用远场资料反演西藏玛尼地震的高阶地震矩张量

采用扩展震源模型测定出更多的震源参数 .我们把震源用高阶地震矩张量表示 .为了减少在高阶地震矩张量表达式中出现的大量项 ,采用了 Haskell断层模型 .利用 GSN台网 32个台站的宽频带体波资料 ,反演了西藏玛尼地震的震源参数 .通过实际计算表明 ,该震源是一个走滑断层 ,破裂方向 75°,断层面为=77°、δ=88°,λ=0°,辅助面为=347°、δ=90°、λ=1 78°,破裂持续时间为 1 9s,断层尺度为 47km× 2 8km.这些结果将为地球动力学研究提供新的定量资料 ,对于震源层析成像研究等有实际意义 .     

Applications of seismic moment tensor inversion in fast response to earthquakes

IntroductionAfteramoderateorstronger(Ms25.0)earthquake,themosturgentworkofthedivisionforearthquakemonitoringandpredictionistodetermineitstimeoforigin,hypocentrallocation(longitude,latitudeanddepth)andmagnitudeandtojudgethetrendofseismicregimedevelopmentassoonaspossible.Ingeneralcases,whenanearthquakewithMS25.0insideChinaoraonewithMS26.0inneighboringareasofChinahasoccurred,theEarthquakeBulletinofChineseSeismologicalNetworkcanprovidedeterminationoftheorigintime,hypocentrallocation(longitude,…     

Moment tensor inversion of near-source broadband data

Ｍｏｍｅｎｔ　ｔｅｎｓｏｒ　ｉｎｖｅｒｓｉｏｎ　ｏｆ　ｎｅａｒ－ｓｏｕｒｃｅ　ｂｒｏａｄｂａｎｄ　ｄａｔａ（吴忠良）（陈运泰（倪江川）（王培德）（王鸣）Ｍｏｍｅｎｔｔｅｎｓｏｒｉｎｖｅｒｓｉｏｎｏｆｎｅａｒ－ｓｏｕｒｃｅｂｒｏａｄｂａｎｄｄａｔａ￥Ｚ...     

2009年3月19日汤加地震快速矩张量解

2009年3月20日2点17分37秒(北京时间),在汤加群岛发生了Ms7.9地震.我们利用多年来发展的矩张量快速反演技术,通过反演全球台网的宽频带P波波形得到了这次地震的矩张量解,并确定了发震断层参数.     

A new technique for moment tensor inversion with applications to the 2008 Wen-chuan M_s8.0 earthquake sequence

A MS8.0 earthquake occurred in Wenchuan County, Sichuan Province, China, on May 12, 2008, and subsequently, numerous aftershocks followed. We obtained the moment tensor solutions and source time functions (STFs) for the Wenchuan earthquake and its seven larger aftershocks (MS5.0~6.0) by a new technique of moment tensor inversion using the broadband and long-period seismic waveform data from the Global Seismic Network (GSN). Firstly, the theoretical background and technical flow of the new technique was brie...     

1996年5月3日包头西Ms=6.4地震的矩张量解

利用ＣＤＳＮ及ＧＤＳＮ数字化Ｐ波波形资料,用遗传算法反演１９９６年包头西ＭＳ＝６．４地震的地震矩张量解。结果表明该地震矩张量解以双力偶成分为主,是断层面接近南北走向的左旋走滑错动,断裂面走向与大震后５天内余震的分布带走向基本一致。压应力轴与张应力转接近水平,前者近北西西走向,后者近北北东走向。     

A new technique for moment tensor inversion with applications to the 2008 Wenchuan M S8.0 earthquake sequence

A MS8.0 earthquake occurred in Wenchuan County, Sichuan Province, China, on May 12, 2008, and subsequently, numerous aftershocks followed. We obtained the moment tensor solutions and source time functions (STFs) for the Wenchuan earthquake and its seven larger aftershocks (MS5.0~6.0) by a new technique of moment tensor inversion using the broadband and long-period seismic waveform data from the Global Seismic Network (GSN). Firstly, the theoretical background and technical flow of the new technique was briefly introduced, and an aftershock of the Wenchuan earthquake sequence was employed to illustrate the real procedure for inverting the moment tensor; secondly, the moment tensor solutions and STFs of the eight events, including the main shock, were presented, and finally, the interpretation of the results was made. The agreement of our results with the GCMT results indicates the new approach is efficient and feasible. By using this approach, not only the moment tensor solution can be obtained but also the STF can be retrieved; the inverted STFs indicate that the source rupture process may be com-plicated even for the moderate earthquakes. The inverted focal mechanisms of the Wenchuan earthquake sequence show that the most of the aftershocks occurred in the main faults of the Longmenshan fault zone with predomi-nantly thrustingwith minor right-lateral strike-slip component, but some of them may have occurred in the sub-faults with strike-slip faulting in the vicinity of the main faults.     

Seismic moment tensor inversion using 3D velocity model and its application to the 2013 Lushan earthquake sequence

Source inversion of small-magnitude events such as aftershocks or mine collapses requires use of relatively high frequency seismic waveforms which are strongly affected by small-scale heterogeneities in the crust. In this study, we developed a new inversion method called gCAP3D for determining general moment tensor of a seismic source using Green's functions of 3D models. It inherits the advantageous features of the “Cut-and-Paste” (CAP) method to break a full seismogram into the Pnl and surface-wave segments and to allow time shift between observed and predicted waveforms. It uses grid search for 5 source parameters (relative strengths of the isotropic and compensated-linear-vector-dipole components and the strike, dip, and rake of the double-couple component) that minimize the waveform misfit. The scalar moment is estimated using the ratio of L₂ norms of the data and synthetics. Focal depth can also be determined by repeating the inversion at different depths. We applied gCAP3D to the 2013 M_s 7.0 Lushan earthquake and its aftershocks using a 3D crustal-upper mantle velocity model derived from ambient noise tomography in the region. We first relocated the events using the double-difference method. We then used the finite-differences method and reciprocity principle to calculate Green's functions of the 3D model for 20 permanent broadband seismic stations within 200 km from the source region. We obtained moment tensors of the mainshock and 74 aftershocks ranging from M_w 5.2 to 3.4. The results show that the Lushan earthquake is a reverse faulting at a depth of 13–15 km on a plane dipping 40–47° to N46° W. Most of the aftershocks occurred off the main rupture plane and have similar focal mechanisms to the mainshock's, except in the proximity of the mainshock where the aftershocks' focal mechanisms display some variations.     

一种矩张量反演新方法及其对2008年汶川Ms 8.0地震序列的应用

本文利用全球地震台网（GSN）的宽频带与长周期地震波形资料,采用矩张量反演的新方法,反演得到了2008年5月12日四川省汶川县MS8.0地震及其7个较大余震（MS5.0-6.0）的矩张量解与震源时间函数等震源参数.文章首先简要叙述矩张量反演新方法的理论背景和技术途径,并以汶川大地震的一个余震为例阐述了具体的实现过程;然后给出包括主震在内的8次地震的矩张量解和震源时间函数;最后分析探讨这些结果的构造意义.本文提出的矩张量反演新方法,不但与全球矩心矩张量（GCMT）一样,可以给出点源矩张量解,而且还可以给出点源的震源时间函数. 反演得到的汶川大地震的7个较大余震的震源时间函数表明,即使是中等强度的地震也可能有复杂的震源过程;汶川大地震的多数余震发生在以逆冲为主、兼具小量走滑分量的龙门山断裂带的主断裂上,但很可能有些余震则发生在主断裂附近的次级走滑断裂上.      

2009年12月19日台湾花莲地震快速矩张量解

2009年12月19日13点2分16秒协调世界时(UTC),在台湾花莲海域发生了MW6.7地震.作者利用矩张量快速反演技术,通过反演全球地震台网的宽频带P波波形资料得到了这次地震的矩张量解,并判断走向4°、倾角75°、滑动角76°的节面是本次地震的发震断层面.     

地震矩张量反演在地震观测报告中的应用

针对我国地震工作的实际需要,从１９９５年起,《中国地震台网目录和地震矩张量解》刊登了国内较大地震和全球大震的地震矩张量解和震源机制解。同时在《中国地震年报》上也刊登国内及邻区较大地震的地震长张量解和震源机制解。为了方便用户使用,本文对有关参数进行了说明。     

2010年1月12日海地地震快速矩张量解

2010年1月12日21点53分9秒协调世界时(UTC),在加勒比海域的海地发生了MW7.2地震.作者利用矩张量快速反演技术,通过反演全球地震台网的宽频带P波波形资料得到了这次地震的矩张量解,并判断走向253°、倾角74°、滑动角17°的节面是本次地震的发震断层面.     

2009年4月6日意大利拉奎拉(L＇Aquila)地震快速矩张量解.

2009年4月6日1点32分42秒协调世界时（UTC）,在意大利中部地区发生了MW6.4地震．作者利用矩张量快速反演技术,通过反演全球台网的宽频带P波波形得到了这次地震的矩张量解,并判断走向132deg;、倾角53deg;、滑动角——103deg;的节面是地震发生的断层面．      

Discussion on moment tensor solution and seismogenic structure of Ruichang-Yangxin earthquake on 10 September 2011

Ruichang-Yangxin earthquake is another moderate earthquake in Yangxin-Jiujiang area since 2005 Jiujiang-Ruichang M5.7 earthquake. In order to more understand the seismic activities in this area, we study the moment tensor solution and the seismogenic structure of the Ruichang-Yangxin earthquake. Precise earthquake relocation shows that the mainshock occurred on the southwestern part of the NE-trending fault and aftershocks are distributed not only along the NE-trending fault but also along its conjugated NW-trending fault. By comprehensive analysis on the earthquake distribution, characteristics of isoseismal curve, focal mechanism, and regional structure characteristics, it is inferred that this earthquake is caused by the NE-trending Tanlu fault. In addition, it has close relationship with the conjugated NW-trending fault as well. Many researches have shown that the junction area is the earthquake-prone area, and should be paid more attention to. And our study also proves this viewpoint.     

2022年1月23日青海德令哈MS5.8地震全矩张量反演及发震构造初步分析

基于青海和甘肃区域地震台网记录的宽频带地震波形和震相观测数据,利用近震全波形反演方法和双差定位方法分别对2022年1月23日青海德令哈M_S5.8地震进行全矩张量反演和地震序列重定位研究。矩张量反演结果表明主震为一次典型走滑型地震,最佳断层面节面Ⅰ走向78°、倾角88°、滑动角－22°,节面Ⅱ走向169°、倾角68°、滑动角－177°,矩心深度为9 km,矩震级为M_W＝5.5。定位结果显示余震优势展布方向为NNW－SSE,长度约16 km,余震震源深度优势分布在7～12 km之间。综合分析表明,节面Ⅱ与余震精定位所勾勒出的断层面走向和倾向较为一致,推断NNW走向的断层面为可能发震断层面,认为德令哈地震是发生在祁连山断裂带的向W倾、倾角约为68°的右旋走滑断裂上。在印度板块向欧亚板块俯冲挤压作用下,青藏高原东北部构造块体应力不断积累,造成祁连山断裂带内断层失稳而发生此次青海德令哈M_S5.8地震。     

Moment tensor inversion for the focal mechanism of the Dongfang (Hainan) earthquake swarm

IntroductionOnJanuary4,1992,twoearthquakesoccurredconsecutivelyaroundtheGancheng-BanqiaoatDongfangCounty,HainanProvince.Theirorigintimeandmagnitudewere23:01:24,ML=3.4and23:01:54,ML=3.7,respectively.Theepicentrallocationoftwoearthquakeswere18°46′N,108°42′Eand18°45′N,108°42′E,respectively.Thefocaldepthswereabout10kin.Followingthesetwoearthquakes,alotofsmallearthquakesoccurredinthisregion.ThebiggestearthquakeoccurredonMay26,1992.Itsorigintimewas18f43f25andthemagnitudewasML=4.5.Ac…     

2010年4月14日青海玉树地震快速矩张量解

北京时间2010年4月14日7时49分37秒,在中国青海省玉树县发生了MW7.0地震.作者利用矩张量快速反演技术,通过反演全球台网的宽频带P波波形资料得到了这次地震的矩张量解,并判断走向119°、倾角83°、滑动角-2°的节面是本次地震的发震断层面.     

Quick moment tensor solution for 6 April 2009, L'Aquila,Italy, earthquake

A M_W6.4 earthquake occurred in L'Aquila, central Italy at 1:32:42 (UTC), April 6, 2009. We quickly obtained the moment tensor solution of the earthquake by inverting the P waveforms of broadband recordings from the global seismographic network (GSN) stations using the quick technique of moment tensor inversion, and further inferred that the nodal plane of strike 132°, dip 53° and rake ?103° is the seismogenic fault.     

断层厚度的地震效应和非对称地震矩张量

本文导出了具有厚度和滑动弱化区域的断层的非对称地震矩张量表示式,指出要求地震矩张量具有对称性不是一个绝对必要的限制.在非对称地震矩张量中,位错项对应于对称地震矩张量,拉力项对应于非对称地震矩张量.由于拉力项等效于单力偶,所以在非对称地震矩张量解的两个节面上,沿滑动矢量方向的力偶强度不再相同,与较大力偶相联系的节面为断层面,与较小力偶相联系的节面为辅助面.这一性质可用以从两个正交的节面中判断哪一个节面是断层面.如果忽略拉力项,会高估与位错对应的标量地震矩.只有满足相应的约束条件的非对称地震矩张量才能表示具有厚度和滑动弱化区域的断层模型,并从中分离出与位错和拉力对应的地震矩张量.