级Mw7.3,破裂速度为2.4 km/s。通过选择不同的中小震组合进行波形反演,结果对该震源模型特性无显著影响,揭示了该震源模型的稳健性;基于该震源模型合成反演分析中未使用的强震观测台站强震动,获得的合成波形与观测波形有很好的相关性,充分证明了该震源模型时空特征的可靠性。 相似文献
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震源机制解是地震学研究的重要组成部分, 它从一定程度上描述了震源的性质及其破裂过程, 对其正确、 全面地认识可深化理解地震的孕育、 发生和演化。 而地震波形自动反演系统的建立, 不仅实现了利用地震波形信息进行震源机制解的自动反演, 更重要的是加快了反演的速度, 充分体现了提取震源信息的实效性, 从而有力地帮助震情分析、 余震趋势预测、 震后救援等工作的展开。 本文系统地阐述了震源机制解反演方法, 总结了自动反演系统构建思路以及波形自动反演系统的实现, 为国内构建自动反演系统提供了可鉴的技术思路。 相似文献
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微地震矩张量能够描述储层岩石破坏的细节,有助于了解水力压裂储层的地质力学特征,震源机制矩张量反演对于非常规油气开发具有重要的作用.水力压裂通常在页岩油气储层中进行,震源区介质表现出速度和衰减各向异性,需要研究衰减各向异性介质中微地震信号的传播规律.基于观测到的微地震记录,通过波形反演能够获得矩张量,忽视震源区介质的衰减和速度各向异性会导致震源机制反演结果的误差.本文提出了一种考虑地层各向异性吸收衰减作用的震源机制全波形反演方法,对于黏弹性VTI介质,采用GPU并行的伪谱法计算合成地震记录,通过全波形反演方法匹配合成波形和记录波形,借助优化算法获得震源机制矩张量反演结果.本文通过实验测试验证了该方法的有效性,分析了震源区各向异性速度和衰减参数、噪声以及观测系统等对于微地震震源机制各分量及成分反演结果的影响,研究表明考虑模型中的黏弹性各向异性对于获得可靠的震源机制反演结果非常重要. 相似文献
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应用矩张量概念对震源物理的研究是当代地震学的一个重要的前沿课题。近20年来,随着宽频带数字地震仪的广泛应用,地震波形记录的质量明显提高,极大地推动了对震源物理过程研究的进展。对于区域性中、小地震,由于区域性地震的波形记录包含了有关震源和区域地壳的丰富的信息,利用波形资料研究区域性中、小地震的震源机制,其结果有助于了解震源区和区域性应力状态以及断层的构造特性,是理解地震孕育过程的重要途径。近年来,随着计算合成理论地震图的理论和方法的进步,使用矩张量反演方法确定中小地震的点源机制解以及有限破裂参数等研究领域取得了显著进展。本论文在前人研究的基础上,发展了两种针对区域中、小地震震源参数反演的求解方法,通过数值试验讨论了震源机制反演结果的稳定性,并结合实际地震观测资料进行了检验。 相似文献
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用地震波波形拟合方法研究中小地震的震源机制 总被引：2，自引：0，他引：2
采用网格搜索方法,利用区域地震三分量全波形资料,对中小地震震源机制的反演方法进行了研究。反演采用初动约束、分段求相关系数,以及幅值加权的混合方法计算误差函数,通过格点搜索法确定震源深度。理论模型试验表明,反演结果具有较好的稳定性和可靠性。云南地区区域数字地震台网的观测资料反演表明,该方法可以合理地拟合观测波形资料。将2001年7月9日(24.93°N,101.47°E)发生的MS 5.3地震的震源机制解与哈佛大学CMT进行了对比,结果表明,Z分量波形拟合略比CMT拟合的好,R分量和T分量的波形拟合明显好于CMT的对应分量。 我们对2001年4月5日在(25.77°N,102.30°E)发生的mb 4.8地震进行了震源机制反演。结果表明,该地震主要表现为走滑断层,震源机制解为(180°,80°,11°)。根据这两个地震震源机制推断的主应力轴,与该地区现代构造应力场特征基本一致。 相似文献
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利用2001年1月~2014年4月江苏及邻区数字地震波形资料,采用P波、S波初动和振幅比联合求解方法计算了茅山断裂带及邻区149次中小地震震源机制解。震源机制解特征分析表明,研究区中小地震震源类型以走滑型为主,兼有一定比例的正断层类型,而逆冲型相对较少,P、T轴优势方向分别为NEE-SWW、NNW-SSE向。利用149次地震的震源机制解,采用自助线性应力反演(LSIB)方法反演了研究区应力张量。结果显示,最大主应力S_1方位角为254.2°,俯角为2.6°,最小主应力S_3方位角为163.9°,俯角为9.5°。为了进一步印证所得应力张量的可靠性,又利用1970年以来M_L≥3.5地震震源机制解再次反演,所得结果中最大主应力S_1方位角为252.4°,俯角为8.4°,最小主应力S3方位角为160.4°,俯角为12°。2份不同的震源机制解资料反演所得应力张量十分接近。应力张量结果表明,茅山断裂带及邻区处于以NEE-SWW向水平压应力和NNW-SSE向水平张应力为主的现代构造应力场中。 相似文献
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本文应用ISOLA近震全波形方法，以2017年1月4日西藏仲巴4.7级地震为例，反演稀疏台网记录的中小地震震源机制解。该地震反演所得最佳双偶机制参数为：节面Ⅰ的走向109°/倾角85°/滑动角-177°，节面Ⅱ的走向19°/倾角88°/滑动角-4°，最佳矩心位置为30.590°N、83.784°E，最佳质心深度为6km，矩震级MW4.6。震源机制反演结果表明此次地震是一次走滑型为主的事件，其与震源区域附近历史地震震源机制解具有相同性质。本文还应用CSPS初动扫描法，利用P波初动资料和近震波形联合约束反演此次地震的震源机制，并与ISOLA近震全波形反演结果进行比较，结果表明，联合少量台站的的三分量波形数据，能够定量地判断最佳震源机制解，降低了P波初动反演结果的非唯一性，同时也约束了由于少量台站参与全波形反演引起的解的不稳定性。本文研究为中小地震震源参数测定提供了一种简单有效的方法，具有较高的稳定性和可靠性。 相似文献
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目前对首都圈地区中小地震的震源机制研究所用的方法主要有P波初动极性法、 振幅比法及波形反演方法。 前两种方法只利用了波形中很少量的信息, 且对于稀疏台阵效果较差, 而传统的波形反演法也仅利用了波形的部分信息, 且对于震级、 数据资料等有一定的要求。 为克服上述传统方法中的局限并进一步提高震源机制解的准确性, 本文采用一种新的综合利用上述各种信息的全波形匹配方法来反演首都圈地区中小地震的震源机制解, 提高反演解的可靠性。 为了检验所使用的全波形匹配震源机制反演方法的可靠性, 我们首先进行了合成数据测试, 结果表明全波形匹配方法可以得到稳定可靠的震源机制解。 利用新的全波形匹配方法计算了2019年4月北京发生的两次地震震源机制解, 并结合活动断裂进行分析。 将新的全波形震源机制反演方法应用于首都圈地区2015年以来的22个地震(2.2≤M≤4.3), 并对22个地震的震源机制解及应力轴分布进行了分析, 与前人研究结果具有较好的一致性。 相似文献
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Preliminary research to determine stress districts from focal mechanism solutions in Southwest China and its adjacent area 总被引：5，自引：1，他引：4
XIAO-FENG CUI 《地震学报(英文版)》1999,12(5):562-572
The method of sliding direction fitting is used to determine stress districts, taking the shear stress directions and ratios of shear stress to stress on fault planes given by focal mechanism solutions as the criteria to select focal mechanism solutions of one region and sorting out the earthquakes controlled by different tectonic stress fields, and then determining the stress districts from epicenter distribution of earthquakes. We call this method as step by step convergence method. By inversion analyzing of 297 focal mechanism solutions, we consider that Southwest China and its adjacent area can be divided into 5 stress districts, and we worked out directions of the three principal stresses and values of shape factor φin 5 stress districts. 相似文献
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Using the seismic waveform data recorded by regional seismic network of Yunnan and Sichuan and the method of CAP, we calculate and obtain the focal mechanism of 268 earthquakes with the magnitude of ML≥4.0 occurring in Yunnan during Jan. 1999 to Aug. 2014; then, we analyze the types and the regional feature of the focal mechanism of earthquakes in Yunnan, on the basis of the focal mechanism of 109 earthquakes analyzed by Harvard University. Based on the data of the above focal mechanism solutions, we adopt the method of damped regional-scale stress inversion to calculate the best-fitting tectonic stress tensor of every grid in Yunnan; and adopt the method of maximum principal stress to calculate the direction of maximum horizontal principal stress in Yunnan. The result shows that: (1)the strike-slip type is the most principal type of the earthquake focus in the study area and the second is the normal faulting type; while, the reverse-fault type is relatively small. The spatial distribution of focal mechanism is obvious. This reflects that the dynamic source and acting force are different in different parts of the study area. (2)The direction of the stress field in Yunnan shows a certain spatial continuity. Maximum horizontal principal compressive stress is mainly clockwise from north to south and counterclockwise from the west to the east. The direction of stress field shows inhomogeneity in space. There exist two stress conversion zones respectively in EW and NS direction. The inversion result of stress field shows that the stress field in Yunnan is complex and the principal stress direction changes greatly; and there are obvious differences in different regions. 相似文献
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为了提高表层速度反演精度,本文提出了一种新的波形反演方法.该方法只利用初至波波形信息以减少波形反演对初始模型的依赖性,降低反演多解性与稳定性.由于只利用初至波波形信息,所以该方法利用高斯束计算格林函数和正演波场,以减少正演计算量.为了避免庞大核函数的存储,该方法基于Born波路径,利用矩阵分解算法实现方向与步长的累加计算.将此基于Born波路径的初至波波形反演方法应用于理论模型实验,并与声波方程全波形反演和初至波射线走时层析方法相对比,发现该方法的反演效果略低于全波形反演方法,但明显优于传统初至波射线走时层析方法,而计算效率却与射线走时层析相当.同时,相对于全波形反演,本文方法对初始模型的依赖性也有所降低. 相似文献
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The main goal of this study is to provide moment tensor solutions for small and moderate earthquakes of the 2009 L’Aquila seismic sequence (central Italy). The analysis was performed by using data coming from the permanent Italian seismic network run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the “Cut And Paste” (CAP) method based on broadband waveform inversion. Focal mechanisms, source depths and moment magnitudes are determined through a grid search technique. By allowing time shifts between synthetics and observed data the CAP method reduces dependence of the solution on the assumed velocity model and on earthquake location. We computed seismic moment tensors for 312 earthquakes having local magnitude in the range between 2.7 and 5.9. The CAP method has made possible to considerably expand the database of focal mechanisms from waveform analysis in the lowest magnitude range (i.e. in the neighborhood of magnitude 3) without overlooking the reliability of results. The obtained focal mechanisms generally show NW–SE striking focal planes in agreement with mapped faults in the region. Comparisons with the already published solutions and with seismological and geological information available allowed us to proper interpret the moment tensor solutions in the frame of the seismic sequence evolution and also to furnish additional information about less energetic seismic phases. Focal data were inverted to obtain the seismogenic stress in the study area. Results are compatible with the major tectonic domain. We also obtained a relation between moment and local magnitude suitable for the area and for the available magnitude range. 相似文献
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Based on analysis of background of geological tectonic movement and strong earthquake activity, we first obtained the focal mechanism solutions using amplitude ratio and CAP method, then determined the characteristic of average stress field of the study area by inversion of the stress field. On this basis, we selected the source mechanism consistency parameter as the inspection index to obtain the latest changes of stress field in Hetao seismic zone based on its temporal and spatial analysis. Two methods were used in the stress field inversion for comparison and analysis, which are average stress axis tensor and LSIB(Linear stress inversion bootstrap, LSIB). According to the geological tectonic movement and focal mechanism solutions of MS≥4.0 earthquakes from 1970, we judge that the stress field evolution process of Hetao seismic belt is controlled jointly by vertical difference movement and horizontal shear movement, resulting in that the normal fault and strike-slip fault mechanisms are dominating.Taking into account the station layout of the study area, and in order to ensure the accuracy of calculation, we calculated 224 earthquakes focal mechanism solutions by using amplitude ratio and CAP method, including 164 earthquakes with 2.8≤ML<3.5, 42 earthquakes with 3.5≤ML<4.0, and 18 earthquakes with ML≥4.0; The statistical results on type of focal mechanisms show that, there are 142 strike-slip earthquakes(63.4%), 50 normal fault earthquakes(22.3%)and 32 thrust fault earthquakes(14.3%). In this study period(from 2001 to 2012), most earthquakes had a strike-slip mechanism in Hetao seismic belt, this is one of the inherent characteristics of the stress field.The result of average stress axis tensor and LSIB shows that, the azimuth of maximum compressional stress is 47°～52°, direction is NE-SW; The azimuth of minimum compressional stress is 313°～322°, direction is NW-SE; This indicates that, the stress field characteristics of Hetao seismic belt and its sub-block are not completely consistent. Linhe Basin exhibits coordinated stress field characteristics with Hetao seismic belt, but Hubao Basin exhibits regional differences, direction of compressive stress has clockwise deflection in Baotou area, and the compressive stress direction is NEE. This heteropical character of stress field is also confirmed by horizontal projection distribution of stress axis of historical strong earthquakes and recent moderate and small earthquakes. Since 2003, the temporal sequence curve of consistency parameter of Hetao seismic belt had a downward trend, this change was caused by focal mechanism consistency parameter of Linhe to Wuhai area, which indicates that this structural position is possible to be a priority area for stress accumulation and accelerated release in future. 相似文献
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利用区域波形数据使用CAP方法反演中强地震的震源机制正逐渐得到广泛应用.本文以胶东半岛近期发生的两次显著中等地震为例,讨论了使用CAP方法反演震源机制时的误差估计,展示了反演结果的不确定性分析过程.2013年11月23日和2014年1月7日在山东莱州和乳山分别发生了M4.6和M4.3级中等地震,两次事件均造成了较大影响.我们基于CAP方法,使用自助抽样(bootstrap)技术多次重复反演过程,得到大样本量的震源机制解数据;基于这些数据,使用粒子群算法和聚类分析技术给出了优化解,估计了震源机制解的误差范围,并利用震源机制解的P、T轴给出了震源球上的概率密度分布. 相似文献