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1.
华南陆块受多阶段超大陆聚合、裂解, 碰撞、陆内造山, 及伸展等作用影响, 造成其深部结构和构造极其复杂。岩石圈有效弹性厚度(Te)是表征地质时间尺度上岩石圈力学强度的定量指标, 可为深入认识岩石圈力学结构及演化提供有效约束。本文基于导纳和相关函数联合方法对地壳布格重力异常和地形数据进行计算, 获得华南陆块Te的空间分布。Te高值(>20 km)区域主要分布于扬子地块的四川盆地周边区域, 而Te低值(<20 km)区域集中于华夏地块和江南造山带区域。由于Te分布特征与地热场、地震关系密切。通过分析研究区Te与地热场(地表热流、居里面深度)、地震之间的关系, 本文得到如下认识: (1)Te与地热场参数具有较好的相关性, 但受浅部地壳被破坏, 深部仍为克拉通地壳影响, 导致龙门山断裂带和江南造山带区域的Te与地表热流或居里面深度之间的部分对应关系相反。(2)Te与地震关系复杂, Te较薄区域并不代表着地震频发区域, 地震活动性与其所处的深部环境相关。龙门山断裂带强震频发的原因是受周边两块体中上地壳刚性地层长期相互作用, 致使应力和能量积累较强; 华夏地块区域地震较少是因为深部热物质上涌对华夏地块的壳幔进行强烈改造, 且地壳中存在横向不均匀分布的软弱地层对应力吸收, 造成能量和应力不易积累; 扬子地块的岩石圈力学强度较强是该区较少发生地震的重要原因。 相似文献
2.
东昆仑、玉树、汶川地震的发生规律和形成机理:兼论大陆地震成因与预测 总被引：6，自引：3，他引：3
青藏高原东北部东昆仑、汶川、玉树等强震的同震地表破裂不对称发育,伴随余震有规律地分别向东、南东和北北东方向迁移,很可能是源于恒河盆地流经亚东、当雄、安多、库赛湖、治多、玉树、甘孜、汶川的弧形下地壳“热河”的流速和流向变化形成的,下地壳热流物质正在向云南及邻区汇聚形成下地壳“热海”,导致长时间跨季度构造热干旱,其影响超过大气环流的作用。地表破裂不一定受断层控制,震源也不在断层面上,下地壳流动导致中地壳发震并进一步影响上地壳形成同震脆性破裂系统。大陆板内盆山过渡带地震密集,大陆板内地震是在下地壳层流的热动力作用下导致活动地壳分层变形的产物。在大陆盆山耦合、圈层耦合的非线性开放系统中,从大洋底部的软流圈层流进入大陆底部使得地幔软流圈加厚,底辟上升为大陆下地壳流动,为地震活动提供了巨量热能;热软化的下地壳缓慢的韧性流动孕育了大陆板内地震;中地壳韧 脆性剪切带易于积累能量,发生热能与应变能的转化,产生地震,形成震源层;上地壳脆性断层活动和地表破裂是地震释放深部能量的载体和方式之一。地壳稳定性评价的依据应当是地壳的活动性而不是断层的活动性。大陆活动构造区地震活跃期与平静期交替实际上是下地壳地震能量的聚散过程,体现在下地壳热主导的韧性流动构造与上地壳应力主导的脆性破裂构造之间的相互作用。下地壳热软化物质流动过程中流速、流向等突然改变触发地震,并产生共振波。大陆下地壳流层在厚度、温度、粘度、流速、流向上的变化产生一定程度的温度异常、流体异常及与其相关的大气层、电场、磁场、重力场、地球化学场、应力场、应变场、生物场等异常。合理布置天空网、地面网、地下网,综合立体监测有效的地震前兆,系统地开展长期、中期和短临地震预测,能够不断地提高地震预测水平。 相似文献
3.
广东省及邻区新生代以来构造运动与地震活动分区的研究 总被引：3，自引：0，他引：3
综合分析多年来地震地质调查资料,将广东省及部分邻区划分为具不同构造活动特点的6个区,分别论述、分析这些区内新生代以来的断裂构造、火山喷发、第四纪沉积及地震活动等。结果认为,由断层样品热释光测定确定的断层最近期活动年龄主要是在中更新世和晚更新世,沿海地带主要为晚更新世和全新世。新生代以来构造具继承性活动的地区是地震最活动地区,如琼雷地区。同时,由于历史上发生过强震,地震后至今具较大速率下沉地区,在今后相当长时间内可能是不易发生强震地区,如琼北东部和南澎-南澳地区;Ms6级地震将主要发生在晚更新世以来的新生盆地,如潮汕盆地和近岸海湾地区;Ms5级地震在一定条件下,几乎可能发生在省内的任何地区。 相似文献
4.
李绍柄 《吉林大学学报(地球科学版)》1990,(2)
地壳表层构造和深部构造互相制约是控制河北地区许多强震发生的必要地质条件。由此地质条件,在水平与垂直两个相互叠加的应力场作用下,使河北地区发生许多强震。这个构造-应力场模式,对华北地区许多强震的发生可能具有普遍意义。 相似文献
5.
Relation between electrical resistivity and earthquake generation in the crust of West Anatolia, Turkey 总被引：1，自引：0，他引：1
In this paper, we present a relation between the earthquake occurrence and electric resistivity structures in the crust, in West Anatolia and the Thrace region of Turkey. The relationship between magnetotelluric georesistivity models and crustal earthquakes in West Anatolia, during a period from 1900 to 2000, is investigated. It is found that most of the large crustal earthquakes occurred in and around the areas of the highest electrical resistivity in the upper crust, although rare small magnitude earthquakes are observed in some parts of the conductive lower crust in West Anatolian extensional terrain. The high-resistivity zones may represent rocks that are probably mechanically strong enough to permit sufficient stress to accumulate for earthquakes to occur in western Anatolia and the Thrace region. However, some recent studies state that the generation of a large earthquake is not only a pure mechanical process, but is closely related to fluid existence. We also reviewed recent world-wide researches including results from the Anatolian data for the first time and discussed all general findings in combination. Our findings show that the boundary between the resistive upper crust and the conductive lower crust correlates well with the cutout depth of the seismicity in West Anatolia and Thrace. This boundary is also attributed to the fluid bearing brittle–ductile transition zone in world literature. Fluid migration from the conductive lower crust to the resistive upper crust may contribute the seismicity in resistive zones. Alternatively, the upper–lower crust boundary may act as a stress concentrator and fluids may help to release strain energy in brittle parts of lower crust, by small magnitude earthquakes, whereas they may help in focusing strain in mechanically strong and electrically resistive zones for large earthquakes to occur. 相似文献
6.
地震成因综述 总被引：2，自引：0，他引：2
本文从地质、地球物理、地球化学和能量等方面分析了地震的成因。源于地核地幔的流体携带大量热能,为岩浆起源、地震形成和地热田提供了充足的能量,然而岩石聚集的应变能不足以产生中等以上的地震。大地震(M≥6.0)绝大部分分布在海沟、火山岛弧和大陆裂谷带等拉张性构造带,如环太平洋海沟、东印度洋海沟、大洋中脊、非洲裂谷、地中海-黑海-里海-波斯湾、欧亚大陆中部的伊塞克湖-阿拉湖-乌布苏湖-库苏古尔湖-贝加尔湖裂谷。流体在地球深部物质运动、地壳运动、地震和火山活动中扮演着重要作用。全球到处发育的隐爆角砾岩表明隐爆作用的普遍性。深部流体向上运移、向地表逃逸的过程中发生爆炸,在地球内部产生了不同震级和震源深度的地震。因此,隐爆应该是产生地震的主要机制。地震成因的隐爆模型不仅能够更好地解释不连续、各向异性的非弹性介质中发生的各类地震,譬如中深源震、震群、慢地震和非双力偶性地震等,而且能够更好地诠释全球地震、火山和地热带在空间上的吻合以及隐爆角砾岩型矿藏的形成。 相似文献
7.
我国是一个强地震较多的国家,几千年来发生了上千次强烈地震,劳动人民与地震灾害作斗争有悠久的历史,但是在历代封建王朝和蒋介石卖国集团统治的旧中国,只留下了悲惨的灾情记载。1920年海源大震时山崩地裂,黑水横流,村镇埋没,死于地震灾害者达二十万人,然而反动统治者置人民生命财产的重大损失于不顾,借地震灾害敲诈勒索,大发横财。 相似文献
8.
LI Wenpeng WEN Dongguang ZHOU Aiguo SUN Xiaoming MENG Hui SHI Jusong CHEN Zongyu ZHANG Liqin FENG Xiaoming LIU Changli ZHOU Jianwei 《《地质学报》英文版》2009,83(4):816-825
Abstract: The Wenchuan earthquake in 2008 and geo-hazards triggered by the earthquake caused large injuries and deaths as well as destructive damage for infrastructures like construction, traffic and electricity. It is urgent to select relatively secure areas for townships and cities constructed in high mountainous regions with high magnitude earthquakes. This paper presents the basic thoughts, evaluation indices and evaluation methods of geological security evaluation, water and land resources security demonstration and integrated assessments of geo-environmental suitability for reconstruction in alp and ravine with high magnitude earthquakes, which are applied in the worst-hit areas (12 counties). The integrated assessment shows that: (1) located in the Longmenshan fault zone, the evaluated area is of poor regional crust stability, in which the unstable and second unstable areas account for 79% of the total; (2) the geo-hazards susceptibility is high in the evaluation area. The spots of geo-hazards triggered by earthquake are mainly distributed along the active fault zone with higher distribution in the moderate and high mountains area, in which the areas of high and moderate susceptibility zoning accounts for 40.1% of the total; (3) geological security is poor in the evaluated area, in which the area of the unsuitable construction occupies 73.1%, whereas in the suitable construction area, the areas of geological security, second security and insecurity zoning account for 8.3%, 9.3% and 9.3% of the evaluated area respectively; (4) geo-environmental suitability is poor in the evaluated area , in which the areas of suitability and basic suitability zoning account for 3.5% and 7.3% of the whole evaluation area. 相似文献
9.
LI Wenpeng WEN Dongguang ZHOU Aiguo SUN Xiaoming MENG Hui SHI Jusong CHEN Zongyu ZHANG Liqin FENG Xiaoming LIU Changli ZHOU Jianwei China Institute of Geo-Environmental Monitoring Beijing China Geological Survey Beijing Institute of Geomechanics China Academy of Geological Science Beijing Tianjin Geological Survey Center of CGS Tianjin Geomechanics Institute of Chinese Geological Academy Beijing Nanjing Geological Survey Center of... 《《地质学报》英文版》2009,83(4)
The Wenchuan earthquake in 2008 and geo-hazards triggered by the earthquake caused large injuries and deaths as well as destructive damage for infrastructures like construction,traffic and electricity.It is urgent to select relatively secure areas for townships and cities constructed in high mountainous regions with high magnitude earthquakes.This paper presents the basic thoughts, evaluation indices and evaluation methods of geological security evaluation,water and land resources security demonstration ... 相似文献
10.
1976年唐山大地震的孕震环境:密集地震台阵观测得到的结果 总被引：7，自引：0，他引：7
1976-07-28唐山地区发生了震惊中外的7.8级大地震。为什么在华北古老克拉通内部的唐山地区能够发生如此的大地震一直是一个令人费解的问题。是否会在唐山地区再次出现同样的破坏性地震值得认真研究。利用流动地震观测台阵数据和接收函数反演方法,我们研究了唐山地区60 km深度范围内的三维地壳上地幔速度结构。结果表明:(1)由活动断裂切割的唐山断块与周围介质存在明显差异,围限唐山断块的断裂均为超壳的活动断裂;(2)唐山大震区中上地壳具有明显的非均匀壳内低速体;(3)该地区壳幔界面表现为明显的断块式隆升,与两侧相比,唐山菱形地块下方的上地幔顶部异常隆起的高度达到10 km左右,下伏的上地幔具有异常的非均匀结构;(4)唐山大震区可能有幔源物质较大规模的侵入,形成了中、上地壳内的低速体。由于较已往的研究结果有更高的空间分辨率,我们得到了一些以往尚未发现的有关唐山地区深部结构的异常特征;(5)首都圈地区内破坏性地震发生的地点绝非偶然,它们均与其相应的深部构造背景密切有关,这为强震发生地点的预测提供了可能。根据本文结果,我们认为,1976年唐山大地震的主因源于上地幔的垂向运动变形及壳幔之间物质及能量的交换,区域水平向应力场为次要作用。这有助于解释为什么能够在我国华北古老克拉通地区发生7级以上强震,在唐山地区再次发生7级以上大地震的可能性值得给予进一步的研究和关注。 相似文献
11.
2008年5月12日汶川特大地震震害调查及分析表明,目前以活动断裂和历史地震调查为重点的工程区域构造稳定性评价方法存在漏判与误判特大地震问题,从而为工程安全埋下重大安全隐患。以龙门山活动推覆体为例,在已有研究成果基础上,利用岩体结构控制论、拜尔利定律等普适性原理对龙门山地壳岩体结构力学特征、控震结构面的抗剪强度与地震震级的线性相关性、地震震级与抗震设防烈度的关系进行了定量研究,对评价区域构造稳定性的关键问题进行了探讨。结果表明,推覆体型活动地块边界带中的滑脱层是对推覆体区域构造稳定性起主要控制作用的构造结构面--控震结构面,地震震级与滑脱层的埋深、抗剪切强度存在显著相关性：8级地震的震源深度接近20 km、7级地震的震源深度接近14 km、6级地震的震源深度接近10 km,据此对研究区及邻近的古地震进行了深度核定,圈定了龙门山活动推覆体-岷山地块的6级以上强震可能发生的范围、对应Ⅶ－Ⅺ度的抗震设防烈度范围。此研究成果弥补了以往根据活动断裂-发震断裂-历史最大震级与对应地震烈度评价工程区域构造稳定性,因历史地震资料疏漏不全、活动断裂带研究平面与深度范围局限以及忽视区域构造稳定性的岩体力学实质而导致评价结果常常出现误判与漏判的诸多缺陷。 相似文献
12.
青藏高原及邻区三角形发震构造域是全球大陆最显著的地震多发区.脆性活动断层及其弹性回跳模式无法合理解释该区深度集中分布在10~40 km的点状震源.针对发震构造和地震机理不明确这一重大科学问题, 以大陆动力学和地球系统动力学新思想为指导, 对青藏高原及邻区发震构造系统进行域、层、带、点相关研究, 阐明大陆地震构造系统的结构型式, 认为下地壳固态流变及其韧性剪切带是提供地震能量的孕震构造, 中地壳韧-脆性剪切带是累积地震能量的发震构造, 上地壳脆性断裂是释放地震能量的释震构造.在研究青藏高原及邻区地震构造系统及其形成背景的基础上, 进一步论证了大陆地震热流体撞击的形成机理: 地幔墙导致大洋中脊之下的软流圈热流物质层流到大陆特定部位汇聚加厚并底辟上升, 造成大陆下地壳部分熔融和固态流变, 并改变莫霍面的产状, 固态流变物质侧向非均匀流动, 形成大陆盆山体系, 流动的韧性下地壳与脆性上地壳之间具有韧-脆性剪切滑脱性质的中地壳不断积累由下地壳热能转换而来的应变能, 形成发震层, 震源定位于下地壳热流物质富集带("热河")中的固态-半固态流变物质撞击到强弱层块之间的构造边界, 不同热构造环境和撞击角度产生5种不同类型的地震.从而为大陆地震的科学预测奠定了全新的理论基础. 相似文献
13.
青藏高原东南缘活动断层相互作用、应力触发与差别响应 总被引：2，自引：0，他引：2
岩石圈、地壳由众多板块、地块及层圈组合而成,是开放性复杂巨系统,活断层在地壳中犹如神经网络也是复杂的开放体系。因此活断层之间存在复杂的相互作用,例如地震断层破裂产生应力扰动,可能触发其他断层破裂,不仅在近处,也会在远处发生。不同的活断层构造产状、活动方式及应变阶段不同,对同一次触发响应不同。触发与差别响应二者的叠加效应在地震活动性上有重要表现。表现之一是区域大震后,余震区外地震活动显著增强处发生继发性大震的概率最大,也即率先出现"远余震、诱发前震、响应震"的地方地震危险性增大,对预测未来地震位置有效。对本区1950—2013年地震统计表明,预测成功率W=1-漏报率-虚报率=80%。同时,对当前地震危险区作了预测。 相似文献
14.
Yuanzhong Lu Shuxin Yang Lianwang Chen Jianshe Lei 《Journal of Asian Earth Sciences》2011,40(4):990-1001
Strong earthquakes that occurred in the Chinese continent are usually characterized by grouped activity, long-distance jumping migration, and different main activity areas formed in different times. In the present study, a three-dimensional (3-D) finite element model was set up for the Chinese continent involving surface topography, major active fault zones and initial stress field to study the mechanism of the long-distance jumping migration of main active areas for the strong earthquakes that occurred in the Chinese continent. A number of numerical simulation experiments have been made by introducing the birth and death of element groups under different boundary loading configurations. Our results show that (1) in an environment where always exists an initial stress field in the Earth’s crust, the areas where strong earthquakes have occurred (taken as a killed element in the model) have no longer abilities to concentrate the stress largely enough and can cause the stress adjustment by an order of MPa in a large area, which may be one of the main factors affecting the long-distance jumping migration of the follow-up strong earthquakes, and (2) it is hard to accurately predict where the follow-up strong-earthquakes will occur because it could be affected by many factors such as the loading manner, geological structure, active fault zones, initial stress field, or stress field adjustment induced by strong earthquakes, but in an active period of earthquakes, the major activity area migration of strong earthquakes may be affected largely by the boundary loading configurations. These results suggest that it is helpful to predict a trend of the strong earthquake migration by investigating various kinds of boundary loading manners and the relationship between stress field adjustment induced by strong earthquakes and the regions where the strong earthquakes occurred. 相似文献
15.
A. Manglik S. Thiagarajan A. V. Mikhailova Yu. Rebetsky 《Journal of Earth System Science》2008,117(2):103-111
Deep lower crustal intraplate earthquakes are infrequent and the mechanism of their occurrence is not well understood. The
Narmada-Son-lineament region in central India has experienced two such events, the 1938 Satpura earthquake and the 1997 Jabalpur
earthquake, having a focal depth of more than 35 km. We have estimated elastic stresses due to the crustal density and mechanical
properties heterogeneities along the Hirapur-Mandla profile passing through the Jabalpur earthquake region to analyse conditions
suitable for the concentration of shear stresses in the hypocentral region of this earthquake. Elastic stresses have been
computed by a finite element method for a range of material parameters. The results indicate that the shear stresses generated
by the density heterogeneities alone are not able to locally enhance the stress concentration in the hypocentral region. The
role of mechanical properties of various crustal layers is important in achieving this localization of stresses. Among a range
of material parameters analysed, the model with a mechanically strong lower crust overlying a relatively weak sub-Moho layer
is able to enhance the stress concentration in the hypocentral region, implying a weaker mantle in comparison to the lower
crust for this region of central India. 相似文献
16.
ZHANG Jisheng GAO Rui ZENG Lingsen LI Qiusheng GUAN Ye HE Rizheng WANG Haiyan LU Zhanwu Institute of Geology Chinese Academy of Geological Sciences Eearthprobe Geodynamics Open Laboratory of CAGS Beijing China 《《地质学报》英文版》2009,83(4)
This paper presents the 3D density structure of crust in the Longmenshan range and adjacent areas,with constraints from seismic and density data.The density structure of crust shows that the immense boundary plane of density distribution in relation to the Longmeshan fault belt is extended downward to～80 km deep.This density boundary plane dips towards the northwest and crosses the Moho.With the proximity to the Longmenshan fault belt,it has a larger magnitude of undulation in the upper and middle crust ... 相似文献
17.
东昆仑大地震的深部构造背景 总被引：4，自引：1，他引：3
本文以深地震测深剖面资料揭示的地壳结构形态为切入点 ,探讨东昆仑 8.1级大地震的深部构造背景。沱沱河—小柴旦长 5 0 0km的剖面范围内发现两处大的莫霍面错断 ,分别位于东昆仑 柴达木结合带之下和金沙江断裂之下。青藏高原北部的地壳厚度 6 1～ 75km :莫霍面具有一致南倾 ,逐步加深的产状及弱反射性特征 ;下地壳明显增厚 ,但速度未见明显降低 ;上地壳发育逆冲、走滑断裂 ;地壳中部存在低速层。北邻的柴达木盆地地壳相对刚性 ,厚 5 2± 2km。东昆仑及邻区的壳幔结构有利于强地震孕育。在印度板块向北推挤和柴达木地块的向南插入的区域挤压应力场中 ,青藏高原北部较弱的下地壳缩短增厚 ,变形过程中的蠕滑引起地壳浅部的应力放大。但NE向主压应力的作用不是大地震形成的唯一要素 ,与青藏高原北部各地体侧向运动有关。侧向运动速率和幅度的差异使应力在各地体的边界断裂积累并使其复活。而低速层对形成孕育大地震需要的“立交桥式”的局部应力环境是必不可少的条件。 相似文献
18.
全球到处发育的隐爆角砾岩表明隐爆作用的普遍性,并标志着古地震的一种形成机制。隐爆角砾岩具有特殊的角砾形状和构造。地震地质资料表明大地震产生的地表破裂带没有肉眼可观测到的断层位移。材料聚集应变能估算值表明岩石聚集的应变能不足以产生大地震。携带高能量的地核-地幔流体不仅为自己逸散提供了能量,而且为产生地震提供了充足的能量。深部流体以运移-聚集-爆炸-运移-聚集-爆炸的循环方式向地表逃逸,在地球内部不同深度产生了不同震级的地震。因此,超高压流体隐爆应该是地震形成的主要机制。地震隐爆成因机制不仅能够更好地解释各种天然地震(中深源地震、震群、慢地震和非双力偶性地震等)以及全球地震、火山和地热带的空间吻合,而且能够解释隐爆角砾岩及其伴生矿的形成。 相似文献
19.
ZHANG Jisheng GAO Rui ZENG Lingsen LI Qiusheng GUAN Ye HE Rizheng WANG Haiyan LU Zhanwu 《《地质学报》英文版》2009,83(4):740-745
Abstract: This paper presents the 3D density structure of crust in the Longmenshan range and adjacent areas, with constraints from seismic and density data. The density structure of crust shows that the immense boundary plane of density distribution in relation to the Longmeshan fault belt is extended downward to ~80 km deep. This density boundary plane dips towards the northwest and crosses the Moho. With the proximity to the Longmenshan fault belt, it has a larger magnitude of undulation in the upper and middle crust levels. Density changes abruptly across Longmeshan fault belt. Seismic data show that most of the earthquakes in the Longmenshan area after the 2008 Ms8.0 Wenchuan Earthquake occurred within the upper to middle crust. These earthquakes are clearly distributed in the uplifted region of the basement. A few of them occurs in the transitional zone between the uplifted and subsided areas. But most of the earthquakes distributes in transitional zone from subsided to uplifted areas in the upper and middle crust where relatively large density changes occurr The 3D density structure of crust in the Longmenshan and adjacent areas can thus help us to understand the pattern of overthrusting from the standpoint of deep crust and where the earthquakes occurred. 相似文献
20.
The epicenters of earthquakes which occurred in the vicinity of Tokyo during the period 1926–1967 have been plotted by an IBM 360/40 computer at the Earthquake Prediction Observation Center. As a result, a seismically quiescent area is found to the south of Tokyo. The area coincides with the shallower part of the focal plane of the great Kanto earthquake of 1923 as obtained from the analyses of seismological and geodetic data. In historical times, many large earthquakes having a magnitude of 7.0 or greater took place in this area. If it is assumed that the strain energy has been constantly accumulated in this area, an energy potentially equivalent to that of a large earthquake of which the magnitude exceeds 7.7 seems to be stored in the crust there. 相似文献