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1.
1902年阿图什81/4级地震发生在西南天山山前推覆构造体中,逆冲推覆构造由推覆体的根部断裂、推覆体、滑脱断层和前缘逆断裂-褶皱等组成,大地震的发震断裂往往是推覆构造的根部断裂,而地震地表破裂和同震褶皱隆起则位于山前逆断层-褶皱带内。高震级的潜在震源区(MU7.5)对应于低速的天山地块和高速的塔里木地块之间的根带断裂,其长度对应于推覆体根带断裂的长度,宽度对应于根带隐伏逆冲断裂在地表的投影宽度。推覆体前缘的每个活动逆断裂-背斜对应于一个潜在震源(MU≤7.5),其长度与活动逆断裂-背斜的长度相等,宽度应覆盖活动褶皱的两翼。潜在震源的矩震级上限由W-C统计关系式确定,其中发震断裂的面积为活动褶皱的长度与隐伏断坡宽度的乘积。 相似文献
2.
通过对天山北麓 190 6年玛纳斯 7 7级地震区的浅层地震探测资料、石油地震反射剖面、二维电性结构剖面、深地震反射剖面的研究 ,发现玛纳斯地震区多层次活动构造系统的根带 ,它通过脆 -韧转换带与天山活动构造块体内上地壳中的低速、高导层连为一体。低速、高导层可能是天山地壳内正在活动的韧性剪切带 ,而齐古逆断裂 -褶皱带下的脆 -韧转换带是连接深部活动韧性剪切带与地壳浅部脆性破裂的枢纽 ,也是现今孕育和发生大地震的重要构造部位。 190 6年玛纳斯地震发生在脆韧转换带的底部 ,地震区的活动逆断裂和褶皱只是部分记录了深部韧性剪切带活动的信息 相似文献
3.
A strong earthquake with magnitude MS6.2 hit Hutubi, Xinjiang at 13:15:03 on December 8th, 2016(Beijing Time). In order to better understand its mechanism, we performed centroid moment tensor inversion using the broadband waveform data recorded at stations from the Xinjiang regional seismic network by employing gCAP method. The best double couple solution of the MS6.2 mainshock on December 8th, 2016 estimated from local and near-regional waveforms is strike:271°, dip:64ånd rake:90° for nodal plane I, and strike:91°, dip:26ånd rake:90°for nodal plane Ⅱ; the centroid depth is about 21km and the moment magnitude(MW)is 5.9. ISO, CLVD and DC, the full moment tensor, of the earthquake accounted for 0.049%, 0.156% and 99.795%, respectively. The share of non-double couple component is merely 0.205%. This indicates that the earthquake is of double-couple fault mode, a typical tectonic earthquake featuring a thrust-type earthquake of squeezing property.The double difference(HypoDD)technique provided good opportunities for a comparative study of spatio-temporal properties and evolution of the aftershock sequences, and the earthquake relocation was done using HypoDD method. 486 aftershocks are relocated accurately and 327 events are obtained, whose residual of the RMS is 0.19, and the standard deviations along the direction of longitude, latitude and depth are 0.57km, 0.6km and 1.07km respectively. The result reveals that the aftershocks sequence is mainly distributed along the southern marginal fault of the Junggar Basin, extending about 35km to the NWW direction as a whole; the focal depths are above 20km for most of earthquakes, while the main shock and the biggest aftershock are deeper than others. The depth profile shows a relatively steep dip angle of the seismogenic fault plane, and the aftershocks dipping northward. Based on the spatial and temporal distribution features of the aftershocks, it is considered that the seismogenic fault plane may be the nodal plane I and the dip angle is about 271°. The structure of the Hutubi earthquake area is extremely complicated. The existing geological structure research results show that the combination zone between the northern Tianshan and the Junggar Basin presents typical intracontinental active tectonic features. There are numerous thrust fold structures, which are characterized by anticlines and reverse faults parallel to the mountains formed during the multi-stage Cenozoic period. The structural deformation shows the deformation characteristics of longitudinal zoning, lateral segmentation and vertical stratification. The ground geological survey and the tectonic interpretation of the seismic data show that the recoil faults are developed near the source area of the Hutubi earthquake, and the recoil faults related to the anticline are all blind thrust faults. The deep reflection seismic profile shows that there are several listric reverse faults dipping southward near the study area, corresponding to the active hidden reverse faults; At the leading edge of the nappe, there are complex fault and fold structures, which, in this area, are the compressional triangular zone, tilted structure and northward bedding backthrust formation. Integrating with geological survey and seismic deep soundings, the seismogenic fault of the MS6.2 earthquake is classified as a typical blind reverse fault with the opposite direction close to the southern marginal fault of the Junggar Basin, which is caused by the fact that the main fault is reversed by a strong push to the front during the process of thrust slip. Moreover, the Manas earthquake in 1906 also occurred near the southern marginal fault in Junggar, and the seismogenic mechanism was a blind fault. This suggests that there are some hidden thrust fault systems in the piedmont area of the northern Tianshan Mountains. These faults are controlled by active faults in the deep and contain multiple sets of active faults. 相似文献
4.
新疆主要逆断层-褶皱构造区基本地震构造特征与潜在震源划分问题 总被引：3，自引：1，他引：2
本文介绍了新疆主要逆断层-褶皱构造区的基本特征,并对其潜在震源划分问题进行了初步的讨论。北天山山前推覆构造及乌鲁木齐以南的逆断裂-褶皱构造相对比较简单,由根部断裂、推覆体和前缘逆断裂-褶皱构造所组成;强地震的极震区或地震动的高值区可能位于推覆构造的根部断裂附近,而地震地表破裂和同震地表变形则位于山前逆断层-褶皱带内。南天山的柯坪推覆构造、库车推覆构造、帕米尔东北缘的弧形推覆构造,虽然也由多排逆断裂-褶皱构造带组成,但是其中的规模巨大、发育时间较长的逆断裂-背斜带,往往具备发生强震的条件。强震的极震区分布与地震地表断层位置比较一致,可作为强震的潜在震源。盆地内的新的盲逆断层-褶皱构造也具备发生6.5—7.0 级地震的能力,应作为震级上限为 7.0 级的潜在震源。由于对逆断层-褶皱构造的深浅构造关系及发震模型认识的不足,在潜在震源划分中应考虑这种不确定性。同时在潜在震源区划分中,还应考虑地震构造区的地震活动历史及构造活动性参数。 相似文献
5.
新生代期间强烈而持久的再生造山作用,在天山地区形成了大量近EW向逆断裂-褶皱带,引起地壳强烈缩短,穿插有NW向“类转换断层”,显示出天山地区近NS向不均匀的构造挤压作用;区域上地震构造主要为近EW向逆断裂-褶皱带或盲逆断层,其次为NW向“类转换断层”。巴楚-伽师地震区位于南天山柯坪塔格推覆构造系以南,NE向跨越极震区、长约50km的深地震反射探测表明,1997年伽师强震群的发震构造推测为NW向隐伏“类转换断层”,2003年巴楚-伽师地震(MS6·8)的发震构造为柯坪塔格推覆构造系南缘尚未出露地表的近EW向盲逆断层系 相似文献
6.
柯坪逆冲推覆构造带是西南天山山前晚新生代以来形成的活动逆断裂-褶皱带,由5~6排近平行的弧形褶皱带组成,出露地层为寒武系—第四系。背斜形态多为复式箱状背斜和不对称的斜歪背斜,分别与断层弯曲背斜和断层扩展背斜的几何形态一致。地震勘探资料显示,各褶皱带前缘活动逆断裂在深部归并于统一的、由寒武系中的石膏层组成的滑脱面。滑脱面深度具有南浅北深、东浅西深的特点,皮羌断裂西侧滑脱面深度约为9km,东侧滑脱面深度为5km。在柯坪逆冲推覆构造中部的皮羌断裂东西两侧各5km和8km的位置,以断层弯曲褶皱和断层扩展褶皱构造模型为指导,用线长平衡的方法完成了2条长度分别为78km和73km的平衡地质剖面,恢复到变形前的形态后计算出这2条剖面上的地壳缩短量分别为40km和45km,缩短率为33%和37%。由于对柯坪逆冲推覆构造开始形成时间的证据较少,所以要计算长期的缩短速率是比较困难的。对比天山南麓库车活动逆断裂-褶皱带的形成时代,以及柯坪逆冲推覆构造与印干断裂的关系,认为柯坪逆冲推覆构造形成于第四纪早期的西域砾岩沉积阶段,按距今2.5Ma计算,柯坪逆冲推覆构造的地壳缩短速率是15.4~17.3mm/a 相似文献
7.
The Taigu fault zone is one of the major 12 active boundary faults of the Shanxi fault-depression system, located on the eastern boundary of the Jinzhong basin. As the latest investigation indicated, the fault zone had dislocated gully terrace of the first order, forming fault-scarp in front of the loess mesa. It has been discovered in many places in ground surface and trenches that Holocene deposits were dislocated. The latest activity was the 1303 Hongdong earthquake M=8, the fault appeared as right-lateral strike-slip with normal faulting. During that earthquake, the Taigu fault together with the Mianshan western-side fault on the Lingshi upheaval and the Huoshan pediment fault on the eastern boundary of the Linfen basin was being active, forming a surface rupture belt of 160 km in length. Moreover, the Taigu fault were active in the mid-stage of Holocene and near 7 700 aB.P. From these we learnt that, in Shanxi fault-depression system, the run-through activity of two boundary faults of depression-basins might generate great earthquake with M=8. 相似文献
8.
9.
2013年4月20日发生在龙门山南段的芦山MS7.0地震是继发生在龙门山中北段的汶川MS8.0地震之后的又一次强震。本文通过震后地表变形特征、余震分布、震源机制解、石油地震勘探剖面、历史地震数据等资料,结合前人对龙门山南段主干断裂、褶皱构造特征的研究以及野外实地考察,应用活动褶皱及"褶皱地震"的相关理论,初步分析芦山地震的发震构造模式。认为芦山地震为典型的褶皱地震,发震断裂为前山或山前带一隐伏断裂。构造挤压产生的地壳缩短大部分被褶皱构造吸收。认为龙门山南段前缘地区具有活褶皱-逆断层的运动学特征,表明龙门山逆冲作用正向四川盆地内部扩展。 相似文献
10.
乌鲁木齐市活断层强地面运动预测研究 总被引：1，自引：0，他引：1
介绍了基于乌鲁木齐活断层发震构造模型的强地面运动的预测结果.该项工作是在乌鲁木齐城区开展的活断层探测与地震危险性评价的基础上,设定了两个发震构造,分别为北天山山前逆冲推覆构造和博格达弧西翼逆冲推覆构造,前者可能最大地震震级为7.5级,后者为7.0级,据此建立了分析计算模型.根据地脉动观测分析结果,结合浅层地震勘探、地质图、地形图和钻孔资料,建立了地下三维速度模型,采用统计学的格林函数法、三维有限差分法和混合计算方法,对目标区的地震动进行了预测研究.预测结果表明,断层的结构、破裂方式和三维速度模型对地震动的分布具有显著的影响.沿断层前缘、盆地边缘、覆盖层较厚的地区,以及断层破裂的前方地震动比较显著. 相似文献
11.
Tian Qinjian 《中国地震研究》2007,21(1):74-84
The interaction zone between southern Tianshan and northern Tarim is located at the northeast side of Pamir. It is a region with high seismicity. We constructed a seismotectonic model for the west part of this zone from geological profiles, deep crust seismic detection and earthquake focal mechanisms data. Based on the synthesized geological features, deep crust structure, and earthquake focal mechanisms, we think that the main regional tectonic feature is that the Tianshan tecto-lithostratigraphic unit overthrusts on the Tarim block. The Tianshan tectonic system includes the Maidan fault and thrust sheets in front of the fault; The Tarim tectonic system includes the underground northern Tarim margin fault, conjugate faults in basement and overthrust fault in shallow. The northern Tarim margin fault is a high angle fault deep in the Tarim crust, adjusting different trending deformation between Tianshan and Tarim. It is a major active fault that can generate large earthquakes. The other faults, such as the Tianshan overthrust system and the Tarim basement faults in this area may generate moderately strong earthquakes with different styles. 相似文献
12.
利用Sentinel-1A升轨和降轨数据,基于D-InSAR技术,获取2020年1月19日伽师MS6.4地震同震形变场,并结合其他研究机构给出的震源机制解参数和已有研究成果,反演得到伽师地震的发震断层几何特征和滑动分布。研究结果表明,伽师地震同震形变在地表有明显差异;升轨同震形变在卫星视线方向北侧抬升55 mm,南侧下降42 mm;降轨同震形变在卫星视线方面北侧抬升63 mm,南侧下降23 mm。通过反演得到发震断层走向为275°,倾角为20°,地震滑动主要分布在地下5 km处,最大滑动量约为0.32 m,平均滑动角为89.3°,累积地震矩为1.46×1018 N·m,合矩震级MW6.1,发震构造为具有少量走滑性质的逆冲断裂。从发震构造特征、同震滑动分布推测,伽师地震发震构造是柯坪塔格褶皱带滑脱面以上沉积盖层内的逆冲断裂,支持了柯坪推覆体的薄皮构造模型观点。 相似文献
13.
The seismogenic fault and the dynamic mechanism of the Ning’er, Yunnan Province MS6.4 earthquake of June 3, 2007 are studied on the basis of the observation data of the surface fissures, sand blow and water eruption, landslide and collapse associated with the earthquake, incorporating with the data of geologic structures, focal mechanism solutions and aftershock distribution for the earthquake area. The observation of the surface fissures reveals that the Banhai segment of the NW-trending Ning’er fault is dominated by right-lateral strike-slip, while the NNE-trending fault is dominated by left-lateral strike-slip. The seismo-geologic hazards are concentrated mainly within a 330°-extending zone of 13.5 km in length and 4 km in width. The major axis of the isoseismal is also oriented in 330° direction, and the major axis of the seismic intensity VIII area is 13.5 km long. The focal mechanism solutions indicate that the NW-trending nodal plane of the Ning’er MS6.4 earthquake is dominated by right-lateral slip, while the NE-trending nodal plane is dominated by left-lateral slip. The preferred distribution orientation of the aftershocks of MS≥2 is 330°, and the focal depths are within the range of 3～12 km, predominantly within 3～10 km. The distribution of the aftershocks is consistent with the distribution zone of the seismo-geologic hazards. All the above-mentioned data indicate that the Banhai segment of the Ning’er fault is the seismogenic fault of this earthquake. Moreover, the driving force of the Ning’er earthquake is discussed in the light of the active block theory. It is believed that the northward pushing of the Indian plate has caused the eastward slipping of the Qinghai-Tibetan Plateau, which has been transformed into the southeastern-southernward squeezing of the southwest Yunnan region. As a result, the NW-trending faults in the vicinity of the Ning’er area are dominated by right-lateral strike-slip, while the NE-trending faults are dominated by left-lateral strike-slip. This tectonic framework might be the main cause of the frequent occurrence of MS6.0～6.9 earthquakes in the area. 相似文献
14.
2015年4 月25 日尼泊尔MW7.8特大地震发生在喜马拉雅山南麓, 震源机制解表明该地震为低角度逆冲型地震.通过收集地震区的活动构造研究资料、卫星影像解释和野外实地考察,认为尼泊尔MW7.8地震区地表分布三条主要的逆冲断裂,由北向南分别为喜马拉雅主中央断裂(MCT)、喜马拉雅主边界断裂(MBT)和喜马拉雅主前缘断裂(MFT).主边界断裂和主前缘断裂为晚更新世以来的活动断裂,但至今为止也没有发现喜马拉雅主中央断裂晚第四纪活动的依据.野外调查未发现尼泊尔MW7.8地震在喜马拉雅山南麓的主要断裂上形成地震地表破裂带.喜马拉雅山南麓的构造特征为薄皮构造,表现为浅部陡倾断坡-深部缓倾断坪(7°左右)-深部断坡(11°左右)的构造样式.深部断坡-断坪又称为主喜马拉雅断裂(MHT),其中的深部断坡是尼泊尔地震主震(MW7.8)和最大余震(MW7.3)的发震构造.余震大致沿北西向的高喜马拉雅山前缘呈条带状分布,主要分布在低喜马拉雅山区内.剖面上,余震大致分布在主喜马拉雅断裂的上盘推覆体内,推测尼泊尔MW7.8地震时深部断坡发生错动,其地震位移沿深部断坡-断坪向南传播引起上盘的褶皱带缩短变形,进而触发低喜马拉雅和次喜马拉雅褶皱带内产生次级破裂从而产生余震. 相似文献
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芦山地震发生在龙门山断裂带前缘.关于芦山地震的发震断层,有的认为是前山断裂——双石—大川断裂,有的认为是山前断裂——大邑断裂拟或其他隐伏断裂,发震断裂究竟是哪条断裂以及芦山地震是不是汶川地震的余震?目前仍存在较大争议.震后穿过芦山地震区完成了一条长近40km的深地震反射剖面,以确定芦山地震的发震构造.反射剖面显示浅部褶皱和断裂构造发育,在上地壳存在6条逆冲断裂,下地壳存在一条非常明显的变形转换带,在深度16km左右还存在一个滑脱层,浅部的6条断裂最终都归并到该滑脱层上.参考主余震精定位结果,芦山地震的发震断裂应该是位于双石—大川断裂和大邑断裂之间的隐伏断裂F4,F2和F3断裂受控于发震断裂而活动,形成剖面上"Y"字型余震分布现象.隐伏断裂F4属山前断裂,不是前山断裂,因此芦山地震不是汶川地震的余震. 相似文献
16.
THE RESEARCH OF THE SEISMOGENIC STRUCTURE OF THE LUSHAN EARTHQUAKE BASED ON THE SYNTHESIS OF THE DEEP SEISMIC DATA AND THE SURFACE TECTONIC DEFORMATION 
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下载免费PDF全文 WANG Lin ZHOU Qing-yun WANG Jun LI Wen-qiao ZHOU Lian-qing CHEN Han-lin SU Peng LIANG Peng 《地震地质》2016,38(2):458-476
The seismogenic structure of the Lushan earthquake has remained in suspensed until now. Several faults or tectonics, including basal slipping zone, unknown blind thrust fault and piedmont buried fault, etc, are all considered as the possible seismogenic structure. This paper tries to make some new insights into this unsolved problem. Firstly, based on the data collected from the dynamic seismic stations located on the southern segment of the Longmenshan fault deployed by the Institute of Earthquake Science from 2008 to 2009 and the result of the aftershock relocation and the location of the known faults on the surface, we analyze and interpret the deep structures. Secondly, based on the terrace deformation across the main earthquake zone obtained from the dirrerential GPS meaturement of topography along the Qingyijiang River, combining with the geological interpretation of the high resolution remote sensing image and the regional geological data, we analyze the surface tectonic deformation. Furthermore, we combined the data of the deep structure and the surface deformation above to construct tectonic deformation model and research the seismogenic structure of the Lushan earthquake. Preliminarily, we think that the deformation model of the Lushan earthquake is different from that of the northern thrust segment ruptured in the Wenchuan earthquake due to the dip angle of the fault plane. On the southern segment, the main deformation is the compression of the footwall due to the nearly vertical fault plane of the frontal fault, and the new active thrust faults formed in the footwall. While on the northern segment, the main deformation is the thrusting of the hanging wall due to the less steep fault plane of the central fault. An active anticline formed on the hanging wall of the new active thrust fault, and the terrace surface on this anticline have deformed evidently since the Quaterary, and the latest activity of this anticline caused the Lushan earthquake, so the newly formed active thrust fault is probably the seismogenic structure of the Lushan earthquake. Huge displacement or tectonic deformation has been accumulated on the fault segment curved towards southeast from the Daxi country to the Taiping town during a long time, and the release of the strain and the tectonic movement all concentrate on this fault segment. The Lushan earthquake is just one event during the whole process of tectonic evolution, and the newly formed active thrust faults in the footwall may still cause similar earthquake in the future. 相似文献
17.
徐州活动断层探测项目主要断层活动性研究 总被引：2，自引：0，他引：2
对徐州市主要可能的发震断层开展了活动性探测及地震危险性评价工作,这对徐州市开展防震减灾工作具有重大意义.根据前人资料,分析了威胁徐州市区安全的主要5条隐伏断层,它们分别为幕集-刘集断裂、不老河断裂、废黄河断裂、班井断裂和邵楼断裂.同时根据徐州市活动断层探测项目的要求,针对这5条主要断层开展了浅层地震勘探、钻孔联合剖面探测、野外地震地质调查等相关工作,评价了这5条断层的活动历史、活动性质、规模、展布和地貌特征,及其最新活动时代.结果表明,废黄河断裂最新活动时代为中更新世中期,邵楼断裂最新活动时代为早更新世,这2条断层是目标区具备一定程度发震能力和地震危险性最大的断层. 相似文献
18.
南天山及塔里木北缘构造带位于帕米尔地区东北侧,地震活动强烈。文中通过地质构造剖面、深部探测资料和地震震源机制解资料,综合研究了该区的地震构造模型。结果认为,该区的构造活动主要表现为天山地块逆冲于塔里木地块之上。天山构造系统包括迈丹断裂及其前缘推覆构造;塔里木构造系统包括深部的塔里木北缘断裂、基底共轭断层和浅部的推覆构造。塔里木北缘断裂是发育于塔里木地壳内部的高角度断裂,其形成原因在于塔里木和天山构造变形方向的差异。塔里木北缘断裂为研究区大地震的主要发震构造,天山推覆构造和塔里木基底断裂系统均具有不同性质的中强地震发震能力 相似文献
19.
Gravity anomaly and crustal density structure in Jilantai rift zone and its adjacent region 下载免费PDF全文
下载免费PDF全文 This paper deals with the interpretation of Bouguer gravity anomalies measured along a 250 km long Suhaitu-Etuokeqi gravity profile located at the transitional zone of the Alxa and Ordos blocks where geophysical characteristics are very complex. The analysis is carried out in terms of the ratio of elevation and Bouguer gravity anomaly, the normalized full gradient of a section of the Bouguer gravity anomaly (G h ) and the crustal density structure reveal that (1) the ratio of highs and lows of elevation and Bouguer gravity anomaly is large between Zhengyiguan fault (F4) and Helandonglu fault (F6), which can be explained due to crustal inhomogeneities related to the uplift of the Qinghai-Tibet block in the northeast; (2) the main active faults correspond to the G h contour strip or cut the local region, and generally show strong deformation characteristics, for example the Bayanwulashan mountain front fault (F1) or the southeast boundary of Alxa block is in accord with the western change belt of G h , a belt about 10 km wide that extends to about 30 km; (3) Yinchuan-Pingluo fault (F8) is the seismogenic structure of the Pingluo M earthquake, and its focal depth is about 15 km; (4) the Moho depth trend and Bouguer gravity anomaly variation indicates that the regional gravity field is strongly correlated with the Moho discontinuity. 相似文献
20.
文中收集了1999—2015年天山地震带及其周边地区的GNSS数据,计算得到了速度场结果,并利用弹性块体模型计算了研究区域内各块体的闭锁深度和主要断层的滑动速率。研究结果表明:南天山断裂带西段的迈丹断裂的缩短速率处于高值状态,达(-6.3±1.9) mm/a,高于南天山东段;北天山断裂带西段的缩短速率同样高于东段。利用主要断裂带的滑动速率计算出各地震带的地震矩积累变化及1900年以来的地震矩释放变化量,以分析地震矩亏损分布,结果显示北天山山前断裂、迈丹断裂、额尔齐斯断裂带北段和喀什河断裂西段存在较大的地震矩亏损,具有孕育7级以上地震的潜能,而北轮台断裂、柯坪断裂带中段则呈现地震矩盈余状态,在未来的一段时间内不具备发生强震的可能。 相似文献