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应用射线追踪方法及由震源参数和速度联合反演获的地壳速度结构,对吴忠、灵武地区1982-19983年发生的全部地震进行了精确定位。 相似文献
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依据《地震分析预报方法指南》,利用MAPSIS软件,对南黄海地区发生中强地震前的地震活动及相关地震学参数进行了分析研究,概述了该地区中强震前的发震背景。 相似文献
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淮河流域中强震活动区的地震构造背景 总被引:1,自引:0,他引:1
介绍了沿淮河干流展布的淮河构造变形带的断裂构造特征,分析了该构造变形带内中强地震与断层构造的关系,并结合淮河流域地球物理场资料的分析,提出了中强地震发生的地震地质标志。 相似文献
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华东地区中强地震构造背景和地质标志研究 总被引:3,自引:0,他引:3
华东地区,特别是下扬子-南黄海地区,是我国一个重要的中强地震活跃区,在地震区(带)划分上,华东地区北半部属华北地震区,南半部属华南地震区。根据我们的研究,其边界大致从大别山北麓到杭州湾南岸一带,这条边界也是一条重要的鹇构造运动边界,其北部为华北新生代断陷区,南部为华南新生代隆起区,下扬子-南黄海地区的地震活动性,虽比华北其他地区低,但比华南大部地区,尤其比浙南和闽北地区高得多。华东地区中强地震在空间分布是不均匀的,它们只发生在某些地区和某些特定构造部位,其地质标志主要可归结为以下5点:1.新构造差异带;2.活动断裂带;3.断陷陡深带;4.构造分水岭;5.地貌断阶带。 相似文献
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中强地震活动区地震动衰减关系的确定 总被引:3,自引:0,他引:3
地震动衰减关系是影响地震安全性评价特别是地震区划结果的重要因素.我国现行的地震动衰减关系主要是依据6级以上地震的地面运动资料得到的,并没有考虑中强地震的衰减特性.为此,文中利用现有的烈度资料和其他可供参考的研究成果来建立我国中强地震活动区的地震动衰减关系.收集了我国华中、华南、东北等地区的51次地震的烈度等震线资料,运用单随机变量加权最小二乘回归法得到中强地震活动区烈度衰减关系.然后以美国西部地区为参考地区,运用缺乏地震动参数的地震动估计方法-地震对映射法得到中强地震活动区峰值加速度和有效峰值加速度衰减关系.最后,通过与我国强地震区和中强地震区已有的烈度衰减关系和地震动衰减关系的对比,验证了得出的我国中强地震活动区烈度衰减关系和地震动衰减关系的合理性. 相似文献
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广西北流地区的地震构造与地震活动 总被引:1,自引:0,他引:1
根据地质调查资料,研究了广西北流地区的地震构造及其中与中小地震的关系,结果表明,北流地区的构造格架属于右行右阶拉分区型,在容县-玉林-带形成拉分区,区内及附的 在多组断裂,构造复杂,易于积聚应变能,是中小地震的多发区。 相似文献
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祁连山中东段的范围东起宁夏固原,西至青海祁连县以西的托莱山一带.该区曾发生过1920年海原8.6级地震,1927年古浪8.0级地震,近期还发生过一系列中强地震,如1986年门源6.4级、1990年景泰—天祝6.2级、1995年永登5.8级等地震.该地区是我国构造活动和地震活动最强烈的地区之一.存在连绵不断的一系列的全新世活动断裂,其中自西向东最重要的有海原活动断裂、古浪活动断裂、老虎山活动断裂、毛毛山金强河活动断裂、冷龙岭活动断裂、托莱山活动断裂、庄浪河活动断裂、马衔山活动断裂等.前4条断裂的定量研究已在“八五”期间基本完成.在“九五”项目… 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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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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云南地区处于印度板块与欧亚板块中国大陆碰撞带的东缘,地壳运动剧烈,活动块体特征明显,中强以上地震频发,是研究大震活动规律的理想场所。通过过去一个世纪的6.7级以上地震活动的时空分布以及地震动力分析认为,云南地区存在的4个具东西交替活动特征的地震活跃期,可能是东、西部各自地震活跃与平静过程叠加的结果,100a左右可能出现1次东、西部同时爆发大震的时段;云南地区地震活动与外围地区存在较好的呼应关系,安达曼-缅甸弧形带的巨震活动对云南地区地震活跃期的启动有一定的指示意义,而云南东部强震也与四川西部大震密切相关,四川大震活动往往滞后于云南地区;中强地震连发—平静—首发大震可能是云南以东部为活动主体的地震活跃期的启动模式。这些认识对云南地区大震预测、地震机理以及板缘动力学研究会有所帮助 相似文献
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对京津唐张地区地震震级频度关系进行空间扫描后,发现该区的震级频度关系有三种类型:第1类符合线性b值模型,第Ⅱ、第Ⅲ类符合特征震级模型。近22年来未发生大震的地区往往属第1类。大震区往往属第Ⅱ、Ⅲ类。岩石力学实验结果表明,在岩石破裂及破裂连结过程中声发射事件的震级频度关系符合高b值线性模型。在岩石伴有粘滑的摩擦滑动过程中声发射事件的震级频度关系符合低b值线性模型。但是在一个完整岩石的破裂和失稳错动全过程中声发射事件震级频度关系符合特征震级模型。由此说明某一区域的震级频度关系可能反映了该区构造变形所处的阶段。一个地区震级频度关系上的多次转折可能包含了地区构造几何信息。一些未发生大震的地区,在中等震级段出现b值非线性现象,这可能意味着它更接近失稳前的临界状态 相似文献
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研究了川滇地区强震活动分布特征及其与地质构造背景,重点是与川滇、川青地壳块体的关系,认为: ①川滇强震主要集中分布在川滇和川青两个地壳块体. 其外侧的中强震活动也明显受这两块体向南东方向滑移侧压的影响;②川滇和川青块体的强震主要分布在边界断裂带上. 块体内部的活断层上也有一些强震或中强震发生. 规模较大的也许是划分次一级块体的边界;③也确有个别强震与活断层关系不明显,表现出地震与地质构造关系的复杂性;④这两块体各边界带的地震活动性,包括盛衰交替性有一定程度的相关性,但也各有特点. 川滇块体东带7级以上地震比西带的多,且最大地震强度达8级,而西带的中强震频度高于东带. 东带的b值低于西带. 无论是地质证据,还是近年GPS观测资料都表明,东带左旋走滑速率都大于西带右旋走滑速率. 川青块体的西边界鲜水河带的地震活动性总的来说高于东边界松潘、龙门山带,且震级越高,差异越大. 前者的b值低于后者. 说明块体各带介质的不均匀性或应力状态是有所不同的;⑤ 川滇和川青块体的边界断裂带在地壳深部速度结构上都有异常变化. 多数边界断裂带切割了莫霍面,尤以倾滑为主的龙门山断裂带切割得最明显. 典型的走滑型鲜水河断裂带虽无切割莫霍面的明显迹象,但确在不同深度上都是明显的低速异常带. 相似文献
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华南地震区地震带划分的新研究 总被引:2,自引:1,他引:2
对华南地区地震带的划分提出了一个新方案。认为北东东向断裂是控制华南地震区地震活动的主要断裂,同时东部有北西向巴士系裂交汇,迭加。 相似文献