荥经-马边-盐津断裂带新活动特征分析

分析了荥经-马边-盐津断裂带地震活动特征,提出荥经-马边-盐津断裂带具有明显的分段活动特征,在活动时代、活动强度上具有明显的北老南新和北弱南强的特点;其地震活动呈现小震活动密集;中段为典型的震群型活动区;南段为强度较大的强震区,但北段的地震活动的频度和强度都相对较弱.并提出了该断裂带新构造活动与地震相关性是值得研究的问题,并对该地区今后的防震减灾工作提出一些建议.     

关于2008年汶川M_s8.0地震震源断裂破裂机制几个问题的讨论

2008年5月12日四川汶川Ms8.0地震是一条陆内活动逆断裂带最新活动的结果.地震震源断裂沿龙门山构造带中央断裂发生斜滑作用和沿前山断裂发生纯逆断裂作用,断裂产状前者陡后者缓,垂直位移前者大后者小,这是一条少见的具有右旋走滑特征的挤压性质双断坡破裂,它是深部斜滑断裂在上地壳脆性域发生应变分解的结果.地震地表破裂带的分段活动和位移分布、地震波反演、余震空间分布、主震和余震震源机制解都说明这一条活动断裂带的活动机制和震源断裂破裂机制的复杂性.北西向小鱼洞左旋走滑破裂带是调节北东向破裂带中缩短量不同的破裂段之间的捩断裂,但由于震源断裂西南段经受着强烈挤压,左旋走滑的小鱼洞断裂也具有明显的挤压分量.在中央断裂这一条走滑逆冲和逆走滑性质的断裂和破裂带中出现的走滑正断裂控制的沙坝沟槽是在一个特殊的构造和地貌条件下,由震源断裂滑动和重力共同作用的结果,重力作用加大了该段破裂的正断层型垂直位移量,它不能真正代表震源断裂的最大地表垂直位移.     

马边—大关构造带震源参数及应力状态研究

利用2000～2009年马边—大关构造带上的115次3级以上中小地震波形资料,计算了地震震源机制解和视应力等震源参数。根据震源机制解分析,马边—大关构造带平均主应力方向为NWW—SEE,错动类型显示,走滑型和倾滑型的地震所占比例相当。地震活动丛集的3个区段荥经—峨边、马边—盐津、鲁甸—巧家的平均主应力方向分别为NWW—SEE、NW—SE、NWW—SEE,呈现局部构造应力场方向特征。马边—大关构造带视应力分布不均匀,高值出现在云南大关—盐津一带地下20km区域,而利店断裂及以北的地区视应力值相对较低。分析认为马边—大关构造带南段未来存在潜在的强震危险性。     

2008年汶川Ms8．0地震多断裂破裂的近地表同震滑移及滑移分解

为深入理解汶川地震破裂的构造运动机制,本文选取典型的观测点,利用多种地质地貌标志测绘分析得到了汶川Ms8.0地震发震断裂的近地表三维同震滑移矢量.结果显示,北川-映秀断裂上的白水河-高川破裂段北西盘沿88°方位角水平滑移2.58 m、垂直滑移3.70 m;安县-灌县断裂上的白鹿-汉旺破裂北西盘沿134°方位角水平滑移1.63 m,垂直滑移2.00 m;小鱼洞破裂带南西盘沿76°～79°方位角水平滑移2.15～2.71 m,垂直滑移1.36～1.51 m.平行的白水河-高川破裂段和白鹿-汉旺破裂段合计形成1.72 m右旋走滑和3.49 m垂直断裂带的NW向水平缩短,总滑移方向(106°)与断裂带整体走向(42°)呈64°夹角,整个龙门山推覆构造带处于斜向挤压的构造环境.结合震源过程反演成果的分析显示,斜滑的白水河-高川破裂段和逆冲型白鹿-汉旺破裂段可能是在汶川地震中最大的一次子事件过程以滑移分解的形式而同时破裂形成的,滑移分解作用使两条断裂以斜滑与逆冲组合的力学性质产生破裂而非相同件质的斜滑破裂.小鱼洞破裂以低角度斜滑为主,可能是安县-灌县断裂与北川-映秀断裂以滑移分解形式同时破裂的纽带.小鱼洞断裂是龙门山断裂带长期处于斜向挤压的构造环境的产物,不只是逆冲断裂系中的捩断层.     

四川马边地震地质背景浅探

马边是川南地震活动较活跃的地区，地震活动显示出一种与四川其它地区不同的特点。马边地区地震活动具有地台区地震活动的一般规律，即地震活动与荥经一马边一盐津深大活动断裂带和上、下地壳间的滑脱面有关。该地区的6．0级以上强震与川西地区的强震活动相一致，它们受到地表活动断裂的控制；6．0级以下地震则与地表活动断裂关系不密切，呈现出一种弥散的图像，但其空间展布范围不超过荥经—马边—盐津深大活动断裂带所展布的区域。     

有关1976年唐山地震发震断层的讨论

对《地震地质》刊登的两篇文章中有关唐山断裂是高角度西倾的逆冲走滑断裂及唐山市东侧付庄-西河断裂是唐山地震的发震断裂的观点进行讨论。笔者认为,如果唐山地震断层是西倾的逆冲走滑活动,需要考虑唐山逆冲断裂的活动方式与唐山市西侧第四纪凹陷之间的关系;如果付庄-西河断裂是唐山地震震源构造的地表破裂,需要解释该西倾的倾滑断裂带与唐山市内走滑地裂缝带的成因联系。此外,还需要更有说服力的证据排除该地表破裂带是次生构造破裂的可能。建议对控制草泊第四纪凹陷的活动断裂开展调查     

2008年汶川M_S8.0地震多断裂破裂的近地表同震滑移及滑移分解

为深入理解汶川地震破裂的构造运动机制,我们选取典型的观测点,利用多种地质地貌标志测绘分析得到了汶川MS8.0地震发震断裂的近地表三维同震滑移矢量。结果显示,北川-映秀断裂上的白水河-高川破裂段北西盘沿88°方位角水平滑移2.58m、垂直滑移3.70m;安县-灌县断裂上的白鹿-汉旺破裂北西盘沿134°方位角水平滑移1.63m,垂直滑移2.00m;小鱼洞破裂带南西盘沿76°~79°方位角水平滑移2.15~2.71m,垂直滑移1.36~1.51m。平行的白水河-高川破裂段和白鹿-汉旺破裂段合计形成1.72m右旋走滑和3.49m垂直断裂带的NW向水平缩短,总滑移方向(106°)与断裂带整体走向(42°)呈64°夹角,整个龙门山推覆构造带处于斜向挤压的构造环境。结合震源过程反演成果的分析显示,斜滑的白水河-高川破裂段和逆冲型白鹿-汉旺破裂段可能是在汶川地震最大的一次子事件过程中以滑移分解的形式同时破裂形成的,滑移分解作用使两条断裂以斜滑与逆冲组合的力学性质产生破裂而非相同性质的斜滑破裂。小鱼洞破裂以低角度斜滑为主,可能是安县-灌县断裂与北川-映秀断裂以滑移分解形式同时破裂的纽带。小鱼洞断裂是龙门山断裂带长期处于斜向挤压的构造环境的产物,不只是逆冲断裂系中的简单捩断层。     

祁连山北缘玉门-北大河断裂晚第四纪活动特征

通过卫星影像解译、野外实地调查并结合前人研究成果,对位于祁连山北缘的玉门—北大河断裂晚第四纪构造活动特征进行研究。结果表明,玉门—北大河断裂为一条全新世活动的逆冲断裂,该断裂西起玉门青草湾,向东经老玉门市、大红泉止于骨头泉,全长约80km,整体走向NWW。根据断裂的几何结构及活动习性可将其分为三段:东段构造形态简单连续,为逆冲断层陡坎为主的古地震地表破裂带;中段结构复杂,由多条次级断层组成,以逆冲扩展为主;西段未出露地表而成为盲断裂-褶皱带。通过对断层陡坎差分GPS测量及相应地貌面年代测试,得到断裂晚更新世以来逆冲速率约为(0.73±0.09)mm/a。     

四川活动断裂带的基本特征

根据大量的实际资料，总结了四川活动断裂带的基本特征：即大致以北东向龙门山断裂带与北西向荣经－马边－盐津断裂带为界，显示了西强东弱的分区活动特点。断裂活动在时间、空间和强度上都具有明显的不均匀性与分段活动特征；晚更新世～全新世以来发生的强震破裂活动大都是沿袭先存断裂进行的，从古地震研究及较短时间尺度（有历史地震记录以来）来看，反映出断层上的位移是以一种地震构造脉冲形式出现     

2008年汶川MS8.0地震多断裂破裂的近地表同震滑移及滑移分解

为深入理解汶川地震破裂的构造运动机制,本文选取典型的观测点,利用多种地质地貌标志测绘分析得到了汶川M_S8.0地震发震断裂的近地表三维同震滑移矢量.结果显示,北川—映秀断裂上的白水河—高川破裂段北西盘沿88°方位角水平滑移2.58 m、垂直滑移3.70 m;安县—灌县断裂上的白鹿—汉旺破裂北西盘沿134°方位角水平滑移1.63 m,垂直滑移2.00 m;小鱼洞破裂带南西盘沿76°~79°方位角水平滑移2.15~2.71 m,垂直滑移1.36~1.51 m.平行的白水河—高川破裂段和白鹿—汉旺破裂段合计形成1.72 m右旋走滑和3.49 m垂直断裂带的NW向水平缩短,总滑移方向（106°）与断裂带整体走向（42°）呈64°夹角,整个龙门山推覆构造带处于斜向挤压的构造环境.结合震源过程反演成果的分析显示,斜滑的白水河—高川破裂段和逆冲型白鹿—汉旺破裂段可能是在汶川地震中最大的一次子事件过程以滑移分解的形式而同时破裂形成的,滑移分解作用使两条断裂以斜滑与逆冲组合的力学性质产生破裂而非相同性质的斜滑破裂.小鱼洞破裂以低角度斜滑为主,可能是安县—灌县断裂与北川—映秀断裂以滑移分解形式同时破裂的纽带.小鱼洞断裂是龙门山断裂带长期处于斜向挤压的构造环境的产物,不只是逆冲断裂系中的捩断层.     

Kinematical and Structural Patterns of the Yingjing-Mabian- Yanjin Thrust Fault Zone, Southeast of the Qinghai-Xizang （Tibet） Plateau and Its Segmentation from Earthquakes

INTRODUCTIONThe Yingjing-Mabian-Yanjinthrust fault zone lies on the southeastern margin of Tibet .It startsfromthe south of Tianquaninthe north,and it extends southwards through Yingjing, Emei , Ebian,Mabian,Lidian to the north of Yanjin of Yunnan, with a total length of 275 km. The fault zoneintersects withthe southernsegment of the Longmengshanthrust fault zone onits northernsegment andborders the Huayingshan-Lianfengfault zone onits southernsegment .It is a 30 km-wide NW-trendin…     

老虎山断裂带的分段性研究

本文分析了老虎山断裂的基本特征，在此基础上运用活断层的自然分段、几何学特征分段、运动学分段及破裂分段等分段原则，对老虎山断裂带进行了分段研究，其中着重研究了破裂分段问题。老虎山断裂带可以分成４段，从东到西依次为喜集水段、老虎山段、草峡段和黑马圈河段。对断裂分段的研究可以为地震的中长期预报提供重要依据。     

新疆尼勒克1812年地震断层构造特征

研究了1812年尼勒克地震断层的展布、构造类型和组合型式等地表特征，认为属倾滑型地盐碱地。破裂展布与逆冲性质的喀什河断裂一致，可分为三段。地震破裂的类型有正断层、走滑正断层、逆断层和地震裂缝四种，连续性较差，垂直错距约为水平位移的4倍，断裂带东西两端具有不同的特点。最后对发震构造与地表地震破裂的性质不一致问题进行了简单讨论。     

MECHANISM OF THE 2016 HUTUBI,XINJIANG, MS6.2 MAINSHOCK AND RELOCATION OF ITS AFTERSHOCK SEQUENCES

A strong earthquake with magnitude M_S6.2 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 M_S6.2 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(M_W)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 M_S6.2 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.     

对汶川地震小鱼洞地表破裂带的调查分析

2008年5月12日的汶川8.0级地震使龙门山断裂带形成了3条同震地表破裂带,这表明有多条活动断层同时参与地震破裂,其过程复杂,现象丰富。本文对小鱼洞地表破裂带及其与另2条地表破裂带的交汇区域进行了野外调查,并对小鱼洞地表破裂带的活动性质和展布特征进行了分析。小鱼洞地表破裂带位于彭州市小鱼洞镇附近,是汶川8.0级地震形成的一条走向NW的逆冲并具有左旋走滑分量的同震地表变形带。调查结果显示,小鱼洞地表破裂带表现出明显的分段性特征：小鱼洞镇一带的中段,逆冲量和走滑量最大;小鱼洞镇向东南方向延伸的南段,逆冲量和走滑量逐渐变小;小鱼洞镇向西北方向进入山区的北段,则表现为以逆冲为主的活动性质。     

新疆伊犁喀什河断裂带及其活动性研究

通过对1812年新疆伊犁尼勒克地震的考察研究，认为该地震以地震断层为主体的地表地震形变带展布方向与发震断裂喀什河断裂带的走向一致。喀什河断裂带可分为3段，全长315km，它是由多条断层组成的活动断裂带，总体以逆冲活动为主，东段具有右旋扭错性质。喀什河断裂带具有长期发育的历史，它控制了中生代地层的分布，在新生代仍有多次活动并以垂直运动为主，晚第四纪以来的垂直活动速率为O．9—6mm／a。     

蒙古阿尔泰东缘新发现的地震地表破裂带

阿尔泰构造带的活动断裂主要为NW—NNW向。按构造位置可分为阿尔泰西缘活动断裂带、阿尔泰中央活动断裂带和阿尔泰东缘活动断裂带。阿尔泰东缘活动构造带由科布多(Hovd)活动断裂带、哈尔乌苏湖(Har Us)活动断裂带2条大型右旋走滑活动断裂和中间的挤压盆地带构成。在2条走滑断裂带上,前人发现多处地震地表破裂带。通过对阿尔泰东缘构造带中南段地区的野外调查,在哈尔乌苏湖断裂带中段的Jargalant断裂、科布多断裂带南段的Tugen gol断裂上新发现地震地表破裂带。其中,沿Jargalant断裂地震地表破裂带长约50km,右旋位错量约4~5m,是一次规模大、活动较新的破裂事件。可见,在阿尔泰东缘活动断裂带的不同断裂段上均有保存较好的地震地表破裂,显示阿尔泰东缘是活动强烈的地震构造带     

GEOMETRIC DISTRIBUTION AND CHARACTERISTICS OF THE SURFACE RUPTURE OF TWO HISTORICAL EARTHQUAKES IN THE BARKOL BASIN,XINJIANG

Surface rupture zone of historical earthquake is the most intuitive geomorphological response to fault activity. The rupture pattern, coseismic displacement and its geometric spatial distribution are important for determining segmentation and long-term movement behaviors of active fault. In the Barkol Basin of Xinjiang, according to the comprehensive result from remote sensing image interpretation, field surgery, high-resolution small unmanned aerial vehicles photography, terrain deformation measurements and trench excavation on geomorphological points, not only the new surface ruptures of the two M7 1/2 historical earthquakes in Barkol in 1842 and 1914 were found and defined between Xiongkuer and the southwest of Barkol County in southwestern part of the basin, but also the latest deformation evidence of the EW fold-up faults in the eastern part of the Basin was identified. Combined with the ancient document analysis of the two historical earthquakes, we finally conclude that the surface rupture zone in the western segment on the southern margin of the Barkol Basin is the seismogenic structure of the M7 1/2 earthquake in 1842. The surface rupture zone is mainly characterized by left-lateral strike-slip, roughly with en echelon arrangement spreading from Xiongkuer to the south of Barkol County. The length of the surface rupture zone determined by field investigation is at least about 65km, and the maximum horizontal displacement appears around the Xiongkuer Village. At the same time, the surface rupture zone gradually shows more significant thrust extrusion from west to east, and has a tendency of extension towards the central of the Barkol Basin. The average observed displacement of the entire surface rupture obtained by counting the coseismic offsets of multiple faulted gullies is(4.1±1.0)m, with the coseismic characteristic displacement of ~4m. The epicenter position should appear at the place with the largest horizontal dislocation amount near Xiongkuer Village. In addition, the length of the fold-blind fault zone in the vicinity of the Kuisu Town and the eastward extension to the Yanchi Township of the Yiwu Basin, which was discovered in the center of the Barkol Basin, is about 90km. The folded blind fault causes significant fold deformation in the latest sedimentary strata such as floodplain, and in addition, as shown on many outcrop sections, the bending-moment faults associated with the coseismic fold deformation have ruptured the surface. Therefore, the location of the epicenter should be located at the maximum fold deformation, which is near the Kuisu Town. The new research results not only further improve the understanding of the epicenter location and seismogenic faults of the two historical earthquakes in the Barkol Basin, but also provide an important reference for analyzing regional seismic hazards.     

Study of the segmentation of active fault by the boundary element method──analysis of the Xianshuihe fault zone

Ｓｔｕｄｙ　ｏｆ　ｔｈｅ　ｓｅｇｍｅｎｔａｔｉｏｎ　ｏｆ　ａｃｔｉｖｅ　ｆａｕｌｔ　ｂｙ　ｔｈｅ　ｂｏｕｎｄａｒｙ　ｅｌｅｍｅｎｔ　ｍｅｔｈｏｄ──ａｎａｌｙｓｉｓ　ｏｆ　ｔｈｅ　Ｘｉａｎｓｈｕｉｈｅ　ｆａｕｌｔ　ｚｏｎｅ（张超）（陈连旺）（赵国光）...     

Average slip rate,earthquake rupturing segmentation and recurrence behavior on the Litang fault zone,western Sichuan Province,China

The Litang fault zone (LFZ) is an important active fault within the northwestern Sichuan sub-block. To-gether with the Garzê-Yushu, Xianshuihe, and An-ninghe fault zones on its northern, eastern and south-eastern sides, the LFZ constitutes the lateral extrusion tectonic system in the southeastern part of the Qing-hai-Tibetan Plateau[1,2] (Fig. 1). According to instru-mental records, historical recordings and field investi- gation, an earthquake (Ms7.3) occurred on its middle to south se…