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1.
A STUDY REVIEW ON CHARACTERISTICS OF SEISMIC ACTIVITY OF ACTIVE-TECTONIC BLOCK BOUNDARIES IN MAINLAND CHINA 
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下载免费PDF全文 More than 80 percent of strong earthquakes(M≥7.0)occur in active-tectonic block boundaries in mainland China, and 95 percent of strong earthquake disasters also occur in these boundaries. In recent years, all strong earthquakes(M≥7.0)happened in active-tectonic block boundaries. For instance, 8 strong earthquakes(M≥7.0)occurred on the eastern, western, southern and northern boundaries of the Bayan Har block since 1997. In order to carry out the earthquake prediction research better, especially for the long-term earthquake prediction, the active-tectonic block boundaries have gradually become the key research objects of seismo-geology, geophysics, geodesy and other disciplines. This paper reviews the research results related to seismic activities in mainland China, as well as the main existing recognitions and problems as follows: 1)Most studies on seismic activities in active-tectonic block boundaries still remain at the statistical analysis level at present. However, the analysis of their working foundations or actual working conditions can help investigate deeply the seismic activities in the active-tectonic block boundaries; 2)Seismic strain release rates are determined by tectonic movement rates in active-tectonic block boundaries. Analysis of relations between seismic strain release rates and tectonic movement rates in mainland China shows that the tectonic movement rates in active-tectonic block boundaries of the eastern region are relatively slow, and the seismic strain release rates are with the smaller values too; the tectonic movement rates in active-tectonic block boundaries of the western region reveal higher values, and their seismic strain rates are larger than that of the eastern region. Earthquake recurrence periods of all 26 active-tectonic block boundaries are presented, and the reciprocals of recurrence periods represent high and low frequency of seismic activities. The research results point out that the tectonic movement rates and the reciprocals of recurrence periods for most faults in active-tectonic block boundaries exhibit linear relations. But due to the complexities of fault systems in active tectonic block boundaries, several faults obviously deviate from the linear relationship, and the relations between average earthquake recurrence periods and tectonic movement rates show larger uncertainties. The major reason is attributed to the differences existing in the results of the current earthquake recurrence studies. Furthermore, faults in active-tectonic boundaries exhibit complexities in many aspects, including different movement rates among various segments of the same fault and a certain active-tectonic block boundary contains some parallel faults with the same earthquake magnitude level. Consequently, complexities of these fault systems need to be further explored; 3)seismic activity processes in active-tectonic block boundaries present obvious regional characteristics. Active-tectonic block boundaries of the eastern mainland China except the western edge of Ordos block possess clustering features which indicate that due to the relatively low rate of crustal deformation in these areas, a long-time span is needed for fault stress-strain accumulation to show earthquake cluster activities. In addition, active-tectonic block boundaries in specific areas with low fault stress-strain accumulation rates also show seismic clustering properties, such as the clustering characteristics of strong seismic activities in Longmenshan fault zone, where a series of strong earthquakes have occurred successively, including the 2008 M8.0 Wenchuan, the 2013 M7.0 Lushan and the 2017 M7.0 Jiuzhaigou earthquakes. The north central regions of Qinghai-Tibet Plateau, regarded as the second-grade active-tectonic block boundaries, are the concentration areas of large-scale strike-slip faults in mainland China, and most of seismicity sequences show quasi-period features. Besides, most regions around the first-grade active-tectonic block boundary of Qinghai-Tibet Plateau display Poisson seismic processes. On one hand, it is still necessary to investigate the physical mechanisms and dynamics of regional structures, on the other hand, most of the active-tectonic block boundaries can be considered as fault systems. However, seismic activities involved in fault systems have the characteristic of in situ recurrence of strong earthquakes in main fault segments, the possibilities of cascading rupturing for adjacent fault segments, and space-time evolution characteristics of strong earthquakes in fault systems. 4)The dynamic environment of strong earthquakes in mainland China is characterized by “layering vertically and blocking horizontally”. With the progresses in the studies of geophysics, geochemistry, geodesy, seismology and geology, the physical models of different time/space scales have guiding significance for the interpretations of preparation and occurrence of continental strong earthquakes under the active-tectonic block frame. However, since the movement and deformation of the active-tectonic blocks contain not only the rigid motion and the horizontal differences of physical properties of crust-mantle medium are universal, there is still need for improving the understanding of the dynamic processes of continental strong earthquakes. So it is necessary to conduct in-depth studies on the physical mechanism of strong earthquake preparation process under the framework of active-tectonic block theory and establish various foundation models which are similar to seismic source physical models in California of the United States, and then provide technological scientific support for earthquake prevention and disaster mitigation. Through all kinds of studies of the physical mechanisms for space-time evolution of continental strong earthquakes, it can not only promote the transition of the study of seismic activities from statistics to physics, but also persistently push the development of active-tectonic block theory. 相似文献
2.
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
3.
MIGRATION OF LARGE EARTHQUAKES IN TIBETAN BLOCK AREA AND DISSCUSSION ON MAJOR ACTIVE REGION IN THE FUTURE 下载免费PDF全文
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
4.
系统地总结分析了巴颜喀拉地块北、东、南边界带的构造特征、各个边界带上的强震活动、部分强震的震源机制解和区域地震活动,从而探讨了2010年玉树7.1级地震发生前巴颜喀拉地块地震活动特征。从2008年玉树地区地震活动变化、巴颜喀拉块体北边界和南边界强震呼应及块体动力学过程进行了地震趋势预测的思考。 相似文献
5.
《地震研究进展（英文）》2023,3(1):100177
The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland. Based on the strong earthquake recurrence model, the cumulative probability of each target fault in the next 10 years is given by the recurrence period and elapsed time of each fault, which are adopted from relevant studies such as seismological geology, geodesy, and historical earthquake records. Based on the long-term predictions of large earthquakes throughout the world, this paper proposes a comprehensive judgment scheme based on the fault segments with the seismic gap, motion strongly locked, sparse small-moderate earthquakes, and apparent Coulomb stress increase. This paper presents a comprehensive analysis of the relative risk for strong earthquakes that may occur in the coming 10 years on the major faults in the active tectonic block boundary zones in the Chinese mainland. The present loading rate of each fault is first constrained by geodetic observations; the cumulative displacement of each fault is then estimated by the elapsed time since the most recent strong earthquake. 相似文献
6.
Introduction ZHANG and ZHONG (1977), ZHANG, et al (1978) and ZHANG (1984) pointed out that Chinese mainland is divided into two parts by the NS-trending tectonic belt, i.e., the eastern area and the western area, and each area is divided into tectonic blocks by faults. In the eastern area, the faults are trending NNE and NNW, mainly NNE, and the long axis strike of blocks is nearly trending NS. In the western area, faults are trending NEE and NWW, mainly NWW, long axis strike … 相似文献
7.
Relation between the characteristics of strong earthquake activities in Chinese mainland and the Wenchuan earthquake 下载免费PDF全文
下载免费PDF全文 This paper studies the relations between the great Wenchuan earthquake and the active-quiet periodic characteristics of strong earthquakes, the rhythmic feature of great earthquakes, and the grouped spatial distribution of MS8.0 earthquakes in Chinese mainland. We also studied the relation between the Wenchuan earthquake and the stepwise migration characteristics of MS?≥7.0 earthquakes on the North-South seismic belt, the features of the energy releasing acceleration in the active crustal blocks related to the Wenchuan earthquake and the relation between the Wenchuan earthquake and the so called second-arc fault zone. The results can be summarized as follows: ① the occurrence of the Wenchuan earthquake was consistent with the activequiet periodic characteristics of strong earthquakes; ② its occurrence is consistent with the features of grouped occurrence of MS8.0 earthquakes and follows the 25 years rhythm (each circulation experiences the same time) of great earthquakes; ③ the Wenchuan MS8.0 earthquake follows the well known stepwise migration feature of strong earthquakes on the North-South seismic belt; ④ the location where the Wenchuan MS8.0 earthquake took place has an obvious consistency with the temporal and spatial characteristic of grouped activity of MS≥?7.0 strong earthquakes on the second-arc fault zone; ⑤ the second-arc fault zone is not only the lower boundary for earthquakes with more than 30 km focal depth, but also looks like a lower boundary for deep substance movement; and ⑥ there are obvious seismic accelerations nearby the Qaidam and Qiangtang active crustal blocks (the northern and southern neighbors of the Bayan Har active block, respectively), which agrees with the GPS observation data. 相似文献
8.
川滇交界东段NE向昭通、莲峰断裂带的研究程度较低.为了了解该断裂带是否存在发生强震/大地震的危险背景,我们基于区域活动构造与动力学、重新定位的小震分布和震源机制解、历史地震破裂区、GPS形变场、现代地震活动及其参数图像等多学科的信息进行综合研究.结果表明:昭通、莲峰断裂带是川滇-华南活动块体/地块边界带的一部分,也是活动及变形的大凉山次级块体与相对稳定的华南地块之间的边界带;结构上表现为2个平行展布、朝南东推覆的断裂带,现今运动为带有显著逆冲分量的右旋走滑性质.沿昭通断裂带无大地震的时间至少为1700 余年,目前存在地震空区.GPS变形图像反映昭通、莲峰断裂带已不同程度闭锁.另外,昭通断裂带的鲁甸附近以及莲峰断裂带的南段分别存在异常低b值区或高应力区.已由低b值区和小震空白区识别出昭通断裂带上的鲁甸-彝良之间存在高应力闭锁段,并估计出其潜在地震的最大矩震级为MW7.4.本研究因此认为昭通断裂带存在发生强震/大地震的中-长期危险背景, 而莲峰断裂带的危险性还需进一步研究. 相似文献
9.
华北地区是我国的政治、 经济和文化中心, 也是我国地震多发地区之一。 华北地区历史地震资料记载时间较早且较为连续, 是研究我国强震活动的理想试验场。 选取第三、 第四活动期M≥6.0地震目录作为基础资料研究华北地区强震活动特点。 首先探讨华北地区强震活动与活动地块、 边界带的关系, 然后从时间和空间上分析华北地区强震活动的轮回性阶段及其期幕活动特点, 最后计算未来5年华北地区发生下一次M≥6.0地震的累积概率和条件概率。 研究结果表明: ① 华北地区M≥6.0地震活动主要集中在活动地块的边界带, M≥7.0地震则全部发生在活动地块的边界带上, 同时华北地区地震应变释放速率与边界带的构造活动速率呈线性相关; ② 第四活动期各活跃幕的能量释放均低于第三活动期, 因此华北地区未来仍可能发生M≥6.0地震; ③ 第三、 第四活动期的主体活动区存在显著差异, 且第四活动期的强震活动较第三活动期向东迁移; ④ 在2020年年初发生第四活动期闭幕M≥6.0地震的累积概率为80%左右, 而在2022年年底前发生M≥6.0地震的条件概率为50%。 本研究可为华北地区地震大形势分析和中长期地震危险性预测提供重要参考。 相似文献
10.
分析了西南地区的活动构造、 应力场特征, 统计了川滇菱形块体内部理塘-德巫断裂上发生的中强地震与川滇及其附近地区大地震的对应关系。 结果表明, 1900～2000年理塘-德巫断裂上发生的6次5.5级以上地震有5次在其后2～3年内, 川滇菱形块体边界带及其附近地区发生了7.5级以上地震。 反之, 1900年以来西南地区共发生7.5级以上地震7次, 其中5次地震前2～3年内理塘-德巫断裂上均发生了5.5级以上地震。 在此统计基础上讨论了2001年2月23日雅江6.0级地震对西南地区近期地震形势的影响。 相似文献
11.
本文在前人对中国大陆及周边活动地块研究和划分的基础上，系统研究了6个Ⅰ级活动地块区和22个Ⅱ级活动地块之间共26个活动边界带的构造变形与强震活动，包括强震分布与活动边界带的关系，边界带构造活动速率与地震活动水平及强震复发期等的关系. 给出了边界带强震活动水平与构造活动速率之间的线性关系和强震复发期长短与构造活动速率的反向变化关系. 从而进一步揭示了中国大陆活动地块构造及其块体运动特征，以及块体边界带的构造变形对强震的控制作用. 相似文献
12.
Previous studies have shown that the active tectonic block boundaries in the Chinese mainland are the main belts and concentration areas of strong earthquakes occurring in the Chinese mainland.It is essential to carry out follow-up analysis of strong earthquake risk of active tectonic block boundaries.In this paper,we carry out the analysis on the tendency of strong earthquakes along each active tectonic block boundary from three aspects respectively,including the evolutionary characteristics of the Load/Un... 相似文献
13.
强震中期阶段区域性形变异常的共性特征及其机制以青藏块体东北部为例 总被引：2，自引：1，他引：1
强震前中期阶段(1～3年或稍长)区域性形变异常往往表现出3个方面的共性特征: ① 区域垂直运动变形呈现与构造有关的异常隆起区、 垂直差异变形高梯度带(有的还呈“四象限”)分布特征; ② 水平运动变形呈现与活动地块及断裂构造有关的、 以剪切变形为主的高应变集中区(带)特征; ③ 区域性垂直形变异常区与水平形变的高应变分布区共生的特征。 分析这些异常共性特征的形成机制, 初步认为: 它们是在基本统一的大区域构造应力场控制下, 不同层次块体系统运动及其边界带变形的非平稳、 非协调性, 在活动地块边界地带和地块内部次级断裂构造部位产生变形差异而导致应力-应变积累、 孕育强震到一定阶段的结果。 在此基础上, 分析探讨了基于区域性形变异常共性特征、 结合地质构造活动背景进行强震中期预测的意义。 相似文献
14.
兰州地区活动构造的基本特征 总被引：5，自引：0，他引：5
兰州地区发育了NWW向和NWW向2组主导性活动构造带。大致以河口为界，东部地区主要为NWW向的马衔山－兴隆山左旋逆走滑活动断裂系，其新活动明显，是区内的主要控震断裂，1125年兰州7级地震就发生在其中的马衔山北缘断裂带的西端。河口以西为拉脊山北缘断裂和庄浪河断裂等1组NWW向的弧形逆冲断褶带，变形方式以断裂扩展褶皱为主，其新活动可能导致了138年金城－陇西63／4级地震、1440年永登61／4级地震和1995年永登5.8级地震的发生。兰州市区所在的兰州盆地则夹持在上述2组活动构造之间，其内同样发育了NWW向和NWW向的次级断裂，如刘家堡断裂、金城关断裂、雷坛河断裂及深沟桥断裂等，其上具有孕育和发生中强震的构造条件。 相似文献
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天山地块强震活动的时空特征研究 总被引：3，自引：0，他引：3
通过对天山地块近百年地震活动时空特征分析表明: ① MS≥7.0地震沿块体边界成带分布, 南边界带强于北边界带, 南、 北边界带的西部强于东部, 南天山西段是地震活动水平最高、 复发周期最短、 强震序列类型最复杂、 地震危险性最大的地区; ② 地震活动在时间上显示出准周期性, 表现为MS≥7.0地震具有活跃与平静的交替性及5级以上地震活动度曲线的起伏变化; 最大熵谱计算地震活动度的显著周期为40年, 小波分析给出40年左右周期系数的时间曲线表明, 7级以上地震都发生在曲线由最高值至最低值的下降段, 而上升段为强震的平静期; ③ 在强震活跃期及平静期, 中强以上地震(MS≥5.0)在块体的不同部位(地块南、 北边界带及块体内部)的分布状态和活动水平存在明显的差异, 在活跃期南、 北边界带中强以上地震的集中性和成带性强, 且彼此活动水平差异小, 但与块体内部差异大; 而在平静期南、 北边界带的活动水平差异大, 块体内部地震活动显著增强; ④ 在活跃期, 天山地块南、 北边界带强震活动存在一定的呼应关系, 当一个边发生强震后, 另一边在数天至数年也存在发生强震的可能。 相似文献
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Study on distribution characteristics of strong earthquakes in Sichuan-Yunnan area and their geological tectonic background 总被引：2，自引：0，他引：2
Introduction Both Sichuan and Yunnan are provinces with more earthquakes. Based on catalogue of strong earthquakes in China compiled by the Prediction Department of China Earthquake Administration, there are 639 M5.0 earthquakes during 26 B.C.~A.D. 2001. Among them, 475 are M=5.0~5.9 events, 124 are M=6.0~6.9 events, 39 are M=7.0~7.9 events, and one is M=8 event occurred in Sichuan and Yunnan area. Here is one of the areas where seismic activities are most active in China. Sichuan-Yun… 相似文献
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LATE QUATERNARY ACTIVITY OF THE CENTRAL SEGMENT OF THE DARI FAULT AND RESTUDY OF THE SURFACE RUPTURE ZONE OF THE 1947 M73/4 DARI EARTHQUAKE,QINGHAI PROVINCE 下载免费PDF全文
下载免费PDF全文 Bayan Hara Block is one of the most representative active blocks resulting from the lateral extrusion of Tibet Plateau since the Cenozoic. Its southern and northern boundary faults are characterized by typical strike-slip shear deformation. Its eastern boundary is blocked by the Yangze block and its horizontal movement is transformed into the vertical movement of the Longmen Shan tectonic belt, leading to the uplift of the Longmen Shan Mountains and forming a grand geomorphic barrier on the eastern margin of the Tibet Plateau. A series of large earthquakes occurred along the boundary faults of the Bayan Hara Block in the past twenty years, which have attracted attention of many scholars. At present, the related studies of active tectonics on Bayan Hara Block are mainly concentrated on the boundary faults, such as Yushu-Ganzi-Xianshuihe Fault, East Kunlun Fault and Longmen Shan Fault. However, there are also some large faults inside the block, which not only have late Quaternary activity, but also have tectonic conditions to produce strong earthquake. These faults divide the Bayan Hara Block into some secondary blocks, and may play important roles in the kinematics and dynamics mechanism of the Bayan Hara Block, or even the eastern margin of the Tibet Plateau. The Dari Fault is one of the left-lateral strike-slip faults in the Bayan Hara Block. The Dari Fault starts at the eastern pass of the Kunlun Mountains, extends eastward through the south of Yalazela, Yeniugou and Keshoutan, the fault strike turns to NNE direction at Angcanggou, then turns to NE direction again at Moba town, Qinghai Province, and the fault ends near Nanmuda town, Sichuan Province, with a total length of more than 500km. The fault has been considered to be a late Quaternary active fault and the 1947 M73/4 Dari earthquake was produced by its middle segment. But studies on the late Quaternary activity of the Dari Fault are still weak. The previous research mainly focused on the investigation of the surface rupture and damages of the 1947 M73/4 Dari earthquake. However, there were different opinions about the scale of the M73/4 earthquake surface rupture zone. Dai Hua-guang(1983)thought that the surface rupture of the earthquake was about 150km long, but Qinghai Earthquake Agency(1984) believed that the length of surface rupture zone was only 58km. Based on interpretation of high-resolution images and field investigations, in this paper, we studied the late Quaternary activity of the Dari Fault and the surface rupture zone of the 1947 Dari earthquake. Late Quaternary activity in the central segment of the Dari Fault is particularly significant. A series of linear tectonic landforms, such as fault trough valley, fault scarps, fault springs and gully offsets, etc. are developed along the Dari Fault. And the surface rupture zone of the 1947 Dari earthquake is still relatively well preserved. We conducted a follow-up field investigation for the surface rupture zone of the 1947 Dari earthquake and found that the surface rupture related to the Dari earthquake starts at Longgen village in Moba town, and ends near the northwest of the Yilonggounao in Jianshe town, with a length of about 70km. The surface rupture is primarily characterized by scarps, compressional ridges, pull-apart basins, landslides, cleavage, and the coseismic offset is about 2~4m determined by a series of offset gullies. The surface rupture zone extends to the northwest of Yilonggounao and becomes ambiguous. It is mainly characterized by a series of linear fault springs along the surface rupture zone. Therefore, we suggest that the surface rupture zone of the 1947 Dari earthquake ends at the northwest of Yilonggounao. In summary, the central segment of the Dari Fault can be characterized by strong late Quaternary activity, and the surface rupture zone of the 1947 Dari earthquake is about 70km long. 相似文献
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本文以构造应力场观测结果、 岩石圈流变特性为约束, 采用摩擦接触单元反映断裂带空间分段特征, 以最接近真实地下环境的非线性黏弹性材料为模型的本构关系, 建立包括安宁河—则木河—小江断裂带的三维有限元模型, 模拟在速度边界条件和重力势能等动力因素共同作用下的断裂带应力分布特性. 研究结果表明, 模拟得到的断裂带现今构造应力场与地震活动有明显的对应关系, 应力比较集中的区域, 如石棉、 西昌、 巧家、 东川附近, 极有可能是未来的地震危险区域. 相似文献
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地震构造是地震孕育和发生的载体，也是地震危险性预测的基础.中国大陆地震构造具有鲜明的分区特征.不同地区的地震活动都有其自身的强弱变化，很难用统一的活动期或平静期来涵盖.地震活动强度与各个区域的断裂活动水平有较好的一致性.如东、西部断裂活动水平相差约一个数量级，大震发生的频度也相差一个数量级.地震不但与活断层有关，而且与地震构造块体的关系也相当密切.前兆异常和地震不是因果关系，是伴生或孪生的关系，它们都是构造活动的产物.本文从中国大陆地震构造环境出发，研究了典型地震构造块体和主要地震断裂带与地震危险性的关系.结果表明：中国大陆未来十年或更长一段时间大震活动的地区主要在西部.重点应该注意塔里木块体沿南北两侧边缘断裂带由西向东发展的趋势.在川滇地区应重点关注鲜水河-安宁河-小江断裂带及毗邻地区.东部可能会有多次中强地震发生，发震地点可能与渤海-张家口-河套地震断裂带和郯庐地震断裂带有关. 相似文献