京西北盆岭构造区强震复发概率模型及地震潜势的定量评估

基于京西北盆岭构造区活动构造的定量化研究成果 ,视强震复发间隔为一随机变量 ,借鉴NB模型的建模方法 ,结合强震复发过程中存在分形规律的思想 ,建立京西北模型———强震复发间隔的均一化值服从正态分布N(1.0 0 0 3,0 .2 4 6 4 2 ) ;京西北盆岭构造区未来可能发生地震概率较高的断裂是 :天镇 -阳高盆地北缘断裂、阳原盆地南缘断裂、延庆盆地北缘断裂辛韩段、矾山盆地北缘断裂燕水段、宣化盆地南缘断裂     

晋冀蒙交界地区主要断裂的现今活动

用大地水准测量资料分析了晋冀蒙交界地区13条主要断裂的现今活动状态，结果发现，凡是活动断裂带通过的地段，在形变剖面图上一般都出现转折或突变。断裂现今活动与继承性活动是一致的，但是运动速率不均匀，有时快，有时慢，有时甚至作反向运动；同一条断裂有的地段活动强，有的地段活动弱。在1983—1992年间，该地区活动最强，平均速率超过2mm／a的断裂是怀安盆地北缘断裂和怀涿盆地北缘断裂；活动较强，平均速率为1．0—1．9mm／a的有恒山北麓断裂、怀安盆地南缘断裂、太白山山前断裂、蔚—广盆地南缘断裂西段、延矾盆地北缘断裂、张家口断裂、五台山北麓断裂。活动较弱，速率小于1mm／a的有蔚—广盆地南缘断裂东段、恒山南麓断裂、六棱山北麓断裂、阳原盆地北缘断裂。     

京西盆岭构造区积累库仑破裂应力变化对强震的影响

以拉张正断层作用为主的京西盆岭活动构造区(112°～116.2°N, 38.3°～41.5°E)自BC231年以来共记载和记录15次M6～7.5地震。 本研究计算每一次强震产生的以及逐次积累的库仑破裂静应力变化, 并分析强震之间的应力触发关系。 结果显示在14次后发的强震中, 有10次发生在先发强震产生的积累库仑破裂静应力变化为正的触发区, 触发率为71%。 所有15次历史强震作用共同引起研究区积累库仑破裂静应力变化的正值区, 主要分布于六棱山北麓断裂中段、 怀涿盆地北缘断裂、 新保安沙城断裂、 桑干河断裂以及蔚县盆地南缘断裂, 并使得这些断裂(段)的强震危险性有所增加, 这可为分析研究区的未来强震危险性提供参考。     

晋冀蒙交界地区S波分裂研究

选取晋冀蒙交界地区2014年10月—2015年8月M_L 2.0以上地震事件,使用SAM软件进行S波分裂,得到研究时空域内S波分裂的偏振方向和延迟时间。其中:偏振方向在晋冀蒙交界的和林格尔以南及大同盆地、天镇—阳高盆地、阳原盆地和浑源盆地周围区域存在较大幅度变化;延迟时间变化范围在0.01—0.08 s,主要集中在0.01—0.03 s,高值主要出现在恒山南麓断裂和怀安盆地南缘断裂附近。分析认为,晋冀蒙交界地区地下介质各向异性较复杂,需密切注意今后地震地质活动。     

应用断层的活动性分析民乐-张掖盆地及外围地区的强震危险性

依据民乐—张掖盆地及外围地区的断裂活动性对该盆地发生强震的危险地段和时间进行了预测．结果表明，盆地西缘的榆木山断裂西段和红崖堡断裂西段是发生强震的危险地段，在今后５０年内发生６．５≤ＭＳ≤７．０地震的可能性较大     

盆地边界活动正断层多尺度构造地貌研究——以京西北蔚广盆地南缘断裂带为例

京西北盆岭构造区中发育有怀涿、蔚广、延矾、阳原、灵丘、怀安和涞源等一系列断陷盆地单元,这些断陷盆地的边缘大都受到了NE向活动断裂带的控制.该区内的蔚广盆地就是一个受南部边界正断层控制的、南深北浅的不对称的半地堑盆地.而蔚广盆地南缘断裂带即为控制该盆地南边界的正断层系,也就是本文的研究对象.     

鄂尔多斯地块东南缘地带Moho深度变化特征研究

鄂尔多斯地块东南缘是主要的历史强震活跃区,曾经多次发生6级或以上的强烈地震,其边缘边界具有较强的地震活动性.本文利用该区域内分布的固定台站数据记录的大量远震体波波形资料,应用频率域反褶积方法提取远震P波接收函数,由H-κ方法测定了各台站下方的Moho深度和V_p/V_s值.研究结果表明:鄂尔多斯地块东南缘的V_p/V_s值介于1.6~1.9之间.东缘的Moho深度介于33.4~45 km之间,太原断陷盆地附近的Moho深度较浅,最浅处为33.4 km;东部北段的延怀盆地、蔚县盆地、阳原盆地和南段的临汾盆地附近Moho深度变化不大,平均深度为40 km.而在东缘东侧,因存在着山西断陷带,导致块体边缘的Moho深度要小于块体内部的Moho深度.块体南缘的Moho深度介于31.0~53.1 km之间,自东段向西段Moho深度逐渐变大,从渭河盆地附近的31.0 km增厚至秦岭造山带地段的53.1 km.总之,鄂尔多斯地块东南缘地带的Moho深度和V_p/V_s值分布具有明显的分块特征,块体内部结构比较稳定,东缘东段地壳结构相对一致,东缘东侧与西侧地壳深度具有明显的差异性,从山西断陷以东向西地壳厚度逐渐增厚,很好地对应了其地质构造特点.     

2005年前山西地震危险性预测

以一系列断裂盆地为主体的断裂盆地带是山西的地震构造带和未来地震的主要危险区，叙述地的新生性，第四纪活动度，盆地和剪切运动和拉张运动特征及盆地的现代地壳运动特征和现代地壳应力场特征，分析了盆地的特征，地震震级一频度模式，古地震复发间隔和地震活动周期，山西历史强震前的地震活动图像及盆地的各项特征和地震活动的关系，在此基础得到，２００５年山西基本上不具备发生Ｍ≥７地震的危险性，其发震概率在０．０５～０．     

基于b值的晋冀鲁豫交界区强震背景研究

以晋冀鲁豫交界区为研究对象, 利用古登堡的频次与震级关系式, 计算1970年1月~2018年6月该区b值, 进而判断未来强震危险地段。 计算结果显示, 邢台震源区西南端的未破裂区域为低b值异常区。 进一步研究该区的地壳物性结构等资料, 认为其具有高低速相间的地壳介质、 深切地幔的断裂、 大地震破裂空段等利于能量积累、 发生强震的特性。 综合分析认为, 低b值异常区附近的紫山西断裂与曲陌断裂交会区, 是未来晋冀鲁豫交界区最有可能发生强震的区域。     

大同－阳原盆地南缘断裂带的晚第四纪分段和构造地貌变异

大同－阳原盆地南缘断裂带是北京西北～山西北部盆－岭区的一条最大的断层。晚第四纪断层崖高度和高度分布型式把断裂带分为西南和东北两个段落。该断裂带在山前带和山麓坡的构造地貌、微地文期演化历史方面存在着明显的分段变异。构造地貌过程的速度和断层习性差异，以及段落边界的重叠断层特征，是构造地貌变异的直接原因。     

Quantitative data about active tectonics and possible locations of strong earthquakes in the future in the northwestern Beijing

Introduction Northwestern Beijing covers the mountainous area from 114~116.5E and 39~41N, which is located at the joint place of the basically E-W trending Yanshan, the NE to NNE-trending Shanxi and the NW-trending ZhangjiakouPenglai active tectonic belts (regions). The long history of development and evolution in tectonics have formed the features of basin-range tectonics and multi-sets of fault systems with different ranges. Generally, they can be divided as NNE-NE, NNW-NW and appr…     

岷山断块的发震构造与地震活动性分析

岷山断块位于中国南北强震构造带的中段,区域地质构造复杂,活动断裂众多,强震频发。4条不同走向的活动断裂——NE向龙门山构造带的茂汶断裂、 NWW向东昆仑断裂带的塔藏断裂、近NS向的岷江断裂和NNW—NS向的虎牙断裂构成岷山断块的南北西东边界。638—2017年该区域共发生了10次6级以上破坏性地震, 2017年九寨沟7.0级地震就是其中之一。结合区域构造背景,对岷山断块所发生的6级以上地震的发震构造特征、地震活动特性进行归纳总结,综合分析该区域地震地质特征及地震危险性,得出以下认识:①地震分布空间分区特征显著,破坏性强震发震构造多为活动性较强的岷山断块东西边界断裂,震中位置多位于两组或多组活动断裂构造的交会或穿切部位;②地震分布时间特征表现为随着时间发展具有迁移回返和原地复发性等特点;③岷山断块东西边界断裂破坏性地震的发生具有一定的时间关联性,东边界虎牙断裂1973—2017年的地震序列为西边界岷江断裂1933—1960年地震序列约40年后的地震构造响应;④未来岷山断块仍应是继续关注的强震潜在危险区,岷江断裂中北段的强震潜在危险区是近期值得深入研究的地区之一。     

2014年新疆于田MS7.3级地震:巴颜喀喇地块侧向挤出的构造响应

青藏高原中北部的巴颜喀喇地块是近年来强震最为活跃的地区,自1997年以来在地块周围发生了一系列7级以上地震.2014年于田M_S7.3级地震就发生在该地块西边界附近的硝尔库勒盆地南缘,该区是阿尔金断裂、康西瓦断裂和东昆仑断裂等多组不同走向大型走滑活动断裂带的交汇部位,不同断裂走向的突然转变及滑动速率差异使该地区形成局部的拉张应力状态,发育了多条NE和近SN向的左旋正断裂. 通过余震分布、震源机制解结果等资料分析,认为此次地震的发震构造为阿尔金断裂西南端的一条次级断裂——硝尔库勒断裂,地震破裂特征为左旋走滑兼正断性质. 在巴颜喀喇地块这一轮的强震活动中,其北边界和东边界都显示块体向东挤出约7 m的位移量,但块体西边界产生的伸展量明显与整个块体向东的位移量不协调,2014年于田M_S7.3级地震是巴颜喀喇地块向东挤出的构造响应和应变调整.模拟结果显示阿尔金主断裂上的库仑应力有所增加,东昆仑—柴达木地块可能为下一个强震活跃区,特别是阿尔金断裂的中西段,是今后应该重点关注和监视的地区.     

MIGRATION OF LARGE EARTHQUAKES IN TIBETAN BLOCK AREA AND DISSCUSSION ON MAJOR ACTIVE REGION IN THE FUTURE

On the basis of summarizing the circulation characteristics and mechanism of earthquakes with magnitude 7 or above in continental China, the spatial-temporal migration characteristics, mechanism and future development trend of earthquakes with magnitude above 7 in Tibetan block area are analyzed comprehensively. The results show that there are temporal clustering and spatial zoning of regional strong earthquakes and large earthquakes in continental China, and they show the characteristics of migration and circulation in time and space. In the past 100a, there are four major earthquake cluster areas that have migrated from west to east and from south to north, i.e. 1)Himalayan seismic belt and Tianshan-Baikal seismic belt; 2)Mid-north to north-south seismic belt in Tibetan block area; 3)North-south seismic belt-periphery of Assam cape; and 4)North China and Sichuan-Yunnan area. The cluster time of each area is about 20a, and a complete cycle time is about 80a. The temporal and spatial images of the migration and circulation of strong earthquakes are consistent with the motion velocity field images obtained through GPS observations in continental China. The mechanism is related to the latest tectonic activity in continental China, which is mainly affected by the continuous compression of the Indian plate to the north on the Eurasian plate, the rotation of the Tibetan plateau around the eastern Himalayan syntaxis, and the additional stress field caused by the change of the earth's rotation speed.
Since 1900AD, the Tibetan block area has experienced three periods of high tides of earthquake activity clusters(also known as earthquake series), among which the Haiyuan-Gulang earthquake series from 1920 to 1937 mainly occurred around the active block boundary structural belt on the periphery of the Tibetan block region, with the largest earthquake occurring on the large active fault zone in the northeastern boundary belt. The Chayu-Dangxiong earthquake series from 1947 to 1976 mainly occurred around the large-scale boundary active faults of Qiangtang block, Bayankala block and eastern Himalayan syntaxis within the Tibetan block area. In the 1995-present Kunlun-Wenchuan earthquake series, 8 earthquakes with M_S7.0 or above have occurred on the boundary fault zones of the Bayankala block. Therefore, the Bayankala block has become the main area of large earthquake activity on the Tibetan plateau in the past 20a. The clustering characteristic of this kind of seismic activity shows that in a certain period of time, strong earthquake activity can occur on the boundary fault zone of the same block or closely related blocks driven by a unified dynamic mechanism, reflecting the overall movement characteristics of the block. The migration images of the main active areas of the three earthquake series reflect the current tectonic deformation process of the Tibetan block region, where the tectonic activity is gradually converging inward from the boundary tectonic belt around the block, and the compression uplift and extrusion to the south and east occurs in the plateau. This mechanism of gradual migration and repeated activities from the periphery to the middle can be explained by coupled block movement and continuous deformation model, which conforms to the dynamic model of the active tectonic block hypothesis.
A comprehensive analysis shows that the Kunlun-Wenchuan earthquake series, which has lasted for more than 20a, is likely to come to an end. In the next 20a, the main active area of the major earthquakes with magnitude 7 on the continental China may migrate to the peripheral boundary zone of the Tibetan block. The focus is on the eastern boundary structural zone, i.e. the generalized north-south seismic belt. At the same time, attention should be paid to the earthquake-prone favorable regions such as the seismic empty sections of the major active faults in the northern Qaidam block boundary zone and other regions. For the northern region of the Tibetan block, the areas where the earthquakes of magnitude 7 or above are most likely to occur in the future will be the boundary structural zones of Qaidam active tectonic block, including Qilian-Haiyuan fault zone, the northern margin fault zone of western Qinling, the eastern Kunlun fault zone and the Altyn Tagh fault zone, etc., as well as the empty zones or empty fault segments with long elapse time of paleo-earthquake or no large historical earthquake rupture in their structural transformation zones. In future work, in-depth research on the seismogenic tectonic environment in the above areas should be strengthened, including fracture geometry, physical properties of media, fracture activity behavior, earthquake recurrence rule, strain accumulation degree, etc., and then targeted strengthening tracking monitoring and earthquake disaster prevention should be carried out.     

THE ANALYSIS OF VERTICAL MOTION CHARACTERISTICS IN YUNNAN AREA BASED ON PRECISE LEVELING

In this study, vertical deformation of different regions of Yunnan area in 1993-2013, 2001-2006, 2011-2017 is obtained using observational data of precise leveling. The results show that:1) In the whole, Yunnan area exhibits uplifting in the east of Yunnan and subsiding in the south of Yunnan, which is well consistent with the current horizontal velocity field obtained by GPS. In the east of Yunnan, southeastward horizontal velocity at the east boundary of Sichuan-Yunnan block is significantly decreased, which indicates extrusion deformation. This result is in accordance with the result that there is uplift in the east of Yunnan with precise leveling data. GPS velocity field rotates clockwise at Eastern Himalayan Syntaxis, therefore east-west extension is formed in central and southern Yunnan, which coincides with crustal subsidence observed by precise leveling. 2)The vertical movement in the northwest of Yunnan mainly exhibits the succession movement of basin subsidence and mountain uplift, in which, in the rift zone, Chenghai Basin, Qina Basin, Binchuan Basin and Midu Basin distributed along Chenghai Fault are all in the sinking state and the sinking velocity of Binchuan Basin located in the end of the sinistral strike-slip Chenghai Fault is the maximum. The sinking velocity of Dali Basin distributed along Honghe Fault is approximately 0.5mm/a and the sinking velocity of Midu Basin is approximately 1mm/a under the comprehensive action of right-lateral Honghe Fault and left-lateral Chenghai Fault. On the northwest boundary of the fault zone, the vertical movement of the basins (Lijiang Basin, Jiangchuan Basin)under the control of the nearby Lijiang-Jianchuan Fault is not obvious and the nearby mountain area exhibits uplift. 3)In the Honghe Fault, the southern region still possesses strong activity. Seeing from the leveling profile and vertical deformation field, the Honghe Fault still possesses the significance of block boundary fault and strong activity. GPS velocity field reveals that the southeast movement velocity of the Sichuan-Yunnan rhombic block is rapidly decreased near Xiaojiang Fault and the earth's crust is shortened and deformed. In the vertical deformation field, the uplift is formed near Xiaojiang Fault and there is obvious vertical deformation gradient. 4)Notably, deformation contour in the junction of Qujiang Fault and Xiaojiang Fault is characterized by four quadrant distribution, which indicates the possibility of earthquake.     

断层破裂面倾角变化对断陷盆地强地面运动的影响

地震事件中,断层破裂面的倾角大小直接影响到地表强地震动的分布状态,尤其在断陷盆地中,强地面运动特征还可能受到盆地结构及盆地内多条围限断层的影响.本文模拟了银川断陷盆地内的活动断层--银川隐伏断层南段发生M_w6.5特征地震时,断层破裂面倾角在30°~85°范围内变化时引起的强地面运动,探讨了断层破裂面倾角变化对盆地内强地面运动分布特征和强度的影响.结果表明:破裂面倾角较缓时,银川盆地内的强地面运动分布区域不仅仅决定于发震断层的产状,同时还受到断层上盘距离最近的芦花台断层的影响,致使强地面运动集中于两条断层所围限的区域;随着发震断层破裂面的倾角逐渐增大,强地面运动以发震断层产状的影响为主,强震集中区向发震断层靠近并分布于发震断层上盘,且沿断层走向方向出现了强度不同的地震动反射区;尤其是发震断层破裂面倾角接近垂直时,受银川盆地"西陡东缓"结构和盆地西边界贺兰山东麓断裂反射作用的影响,竖向地震动反射区强度在远离发震断层的西北方向明显增大,致使芦花台断层附近区域与银川断层南段上盘区域成为地震发生时可能遭受震害最严重的地区.本文探讨结果提醒我们在类似区域的活动断层附近进行建(构)筑规划和地震工程设计时,有必要考虑发震断层破裂面倾角大小和盆地内其它断层构造的共同影响,综合评价潜在地震对盆地内近断层地表及各类建(构)筑物的危害性.     

2003年青海德令哈M6.6地震序列的活动特征

分析了2003年4月17日青海省德令哈6.6级地震序列活动的空间和时间变化特征及其发震构造,得到以下结果:①主震发生在地震活跃区与相对平静区的分界带上;②主震后半个多月内余震快速衰减,初期余震持续到7月底,以后平静了4个多月,接着震源区东部又发生第2期余震活动,连续发生5次5.0级以上地震,最大余震震级5.9;③震源区...     

郯庐断裂带中段全新世活断层的特征滑动行为与特征地震

郯庐断裂带中段全新世活断层由３个独立的破裂段组成。从各破裂段的运动性质、位移分布看，断层的运动属特征地震型滑动。地震活动以强震活动为主，强震具有周期性原地重复发生的特点，且其强度基本相同；中强地震缺失或很少发生；ｂ值在高震级范围内具低ｂ值的非线性关系。这些特点正是特征地震的典型表现．根据郯庐断裂带中段活断层全新世以来的活动特点看，未来该区仍然以特征地震方式活动．按郯庐带的强震复发间隔和各段的最新一次活动时代推算，未来一段时期内新沂－宿迁段复发大震的可能性较大，安丘段次之，莒县－郯城段复发大震的可能性则很小。     

由构造应力场研究汶川地震断层的分段性

采用构造应力场均匀性对断层或板块边界进行分段的方法, 利用ldquo;裁剪-粘贴rdquo;法给出的余震震源机制解资料, 进一步从应力场角度确定汶川地震发震断层南、 北段分界点位置及南、北段震后应力场. 研究结果表明, 发震断层南、北段分界点位于北川附近, 与先前的研究结果较为一致. 南、 北段震后应力场反演结果显示, 南、北段的最大主应力轴方位均呈北东东向, 且近水平. 南、北段应力场反演的平均拟合残差和置信区间均较大, 主要原因可能是因为南、北段内应力场不均匀性造成的. 因为本文仅由大余震给出了震源断层的一级分段, 南、北段内应做进一步的细分.      

合肥市地壳浅部三维速度结构及城市沉积环境初探

合肥市位于合肥盆地东南缘,东侧紧邻郯庐断裂带,多条大型隐伏断裂穿过市区.为进一步认识合肥城市下方隐伏断裂的空间展布、性质,以及城市复杂的沉积环境,本文利用布设在合肥市区的58套三分量短周期地震仪组成的台阵,获得了37天的三分量连续波形数据,通过基于射线追踪的面波走时直接成像方法反演得到了合肥市地壳浅部0.6~3.6 km的三维剪切波速度结构,速度结构图像展现了地壳浅部的横向不均匀性和纵向成层性,揭示出NNE、NWW和近EW三组不同走向的隐伏断裂在城市地下浅部的构造特征.取得以下认识：（1）合肥市南、北方向在浅地表（2 km以内）存在显著速度差异,速度分界线位置与已知的近EW向的蜀山断裂一致,断裂南侧呈现低速凹陷,北侧则为高速隆起.低速中心深度达2~3 km,速度异常与该断裂在合肥盆地东部演化过程中的构造反转沉积了不同地层有关;（2）合肥市区存在明显的高速异常带,其走向、位置与穿过该区域的郯庐断裂带西支主干断裂相符,其中五河—合肥断裂在市区北部以东呈现低速凹陷特征,低速区范围与肥东凹陷晚白垩纪以来的沉积构造边界一致,认为肥东凹陷的最大沉积厚度可达2 km以上;（3）合肥市中心跨郯庐断裂带西支主干断裂之间呈现明显的凹、隆相间的复杂构造,推测其是在多组断裂的共同拉伸作用下形成的小型沉积盆地,沉积中心位于郯庐断裂带内部,最大厚度可达3~4 km.由于其展布方向在不同深度与该区域断裂的走向具有明显的相关性,推测不同深度的沉积形态与郯庐断裂带在不同时期的构造演化过程有关.