共查询到20条相似文献，搜索用时 15 毫秒
1.
2014年4月1日,智利北部Iquique地区近海发生MW8.1地震,地震发生之后,国际上一些著名的地震科研机构和学者采用不同的数据和方法计算得到此次地震的震源机制解,但这些结果存在较大差异.地球长周期自由振荡的振幅主要依赖于地震矩的大小及地震断层的破裂方式,可以很好地约束地震震源机制.因此,本文根据2014年Iquique地震现有的6个不同震源机制解模拟计算了该地震激发的自由振荡信号,并与全国连续重力台网中16个弹簧重力仪的观测结果进行比对,基于1.5~5.3mHz的球型简正模分析和约束了Iquique地震的震源机制解.研究发现,基于美国地质调查局WPhase Moment Tensor Solution反演的震源机制解的自由振荡模拟值与实际观测符合最好,其相应的震级能较好反映Iquique地震释放的总能量,而利用海啸数据反演的标量地震矩偏小,联合远场和近场长周期观测数据反演可显著改善震源机制解.另外,还基于格尔木重力台站的模拟值与观测值定量分析了不同震源机制解参数对自由振荡振幅的影响.结果表明地震的标量地震矩M0对自由振荡振幅的影响最大,而断层走向、倾角、滑动方向角和震源深度对自由振荡的振幅影响相对较小. 相似文献
2.
Constraining the focal mechanism of the Lushan earthquake with observations of the Earth’s free oscillations 总被引：1，自引：0，他引：1
The amplitudes of the Earth's free oscillations have a close relationship to earthquake focal mechanisms. Focal mechanisms of large earthquakes can be well analyzed and constrained with observations of long period free oscillations. Although the 2013 Lushan earthquake was only moderately sized, observable spherical normal modes were excited and clearly observed by a superconductive gravimeter and a broadband seismometer. We compare observed free oscillations with synthetic normal modes corresponding to four different focal mechanisms for the Lushan earthquake. The results show that source parameters can be analyzed and constrained by spherical normal modes in a 2.3–5 mHz frequency band. The scalar seismic moment M0 has a major influence on the amplitudes of free oscillations; additionally, the strike, dip, rake and depth of the hypocenter have minor influences. We found that the synthetic modes corresponding to the focal mechanism determined by the Global Centroid Moment Tensor show agreement to the observed modes, suggesting that earthquake magnitudes predicted in this way can readily reflect the total energy released by the earthquake. The scalar seismic moment obtained by far-field body wave inversion is significantly underestimated. Focal mechanism solutions can be improved by joint inversion of far- and near-field data. 相似文献
3.
2011年3月11日,日本东北部(Tohoku)太平洋海域发生Mw9.0特大地震.一些国际学术机构用不同的震相和反演方法,计算了大地震的震源机制解.但这些结果存在一定的差异.地球长周期自由振荡的振幅主要依赖于地震矩的大小及地震断层的破裂方式,可以约束地震的震源机制、地震大小及持续时间.本文利用地球自由振荡0S0简正模对Tohoku大地震的震源机制解进行分析和约束.0S0振幅大小与地震断层的倾角(dip)、滑动方向角(slip)、震源深度及地震断层的破裂时间有关.我们利用震源机制解得到大地震后自由振荡模拟值,利用超导重力仪得到自由振荡的高精度重力观测值.二者比较后的结果显示:由GCMT震源机制解得到的0S0振幅与观测值符合较好,而由USGS CMT震源机制解模拟的结果明显大于观测值.2011 Tohoku地震为逆冲型浅源大地震.进一步的分析表明:逆冲型浅源大地震的断层倾角对0S0振幅的影响很大,而滑动方向角以及震源深度对0S0振幅的影响较小.USGS CMT震源机制解中较大的断层倾角是导致其0S0振幅显著偏离观测值的主要原因. 相似文献
4.
文中给出了根据地震释放的总地震矩求解平均应力场的方法,并使用加入随机误差的人工合成震源机制解数据和唐山余震区震源机制解数据对其进行检验。由检验结果可知,该方法可以应用于区域平均应力场的求解。使用的震源机制解资料越多,所得结果越稳定,且更接近真实的区域应力场。该方法的优点是: 用每个地震的震级作为权重,能够较好地反映出大小地震在应力场反演中的不同贡献; 并且在计算过程中不需要知道震源机制解2个节面中哪个节面为地震断层面。 相似文献
5.
CHARACTERISTICS OF TECTONIC STRESS FIELD OF THE XIAOWAN RESERVOIR BEFORE AND AFTER THE IMPOUNDMENT 
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下载免费PDF全文 Using the seismic waveform data of Xiaowan seismic network and Yunnan seismic network, we determined the focal mechanisms of 36 earthquakes(ML ≥ 3.0)from Jun. 2005 to Dec. 2008 and 51 earthquakes(ML ≥ 2.5)from Jan. 2009 to Dec. 2015 by generalized polarity and amplitude technique.
We inverted tectonic stress field of the Xiaowan reservoir before impounding, using the focal mechanisms of 36 earthquakes(ML ≥ 3.0)from Jun. 2005 to Dec. 2008 and CAP solutions of 58 earthquakes(ML ≥ 4.0)collected and the solutions in the Global Centroid Moment Tensor(GCMT)catalog; We inverted local stress field of the reservoir-triggered earthquake clustering area, using 51 earthquakes(ML ≥ 2.5)from Jan. 2009 to Dec. 2015.
Focal mechanisms statistics show that, the Weixi-Qiaohou Fault is the seismic fault. Focal mechanisms were strike-slip type in initial stage, but normal fault type in later stage. Focal depths statistics of 51 earthquakes(ML ≥ 2.5)show that, the average value of focal depths in period Ⅰ, period Ⅱ and period Ⅲ are 8.2km, 7.3km and 7.8km respectively and the standard deviations are 4.3km, 3.5km and 6.0km respectively. The average value of focal depths is basically stable in different period, only the standard deviation is slightly different. Therefore, there is not positive connection between focal depth and deviation of focal mechanisms. What's more, there are 2 earthquakes(number 46 and number 47 in Fig.5 and Table 3)with almost the same magnitude, epicenter and focal depth, but they have different faulting types as normal and strike-slip. The focal mechanism of event No.46 is strike:302°, dip:40° and rake:-97° for plane Ⅰ, however, the focal mechanism of event No.47 is strike:292°, dip:82° and rake:140° for plane Ⅰ. Likewise, earthquake of number 3 and number 18 have similar characteristic. Therefore, the obvious focal mechanism difference of similar earthquake pair indicates the complexity of Weixi-Qiaohou Fault.
Considering the quiet-active character of reservoir-triggered earthquakes, we discussed the change of local stress field in different period. The σ1 of tectonic stress field was in the near-south direction, with a dip angle of 14° before the impoundment, however, the direction of σ1 of local stress field changed continuously, with the dip angle getting larger after the impoundment. The direction of σ1 of local stress field of reservoir-triggered earthquake clustering area is close to the strike of Weixi-Qiaohou Fault, and reservoir impoundment increased the shear stress in the fault, so the weakening of fault was beneficial to trigger earthquakes. Comprehensive analysis suggests that fluid permeation and pore pressure diffusion caused by the water impounding, and the weakening of fault caused by local stress field are the key factors to trigger earthquake in the Xiaowan reservoir. 相似文献
6.
The parameters of the September 3, 1978, earthquake in the Western Caucasus are presented according to data from different seismological agencies. This event, along with the 1966 earthquake in Anapa, is the strongest seismic event in the region. The solutions suggested in the main international and national seismological agencies contradict the well-known fact that the earthquake did not have catastrophic consequences. This is confirmed only by the position of the epicenter according to GCMT data intended for determining somewhat different earthquake parameters: the focal mechanism and seismic moment. Despite the fact that there was no expedition to perform a macroseismic study of the earthquake, some information was collected by phone survey. Information on the spatial distribution of the macroseismic effect made it possible to more accurately determine the epicenter position according to the GCMT data. 相似文献
7.
利用国家测震台网记录到的2018年9月12日陕西宁强M_S 5.3地震的波形数据,使用新震级国标计算了此次地震宽频带面波震级M_(S(BB)),利用CAP波形反演方法得到震源机制解及矩震级M_W。结果显示:利用50个宽频带测震台站的波形数据测得此次地震的M_(S(BB))为5.0,与GCMT测定的M_S震级一致;由CAP方法反演得到的最佳双力偶参数为节面Ⅰ:走向169°/倾角81°/滑动角9°,节面Ⅱ:走向78°/倾角81°/滑动角171°;矩震级M_W为5.0,与USGS公布的结果较一致,与GCMT公布的结果仅差0.1。研究认为,此次地震震级应为5.0左右,在日常地震速报中可将M_W作为首选发布震级;而对于中强地震,M_(S(BB))震级相较于M_S震级作为发布震级更为合理。 相似文献
8.
Based on the phase report of Xinjiang Seismic Network, the Hutubi MS6.2 earthquake sequence ML ≥ 1.0 was relocated by the HypoDD method. The results show that the aftershocks were distributed along NE and NW direction. The aftershocks were in the depths of 5~15km. In addition, by using the digital waveforms of Xinjiang Seismic Network, the best double-couple focal mechanism of the main shock and some aftershocks of MS ≥ 3.8 were determined by the CAP method. Based on the above studies, the source depth, focal mechanism and aftershock distribution of the Hutubi MS6.2 earthquake were analyzed and the seismogenic structure was discussed. The nodal plane parameters of the best double-couple focal mechanism are strike 144°, dip 26°, rake 118°, and strike 293°, dip 67°, rake 77°, respectively. The moment magnitude MW is about 5.9, with centroid depth of 15.2km. These show that the main shock was a thrust type. Most focal mechanism solutions of the aftershocks were shown as a thrust type, which are similar to the main shock. It is speculated that the possible seismogenic fault of this earthquake is the Huorgosi-Manas-Tugulu Fault. 相似文献
9.
本研究基于地震危险性分析中地震重复原则和构造外推原则,以及一段时期内活动断裂上发生地震机制是相似或相近的假设,利用中国已发生的震级为MS5.0以上的地震震源机制解,将其中的一个节面视为实际地质断层参数和静态应力触发计算中的接收断层面,计算了2015年4月25日尼泊尔MS8.1地震对中国大陆地区的静态应力触发情况.研究结果表明:2015年4月25日尼泊尔MS8.1地震,触发了其后续的2次强余震的发生;本次地震对中国大陆产生的应力变化量值很小,其产生的应力加载主要集中在其邻近的西藏和新疆地区的部分断层上,而其余地区的断层则主要受到了应力卸载作用. 相似文献
10.
Moment tensor inversion of nine events in Iran using INSN data 总被引：1，自引：0，他引：1
Aref Bali Lashak Mehdi Zare Gholamreza Mortezanejad Shahrokh Pour Beyranvand 《Journal of Seismology》2010,14(4):751-760
In this research, moment tensor (MT) inversion procedure in frequency domain is applied to nine events in order to evaluate
the data efficiencies in computing source parameters of earthquakes in Iran. The events are recorded by Iranian National Seismological
Network (INSN) stations, currently comprising 22 broadband stations. For the purpose of this study, first, the inversion procedure
is applied to obtain source parameters. Then, the results obtained here are compared with those of Harvard global centroid
moment tensors (GCMT) in order to estimate their reliabilities. The results show reasonable consistencies with those of Harvard
GCMT within 0.075 uncertainties in logarithmic scalar moment or 0.05 in moment magnitude and 20° in Kagan angle for focal
angles. Furthermore, according to the present research, the calculated source parameters are not significantly sensitive to
the azimuthal gap. 相似文献
11.
使用中国地震台网资料快速测定中强地震矩震级 总被引：1，自引：1，他引：0
利用中国地震台网数字地震资料,选取国内Ms≥5.3地震波形数据,采用长周期波形拟合方法,快速计算2008年至今86个中强震的标量地震矩MO和矩震级Mw,并将Mw与GCMT的测定结果及中国地震台网中心测定的面波震级Ms进行对比.结果表明：矩震级与GCMT测定一致,与中国地震台网中心测定的面波震级关系为Mw=0.86Ms＋0.63. 相似文献
12.
使用小震机制解资料 ,分析了 1975年海城 7 3级和 1976年唐山 7 8级强震及 1983年菏泽 5 9级和 1995年苍山 5 2级中强震前 ,震源区及其周围不同构造部位应力场的时、空变化 ,证实震前震源区附近应力场曾有某些异常改变 ,如唐山强震前震源区周围出现长达 4a多的小震机制解主应力轴一致性取向的现象 ,菏泽地震前小震机制解P轴“集中—转向” ,苍山地震前P轴偏转且一致性增强。同时还发现 ,唐山地震前应力场异常变化开始时间可能早于 1972年 ;震源区内的陡河台与源外区的昌黎台小震综合机制解反映出震前的受力差异 ;震源断层附近不同应力区内震源机制解和地震活动有时空动态差异。这些现象一定程度上提供了不同构造条件和应力背景下 ,中、强震前震源区不同构造部位力学状态的改变或地震孕育过程的信息 ,对研究不同地震的孕震过程及差异有一定意义。 相似文献
13.
北部湾地震的动力学参数与应力场 总被引：3，自引：0，他引：3
从震源机制和动力学参数方面讨论了北部湾地震的震源应力场，结果表明，主震是在北东东向构造的作用下发生的，同时计算了动力学参数如破裂长度，地震矩，应力降，破裂面积和平均位错等，并探讨了非线性地震与较大余震的关系。 相似文献
14.
海域地震对我国海洋资源开发和沿海地区的经济建设形成严重威胁,开展相关地震活动性研究的重要前提是编译我国海域及邻区的地震目录。我国常用的震级标度为面波震级(MS),而国际上最新的地震活动模型多采用矩震级(MW),因此在应用这些模型时需要拟合面波震级与矩震级之间的转换关系。本文以中国海域及邻区为研究区,收集了1988—2020年中国地震台网的面波震级和全球矩心矩张量(GCMT)项目的矩震级数据,从中提取年份、深度、经度、纬度、面波震级作为影响因子,以实际记录的矩震级值作为标记,训练BP神经网络建立以GCMT的矩震级为目标的震级转换模型。同时,使用最小二乘回归和正交回归建立线性模型作为对比。结果显示,最小二乘回归和正交回归的平均绝对误差和均方根误差比BP神经网络高40%左右。此外,BP神经网络的残差绝对值更小、分布更集中。 相似文献
15.
使用最近构建的虚拟全球地震台网记录的波形数据,采用OpenMP的并行编程技术优化原有算法, 研制了基于W震相技术的全球强震(MW≥6.5)矩心矩张量自动反演系统.为了评估该系统的准确度和时效性,将离线自动测定的2008年1月—2013年7月全球140次地震(MW6.5—9.0)的矩心矩张量与全球矩心矩张量工作组(GCMT)的结果进行了比较.结果表明:该系统可准确测定全球MW≥6.5地震的矩张量,绝大多数地震矩震级与GCMT给出的矩震级呈现出良好的线性趋势,两者之差ΔMW的标准方差约0.13,ΔMW位于区间(-0.2,0.2)的地震占总数的96%;地震矩6个分量分别与GCMT相应的结果沿对角线近线性分布,多数地震矩心水平位置与GCMT给出的矩心水平位置比较接近,两者间大圆弧距离位于区间(0,50km)的地震次数占总数的84%;在台站覆盖较均匀的条件下,该系统能够实现震后25—40分钟自动准确测定全球MW≥6.5地震的矩心矩张量. 相似文献
16.
Ya. B. Radziminovich A. I. Seredkina V. I. Melnikova N. A. Gilyova 《Seismic Instruments》2017,53(4):323-332
The paper considers the Argun earthquake of July 22, 2011 (M w = 4.5), which occurred in the Argun River valley in a low-seismicity territory in China. The focal parameters of the earthquake (depth of the hypocenter, moment magnitude, scalar seismic moment, and focal mechanism) were determined by calculating the seismic moment tensor from the amplitude spectra of surface waves and the data on the signs of the first arrivals of body waves at regional stations. The solution of the focal mechanism makes it possible to assume a relationship between the earthquake focus and a fault with a northeastern strike bordering the southeastern side of the Argun Basin (in Chinese territory). The Argun earthquake was felt in Russia with an intensity of II–III to V at the epicentral distances up to 255 km. The intensity of shaking did not exceed values suggested by new GSZ-2012 and GSZ-2014 seismic zoning maps of Russian territory. Nevertheless, the question on the possible occurrence of stronger earthquakes in the studied region remains open. 相似文献
17.
本文利用球对称、非自转、弹性和各向同性地球模型(SNREI)理论模拟计算了地球内核平动振荡的地震激发.以2004年12月26日苏门答腊大地震为例,讨论震源机制解(标量地震矩、走向、倾角、滑动角和深度)对内核平动振荡振幅激发的影响;基于全球21个Mw8.0级以上的大地震,分别计算10个数据资料较好的超导重力台站理论上可以接收到的内核平动振荡信号的频率域振幅.结果表明标量地震矩对内核平动振荡振幅的影响最大,走向、倾角、滑动角和深度对内核平动振荡振幅也有一定影响,但是影响相对较小;不同区域获得的由大地震引起的内核平动振荡信号的幅度存在显著差异,此结果为频率域多台站加权迭积提供了计算基础.另外,只有武汉台站接收到的2011年日本Tohoku Mw9.1地震激发的内核平动振荡的振幅值达到了地球表面高精度、高灵敏度的超导重力仪检测水平,振幅值为0.0103nm·s-2.结果说明地震激发的内核平动振荡的信号极其微弱,信号几乎淹没在背景噪声中,必须利用多台站迭积法才有可能将信号提取出来. 相似文献
18.
丁青地区地震重定位、震源机制及其发震构造初步分析 总被引：1，自引：0，他引：1
文中利用青海省地震台网的宽频带数字记录,通过CAP反演等方法获取了西藏丁青8次MS≥3.0地震的震源机制解(1次地震的震源机制解来自USGS)。结果显示,7次地震以正断破裂为主,兼具少量右旋走滑分量,断层优势走向为NNE,P轴的优势方位为SWW,T轴的优势方位为SEE。同时,利用双差相对定位法获得了217个地震的重定位结果。重定位后,余震沿NE-SW向展布,与震源机制解的走向基本吻合,但与区域内主要走滑型断裂近EW的走向不一致。2015—2018年发生的地震主要分布在5~15km深度范围,2018—2020年震源深度范围缩小至7~12km,2018年以后震源深度的分布范围明显收窄。丁青地震发生在羌塘块体中部,域内既受到SN向印度洋板块与亚欧板块的强烈碰撞挤压作用,也存在EW向伸展构造活动。综合分析重定位、震源机制结果及地质构造背景等资料,认为2016年MS5.5、2020年MS5.1地震的发震构造可能是同一条NE走向的正断型断裂,发震断层面可能为节面I,即走向、倾角和滑动角分别为12°、58°、-103°与9°、57°、-101°的节面。由于丁青地区地质资料匮乏,无法明确具体的发震断裂。 相似文献
19.
海城-岫岩地区是辽宁省小震、震群多发地区。本文选用1975年以来具有一定发震规模,且仪器记录相对较完整的3个显著震群（1975年海城7.3级,1999年岫岩5.4级和2008年海城ML4.8级地震）,将其较大地震前ML≥4.0级地震震源机制结果进行比较,发现海城7.3级和岫岩5.4级地震前ML≥4.0级地震震源机制解与主震有较好的一致性,而2008年11月海城4.8级地震前ML≥4.0级地震震源机制一致性较差。我们对能否借鉴前震震源机制一致性的差异快速判断中强震发展的趋势,进行了探讨和研究。 相似文献
20.
本文根据建立在平均二维破裂模式基础上的地震定标律,导出了地震矩 M0与各常用震级之间（1gM0-MS,ML,mb）,各种震级之间（Ms-ML,Ms-mb,ML-mb）,各震源参数之间（断层长度IgL,断层面积 lgS,平均错距 lgD-Ms,拐角频率 1gfc-ML）的各种常用的关系式.利用这些关系式,由一个震级值就可以估算出一系列震源参数.本文还求出了平均破裂速度 Vr=2.65km/s,总破裂时间 T（s）=0.5L（km）,平均位错速度 D（t）=11.4m/s.用矩震级 Mw 度量地震的大小,有四个优点:（1）地震矩反映了形变规模的大小,因此是度量地震大小的最佳物理量.（2）它是一个绝对力学标度,对任何大小地震都有意义,可测量,且不产生饱和问题.（3）它和我们已熟悉的震级标度可衔接.（4）它是一个均匀的震级标度,适用于宽尺度的地震统计.因此,Mw 是一种值得推广的震级标度. 相似文献