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昆仑山口西8.1级地震前青藏块体边界断层异常活动 总被引：5，自引：0，他引：5
系统分析了青藏块体边界断层的形变资料，研究了断层活动的动态过程及空间分布。结果表明，昆仑山口西8．1级地震前孕震影响范围达到青藏块体的周边地区；发震断层所在的构造带震前断层活动最为剧烈；加强对构造块体断层整体活动的宏观动态比较和分析，有助于判定未来强震发生的危险地段；震后应力将转移并集中到西秦岭构造带及其邻近地区。 相似文献
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通过研究西部构造运动及强震的相关性分析，结果表明：地震构造对西部的强震活动显示出很强的控制力；大华北强震与西部强震具有同步活动特点，但滞后于西部强震活动，山西地震带在整个华北地震带中起着重要的作用；西部强震第三活跃时段已经开始，对全国和山西地震形势将产生深远的影响。 相似文献
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结合新疆构造活动的特点及地震活动的分区,探讨了境内强震活动的迁移特征,结果表明新疆强震活动始于乌恰地区,分别沿南天山西段由南向北迁移和沿西昆仑带由西向东迁移。其迁移方式主要表现为天山带强震活动由低纬向高纬地区成组迁移,各带内次级活动区的往返迁移。研究结果将为判断新疆各区(带)地震活动的趋势及强震危险地区提供依据。 相似文献
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东昆仑活动断裂带及其强震活动 总被引：17，自引：0，他引：17
本文在简述东昆仑活动断裂带的构造背景与演化历史的基础上，重点叙述了该活动断裂带的展布，几何结构，第四纪运动和强震活动等特征，指出，这是一条具有长期演化历史，深部构造背景和第四纪乃至全新强烈活动的断裂带。因而在我国大地构造演化，尤其在青藏高原隆起形成，占有重要地位，同时，它还是我国西部地区一条主要的强震活动构造带，根据现代强震活动记录和在全带新发现的多期全新世古地震及其地表破裂带，分析了大震在断裂带 相似文献
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地震构造是强震发生的必要基础，强震的孕育和发生与构造密切相关。强震的孕育和发生不仅与震中周围构造有关，而且与孕震区所在的整个构造带有关。这就表明整个构造带的地震活动性与未来强震都有关联，因此，我们在做测震学参数异常预测地震时，必须考虑整个构造带的地震活动。过去我们常以震中周围地区的地震活动资料来做测震学参数的异常分析，可能会丢失部分信息。本文进行了地震构造分区和构造单元的划分，把加卸载响应比参数和张家口一渤海边界带有机结合，对基于活动地块边界带的加卸载响应比参数在海城地震预测中的应用进行了研究，结果预测效果很好。这种方法对边界带的地震危险性判定有某种参考价值。 相似文献
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地震构造是强震发生的必要基础,强震的孕育和发生与构造密切相关。强震的孕育和发生不仅与震中周围构造有关,而且与孕震区所在的整个构造带有关。这就表明整个构造带的地震活动性与未来强震都有关联。因此,在做测震学参数异常预测地震时,必须考虑整个构造带的地震活动。过去人们常以震中周围地区的地震活动资料来做测震学参数的异常分析,可能会丢失部分信息。文中以金沙江—红河边界带和地震学参量Mf值的结合为例,对基于活动地块边界带的测震学参数强震预测进行了探索,其结果对丽江地震预测效果很好,这对边界带的地震危险性判定有某种参考价值。 相似文献
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分析了帕米尔─西昆仑带的强震活动规律，指出该带强震活动在时间轴上可划为６个活动幕，在空间上可划为３个优势分布区域，地震活动水平呈西强东弱态势，并且存在强震从帕米尔向东南方向沿地震带作定向迁移规律，文章对此现象作出了物理解释． 相似文献
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北祁连山构造带位于青藏髙原的东北部边缘，隶属于秦岭-祁连-昆仑褶皱系，为一发育良好的加里东优地槽褶皱带，在近代曾发生过1927年古浪8级大震和1932年昌马7.5级强震。近年来，许多学者都运用板块构造理论对该带的构造特征和地震活动进行了重新分析和研究，並一致认为北祁连山构造带是一条巨大的早古生代晚期结束地槽活动的加里东古板块缝合线。 相似文献
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根据中国大陆不同来源的多个GPS区域监测网1991～1999年间的观测资料和“中国地壳运动观测网络”基本网1998～2000年的观测资料，联合处理得到中国大陆地壳水平运动速度场结果，通过最小二乘配置法建立中国大陆水平运动速度场模型，获得了基于连续介质假设的中国大陆水平应变场（或称为视应变场）初步结果. 分析了水平运动、应变场空间分布特征及其与强震的关系，并简要分析了2001年11月14日昆仑山口西8.1级大地震的区域构造变形背景. 结果表明：中国大陆中西部构造变形强烈，应变速率值高，又以青藏块体及其边缘和新疆西部最为显著. 除川滇、新疆西部外，大部分地区的近东西向断裂存在左旋剪切变形，近南北向的断裂存在右旋剪切变形. 而东部地区构造变形相对较弱. 强震通常发生在剪切应变率的高值区及其边缘，尤其是与构造变形背景相一致的剪应变率高值区. 昆仑山口西8.1级地震发生在最显著的东西向左旋剪切应变率高值区，从该区域的应变状态分析，具备近东西向断裂产生巨型走滑破裂错动的构造变形背景. 相似文献
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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． 相似文献
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Based on the studies of earthquake activity, tectonic movement, crustal shortening rate, fault activity, local stress field and historical characteristics of strong earthquake activities in Xinjiang, we divide the south part of Xinjiang into 4 seismotectonic zones, namely, the eastern segment of south Tianshan seismic belt, the Kalpin block, the Kashi-Wuqia junction zone, and the west Kunlun Mountains seismic belt. Using earthquake catalogues from Xinjiang since 1900, and on the basis of integrity analysis of earthquake records in different magnitude ranges, the seismicity state of different seismotectonic zones is analyzed quantificationally by calculating the mean value of annual strain energy release, annual rate of earthquakes with different lower limits of magnitude, b-value, and the parameter m of accelerating strain release model. The characteristic indexes of seismicity state for each of the seismic tectonic zones are then determined, which provide a quantitative basis for earthquake tendency analysis and judgment. 相似文献
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构造应力场往往对地震活动性具有控制作用，应力快速集中的地方常常是地震频繁发生的地方.本文以巴颜喀拉块体及其边界断裂带近20年来的7次中强震为例，结合区域历史地震震源信息、地质背景及GPS等观测数据，利用Monte Carlo方法和库仑-摩尔破裂准则为计算依据，反演该块体的震前初始构造应力场.通过将初始应力场反演中不确定部分限定在一个合理的上下限范围内进行独立的重复性随机试验，并运用统计学方法得到了巴颜喀拉块体1997年玛尼MW7.5地震震前区域初始应力场.计算结果显示：（1）巴颜喀拉块体10 km深度处最大水平主应力方向自西向东呈顺时针旋转趋势，由NS向转变为近EW向，与浅部实测地应力数据、历史地震类型和板块运动方向吻合较好.（2）最大/最小水平主应力和二者差值自西向东均逐渐增加，最大水平主压应力值~400 MPa，最小水平主压应力值~250 MPa.差应力在昆仑山断裂带与阿尔金断裂带交汇处及甘孜—玉树断裂带西段较低（~150 MPa）；在昆仑山断裂带东端和甘孜—玉树断裂带的东南段局部地区较高（~220 MPa）. 相似文献
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MIGRATION OF LARGE EARTHQUAKES IN TIBETAN BLOCK AREA AND DISSCUSSION ON MAJOR ACTIVE REGION IN THE FUTURE 
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下载免费PDF全文 YUAN Dao-yang FENG Jian-gang ZHENG Wen-jun LIU Xing-wang GE Wei-peng WANG Wei-tong 《地震地质》1979,42(2):297-315
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 MS7.0 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. 相似文献
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 MS7.0 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. 相似文献
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2020年6月26日新疆于田西昆仑地区发生MS6.4地震, 这是继2008年MS7.3和2014年MS7.3两次于田地震后发生的又一次强震。 判定此次地震的发震构造是进行地震解剖需要解决的一个基本问题。 本文基于GIS平台与技术, 对构造地质、 高分遥感、 地貌地形、 地震、 GPS速度场、 震源机制等各种资料进行整合, 通过跨学科资料的综合分析, 对地震相关的动力学、 运动学机制进行了研究, 对发震构造进行了初步的判定。 此次于田地震的发生可能是2014年强震破裂段进一步向西南方向破裂的结果。 地震精定位结果显示震中位于琼木孜塔格峰附近。 高分遥感解译及构造地貌变形分析的结果表明极震区是一个典型的张性盆岭构造区, 发育有小型的断陷盆地和正断性质的控盆断裂。 震后高分卫星影像表明在震区未发现明显的地表破裂带以及地震次生灾害。 此次地震可能是由西昆仑地块与松潘—甘孜地块之间NE向构造带内张性构造体系的活动而引发的。 由于构造带两侧地块的斜向拉张运动, 使得正断层、 走滑断层在构造带内先后形成并且持续地、 同步地活动。 正断比走滑更主要一些, 其分别能够很好地适应并吸收张性纯剪切分量以及横向简单剪切分量, 从而使得构造带内正断型、 走滑型地震频发, 此次于田MS6.4地震就是在这种背景下发生的。 构造区范围内的地壳自地表向深部可能存在着多层次的张性构造体系, 各个体系之间可能不具有明显的关联性。 本次地震可能与地表张性构造体系关系不大, 推断是深层次张性构造体系活动的结果。 相似文献
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给出了2003—2008年新疆74次MS≥4.5地震的震源机制解。分析了该期间震源机制反映出的新疆区域应力场特征,并结合1990—2008年的地震活动图像和区域应力场进行了讨论。结果认为:1990—2003年与2004—2008年新疆MS≥5地震活动空间分布图像存在较大的差异性;震源机制得到的主压应力P轴方位为NNW向,与新疆近SN向的背景应力场和作者前期给出的NNE向结果略有差异,反映出不同时期新疆大区域应力场的变化特点;中强地震震源机制主压应力P轴仰角的大小变化与新疆地震活动的强弱相关性明显。 相似文献
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研究华北地区(34-42N,108-124E)地震活动的时空分布表明,不同的时期,主要的地震活动在不同的区域发生,随时空的整体性转移是明显的.太行山前断裂带是该区最重要的构造带之一,它不仅控制了其两端的地震活动,也控制了以它为界的东、西两区的地震活动.并指出,大约从19世纪以来,华北地区的地震活动主要在东区,而不在西区,地震活动格局已经发生了重大改变;作为地震预报的重点监视区,应着重考虑目前正在活动的地区,这对地震的长期预报是重要的. 相似文献