滇西南地区现代构造应力场分析

利用断层滑动资料反演构造应力张量的方法,获得滇西南地区20个构造应力张量数据,并通过与由震源机制解资料求解该地区平均应力场结果的对比,获得了研究区现代构造应力场特征：镇源——营盘山断裂以西至龙陵断裂带以南地区,最大主压应力方向为北北东,应力结构以走滑型为主;龙陵断裂带及其以北的局部地区,最大主压应力方向为近南北或北北西,应力结构为走滑型．     

中国西部及邻区活动地块边界带现代构造应力场

利用哈佛全球矩心矩张量解数据和许忠淮认为1920mdash;1999年可靠的中国大陆震源机制解数据, 反演了中国西部及邻区活动地块边界带上现代构造应力场．通过对FMSI反演程序多次的输入和检验, 得到了边界带上的应力场．边界带上最大主压应力sigma;1轴绝大多数近水平. 在90deg;E以西的中国西部大陆及邻区, sigma;1轴水平方向基本上为近SN向;在青藏高原的东北部, sigma;1轴水平方向基本上为近NE向;在青藏高原的东南部, sigma;1轴水平方向绕喜马拉雅构造东端顺时针方向旋转．最小主压应力sigma;3轴倾角呈两极分布,西域地块区内活动地块边界带和青藏地块区内东北缘部分段sigma;3轴倾角较陡, 而青藏地块区内sigma;3轴倾角近水平, 所以西域地块区和青藏地块区内东北部相对于其它大部分青藏地块区, 有更多的逆冲地震．应力场在同一个边界带具有非均匀性. 北天山带、南天山带、西秦岭mdash;德令哈带、岷山mdash;龙门山带和安宁河mdash;小江带的非均匀性相对要小一些, 西昆仑带、海原mdash;祁连带、东昆仑带、玛尼mdash;玉树带、澜沧江带和滇西西边界带的非均匀性相对要大, 而喀喇昆仑mdash;嘉黎带和喜马拉雅带的非均匀性最显著．由于震源机制解数据的限制, 本文给出的是边界带上部分段的应力场．      

Modern tectonic stress field in the Chinese mainland inverted from focal mechanism solutions

IntroductionTheinversionapproachofregionalstressfielddevelopedinrecent10to20yearsprovidesausefultoolforstudyingthemeanstressinagivenregion(Angeller,1979;Ellsworth,1981,Xu,Ge,1984).Becauseitusesmultitudinousfaultsinsteadofsinglefault,itcanremovetheinhomogeneityoflocalmediumsoastorevealtheregionalstressinformation.Besides,thismethodproducesaRvalue,whichisdefinedby(O-2--q)/(q--q),andmaydescribestherelativemagnitUdeofintermediateprincipalstress,whereq,acand%arethemaximum,theintermediateandthemi…     

滇西区域构造应力场分析

云南地处印度板块、欧亚板块—中国大陆碰撞带东缘,地壳运动剧烈,主要受到印度板块NE向挤压与川滇菱形块体SSE滑移的联合作用.在构造上,云南地区可以划分为滇缅泰板块、印支板块、扬子板块、华南板块等4个一级构造单元和腾冲块体、保山块体、兰坪—思茅弧后盆地、盐源—丽江陆缘坳陷、滇中坳陷、康滇古隆起、滇东坳褶等7个二级构造单元...     

Focal mechanisms and tectonic stress field of the Xinfengjiang earthquake

Altogether 83 events were recorded clearly by all the 8 sub-seismometric stations of the telemetrered seismic network in the Xinfengjiang area during the period from October 1st 1983 to April 30th 1987. Based upon the difference of the initial motion of P waves, the authors divided the 83 earthquakes into 37 pattens. Combining similar pattens, we have got 5 types of focal mechanism solutions. The recent tectonic stress field of the Xinfengjiang region is discussed. The characteristics of the stress axis and the nodal planes are different from which our predecessors got earlier; but the present results is similar to which put forward by the authors in 1981. This paper shows that the tectonic stress field is clearly characterized by a compression in the N-S direction. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica 13. 462–476, 1991.     

乌鲁木齐地区现今构造应力场综合分析

乌鲁木齐地处天山中段.震源机制解研究表明,北天山中段区域主压应力方向为N10°E左右,且具有自西向东逐渐东偏的特点.在乌鲁木齐地区,由中强地震震源机制解反演的主压应力方向为N15°-20°E;由断层滑动资料反演的乌鲁木齐周边构造应力场的主压应力方向为N17°W-N2°E.上述两种资料反演的乌鲁木齐构造应力场主压应力方向...     

Recent tectonic stress field research in Shanxi graben system

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The seismicity and tectonic stress field characteristics of the Longmenshan fault zone before the Wenchuan M_S8.0 earthquake

The seismicity of Longmenshan fault zone and its vicinities before the 12 May 2008 Wenchuan MS8.0 earthquake is studied.Based on the digital seismic waveform data observed from regional seismic networks and mobile stations, the focal mechanism solutions are determined.Our analysis results show that the seismicities of Longmenshan fault zone before the 12 May 2008 Wenchuan earthquake were in stable state.No obvious phenomena of seismic activity intensifying appeared.According to focal mechanism solutions of ...     

鄂尔多斯块体西南缘地区震源机制解与构造应力场特征分析

计算了2001年1月至2018年9月鄂尔多斯块体西南缘地区(33°—38°N,103°—109°E)M_L≥3.0地震的震源机制,分析了该区域震源机制解特征,在此基础上,采用平均矩张量技术反演了该区域的构造应力场特征。结果表明,研究区震源机制类型以走滑型和逆冲型为主,其空间分布基本与区域构造动力背景和断裂性质一致,少量不符合区域构造性质的震源机制则反映了局部地质构造的复杂性。区域构造变形主体为NE向压缩,NW向相对扩张,反映了青藏高原块体对鄂尔多斯块体的直接作用。     

The seismicity and tectonic stress field characteristics of the Longmenshan fault zone before the Wenchuan MS8.0 earthquake

The seismicity of Longmenshan fault zone and its vicinities before the 12 May 2008 Wenchuan M_S8.0 earthquake is studied. Based on the digital seismic waveform data observed from regional seismic networks and mobile stations, the focal mechanism solutions are determined. Our analysis results show that the seismicities of Longmenshan fault zone before the 12 May 2008 Wenchuan earthquake were in stable state. No obvious phenomena of seismic activity intensifying appeared. According to focal mechanism solutions of some small earthquakes before the 12 May 2008 Wenchuan earthquake, the direction of principal compressive stress P-axis is WNW-ESE. The two hypocenter fault planes are NE-striking and NW-striking. The plane of NE direction is among N50°?70°E, the dip angles of fault planes are 60°?70° and it is very steep. The faultings of most earthquakes are dominantly characterized by dip-slip reverse and small part of faultings present strike-slip. The azimuths of principal compressive stress, the strikes of source fault planes and the dislocation types calculated from some small earthquakes before the 12 May 2008 Wenchuan earthquake are in accordance with that of the main shock. The average stress field of micro-rupture along the Longmenshan fault zone before the great earthquake is also consistent with that calculated from main shock. Zipingpu dam is located in the east side 20 km from the initial rupture area of the 12 May 2008 Wenchuan earthquake. The activity increment of small earthquakes in the Zipingpu dam is in the period of water discharging. The source parameter results of the small earthquakes which occurred near the initial rupture area of the 12 May 2008 Wenchuan earthquake indicate that the focal depths are 5 to 14 km and the source parameters are identical with that of earthquake.     

Preliminary analysis on the tectonic stress level in the source region of Tangshan earthquake

Introduction Analyzing tectonic stress field based on focal mechanism data is an important way to the study tectonic evolvement of lithosphere and associated dynamic process. Such studies growrapidly in China and abroad (Zoback, 1992; Plenefisch, Bonjer, 1997; XU, 1985; CUI, XIE, 1999). At present most of the studies focus on the inversion of focal mechanism data for the direction and relative magnitude of stress tensor, and few on absolute stress. Using focal mechanism and fault scratch,…     

Source mechanism of small-moderate earth- quakes and tectonic stress field in Yunnan Province

IntroductionYunnanProvinceislocatedinthesouthofNorth-SouthseismiczoneinChina.ItisoneofthehighseismicactiveregionsinChinesemainland.Morethanonehundredstrongearthquakeswithmagnitude6ormoreoccurredinthisregioninhistory.AsanimportantsoutheasternmarginofTibetanPlateau,YunnanregionisahotspotinstudyonthedynamicsofTibetanPlateau.Theactionsofcompressivestressinnorth-southorientationandgravitationalpotentialcausedlateralextrusionofmaterialintheplateauwiththeupliftingofTibetanPlateau.Severalblocksa…     

晋冀豫交界构造应力场分析

筛选晋冀豫交界2008-2017年468个地震的1 143个P波初动符号,应用综合震源机制解方法,反演该区域构造应力场,结果表明：①晋冀豫交界精细应力场整体受NE向P轴和NW向T轴控制,且P轴和T轴倾角近水平;②薄壁断裂以东出现局部应力场紊乱,安阳南断裂东南部应力场P轴由NE转为NEE至EW向,T轴呈放射状,从NW向逐渐转为NWW向,且倾角较大;③晋冀豫交界除符合华北应力场整体特征外,还具有局部构造应力场独特性。     

Preliminary research to determine stress districts from focal mechanism solutions in Southwest China and its adjacent area

The method of sliding direction fitting is used to determine stress districts, taking the shear stress directions and ratios of shear stress to stress on fault planes given by focal mechanism solutions as the criteria to select focal mechanism solutions of one region and sorting out the earthquakes controlled by different tectonic stress fields, and then determining the stress districts from epicenter distribution of earthquakes. We call this method as step by step convergence method. By inversion analyzing of 297 focal mechanism solutions, we consider that Southwest China and its adjacent area can be divided into 5 stress districts, and we worked out directions of the three principal stresses and values of shape factor φin 5 stress districts.     

怀来盆地的构造应力场

１９９５年７月２０日在北京西北的怀来盆地发生了一次ＭＬ＝４．１地震。在此主震之后该地区小震活动变得十分活跃。在１９９５年７月１日至１９９６年６月３０日期间，中－欧合作怀来数字地震台网记录并精确定位了这个地震序列的４５０多个地震。余震的震源分布表明，余震主要分布在两个共轭的断层上。在盆地南部边缘的余震震源位于走向５０°、倾向南东，倾角８０°的断层上，而盆地北部边缘的余震震源则位于走向１５０°、几乎竖直的断层上。用Ｐ波初动符合资料得到了主震的震源机制解。根据余震震源的分布，确定走向３７°、倾角４０°、滑动角－１５４°的节面为主震的断层面，另一节面走向２８７°、倾角７４°、滑动角－５３°。利用怀来数字地震台网的记录资料，分析了怀来地区近期地震活动性和构造应力场。结果表明，怀来盆地的主压应力轴的方位角为２３６°，倾角４８°，与主压应力轴近水平、北东东向的华北地区的构造应力场一致，表明了ＭＬ（＝４．１地震序列是在怀来盆地北东东向挤压、北北西向拉张的构造应力作用下发生的。处于上述两条共轭断层文汇处的怀来县城附近地区近期小震活动较少，表现出断层闭锁区的特征。怀来盆地潜在的地震危险性应予以特别关注，但其近期的微震活动并未显     

中国大陆现代构造应力场与强震活动

依据应力性状和力源特征,中国大陆现代构造应力场可划分为四级应力区.它们分别是2个一级应力区、4个二级应力区、5个三级应力区和26个四级应力区.通过分析中国大陆现代构造应力分区与强震活动之问的关系,初步获得以下结论:①构造应力作用强烈和复杂的地区是强震频发的地区;②应力区边界是强震集中发生的地带;③应力方向、应力结构类型...     

红河断裂带的震源机制与现代构造应力场

利用震源机制解对红河断裂带的现代构造应力场和震源破裂进行分析,结果表明沿断裂带震源机制、应力场和震源破裂存在着主体类型、优势作用和主要特征,同时也存在着复杂性特征,断裂带北、中、南段存在差异,反映了断裂带各段构造活动的差异。     

Preliminary research to determine stress districts form focal mechanism solutions in Southwest China and its adjacent area

IntroductionManystudies(Kan,etal,1977;Cheng,1981;Xu,etal,1987;Xie,etal,1993,Mulled,etal,1997)indicatedthatthedirectionsofcrustaltectonicstresseshaveregionalvariation.SimpleanalysesbymeansOfthreeprincipalaxesoffocalmechanismsolutions,whichexpressedasP...     

汶川8.0级地震前龙门山断裂带的地震活动性和构造应力场特征

研究了2008年5月12日汶川8.0级地震前龙门山断裂带及其附近地区的地震活动.利用区域地震台网和流动测震台的数字地震波资料,测定了震源机制解.结果表明,震中所在的龙门山断裂带震前地震活动平稳,未出现显著异常增强或平静现象.根据汶川8.0级地震前地震活动求出的震源机制解,其主压应力P轴方位为WNE——ESE向,震源断层面呈NE向与NW 向两组节面走向.其中NE向节面呈N50deg;——70deg;E,断面倾角均陡,达60deg;——70deg;,震源力学作用方式多呈逆倾型,少部分呈走滑型．震前地震活动呈现的主压应力方位、震源断面走向及其错动类型,与汶川8.0级地震给出的解是一致的.巨大地震发生前沿龙门山断裂带微破裂呈现的平均应力场与主震一致．起始破裂区东侧20km内是紫坪铺水库水域区,这一区域发生小震活动增加的现象处于水库放水的卸载阶段.本文研究了汶川8.0级地震起始破裂区附近的小震活动,其震源参数表明,震源位于8.0级地震之上的5——14km深度,其震源参数与8.0级地震给出的解也是一致的．