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2011年Ms4.6瑞昌-阳新地震的震源机制及发震构造探讨 总被引：1，自引：1，他引：0
2011年Ms4.6瑞昌-阳新地震是瑞昌地区继2005年M5.7地震后的又一中等强度地震,文中从多角度对此次地震的发震构造进行了探讨.利用双差定位法进行的地震精定位结果显示,主震发生在NE向断裂的西南端,余震的分布则呈现出沿NNE和NW两个方向展布的特征.野外考察发现,等震线长轴方向为NE,沿此方向烈度衰减较慢.考虑震源时间函数的影响,采用波形反演方法得到了此次地震的震源机制解.节面Ⅰ走向302.2°,倾角68.2°,滑动角-3.8°;节面Ⅱ走向33.6°,倾角86.5°,滑动角-158.1°.综合分析认为,NNE向郯庐断裂的南端隐伏段(瑞昌-武穴断裂)为此次地震的发震构造,而与NW向断裂的共轭作用造成了部分余震沿着NW向分布的特征. 相似文献
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广东省及邻区活动断裂的实验研究 总被引：2，自引：0，他引：2
从实验应力分析和岩石力学的角度,综合其它学科的相关理论,给出了一种有别于传统的活动断裂的新定义及其判据。其定义为:在现代构造应力场中,存在沿原断裂面破裂和扩展的断裂。其判据为:①某断裂走向与主压应力1σ方向所夹的锐角0°≤β≤50°时,其为活动断裂;②β=25°的断裂为最活动的断裂。通过对广东省及邻区活动断裂的实验研究还得到其1σ方向分布图(广东省域从东到西,1σ方向大致为305°～360°～15°)、活动断裂或活动断裂分段的走向范围以及主要活动断裂分段内潜在的最大地震。大致为:①NW走向的断裂,除西部极少数外,全部是活动断裂。各断裂分段内潜在的最大地震在MS 5.1～7.4级之间:②研究区东部的近EW向断裂、西部NE向断裂的部分分段和SN向断裂,也是活动断裂。各分段内潜在的最大地震在MS6.8～7.5级之间。 相似文献
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1654年7月21日甘肃省礼县8级地震发生在南北地震带的中北段,该地区的构造变形和构造活动与青藏高原向北东方向的扩展密切相关,复杂的构造几何特征主要受控于东昆仑断裂、西秦岭北缘断裂和一系列北东向断裂.礼县—罗家堡断裂为一条北东东向的左旋走滑活动断裂,错断了含有仰韶文化红色陶瓷片的一级阶地堆积物,阶地面上断层陡坎高约1.5m.沿断裂带发现冲沟的左旋位错量为3~10m,晚更新世黄土中残留的断层陡坎高4.5~8m.其中两条冲沟中发现裂点,高3.5~3.9m,距断层陡坎的距离为16m.礼县—盐关—罗家堡—天水镇一带发育大量的滑坡,长轴走向与礼县—罗家堡断裂一致,滑坡体后缘、侧壁陡峭,出露晚第四纪黄土,鲜有植被覆盖.礼县—罗家堡断裂为1654年8级地震的发震断裂.综合分析认为,受青藏高原向北东方向的扩展,被西秦岭北缘断裂、礼县—罗家堡断裂和岷县—宕昌断裂围限的礼县次级地块向南东滑动可能导致了1654年礼县8级地震的发生.断裂北、南两侧地壳电性结构的差异为强震的孕育提供了深部构造条件. 相似文献
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无量山断裂带位于云南西南部,主要由磨黑、宁洱、普文和景谷—云仙4条断裂组成,晚第四纪活动特征明显.受青藏高原隆起影响滇西南块体向南运动,中下地壳广泛存在的低速层为块体运动提供了有利条件,但刚性的临沧花岗岩体对其南向运动起着顶托作用,使得东、西两侧块体运动速率出现差异,且块体运动方向与无量山断裂带呈小角度相交.在此背景下,无量山断裂带表现为水平右旋走滑运动,起着滑动分解应变的作用.在其与横向断层交汇部位或在断裂端部,应力易于集中而引发地震,此次MS6.6地震就发生在断裂的端部.据野外科考调查,在宏观震中区集中出现带状砂土液化和地裂缝等地面破坏.喷砂孔呈串珠状线性分布,主要有NW和NE两组;NW向地裂缝呈右阶雁行状、NE向地裂缝呈左阶雁行状排列特征,它们具有明显的构造成因.地震烈度长轴方向、余震分布和震源机制解等显示,此次地震是沿NW向节面右旋走滑所致,宏观地面破坏特征和微观观测结果非常吻合,一致表明此次地震破裂与景谷—云仙断裂运动有关,其孕震构造应是景谷—云仙断裂. 相似文献
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本文讨论了大断裂形成的力源问题,分析了我国一些大地震的资料后认为大断裂形成的力源是板块水平挤压力和上地幔垂直力作用到地壳后引起的应力迭加的结果。综述了前人利用断裂力学理论与实验结果研究地壳中断裂传播时所持的不同观点。地壳中断裝的传播不只是受断裂力学规律本身的制约,外部附加的剪切应力对断裂的传播也起着重要作用。地壳下部大断裂蠕滑所产生的施加在地壳上层底部的分布剪切力在地壳上层中产生的附加剪切力可以增强原来断裂端部的剪切应力,使岩体首先超过抗剪强度因而断裂沿合成剪切力的方向快速错动,从而形成了地壳中长而直的断裂带。利用弹性体的半空间问题推导了分布剪切力在地壳上层产生的附加应力场和估算了附加剪切应力和附加张应力的大小。利用静力弹性位错理论分析了软弱区引起的像力对断裂扩展的影响。在实际地壳中介质並不是均匀的,在地壳上层还可能存在一些局部的破碎区、软弱区。积累单元断层面除受有效构造应力外还受到由于断层物质蠕变形成的附加剪切应力和由于软弱区、破碎区的存在形成的附加剪切应力的作用,这两种附加剪切应力都是时间的函数,随着时间的增加而增加,而且像力还和积累单元断层面到软弱区的距离成反比。断裂的传播要受到软弱区对它作用的像力,即相当于附加了一个剪切应力在断裂端部,增加了断裂端部的应力强度因子。最后讨论了震源断层面的下方有岩浆侵入时的防拐作用。当孕裳的脆性层底部有热物质侵入而形成直线凹槽时断裂沿其传播也不拐弯。 相似文献
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本文对一九七○年一月五日在云南通海、峨山、建水三县交界地区沿曲江河谷发生的7.7极地震序列的时空特征进行了研究。认为通海地震序列是一个前震活动明显,没有临震前震、主震能量大,余震衰减快的典型主震型序列。主震震源机制求得的断层面、主震宏观等震线的长轴方向和余震分布的长轴方向完全一致,都与曲江断裂重合。故认为通海大震是曲江断裂在北北西向压应力作用下的一次从中间开始向两端破裂的新活动。 相似文献
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1966年3月22日邢台7.2级地震极震区的人工爆炸地震波场十分复杂。其运动学和动力学特征表明,沿人工爆炸测线地区的深处存在着许多深断裂,且将全测线切割成为五个块段,断裂面常延伸到莫霍界面和上地幔顶部的坚硬介质。极震区则为更特殊的块段结构。 极震区人工爆炸地震波的视速度V~*、视周期T~*、界面速度V_d、介质对能量的吸收系数α~*均有异常的变化,是一个断裂错综分布,宽约10-20公里的破碎地带。 7.2级地震震中区下面存在着两组深大断裂,且在此汇集。在震源深度附近的介质中,局部水平错动可达4公里左右,上地幔顶部在此隆起。 相似文献
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岩石受载内部微裂纹扩展及其震源机制反演有助于认识宏观裂纹扩展过程的非线性断裂力学行为.借助声发射监测手段,本文建立了仅涉及微裂纹张开/闭合和剪切滑移的位移不连续震源模型,通过各位置处传感器耦合质量标定及点源远场P波矩张量反演获得了含预制裂纹砂岩受载过程的震源机制解及时变响应特征,在全局坐标系下分析了微裂纹的三种断裂力学行为.结果表明:在位移不连续模型中,震源矩张量特征值与试样泊松比之间必须满足特定约束条件,该约束条件下的优化问题可采用拉格朗日乘子和Levenberg-Marquardt迭代法求解;受载砂岩裂纹扩展过程中,声发射震源以剪切滑移机制占优,微裂纹空间取向及运动方向与试样宏观主裂纹夹角平均值分别为40.9°和17.7°;对微裂纹体积分解表明岩体微观破裂机制以沿X方向I型张开为主,而沿Y方向的II型断裂滑移方向与试样全局变形方向相一致,由于试样内部晶粒分布非均质性造成了少量沿Z方向的III型平面外微裂纹滑移行为;受载砂岩裂纹扩展过程中微裂纹模式角与震源极性值变化趋势一致、利用震源震级评估的局部应力降值与实验观测结果相吻合,这两者均表明了位移不连续模型在震源机制定量反演中的适用性. 相似文献
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共搜集到１９６０￣１９９０年中、南美洲地区１０个地震序列。其中１个是板内地震序列。这个板内地震序列表现出的特征是：震中分布区域的长轴较短,长短轴之比低;余震震源机制和主震震源机制相比变化大。其余９个是俯冲带上的板缘地震序列,它们的共同特征是：震中分布区域的长轴较长;震源深度下限超过地壳,可以达到７０ｋｍ以下（第１０号序列例外）;主震的震源机制受俯站带的走向、倾向和倾角的控制。但是这些震序列又分为两 相似文献
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STUDY ON SOURCE PARAMETERS OF THE 8 AUGUST 2017 M7.0 JIUZHAIGOU EARTHQUAKE AND ITS AFTERSHOCKS,NORTHERN SICHUAN 
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下载免费PDF全文 WU Wei-wei WEI Ya-ling LONG Feng LIANG Ming-jian CHEN Xue-fen SUN Wei ZHAO Jing 《地震地质》1979,42(2):492-512
On August 8, 2017, a strong earthquake of M7.0 occurred in Jiuzhaigou County, Aba Prefecture, northern Sichuan. The earthquake occurred on a branch fault at the southern end of the eastern section of the East Kunlun fault zone. In the northwest of the aftershock area is the Maqu-Maqin seismic gap, which is in a locking state under high stress. Destructive earthquakes are frequent along the southeast direction of the aftershocks area. In Songpan-Pingwu area, only 50~80km away from the Jiuzhaigou earthquake, two M7.2 earthquakes and one M6.7 earthquake occurred from August 16 to 23, 1976. Therefore, the Jiuzhaigou earthquake was an earthquake that occurred at the transition part between the historical earthquake fracture gap and the neotectonic active area. Compared with other M7.0 earthquakes, there are few moderate-strong aftershocks following this Jiuzhaigou earthquake, and the maximum magnitude of aftershocks is much smaller than the main shock. There is no surface rupture zone discovered corresponding to the M7.0 earthquake. In order to understand the feature of source structure and the tectonic environment of the source region, we calculate the parameters of the initial earthquake catalogue by Loc3D based on the digital waveform data recorded by Sichuan seismic network and seismic phase data collected by the China Earthquake Networks Center. Smaller events in the sequence are relocated using double-difference algorithm; source mechanism solutions and centroid depths of 29 earthquakes with ML≥3.4 are obtained by CAP method. Moreover, the source spectrum of 186 earthquakes with 2.0≤ML≤5.5 is restored and the spatial distribution of source stress drop along faults is obtained. According to the relocations and focal mechanism results, the Jiuzhaigou M7.0 earthquake is a high-angle left-lateral strike-slip event. The earthquake sequence mainly extends along the NW-SE direction, with the dominant focal depth of 4~18km. There are few shallow earthquakes and few earthquakes with depth greater than 20km. The relocation results show that the distribution of aftershocks is bounded by the M7.0 main shock, which shows obvious segmental characteristics in space, and the aftershock area is divided into NW segment and SE segment. The NW segment is about 16km long and 12km wide, with scattered and less earthquakes, the dominant focal depth is 4~12km, the source stress drop is large, and the type of focal mechanism is complicated. The SE segment is about 20km long and 8km wide, with concentrated earthquakes, the dominant depth is 4~12km, most moderate-strong earthquakes occurred in the depth between 11~14km. Aftershock activity extends eastward from the start point of the M7.0 main earthquake. The middle-late-stage aftershocks are released intensively on this segment, most of them are strike-slip earthquakes. The stress drop of the aftershock sequence gradually decreases with time. Principal stress axis distribution also shows segmentation characteristics. On the NW segment, the dominant azimuth of P axis is about 91.39°, the average elevation angle is about 20.80°, the dominant azimuth of T axis is NE-SW, and the average elevation angle is about 58.44°. On the SE segment, the dominant azimuth of P axis is about 103.66°, the average elevation angle is about 19.03°, the dominant azimuth of T axis is NNE-SSW, and the average elevation angle is about 15.44°. According to the fault profile inferred from the focal mechanism solution, the main controlling structure in the source area is in NW-SE direction, which may be a concealed fault or the north extension of Huya Fault. The northwest end of the fault is limited to the horsetail structure at the east end of the East Kunlun Fault, and the SE extension requires clear seismic geological evidence. The dip angle of the NW segment of the seismogenic fault is about 65°, which may be a reverse fault striking NNW and dipping NE. According to the basic characteristics of inverse fault ruptures, the rupture often extends short along the strike, the rupture length is often disproportionate to the magnitude of the earthquake, and it is not easy to form a rupture zone on the surface. The dip angle of the SE segment of the seismogenic fault is about 82°, which may be a strike-slip fault that strikes NW and dips SW. The fault plane solution shows significant change on the north and south sides of the main earthquake, and turns gradually from compressional thrust to strike-slip movement, with a certain degree of rotation. 相似文献
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基于有限断层模型，利用远场体波波形数据研究了2004年7月11日西藏MW62级地震的震源破裂过程.结果表明该地震是一个以倾滑为主的浅源正断层型地震，震源深度为125km，断层面走向152°，倾角44°，平均倾滑角-117°.破裂在震中处成核，然后以28km/s的平均速度向两侧传播，在震中以东偏北5km处达到最大滑动43cm.该地震主张力轴近E W方向，受浅部NNW SSE或N S向裂谷带控制，青藏高原南部的逆冲运动是引发这次地震的直接原因. 相似文献
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本研究采用双差定位法对2013年4月20日发生在龙门山断裂带上的四川芦山7.0级强震及主震后48小时内504次余震序列进行重新定位,最终得到328个精定位地震事件.结果表明,余震在水平方向上主要沿龙门山断裂带的山前断裂西南段的大川-双石断裂发生,扩展模式以西南向为主(约23 km)兼有弱东北向(约12 km),并非简单的单侧扩展.在深度方向上,余震主要以铲状结构分布在18～22 km之间.通过拟合精定位后的小震空间分布特征,显示本次地震断层面倾角在15～25 km深度范围内由主震处约44°逐渐向西南向扩展增大至约73°,可能表明断层往西南破裂过程中走滑分量逐渐增强,与2008年汶川地震引起中央断裂倾角由西南向东北变化相类似. 相似文献
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北京时间2013年1月29日,哈萨克斯坦发生MS6.1地震,为了提高对地震震源机制解的认识,并进一步了解震源区的应力场特征,利用CAP方法反演了此次地震序列震源机制解.反演结果表明,MS6.1地震节面Ⅰ的参数：走向241°,倾角80°,滑动角7°;节面Ⅱ的参数：走向150°,倾角84°,滑动角170°;P轴方位为196°,倾角2°,T轴方位为105°,倾角12°;矩震级MW为6.1;矩心深度为13km;震源类型是左旋走滑型.此次地震序列破裂优势方向为NEE—SWW,倾角以30°～60°居多,滑动角以60°～120°、-60°～-120°居多;P轴方位的优势取向为近NE—SW向,接近水平的居优;T轴优势取向为近SEE—NWW向,接近垂直的居优;震源机制类型以倾向滑动型为主.反演结果与断层的分布、余震分布及哈萨克斯坦中天山（伊犁盆地西部）NEE—SWW向应力场有很好的一致性. 相似文献
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STUDY ON THE SEISMOGENIC FAULT AND DYNAMICS PARAME-TERS OF THE 2014 MS6.6 JINGGU EARTHQUAKE IN YUNNAN 下载免费PDF全文
下载免费PDF全文 On October 17, 2014, a MS6.6 earthquake occurred in Jinggu, Yunnan. The epicenter was located in the western branch of Wuliang Mountain, the northwest extension line of Puwen Fault. There are 2 faults in the surrounding area, one is a sinistral strike-slip and the other is the dextral. Two faults have mutual intersection with conjugate joints property to form a checkerboard faulting structure. The structure of the area of the focal region is complex. The present-day tectonic movement is strong, and the aftershock distribution indicates the faulting surface trending NNW. There is no obvious surface rupture related to the known fault in the epicenter, and there is a certain distance from the surface of the Puwen fault zone. Regional seismic activity is strong. In 1941, there were two over magnitude 7.0 earthquakes in the south of the epicenter of Jinggu County and Mengzhe Town. In 1988, two mainshock-aftershock type earthquakes occurred in Canglan-Gengma Counties, the principal stress axes of the whole seismic area is in the direction of NNE. Geological method can be adopted to clarify the distribution of surficial fracture caused by active faults, and high-precision seismic positioning and spatial distribution characteristics of seismic sequences can contribute to understand deep seismogenic faults and geometric features. Thus, we can better analyze the three-dimensional spatial distribution characteristics of seismotectonics and the deep and shallow tectonic relationship. The focal mechanism reveals the property and faulting process to a certain extent, which can help us understand not only the active property of faults, but also the important basis for deep tectonic stress and seismogenic mechanism. In order to study the fault characteristic of the Jinggu earthquake, the stress field characteristics of the source area and the geometric parameters of the fault plane, this paper firstly uses the 15 days aftershock data of the Jingsuo MS6.6 earthquake, to precisely locate the main shock and aftershock sequences using double-difference location method. The results show that the aftershock sequences have clustering characteristics along the NW direction, with a depth mainly of 5~15km. Based on the precise location, calculations are made to the focal mechanisms of a total of 46 earthquakes including the main shock and aftershocks with ML ≥ 3.0 of the Jinggu earthquake. The double-couple(DC)component of the focal mechanism of the main shock shows that nodal plane Ⅰ:The strike is 239°, the dip 81°, and the rake -22°; nodal plane Ⅱ, the strike is 333°, the dip 68°, and the rake -170.31°. According to focal mechanism solutions, there are 42 earthquakes with a focal mechanism of strike-slip type, accounting for 91.3%. According to the distribution of the aftershock sequence, it can be inferred that the nodal plane Ⅱ is the seismogenic fault. The obtained focal mechanism is used to invert the stress field in the source region. The distribution of horizontal maximum principal stress orienation is concentrated. The main features of the regional tectonic stress field are under the NNE-SSW compression(P axis)and the NW-SE extension(T axis)and are also affected by NNW direction stress fields in the central region of Yunnan, which indicates that Jinggu earthquake fault, like Gengma earthquake, is a new NW-trending fault which is under domination of large-scale tectonic stress and effected by local tectonic stress environment. In order to define more accurately the occurrence of the fault plane of the Jinggu earthquake, with the precise location results and the stress field in the source region, the global optimal solution of the fault plane parameters and its error are obtained by using both global searching simulated annealing algorithm and local searching Gauss-Newton method. Since the parameters of the fault plane fitting process use the stress parameters obtained by the focal mechanism inversion, the data obtained by the fault plane fitting is more representative of the rupture plane, that is, the strike 332.75°, the dip 89.53°, and the rake -167.12°. The buried depth of the rupture plane is 2.746km, indicating that the source fault has not cut through the surface. Based on the stress field characteristics and the inversion results of the fault plane, it is preliminarily believed that the seismogenic structure of the Jinggu earthquake is a newly generated nearly vertical right-lateral strike-slip fault with normal component. The rupture plane length is about 17.2km, which does not extend to the Puwen fault zone. Jinggu earthquake occurred in Simao-Puer seismic region in the south of Sichuan-Yunnan plate. Its focal mechanism solution is similar to that of the three sub-events of the Gengma earthquake in November 1988. The seismogenic structure of both of them is NW-trending and the principal stress is NE-SW. The rupture plane of the Jinggu main shock(NW direction)is significantly different from the known near NS direction Lancang Fault and the near NE direction Jinggu Fault in the study area. It is preliminarily inferred that the seismogenic structure of this earthquake has a neogenetic feature. 相似文献
18.
2002～2003年长白山火山区的水平运动缺乏中心对称性分布特征,本文采用同一深度沿三个互相垂直方向拉张的点源模式模拟了长白山火山区的岩浆囊压力变形源. 在介质参数为Vp＝6.700 km/s,Vs＝3.8700 km/s,ρ＝2900 kg/m3的均匀弹性半空间中, 联合利用2002～2003年长白山火山区的GPS观测数据和水准数据, 结合PSGRN/PSCMP代码和遗传算法反演长白山火山区的压力变形源特征. 反演结果表明,由三个垂直的不等量扩张方向确定的椭球状点源模型可以较好地模拟长白山火山区岩浆囊压力变形源. 岩浆囊深处9.2 km,在走向为34.4°,倾角为82.2°的断层面的法向方向体积扩张量最大,达到7000000 m3;在走向为3028°,倾角为78.5°的断层面的法向方向体积扩张量次之,达到6598071 m3;在走向为337.7°,倾角为14.0°的断层面的法向方向体积扩张量最小,达到5220160 m3. 相似文献
19.
MECHANISM OF THE 2015 PISHAN,XINJIANG, MS6.5 MAINSHOCK AND RELOCATION OF ITS AFTERSHOCK SEQUENCES 下载免费PDF全文
下载免费PDF全文 Using the digital broadband seismic data recorded by Xinjiang network stations, we obtained focal mechanism of the July 3 Pishan, Xinjiang, MS6.5 earthquake with generalized Cut and Paste(gCAP)inversion method. The strike, dip and rake of first nodal plane are 97°, 27°, 51°, and the second nodal plane are 318°, 70°, 107°. The centroid depth and moment magnitude are calculated to be 12km and 6.4. Combining with the distribution of aftershocks, we conclude that the first nodal plane is the seismogenic fault, and the main shock presents a thrust earthquake at low angle. We relocated 1014 earthquakes using the double-difference algorithm, and finally obtained 937 relocated events. Our results show that the earthquake sequences clearly demonstrate a unilateral extension about 50km nearly in NWW direction, and are mainly located above 25km depth, especially the small earthquakes are predominately located at the shallow parts. Furthermore, the focal depth profile shows a southwestward dipping fault plane at the main shock position, suggesting listric thrust faulting, which is consistent with the dip of the mainshock rupture plane. The spatial distribution of aftershocks represents that the Tarim block was thrust under the West Kunlun orogenic belt. In addition, the dip angle of the fault plane gradually increases along the NWW direction, possibly suggesting a gradual increase of strike-slip component during the NWW rupturing process. From above, we conclude that the Pishan MS6.5 earthquake is the result of Tibet plateau pushing onto the Tarim block from south to north, which further confirms that the continuous collision of India plate and Eurasia plate has strong influence on the seismic activity in and around the Tibet plateau. 相似文献