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LONG Si-sheng 《地震学报(英文版)》2000,13(5):491-498
Twenty-two earthquakes (M
L=2.2–3.7) in the joint region of Xianshuihe, Longmenshan and An’ninghe faults are studied in this paper. The source mechanism
solutions of these events are obtained using P-wave first motion method, and the characteristics of the source stress field
and rupture in the joint region are summarized preliminarily with some results of other researchers. Being strongly extruded
by the approximately horizontal regional stress with the direction from north-west to south-east and the effect of the complex
tectonics in the region, the source stress field has complex and variable characteristics. The earthquakes mainly show normal
or strike-slip faults in Yajiang, North-triangle and west of Chengdu-block areas, indicating that the vertical forces have
been playing an important role in the source stress fields, while the earthquakes mainly show reverse or strike-slip faults
in Baoxing-Tianquan area, with the horizontal components of the principal pressure stress axes identical to the south-west
direction to which the shallow mass is moving. We think that the manifold combinations of earthquake faults are the micro-mechanism
based upon which the large regional shallow crust mass has been moving continually. 相似文献
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V. B. Smirnov R. K. Chadha A. V. Ponomarev D. Srinagesh 《Izvestiya Physics of the Solid Earth》2013,49(2):243-257
In 2000, the region of the Koyna-Warna water reservoirs in West India was hit by two strong earthquakes, which occurred six months apart and had magnitudes M > 5. The Koyna-Warna seismic zone is a typical region of induced seismicity with a pronounced correlation between seismicity and water level variations in the reservoirs. This indicates that the stress level in the region is close to critical; thus, insignificant variations in stress caused by the variations in the water level may trigger a strong earthquake. In order to study the preparatory processes in the sources of the induced earthquakes, in this paper we analyze the seismic catalogue for the Koyna-Warna region before a pair of strong earthquakes of 2000. The induced seismicity is found to exhibit prognostic variations, which are typical of preparation of tectonic earthquakes and indicative of the formation of metastable source zones of future earthquakes. Based on the obtained results, we suggest that initiation of failure in these metastable zones within the region of induced seismicity could have been caused by the external impacts associated with water level variations in the reservoirs and by the internal processes of avalanche unstable crack propagation. 相似文献
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Since 231 B. C.,a total of 15 M6.0 - 7.5 earthquakes have been recorded in the west Beijing basin-range tectonic region( 38.3°- 41.5° E,112°- 116.2° N),a region mainly under the action of tensional normal faulting. In this paper,we calculate the Coulomb stress change of each earthquake and the cumulative Coulomb stress change,and on this basis we analyze the stress triggering of strong earthquakes. The research shows that there are 10 of 14 earthquakes that occurred in the trigger zones,in which the Coulomb stress change is positive,and the trigger rate is 71%. The positive areas of cumulative Coulomb stress change caused by these 15 earthquakes are: middle of northern Liulengshan fault,Northern Huaizhuo basin fault,Xinbaoan-Shacheng fault,Sangganhe fault and Southern Yuxian basin fault. This necessarily increases the seismic risk of these faults and can be used as a reference for future seismic risk analysis in this area. 相似文献
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基于2009年1月至2017年11月首都圈地区发生的8 061个地震事件的23 293条P波初动极性数据,采用改进的格点尝试法计算了首都圈地区单次地震的震源机制解和小震综合断层面解。在初步分析这些数据的基础上,利用计算得到的单次地震的震源机制解和搜集到的已有历史地震的震源机制解数据,运用线性反演法对首都圈地区构造应力场的时空变化特征进行了研究。结果显示:① 研究区的地震震源机制解类型以走滑型为主,正断型次之,这些地震震源机制解的P轴方位大都为ENE向和近EW向,与该地区的构造应力场方向基本一致,仅有个别地震的P轴方位为NNW向;② 首都圈地区的构造应力场具有较好的一致性和连续性,最大主应力轴方位由西部的ENE向至东部的近EW向呈现顺时针旋转的趋势,应力类型整体上为走滑型,这与以往的研究结果相一致;③ 通过与已有研究结果相比较认为:京西北地区现今构造应力场是相对稳定的,最大主应力轴未呈明显改变;唐山地区和北京地区的构造应力场（最大主应力轴）在1976年唐山地震前后可能发生了变化,唐山地震后一年至今（1977—2017年）是否发生变化,依据现有的计算结果尚不得而知,需要更多的研究来进一步验证. 相似文献
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东亚大陆大地震的活动带走向、活动方式、震源主压应力方向、总迁移方向,沿纬度的分布和发震频度随时间的变化,均与地球自转速率变化有成因联系。本文从地球自转加速、减速、匀速的变化趋势进行这方面的观测资料分析,证明地球速率变化是东亚大陆地震的基本动力来源 相似文献
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乌鲁木齐地区构造应力场与中强震活动特征研究 总被引：14，自引：4，他引：10
为了做好中强地震的震预报和震后趋快速判定工作,利用乌鲁木齐地区中强震震源机制解,小震平均震源机制解以及Ｓ波偏振方向综合研究了该区域应力场的分布和中强地震的活动特征。 相似文献
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针对2015年10月29日内蒙古自治区和林格尔出现的小震丛集,以和林格尔地区2010年3月至2015年12月ML 2.0以上地震为研究对象,利用该时段数字地震波形反演震源参数,采用Brune模式,呈现该地区视应力时空变化特征。结果显示：①和林格尔视应力值相对较低;②和林格尔小震频发区视应力时序变化无明显映震规律;③和林格尔小震丛集视应力与震级出现不同步变化规律。 相似文献
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Introduction Whether static stress change generated by earthquakes can trigger subsequent earthquakes heretofore is still in debate. Some researchers believe that seismic Coulomb failure stress change generated by earthquake can affect the seismicity nearby (King, et al, 1994; Toda, et al, 1998; Stein, 1999; Seeber, Armbruster, 2000). However, some researchers believe that this model is wrong. For example, Beroza and Zoback (1993) found that stress change generated by the 1989 Loma Prieta … 相似文献
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D. D. Singh 《Pure and Applied Geophysics》1997,150(1):53-73
—Rayleigh and Love waves generated by sixteen earthquakes which occurred in the Indian Ocean and were recorded at 13 WWSSN stations of Asia, Africa and Australia are used to determine the moment tensor solution of these earthquakes. A combination of thrust and strike-slip faulting is obtained for earthquakes occurring in the Bay of Bengal. Thrust, strike slip or normal faulting (or either of the combination) is obtained for earthquakes occurring in the Arabian Sea and the Indian Ocean. The resultant compressive and tensional stress directions are estimated from more than 300 centroid moment tensor (CMT) solution of earthquakes occurring in different parts of the Indian Ocean. The resultant compressive stress directions are changing from north-south to east-west and the resultant tensional stress directions from east-west to north-south in different parts of the Indian Ocean. The results infer the counterclockwise movement of the region (0°–33°S and 64°E–94°E), stretching from the Rodriguez triple junction to the intense deformation zone of the central Indian Ocean and the formation of a new subduction zone (island arc) beneath the intense deformation zone of the central Indian Ocean and another at the southern part of the central Indian basin. The compressive stress direction is along the ridge axis and the extensional stress manifests across the ridge axis. The north-south to northeast-south west compression and east-west to northwest-southeast extension in the Indian Ocean suggest the northward underthrusting of the Indian plate beneath the Eurasian plate and the subduction beneath the Sunda arc region in the eastern part. The focal depth of earthquakes is estimated to be shallow, varying from 4 to 20 km and increasing gradually in the age of the oceanic lithosphere with the focal depth of earthquakes in the Indian Ocean. 相似文献
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在对山西地区的非弹性衰减系数、场地响应和震源新参数各量关系初步研究之后,利用山西地区2008年8月-2012年5月间发生的ML2.0级以上地震612次,计算其中148次地震的震源新参数.着重研究该时间段内山西地震带连续发生的5次ML4.0级以上地震震源区的背景应力降,阳曲震区的平均应力降为2.586 MPa,其它4个震区都在1～2 MPa间.分析发现山西中部的阳曲震源区、原平震源区、大同震源区震后应力降趋于平稳的低位,而山西中南部地区的洪洞、河津2震源区附近的地震应力降在震后仍处于不断积累、逐步增强的趋势,所以应密切关注山西中南部地区的震情形势. 相似文献
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IntroductionSichuan region is one of the extruded and connected parts between the Qinghai-Xizang (Tibet) Plateau and Yangtze block. And the joint region of Xianshuihe, Longmenshan and An(ninghe faults reflects the structure characteristics formed by the Qinghai-Xizang Plateau(s extruding to Yangtze block and the Sichuan basin evolutionary process as fore-land basin. The researches on seismic activity in Sichuan region were mainly around Xianshuihe, Longmenshan and An(ninghe faults separ… 相似文献
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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
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南天山东段地震活动特征 总被引：1，自引：1，他引：0
分析研究了南天山地震带构造环境、中强地震活动震源机制解、中强地震时空分布以及拜城周围小震群活动与中强地震的关系。结果表明：南天山东段中强震震源断错以倾滑逆断为主,主压应力P轴由西到东呈扇形分布;相距较近的库车与拜城地区地震活动存在较大差异,但均存在明显的成丛性分布特点;拜城地区中强地震分布呈北西向可能预示着该区存在隐伏断裂,小震群活动则可能反映了局部中强震对周围次级小构造的影响。 相似文献
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1970年以来银川地区ML4级地震在时间上丛集发生,分别从主震震前小震与震后余震分布特征、余震序列参数计算和震源机制解的角度,研究了以上地震的活动特征。结果显示:每次地震的发生均具有一定的独立性;可计算余震参数的地震序列为非前兆震群,这一点与实际相符;震源机制解显示几次地震的发震断层主要属于银川隐伏断裂,并可能与该断裂附近的一系列次级断裂有关。分析认为几次地震的发生可能是局部应力调整的结果,与未来该区域是否发生大震关系不大,同时可以推测未来该区域依旧可能发生类似震级的有感地震。 相似文献
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基于435个地震的1580条P波数据,通过综合震源机制解方法,根据地震与网格点之间的距离不一样来确定P波符号的权重,反演得到了湖南地区0.2°×0.2°的二维构造应力场.相较以往利用震源机制求解应力场的方法,该方法不仅能直接采用P波初动资料反演应力场而略去计算震源机制的中间步骤,而且能够尽可能多地使用本地区小震P波数据对应力场方向进行限定.初步研究结果表明：湖南地区综合震源机制解总体分布特点为逆断型和不确定型;P轴倾角近水平,方位具有一定的分区性,总体上呈NWW-SEE向;T轴倾角偏高,方位在局部地区变化较大,统一性相对较差;湖南地区整体上受NWW向的挤压应力,对该区的活动断裂具有一定的控制,这或许也是该区地震多发生于郴州、娄邵、湘西州所构成的NW向空间条带的主要原因之一;湖南地区主要受菲律宾海板块NWW向的推挤作用,其次才受太平洋板块向西俯冲的影响,西面虽受印度洋与欧亚板块的水平碰撞,但由于碰撞主要引起青藏高原向东扩张,同时又受到云贵高原的阻隔,其影响至本区已大为减弱. 相似文献
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强震发生前震源系统可能处于不稳定状态,在这种情况下,震中附近地区的地震活动或许会对微小的应力变化敏感.地球自转会在震源断层面上引起应力,地球自转速率变化也会在震源断层面上引起应力变化.由于地球自转速率变化非常微小,在震源断层面上引起应力变化也非常微弱,如果震源区处于极不稳定状态,这种微弱的应力变化或许会激发一些地震活动.这些被激发的地震活动将会表现出与地球自转速率变化的显著相关性.为了考察2011年3月11日日本本州9.1地震发生前震中附近地区是否存在与地球自转速率变化显著相关的地震活动,选取2000年1月-2011年2月M≥5.0地震集中活动区域为研究区域,根据USGS发布的1991年1月-2011年2月的地震目录,利用舒斯特(Schuster)统计检验方法,研究了地球自转与本州M_W9.1地震前发生的地震活动之间的相关性.检验结果用P值来评估,P值越低表示相关性越显著.结果如下:在研究区内5.4≤M≤6.9地震的P值的时间变化显示本州M_W9.1地震前从2009年6月-2010年1月存在低于0.5%的P值.当P值达最低值时,约82%的5.4≤M≤6.9地震发生在地球自转速率季节性变化的加速期,显示出了地震活动与地球自转速率加速之间的显著相关性.取3°×3°的空间窗,以0.1°的步长沿经度和纬度滑动对P值进行空间扫描,可以得到P值的空间分布.扫描区域远大于研究区,经纬度范围为(33°N-43°N,138°E-147°E).在P值的空间分布图上,可发现在P值处于最低值期间,低于0.5%的P值集中分布在研究区的北部,本州M_W9.1地震震中位于这个低P值区的边缘.因此,本州M_W9.1地震前在其破裂区内存在显著的与地球自转相关的地震活动现象,说明破裂区内存在非常不稳定的地区. 相似文献
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台湾强震对福建水口库区的库仑应力触发研究 总被引：2，自引：0，他引：2
基于简化的水口库区断裂模型,研究了台湾地区1976年以来13次7级以上地震对福建水口水库库区NE和NW向断裂产生的库仑破裂应力。结果表明,台湾7级以上地震对水口库区NE向断裂产生库仑应力累积,而对水口库区NW向断裂的累积库伦应力作用较小,NW向断裂大多处于库伦破裂应力正、负影响区交汇部位,有的还表现为明显的抑制作用。因而,台湾7级以上地震活动对水口库区NE向断裂小震活动有促进作用,但两者之间不是简单的直接触发关系;对水口库区NW向断裂小震活动的库仑应力触发影响可以忽略。 相似文献
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（陈培善，肖磊，白彤霞，王溪莉）Ｔｈｅｅｎｖｉｒｏｎｍｅｎｔｓｈｅａｒｓｔｒｅｓｓｆｉｅｌｄｆｏｒｔｈｅ１９７６Ｔａｎｇｓｈａｎｅａｒｔｈｑｕａｋｅｓｅｑｕｅｎｃｅ￥Ｐｅｉ－ＳｈａｎＣＨＥＮ；ＬｅｉＸＩＡＯ；Ｔｏｎｇ－ＸｉａＢＡＩａｎｄＸｉ－ＬｉＷＡ... 相似文献