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1.
In this article, we have inverted local broadband waveform data to determine the focal mechanism of the 2011 MS4.8 Anqing earthquake. Our results show that the best double couple solution of the MS4.8 event is 16°, 74° and 120° for strike, dip and rake angles of one nodal plane respectively, and 131°, 33°, 30° for the other nodal plane. The estimated focal depth is about 3km. Both strikes of the two nodal planes differ significantly to the strike of Susong-Zongyang fault, along which seismic activity has been at a low level since the Late Quaternary. This implies that this earthquake may not have occurred on the Susong-Zongyang fault, and we infer that a buried fault with strike of NNE may be the seismogenic structure of this event. 相似文献
2.
Study of the Seismogenic Structure of the October 12th, 2019 MS5.2 Beiliu Earthquake, Guangxi, China
On October 12~(th),2019,a M_S5.2 earthquake occurred in Beiliu City,Guangxi Zhuang Autonomous Region,China,with a focal depth of 10 km. The epicenter is located in the junction of Guangxi and Guangdong where the moderate-strong earthquakes are relatively active. The highest intensity of this earthquake is estimated up to Ⅵ besides the isoseismic line showed an ellipse shape with a long axis trend in the NW direction.The aftershocks are not evenly distributed. The parameters of the focal mechanism solutions are: strike 346°,dip 85°,rake 19° for the nodal planeⅠ,and strike 254°,dip 71°,rake 175° for the nodal planeⅡ. The type of the coseismic fault is strikeslip. After analyzing these results above and the active faults near the epicenter,we get that the nodal planeⅠ is interpreted as the coseismic rupture plane and the BamaBobai Fault is a seismogenic structure of M_S5.2 Beiliu earthquake. 相似文献
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Complete records of more than 3,000 earthquake events in the Shanxi, Wenzhou reservoir earthquake sequence were recorded from August to November,2014 by the high-density,high-resolution monitoring stations of the Zhejiang Regional Digital Seismic Network and the reservoir earthquake monitoring network,with a maximum magnitude of M4. 2. Based on 3-D epicenter location, focal mechanism solutions, and in combination with the geological and tectonic characteristics of the reservoir area,the earthquake sequence is discussed in this paper. The linear fitting of the Hypo SAT location results show that the main shock occurred in the NW trending fault and the earthquake sequence is concentrated in bands along the active faults,with a strike of305 °,dipping SW with dip angle of 85 °. By using P-wave first motion symbols, we obtained the average focal mechanism of M ≥ 3. 5 earthquakes,with a strike 308 ° and dip 84 ° for nodal plane II. The field geological survey and research show that the strike,dip and rake of nodal plane II are roughly consistent with the occurrence of the Shuangxi-Jiaoxi fault. The comprehensive analysis reveals that the NW-trending Shuangxi-Jiaoxi fault is the seismogenic structure of the earthquakes. 相似文献
4.
《中国地震研究》1994,(2)
In this paper,the focal mechanisms of the fore-main-after shocks of the 1989 Datong-Yanggao earthquake are determined by fitting Pnl and SH waveforms,and the earthquake processes and seismotectonics are inferred.The results show that the fore-main-after shocks occurred on a composite fault plane,The fault motion at the shallow part is right-lateral strike-slip with mechanisms:strike 201,dip 75,rake 191; at the deeper part,the fault movement is strike 201,dip 58,rake 222.The epicentral area is subject to a ENE-WSW horizontal compression and a NNW-SSE extension which is consistent with the tectonic stress orientation of North China.The P-axis at greater depth has an azimuth of 54.5 and a plunge of 51.The relatively large P-axis plunge in depth corresponds with the great depressive deformation in this area.In addition,the similarities and differences between the Datong-Yanggao earthquakes and general graben-associated earthquakes are discusses. 相似文献
5.
《中国地震研究》2021,(1)
On February 3~(rd), 2020, an isolated M_S5.1 earthquake occurred in the northern section of the Longquanshan fault zone. This study aims at defining the geometry of seismogenic structures of this earthquake. In detail, centroid moment tensor inversion results show that the earthquake is characterized by a focal depth of 3.8 km with no corresponding surface faults. The strike/dip/rake angles for the two nodal planes are 205°/54°/96° and 15°/36°/82°, respectively. With the analyses of coseismic deformation of the surface obtained from InSAR measurements, together with the information of relocated hypocenters for a small number of aftershocks, it is concluded that a northwest-dipping nodal plane corresponds well to the source fault. The fault is suggested to have a length of about 2.8 km and a depth range of 2–5 km, and the centroid of the earthquake is located at 104.48°E and 30.71°N. Furthermore, multiple pieces of evidence indicate that this earthquake is partly driven by the overpressure effect associated with the adjacent natural gas packets, which is similar to several other moderate natural earthquakes in Sichuan Basin. 相似文献
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《中国地震研究》2016,(2)
A M_L3.8 earthquake occurred on February 23,2014 in Rongchang County,which is located at the southern edge of the Sichuan Basin in the border area between Sichuan and Chongqing. This paper presents results of focal mechanism solution of this earthquake using the CAP( cut and paste) method based on broadband seismograms recorded by regional seismic stations. Our results show that the moment magnitude is M_W3. 09 and focal depth is 3km. The hypocenter of this earthquake is located close to a buried fault in the Luoguangshan anticline. Oil prospecting and deep drilling data indicate that this buried fault is a thrust fault,striking SW230°,dipping NW45°,and 1. 7km deep. There are some injection wells within the anticline,and significant injection-induced earthquakes were observed during the periods of injection of waste water into the deep formations through those wells. The best double couple solution of the M_L3.8 earthquake is 247°,48°and 104° for strike,dip and rate,respectively,for one nodal plane( and 46°,44° and 74°for another nodal plane),which is in agreement with the geometry of the buried fault.Therefore,we conclude that the M_L3.8 Rongchang earthquake is possibly the result of faulting along the buried reverse fault induced by water injection under the compressive stress regime in the area. 相似文献
7.
The focal mechanism solution on the seismic fault plane can reflect the geometric and kinematic characteristics of faults, and it is an important way to further study the fine structure of fault plane. From the focal mechanism solution of the earthquakes around the Dujiangyan fault in Longmenshan fault zone, we derived the average dip angle of Dujiangyan fault is 45.1° based on the seismic moment tensor theory. In order to refine the fault geometry structure, this paper decomposed it into multiple sub-fault planes along the length and width of the fault plane and forms a number of models A13, B13, A23 a, A23 b, A23 c, B23 a,B23 b and B23 c, then calculated the sub-fault's dip of each model. In order to clarify exactly which one of the fault models is closest to the real fault model, the fault slip was carried out for each model in turn, then compared the surface displacement of each model with GPS observations. The results show that B23 c model with high dip in shallow and small dip in deep is the best model, the lengths of each subfault of Dujiangyan fault from south to north are 33 km, 21 km and 46 km, respectively. When the depth of the fault bottom is about 11 km, the dip angles are 70.56°, 67.41° and 45.55°.When the depth of the fault bottom is about 30 km, The fault dip angles are 44.55°, 29.18° and 44.25°. 相似文献
8.
Zujun XIE Yong ZHENG Huajian YAO Lihua FANG Yong ZHANG Chengli LIU Maomao WANG Bin SHAN Huiping ZHANG Junjie REN Lingyun JI Meiqin SONG 《中国科学:地球科学(英文版)》2018,(3)
At GMT time 13:19, August 8, 2017, an Ms7.0 earthquake struck the Jiuzhaigou region in Sichuan Province, China,causing severe damages and casualties. To investigate the source properties, seismogenic structures, and seismic hazards, we systematically analyzed the tectonic environment, crustal velocity structure in the source region, source parameters and rupture process, Coulomb failure stress changes, and 3-D features of the rupture plane of the Jiuzhaigou earthquake. Our results indicate the following:(1) The Jiuzhaigou earthquake occurred on an unmarked fault belonging to the transition zone of the east Kunlun fault system and is located northwest of the Huya fault.(2) Both the mainshock and aftershock rupture zones are located in a region where crustal seismic velocity changes dramatically. Southeast to the source region, shear wave velocity at the middle to lower crust is significantly low, but it rapidly increases northeastward and lies close to the background velocity across the rupture fault.(3) The aftershock zone is narrow and distributes along the northwest-southeast trend, and most aftershocks occur within a depth range of 5–20 km.(4) The focal mechanism of the Jiuzhaigou earthquake indicates a left-lateral strike-slip fault, with strike, dip, and rake angles of 152°, 74° and 8°, respectively. The hypocenter depth measures 20 km, whereas the centroid depth is about 6 km. The co-seismic rupture mainly concentrates at depths of 3–13 km, with a moment magnitude(M_w) of 6.5.(5) The co-seismic rupture also strengthens the Coulomb failure stress at the two ends of the rupture fault and the east segment of the Tazang fault. Aftershocks relocation results together with geological surveys indicate that the causative fault is a near vertical fault with notable spatial variations: dip angle varies within 66°–89° from northwest to southeast and the average dip angle measures ~84°. The results of this work are of fundamental importance for further studies on the source characteristics, tectonic environment, and seismic hazard evaluation of the Jiuzhaigou earthquake. 相似文献
9.
The focal mechanism solutions of the Wenchuan earthquake(MS8.0) of May 12,2008 and some of its aftershocks occurring up to December 10,2008 are determined with lower semisphere of equal-projection and first motion sign data of P waves from regional and distant stations.The focal mechanism solutions of the MS8.0 Wenchuan earthquake are:Nodal planeⅠ:strike 5°,dip angle 48°,slip angle 39°; Nodal planeⅡ:strike 247°,dip angle 62°,slip angle 131°; P axis azimuth 309°,plunge 8°,T axis azimuth 208°,plunge 54°,B axis azimuth 44°,plunge 35°.Combining geological tectonics and spatial distribution of aftershocks,nodal plane II can be identified as a seismogenic fault.According to focal mechanism solutions,the fault activity that triggered the huge earthquake is reverse thrusting.The main rupture surface is S67° W,basically identical to the fault strike on which the earthquake occurred.The main compression stress P axis is N51°W,which is basically the same as the direction of the regional tectonic stress field.According to the results of focal mechanism solutions of aftershocks,the aftershocks occurring in the southern and northern sections of the Longmenshan fault zone have predominant orientations and are obviously different.For the main shock and the early aftershocks occurring on the southern section of the Longmenshan fault,the rupturing is mainly characterized by reverse-dip slip with some strike-slip,and over time,the aftershocks migrated towards the northern section.The rupturing in the source is mainly characterized by strike-slip with some reverse-dip slips.The stress field is controlled by the main shock stress field in the southern section of the Longmenshan tectonic zone,while it is controlled by the main shock stress field and regional stress field in the northern section of the Longmenshan tectonic zone. 相似文献
10.
Fault plane parameters of Tancheng M81/2 earthquake on the basis of present-day seismological data 
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下载免费PDF全文 《地震科学（英文版）》2010,(6)
The great Tancheng earthquake of M81/2 occurred in 1668 was the largest seismic event ever recorded in history in eastern China.This study determines the fault geometry of this earthquake by inverting seismological data of present-day moderate-small earthquakes in the focal area.We relocated those earthquakes with the double-difference method and found focal mechanism solutions using gird test method.The inversion results are as follows:the strike is 21.6°,the dip angle is 89.5°,the slip angle is 170°,the fault length is about 160 km,the lower-boundary depth is about 32 km and the buried depth of upper boundary is about 4 km.This shows that the seismic fault is a NNE-trending upright right-lateral strike-slip fault and has cut through the crust.Moreover,the surface seismic fault,intensity distribution of the earthquake,earthquake-depth distribution and seismic-wave velocity profile in the focal area all verified our study result. 相似文献
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叙述了在FreeBSD环境下构建基于PPTP的VPN网关的过程和技术，分析了基本概念、实现方式以及在江西省地震信息网的实际应用等。 相似文献
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山西大同数字遥测地震台网记录的震相特征 总被引：1，自引：0，他引：1
从地球及地壳的分层结构出发，使用较成熟的理论，从地震波传播的基本原理入手，结合多年的震相观察分析工作实践，选取了山西大同数字遥测地震台网近年来的一些典型震相进行了分析，得出本台网记录到震中距小于100km的地方震震相有Pg，P11，Sg，S11震中距在100km～500km的近震震相有Pn，Pg，P11，Sn，Sg,S11对比分析了在本台网内及周边地区发生的爆破与天然地震在震相上的差异性，并对其特征作了较详细的描述。 相似文献
13.
对兰州地震研究所的三段历史作回顾,分别为国家地震局、中国地震局兰州地震研究所的体制沿革变迁,中国科学院地球物理研究所;中国科学院兰州地球物理研究所观象台早期创建;兰州地震研究所硕士点早期阶段。 相似文献
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利用山东数字地震台网的实时记录波形资料,采用在频率域积分方法,计算出各台站背景噪声的位移值。然后进行统计分析,得出了山东地区背景噪声位移值的空间分布和时间变化特征：台站背景噪声幅值与不同地区地质环境、岩性密切相关,位于第四系黄土覆盖层较厚的鲁西聊城、菏泽地区,鲁西北德州地区和鲁北东营、滨州地区各子台的背景噪声位移值较大,鲁中、鲁南山区和胶东半岛地区的基岩台站背景噪声位移值较小;同时,白天噪声值大于夜间噪声值,但深井观测台站的背景噪声值相对稳定。此项研究为绘制台网监测能力图提供基础数据,并为计算各台站的场地响应及震级修正值等测震学研究提供基础资料,促进台网的改建和发展。 相似文献
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本文在理论上研究了对齐误差对测试地震计自噪声的影响。指出对齐误差影响到2台仪器记录间的计算互功率谱密度, 进而影响到被测仪器记录间相干函数计算, 最终影响到被测仪器的自噪声计算。发现当存在对齐误差时, 在信噪比较高频段计算得到的自噪声水平比仪器的实际自噪声水平要高, 在一般的实际测试中可能高20 dB以上。为了消除对齐误差对自噪声测试的影响, 提出通过投影逆变换把观测记录变换到标准坐标系下, 再用变换后的观测记录来计算地震计自噪声。给出了基于以上思路和传感参数对比测试方法的地震计自噪声计算处理流程, 合成数据、 实际测试数据的处理检验计算结果表明, 本文方法可以有效克服地震计自噪声测试中对齐误差的影响。 相似文献
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萧山-球川断裂是浙江地区1条大规模的北东向断裂,在该断裂附近曾发生过多次破坏性地震。本文通过地质调查、电法勘探和探槽开挖等方法,对萧山-球川断裂富阳—建德段第四纪活动性进行了研究。萧山-球川断裂富阳—建德段的遥感影像线性特征清楚,对地貌的控制作用较为明显,对山前的第四系发育有明显影响。通过对断裂露头剖面的分析,认为萧山-球川断裂富阳—建德段活动性质以走滑兼具逆冲为主。通过本次开挖的富阳峙山村探槽,结合ESR年龄测定,判定该断裂在第四纪早、中期有过活动,但未断错上覆中更新统上部地层,其最新活动时代为早、中更新世。 相似文献
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在土-结构的动力相互作用简化分析中,常采用双自由度集中参数模型简化土层.这种模型适合各向同性的单一土层,而实际工程场地的地基土多是各向异性的成层土层.为了将这一模型应用于此类土层,本文根据实际地震动记录,提出了一种变阻尼最小二乘反分析方法,可用来识别模型中的各个参数值.文中提出的方法具有适用范围广、计算精度较高的优点,并已通过编制FORTRAN程序加以实施和应用. 相似文献
19.
采集夏县中心地震台温泉水及周边水点样品进行水化学组分特征分析。利用矩形图、Na-K-Mg三角图等方法,初步分析温泉水的水质类型、水-岩平衡状态、热储温度以及循环深度等,并结合氢氧同位素组成特征,初步分析温泉水补给来源。研究表明,夏县中心地震台温泉水化类型属于Na-Cl·SO4型,水-岩反应属于部分成熟水,热储温度为148.8℃,循环深度为3.91 km,补给源主要为大气降水,温泉为断裂型温泉。以上结果可为该台流体异常分析提供基础研究资料,为夏县地区水化研究奠定基础。 相似文献
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为解决地震台光记录倾斜仪灯光系统故障率高的问题 ,研制了一种时号·光源灯控器。采用了数字钟报时及定闹信号对直接延时时号灯进行控制的措施 ,使仪器的无故障运行期及蓄电池的使用寿命得以延长 ,明显提高了观测质量。 相似文献