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《地球物理学报》2020,(9)
滇西北宾川盆地是发育于红河断裂和程海断裂交汇处的晚新生代张扭断陷盆地,该区活动断裂发育且历史地震比较活跃.对宾川盆地及邻区进行高精度浅层和上地壳精细结构研究,有助于深入认识该区主要发震构造的深浅部特征.基于2017年在宾川盆地及其附近开展的为期2个月的密集台阵观测数据,我们对该区96个小震共拾取了117221条初至P波和5475条初至S波震相,并利用simul2000开展了地震重定位和体波层析成像研究.结果表明:(1)小震活动主要集中在宾川盆地东缘断裂的弧形转折部位,并在洱海南侧呈现沿北东向断裂的条带状分布现象,反映了区域上近南北向至北东向断裂是主要控震构造,其次是北西向断裂带.(2)0 km的速度分布与区域地形有很好的对应关系.山地呈现高速异常,宾川盆地呈现低速异常.从3 km至9 km,高低速分界与断层有很好的对应,并且越往深部,近南北向至北北东向的宾川盆地东缘断裂在上地壳构造的控制作用越明显.(3)上地壳层析成像结果同时揭示了宾川盆地东缘断裂的三维形态变化在空间上呈现出南北部倾角大、中部倾角缓的变化特征,可能与区域地块的旋转变形过程有关.(4)综合高精度浅层速度结构和地震重定位结果可知,区域上的近南北向至北北东向断裂正逐步取代北西向构造,成为主要的区域分界断裂和控震构造.新的研究结果为深入理解该区的主要控震构造及其深部结构特征提供了重要依据. 相似文献
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山西忻定盆地活动断裂几何学、运动学特征及地震活动性研究 总被引：1，自引：0，他引：1
忻定盆地主要受北东和北北东向两组断裂控制,盆地内部还发育一组北西向次级隐伏断裂。研究表明,北东向断裂为张性正断层,其活动主要表现为沿断裂两侧的差异升降运动;北北东向断裂除了表现出沿断裂两侧差异升降运动外,兼有右旋走滑运动。第四纪以来,北西向区域引张应力场对该区断裂的活动有重要影响,使得盆地南东一侧断裂活动加强,北西一侧断裂活动减弱,盆地由北西向南东发生掀斜。此外,在断裂活动程度方面,北东向断裂沿走向具有明显的分段性。区内M≥7级地震的产生主要与盆地南东一侧断裂的强烈活动有关。 相似文献
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福建沿海地区断裂构造发育,有北北东—北东向,北西向、东西向、南北向及环状或弧形断裂等构造系。近期以北北东—北东向压扭性断裂和北西向张扭性断裂活动性最强。它们控制着本区海岸地貌的发育以及地震的发生和分布。本文拟根据地壳垂直形变及海平面变化的资料,讨论本区有强震产生的活动断裂与地震活动。 相似文献
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1969年渤海7．4级地震区地质构造和发震构造的初步研究 总被引：14，自引：0，他引：14
根据石油地质勘探资料和地震学等研究的成果,对1969年渤海7.4级地震的构造条件作了具体而较深入的分析,填补了华北渤海大震区地震构造研究的空白.震区位于渤海湾新生代裂陷盆地的东部,地处北北东向营潍断裂带与北西向北京-蓬莱断裂带交汇的地区.早第三纪断陷阶段,该区于地壳上部主要发育北北东、北西和东西向3组断裂,呈铲状和平面状形态,正断性质,多属断陷主断裂.晚第三纪以来的拗陷阶段,先存断裂有不同程度的活动;同时还新发育一条北东向黄河口-庙西北断裂带.7.4级地震的震源断层走向为北东45°,倾向南东,近于直立,呈右旋走滑性质,埋藏于15～34km的深度范围.大震的发震断裂不是营潍断裂带,而是黄河口-庙西北新生断裂带. 相似文献
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利用双差重定位方法对北京地区(39.2°N～41.2°N,115.2°E～117.6°E)2008年10月至2020年3月期间共6463个地震事件进行重新定位,得到4776个高质量地震事件的空间位置分布。定位结果均方根走时残差显著降低,震源间的相对位置精度明显提高,地震活动的成丛性与活动断层之间的关系更加密切。根据重定位结果探讨了小震活动与活动断裂及深浅构造的关系,得到以下结论:夏垫断裂小震活动强烈,重定位后震中分布明显向断裂靠拢,呈现沿断裂走向延伸的NE向线状分布。结合人工剖面探测结果推测,该区域深度剖面上小震集中带10km深度附近较宽的丛集区主要是浅部铲形断裂活动所致,14～22km深度附近相对较窄近直立的小震丛集为深部断裂活动产生。怀—涿次级盆地北缘断裂现今小震活动活跃,该区域小震深度剖面揭示该断裂为倾向南东、上陡下缓的铲形断层。结合人工剖面探测结果,分析认为该区域深浅断裂共存和非均匀的地壳结构为中强地震发生的深部构造背景。平原区内部小震分布与第四纪断陷盆地和地层厚度分布存在较强的相关性,研究区域内部昌平—海淀小震集中区、顺义小震集中区、夏垫小震丛集区和廊坊小震丛集区分别位于马池口—沙河断陷盆地、顺义断陷盆地、大厂断陷盆地和固安—廊坊—永清断陷盆地。根据小震空间密集成带分布特征来推测未知断裂,推测怀柔南部山区小震集中区下方存在隐伏断层,宝坻至夏垫断裂段之间NW向的小震集中分布区下方存在一条走向NW或者NWW的隐伏断层。 相似文献
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在对 1999年 5月 15日山西省应县—浑源 ML4.6地震宏观烈度考察的基础上 ,得出极震区烈度为 度 ,呈椭圆形 ,长轴走向北东 ,长度 13km,短轴 10 km,面积 10 2 km2的结论。分析了地震的发震构造 ,认为北东向的恒山北麓断裂是控制大同盆地的南部边界断裂 ,为控震构造 ,北西向的次级活动断层为此次地震的发震构造。指出 ,该次地震破坏较重的原因是由于震源浅 相似文献
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本文以1978年8月10日在台湾海峡中北部发生的5.3级地震为典型震例,讨论该区地震构造,认为该区处于北东—北北东、北西、近东西向等多组活动断裂复合交汇的地区,且与台湾陆壳同属一个地质块体。以此为基础进而分析了该区地震活动的时间、空间和强度特征,并和台湾省以东海域强震活动作了对比,认为两区域的地震活动存在一定程度的相关性。 相似文献
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我省属东南地洼区的一部分,地质构造比较复杂,主要有近东西向、北东向(包括北北东向)和北西向三大构造体系。但与破坏性地震有关的孕震构造主要是北东向,特别是其中之北北东向断裂构造,其次是东西向。北西向断裂虽较活跃,但规模小,一般为发震构造。在地震关系密切的晚第三纪以来的新构造运动,比沿着上述老断裂带继承活动为主。但各断裂带及其不同地段活动强度则有较大的差别。 相似文献
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喀喇昆仑断层位于我国新疆、西藏和阿富汗、克什米尔之间,是亚洲大陆中部一条巨型的右旋走滑断裂带,长约1000km,呈北西向展布,十分醒目。喀喇昆仑断层和阿尔金断层形成一个巨大的挤出构造,使青藏高原向东运动,对东亚的新构造和地震活动具有重要的控制作用。木吉-塔什库尔干盆地是公格尔山和慕士塔格山西侧一条串珠状断陷盆地带,东西两侧发育系列山前活动断裂,主要表现为正断层。这里曾发生多次强震活动,3条地震形变带(地震断层)已被发现。塔什库尔干断裂带呈北北西走向,是喀喇昆仑断层北部的一条分支 相似文献
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The morphotectonic framework of the Central Apennines is given by faulted blocks bounded by normal faults, mostly trending NW–SE, NNW–SSE and NE–SW, which cut previous compressive structures. Such a structural setting is consistent with the focal mechanisms of the earthquakes which often occur in this area. In this paper, three lithologically different normal fault-generated mountain fronts are analysed in order to assess the relations between their geomorphic features and active tectonics. They border the Norcia depression (Sibillini Mts, Umbria), the Amatrice–Campotosto plateau (Laga Mts, Lazio) and the Fucino basin (Marsica Mts, Abruzzi). The Norcia depression is bounded by a N20°W trending normal fault to the east and by a parallel antithetic fault to the west. The main fault has a 1000 m throw and gives rise to a wide fault escarpment, characterized by: (1) sharp slope breaks due to low angle gravity faults; (2) important paleolandslides; and (3) several fault scarplets on the piedmont belt affecting Quaternary deposits. The Amatrice–Campotosto plateau is delimited by the western slope of Mt Gorzano which runs along a N20°W trending normal fault having a 1500m throw. Minor parallel faults dislocate Quaternary landforms. Large-scale massmovements also occur here. The Fucino basin was struck by the 1915 Avezzano earthquake (I=XI MCS) which produced extensive surface faulting along two parallel NW trending normal fault escarpments on the eastern border of the basin. There is paleoseismic evidence including buried gravity graben in Late Glacial gravels and tectonic dip-slip striations on Holocene calcitic crusts covering bedrock normal fault planes. These data suggest that active extensional tectonics plays a major role in the slope morphogenesis of the Central Apennines and they indicate the importance of geomorphic analysis in seismic zonation of this area. 相似文献
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Cristiano Collettini Massimiliano Barchi Cristina Pauselli Costanzo Federico Giampaolo Pialli 《Journal of Geodynamics》2000,29(3-5)
This paper deals with the geometry and kinematics of the active normal faults in northern Umbria, and their relationship with the seismicity observed in the area. In particular, we illustrate the contribution of seismic reflection data (a network of seismic profiles, NNW–SSE and WSW–ENE trending) in constraining at depth the geometry of the different active fault systems and their reciprocal spatial relationships. The main normal fault in the area is the Alto Tiberina fault, NNW trending and ENE dipping, producing a displacement of about 5 km, and generating a continental basin (Val Tiberina basin), infilled by up to 1500 m with Upper Pliocene–Quaternary deposits. The fault has a staircase trajectory, and can be traced on the seismic profiles to a depth of about 13 km. A set of WSW-dipping, antithetic faults can be recognised on the profiles, the most important of which is the Gubbio fault, bordering an extensional Quaternary basin and interpreted as an active fault based on geological, geomorphologic and seismological evidence. The epicentral distribution of the main historical earthquakes is strictly parallel to the general trend of the normal faults. The focal mechanisms of the major earthquakes show a strong similarity with the attitude of the extensional faults, mapped at the surface and recognised on the seismic profiles. These observations demonstrate the connection between seismicity in the area and the activity of the normal faults. Moreover, the distribution of the instrumental seismicity suggests the activity of the Alto Tiberina fault as the basal detachment for the extensional tectonics of the area. Finally, the action of the Alto Tiberina fault was simulated using two dimensional finite element modelling: a close correspondence between the concentration of shear stresses in the model and the distribution of the present earthquakes was obtained. 相似文献
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深井盆地南缘断裂特征与活动性研究 总被引：1，自引：0，他引：1
深井盆地是山西断陷盆地带北段内部一个规模很小的次级盆地,为中更新世以来发育的三角型山间小型盆地。盆地附近断裂发育,构造复杂,深井盆地南缘断裂为主控边界断裂,控制着盆地的发展演化。本文通过对地形地貌、断裂剖面、地层测年及地震活动等方面的分析和研究,获得了断裂活动时代和活动速率等参数,综合阐述了断裂的空间展布及活动特征。研究表明:深井盆地南缘断裂晚第四纪期间仍在活动,最新活动时代为晚更新世晚期;断裂具有分段性,西段长约6km,多处可见断裂错断晚更新世地层剖面,属正断倾滑性质;东段表现为盆地与黄土斜坡直接接触,由西向东断裂地貌表现逐渐减弱,未见明显的断裂剖面,止于NW向构造,附近发生的4次4 3/4级地震与该段断裂关系密切。 相似文献
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本文使用新疆区域数字地震台站记录的宽频带长周期数字波形资料,在时间域反演了2008年10月5日新疆乌恰6.8级地震的强余震及其周围先后发生的52次中等强度地震的矩张量解,结合Harvard大学在该区域的地震矩张量结果,研究了帕米尔东北缘的应力场分区特征.研究结果显示,位于印度板块向欧亚板块推挤的前缘及向北凸出的弧型构造的最北缘的卡兹克阿尔特弧形活动褶皱-逆断裂带,以逆冲推覆活动为主,并有部分走滑类型的地震,基本不存在正断层类型的地震;该弧型构造近东西走向的顶部(文中的西区)与其北西走向的东侧(文中的东区)的局部应力场最大主压应力方向不同,分别为NW、NNE方向,显示出在承受印度板块向欧亚板块俯冲作用的同时,东区也更多的受到了塔里木块体顺时针旋转作用的影响.位于帕米尔陆内俯冲和变形作用强烈、碰撞造成深源地震带东段的南区,地震以走滑错动为主, 逆断、正断层都有,显示出相对复杂的应力状态.位于帕米尔高原内部的西区和南区的应力场最大主压应力方向一致,由北向南,由最大主压应力轴接近水平,过渡为最大主张应力轴接近水平,一定程度揭示了板块俯冲的状态.结合南区和西区的地震深度差异及机制解中断层面的倾角,推测在中帕米尔的东部,由北向南的板块俯冲至150~170km深度,俯冲角度为60°左右. 相似文献
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In this paper we discuss the seismogenic structures of the two earthquakes occurring in the Beibu Gulf waters,based on the investigation of geological structure,faults,geophysical fields,seismicity and earthquake focal mechanism.The results show that the NEE trending faults along the boundary of the Wushi depression are the dominating seismogenic structures,and the NW trending faults are the key factors of stress concentration.The results also show that high seismicity has a significant relationship with the late Cenozoic deposition center in the Beibu Gulf,and their NE-NEE trending boundary faults are important to the identification of seismogenic structures.The special arcuate fault segment or the intersection point of the NW trending faults and NE-NEE trending boundary faults is a possible location of future earthquakes. 相似文献
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利用双差定位方法对玉树地震序列2010年4月14日至10月31日间发生的ML≥1.0地震进行双差定位,得到1545个地震的重定位结果.综合分析地震双差定位结果和玉树地震序列中强地震震源机制解,发现玉树MS7.3地震发震构造由北西向和北东东向两条相交断层组成,主震发生在北西走向的甘孜—玉树断裂带上,5月29日的MS5.9余震序列发生在北东东走向的一条隐伏断裂上,两条断裂均接近直立.甘孜—玉树断裂是羌塘地块和巴彦喀拉地块的构造边界,由于羌塘地块和巴颜喀拉地块的差异运动使甘孜—玉树断裂强耦合段应力高度积累,在应变能超过岩石强度时破裂失稳发生了MS7.3地震.主震断层的左旋滑动导致北东东向断层的正应力减小,库伦应力增加,45天后触发了MS5.9余震序列的活动. 相似文献
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帕米尔高原位于地中海－喜马拉雅地震带上,晚新生代以来随着印度板块向欧亚板块持续不断地挤压汇聚,其构造运动是欧亚大陆最强烈的地区。高原腹地发育一系列近SN向正断层,包括近SN向的塔什库尔干正断层所处的帕米尔中部现代区域的构造应力场以EW向水平拉张为主。2016年11月25日发生的阿克陶MS 6.7级地震的发震构造为塔什库尔干断层分支的NWW向木吉盆地北缘断层,其具有右旋走滑兼正断性质。地震在震中附近产生同震地表形变带,全长约1km,呈近SN－NNE向水平拉伸,发育近EW—NWW向的张裂缝,为地震破裂的产物,张裂缝的最大水平拉伸位移量和最大垂直位移量分别为46cm和16cm。地表破裂带中的NE和NW向张剪裂缝只是连接贯通这些雁列的张裂缝,其水平相对位移量取决于张裂缝的水平拉伸量和张裂缝之间的几何关系。地表形变带表现的拉张性质与帕米尔高原腹地区域现代应力场最大主压应力为垂直向基本一致,可能与深部热物质上涌造成的上地壳拉伸有关。而地表形变带呈近SN向水平拉张,与区域近EW向拉张应力场之间存在显著差异,这可能是木吉盆地北缘右旋走滑正断层阶区局部应力场调整的结果。 相似文献
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Bingqiang Yuan Lijun Song Li Han Shaole An Chunguan Zhang 《Geophysical Prospecting》2018,66(8):1586-1601
The Tobago Basin, which is located offshore northern Venezuela with a southern margin close to Trinidad and Tobago, has an area of approximately 59,600 km2. The Tobago Basin has relatively favourable hydrocarbon prospects, and to date, exploration work has mainly concentrated on small areas of the southwestern portion of the basin. To conduct a comprehensive study of the structural framework of the basin and the characteristics of the basement in order to identify prospective zones for hydrocarbon exploration, shipborne‐measured and satellite‐measured gravity data, shipborne‐measured magnetic data, and aeromagnetic survey data were analysed. A regularisation filtering method was used to separate and obtain regional and residual gravity and magnetic anomalies. Directional gradients of gravity and magnetic anomalies and the total horizontal gradient and vertical second derivative of gravity anomalies were employed to extract information about fault structures. Regression analysis methods were used to determine the basement depth. The geological significance of the gravity and magnetic fields was examined, the structural framework of the basin was assessed, the basement depth was estimated, and favourable hydrocarbon exploration prospects within the basin were identified. The results show that the Tobago Basin contains complex structures consisting mainly of two groups of faults trending in northeasterly and northwesterly directions and that the major northeasterly trending faults control the main structural configuration and depositional system within the basin. The basement of the Tobago Basin has deep rises and falls. It can be divided into the following four secondary tectonic units: the western sub‐basin, the central uplift area, the southern sub‐basin, and the northeastern sub‐basin. The central uplift area and northeastern sub‐basin are most likely to have developed hydrocarbon accumulations and should be targeted for further exploration. 相似文献