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1.
基于长江经济带地区活动断裂资料的收集整理和总结,结合新的遥感解译与地表调查结果,初步归纳了该区的活动构造基本特征,梳理出直接或间接威胁重要城市群、国家级新区和区域重要交通过江通道地壳稳定性的主要活动断裂及应对建议或对策,并进一步重点指出长江中下游成都-上海沿江地区的32条重要活动断裂带及其穿越或影响到的主要城市群和重大工程。在活动断裂梳理结果基础上,总结提出长江经济带西部的强烈地壳变形与地震活动主要由印度板块与欧亚板块碰撞作用下在青藏高原东南缘地区形成的“川滇弧形旋扭活动构造体系”所控制,而中-东部地区属于印度板块与西太平洋板块共同作用下区域性挤压-剪切变形导致的具有共轭走滑断裂系统特征的“棋盘格子式”活动构造体系格局,其中需要特别关注7条典型活动断裂带的活动性及其对城市群地壳稳定性的影响。根据区域的活动构造体系、活动断裂与历史地震活动性等特点,初步归纳了该区的未来地震危险性问题及应重点关注的潜在强震危险区段,指出了典型的区域古地震地质遗迹特征及开展古地震调查研究的重要性。同时,依据长江经济带地区初步的区域地壳稳定性评价结果,认为次不稳定区和不稳定区主要集中在西部地区,而中-东部地区以次稳定区与相对稳定区为主,仅郯庐断裂带及其周边存在较明显的次不稳定区。最后,指出了长江经济带活动构造与区域地壳稳定性调查评价工作在活动断裂地质调查研究和城市活断层鉴别与地震危险性评价中面临的主要问题与挑战。 相似文献
2.
南黄海盆地占据了下扬子板块的主体,自元古宙以来经历了多期构造运动,受到华北板块、扬子板块、华南板块、太平洋板块多个板块相互作用的影响,形成多期盆地演化阶段的叠合盆地。分析了南黄海盆地前人钻井资料及最新二维地震资料,并与下扬子苏北盆地地层及构造特征进行对比,认为整个下扬子区域受华北—扬子板块碰撞的影响,经历了中生代前陆盆地演化阶段。下扬子陆域部分地区发育相对完整的中生代沉积,记录了华北—扬子板块之间洋壳消减、陆陆碰撞、前陆盆地发育及碰撞后活动。而在下扬子对应海域延伸部分的南黄海盆地中,仅在盆地北部烟台坳陷东北缘通过钻井证实有侏罗纪前陆盆地地层,钻遇地层仅发育侏罗系上部陆相沉积,在地震剖面中可以解释出侏罗系下部海陆交互相地层,向上转变为陆相沉积地层。对比下扬子陆域与海域地层发育情况,华北—扬子板块碰撞造山过程对于下扬子整个区域的影响因地而异,在三叠纪末期—侏罗纪时期南黄海盆地内沉积缺失,南黄海海域区处于广泛抬升状态,印支运动期间地层挤压活动强烈,烟台坳陷内海相地层中逆冲断层广泛发育。在南黄海盆地东北缘,前陆盆地侏罗系地层发育于南倾边界断层的上盘,认为南黄海盆地侏罗纪前陆盆发育的构造背景受到同期北侧千里岩超高压变质带从深部折返影响,随着千里岩隆起带的快速抬升,为南黄海盆地北缘提供了沉积空间及物源,沉积了大套的侏罗系前陆盆地地层。 相似文献
3.
如何深入了解中国东部北黄海盆地东部坳陷岩浆活动特征是目前研究的前沿之一.为探讨早白垩世异常剧烈岩浆活动的区域构造成因并揭示中国东部的构造动力学机制,利用井-震及岩浆岩测试资料,对北黄海盆地岩浆活动特征及其与区域构造的耦合关系进行研究.在空间上刻画了岩浆的侵入相、喷出相的地震反射特征及沿深大断裂展布的平面分布特征;在时间上划分出了包括早白垩世108~115 Ma、134~145 Ma在内的4期岩浆活动.结合区域地质分析认为早白垩世早期,伊泽奈琦板块沿北北西斜向俯冲于欧亚板块之下,太平洋板块向南西方向俯冲,板块剪切作用导致郯庐断裂带左旋走滑,使得盆地处于左旋伸展环境中,内部形成派生的北西向右旋、近南北向左旋的次级共轭断裂系并控制岩浆上侵底辟活动.经过综合分析,厘清了盆地岩浆活动及断裂演化过程与区域板块运动之间的耦合关系. 相似文献
4.
通过选取南黄海盆地中部隆起内部地震反射清晰、构造特征明显的典型地震剖面,开展精细的构造解释,系统梳理了南黄海盆地中部隆起的构造样式特征,识别出挤压（滑脱、高角度逆冲、对冲/背冲）、走滑（正花状、y字型）、伸展（铲式正断层）等多种构造组合样式.首次提出在中部隆起内部发育2条NW-SE向走滑断层.在此基础上,结合区域应力场特征和深部地球动力学背景,明确了中部隆起构造样式的发育期次、成因机制和构造演化历程.研究结果表明:（1）滑脱构造主要位于中部隆起北部,滑脱面位于志留系底部的泥页岩.滑脱构造应力机制来源于三叠纪末印支运动时期华北板块与下扬子板块之间的碰撞造山作用;（2）高角度逆冲主要位于中部隆起南部,其应力机制来源于早侏罗世燕山运动早期,古太平洋板块初始高速、低角度NW向俯冲;（3）走滑断层主要表现为具有压扭特征的正花状构造,位于中部隆起东南部、中西部,对应于早白垩世时期,古太平洋板块低角度俯冲由NW向转变为NNW向引起的左旋剪切作用,中国东部郯庐断裂在该时期亦表现为左旋剪切特征;（4）伸展正断表现为铲式正断层特征,发育在中部隆起南北边界,即在中部隆起与南黄海盆地南部坳陷、北部坳陷的接触部位,对应于晚白垩世燕山运动晚期,古太平洋板块由低角度俯冲转为高角度俯冲,此时中国东部构造应力体制经历着由挤压向拉张的转换. 相似文献
5.
6.
渤海湾盆地与苏北-南黄海盆地构造特征和成因对比 总被引：2，自引：0，他引：2
渤海湾盆地和苏北-南黄海盆地为我国重要的含油气盆地,但由于所处的构造背景不同,导致石油地质条件相差很大,对比两者在构造特征和形成演化上的异同对于探讨两盆地的油气成藏条件具有重要意义。通过实际资料并分析大量研究成果认为:两盆地均为陆相断陷盆地,内部凹陷受生长断层控制而呈"箕状",在断裂特征、活动性等很多方面具有相似性,而在盆地结构、断裂展布等方面差异明显;盆地浅部构造的形成是深部物质活动的响应,深部热隆升对渤海湾盆地形成起到重要作用但不是引起苏北-南黄海盆地裂陷的原因,扬子板块与华北板块的碰撞对两盆地基底形成起到了决定作用,滨太平洋构造域板块多次转向、俯冲是两盆地裂陷和内部构造形成的重要原因之一,印度板块与欧亚板块碰撞导致大量深部物质向东、东南逃逸而影响两盆地的演化过程。结合盆地形成的影响因素,在区域动力学分析基础上,分六个阶段解释渤海湾盆地和苏北-南黄海盆地的形成演化。 相似文献
7.
本文运用分析几何方法研究了长江下游～南黄海地震活动的时空分布和分形结构问题,认为该区地震的时空分布具有分形结构,这对该区的抗震防灾和区域稳定性评价具有一定的参考价值。 相似文献
8.
中国东部燕山期和四川期岩石圈构造滑脱与岩浆起源深度 总被引：9，自引：0，他引：9
较确切地研究岩石圈内部构造滑脱面在地质历史时期形成的时间和部位是当前大地构造学研究的一个重要课题。通过大量收集中国东部燕山期(205~135Ma)和四川期(135~52Ma)岩浆起源深度资料来判断岩石圈内部和底部是否存在局部的构造滑脱界面,是否发生层圈相互作用,是否发生部分的解耦现象,是一种可行的研究方法。研究表明,中国东部燕山期和四川期岩石圈板块的构造滑脱、圈层的解耦作用及相互作用主要集中在中地壳、莫霍面与区域性主干断层的交线附近,而岩石圈板块的底面却并不存在大幅度的滑移。中国东部燕山期和四川期岩浆活动比较发育的地区基本上都位于大兴安岭—山西西部—武陵山—十万大山一线以东地区,而在此线以西地区岩浆活动相当微弱。笔者认为,在侏罗—白垩纪时期,该线以西缺少岩浆活动的地区可能就是当时的大陆型岩石圈,而该线以东岩浆活动剧烈的地区可能就属于海陆过渡型岩石圈。中国东部岩石圈的转型和"变薄",不太可能是深部地幔羽、去根作用、深部地幔热物质上涌或大陆伸展作用的结果,也不太可能与太平洋板块的俯冲作用有直接联系。 相似文献
9.
以现有地质及地震资料为基础,对阿姆河右岸区块东南部靠近吉萨尔山前地区的中下侏罗统主要构造特征进行探讨,一方面有利于促进该区中下侏罗统油气勘探,同时也有利于深化对造山带向盆地过渡的山前地区构造变形规律的认识。研究表明：该区中下侏罗统整体表现为由三列近似呈雁行状排列的NE向背斜带组成的褶皱-冲断构造。从控制背斜构造发育的断裂活动特征看,东部山前断层表现为由南东向北西方向逆冲,活动强度大,向西逆断层运动的强度逐渐减弱,且由南向北西部断层的逆冲运动方向发生反向变化,在研究区的北部发育典型的构造三角带。西部背斜带可视为断裂运动方式由南向北变化导致的调节构造。沿构造带走向,三列背斜构造高点由南向北逐渐升高。通过对中下侏罗统构造变形与上覆地层构造特征的比较,结合该区侏罗系沉积特征,认为中下侏罗统构造变形是与上覆地层构造变形共同形成于新近纪喜山期统一的区域构造运动背景下。其主要构造变形机制是晚古近-新近纪以来,在印度板块、阿拉伯板块和欧亚板块碰撞远程效应影响下,受吉萨尔山脉的隆升挤压和研究区北部NW向的大型断裂如布哈拉断裂、曼格什拉克断裂的右旋压扭共同作用而成。 相似文献
10.
11.
In estimating the likelihood of an earthquake hazard for a seismically active region, information on the geometry of the potential
source is important in quantifying the seismic hazard. The damage from an earthquake varies spatially and is governed by the
fault geometry and lithology. As earthquake damage is amplified by guided seismic waves along fault zones, it is important
to delineate the disposition of the fault zones by precisely determined hypocentral parameters. We used the double difference
(DD) algorithm to relocate earthquakes in the Koyna-Warna seismic zone (KWSZ) region, with the P- and S-wave catalog data
from relative arrival time pairs constituting the input. A significant improvement in the hypocentral estimates was achieved,
with the epicentral errors <30 m and focal depth errors <75 m i.e. errors have been significantly reduced by an order of magnitude
from the parameters determined by HYPO71. The earthquake activity defines three different fault segments. The seismogenic volume is shallower in the south by 3 km,
with seismicity in the north extending to a depth of 11 km while in the south the deepest seismicity observed is at a depth
of 8 km. By resolving the structure of seismicity in greater detail, we address the salient issues related to the seismotectonics
of this region. 相似文献
12.
A. A. Stepashko 《Russian Journal of Pacific Geology》2011,5(1):1-12
The role of the lateral structure of the lithospheric mantle in the seismotectonics and seismicity of the southern part of
the Russian Far East has been investigated. The positions of the epicenters of all the major earthquakes in Sakhalin (M ≥
6.0), as well as in the Amur region and the Primorye zones (M ≥ 5.0), are defined by the boundaries of the Anyui block of
highly ferruginous mantle, which lies at the base of the Sikhote-Alin area. Three cycles of large earthquakes are recognized
in the region: the end of the 19th-beginning of the 20th century, the mid-20th century, and end of the 20th-beginning of the
21st century. In the seismic zone of the Amur region (hereafter, the Amur seismic zone), the epicenters of the large earthquakes
in each cycle migrate from the SW to NE along the Tan-Lu fault megasystem at a rate of 30–60 km/yr. The specific features
of the seismicity of the region are explained by the repeated arrival of strain waves from the west. The waves propagate in
the upper part of the mantle and provoke the activation of the deep structure of the region. The detailed analysis of the
earthquakes in the Sikhote-Alin area (M ≥ 4.0) in 1973–2009 confirmed the clockwise tectonic rotation of the mantle block.
The characteristics of the Primorye zone of deep-focus seismicity at the Russia-China boundary are stated. Since 1973, 13
earthquakes with M ≥ 6.0 have been recorded in the zone at a depth of 300–500 km. This number of earthquakes is at least twice
as many as the number of large deep-focus earthquakes elsewhere in the Sea of Japan-Sea of Okhotsk transition zone. The unique
genesis of the Primorye seismic zone is related to the additional compression in the seismofocal area due to the creeping
of the Anyui mantle block onto the subduction zone during its rotation. The geodynamic implications of the seismotectonic
analysis are examined, and the necessity of division of the Amur plate into three geodynamically independent lithospheric
blocks is substantiated. 相似文献
13.
The seismically active Northwest (NW) Himalaya falls within Seismic Zone IV and V of the hazard zonation map of India. The
region has suffered several moderate (~25), large-to-great earthquakes (~4) since Assam earthquake of 1897. In view of the
major advancement made in understanding the seismicity and seismotectonics of this region during the last two decades, an
updated probabilistic seismic hazard map of NW Himalaya and its adjoining areas covering 28–34°N and 74–82°E is prepared.
The northwest Himalaya and its adjoining area is divided into nineteen different seismogenic source zones; and two different
region-specific attenuation relationships have been used for seismic hazard assessment. The peak ground acceleration (PGA)
estimated for 10% probability of exceedance in 50 and 10 years at locations defined in the grid of 0.25 × 0.25°. The computed
seismic hazard map reveals longitudinal variation in hazard level along the NW Himalayan arc. The high hazard potential zones
are centred around Kashmir region (0.70 g/0.35 g), Kangra region (0.50 g/0.020 g), Kaurik-Spitti region (0.45 g/0.20 g), Garhwal
region (0.50 g/0.20 g) and Darchula region (0.50 g/0.20 g) with intervening low hazard area of the order of 0.25 g/0.02 g
for 10% probability in 50 and 10 years in each region respectively. 相似文献
14.
A. A. Stepashko 《Russian Journal of Pacific Geology》2010,4(3):228-241
It is shown that the deep structure of the lithosphere played a decisive role in the recent deformations and seismicity in
the Far East. The regional variations in the composition of the mantle xenoliths and Neogene-Quaternary basalts provided grounds
for mapping the NE-extending wedge-shaped block of the Fe-rich mantle at the base of Sikhote Alin. Its boundaries continue
the Yilan-Yiton and Fushun-Mishan strike-slip faults of the Tan-Lu zone, along which this mantle block was displaced along
the continental margin in the Jurassic-Cretaceous. The localization of strong (M ≥ 5.0) earthquake epicenters in the Amur
region shows that such a mantle structure determines the key features of the regional deformations and seismotectonics. Under
the dominant western compression due to the Amur Plate’s motion, the mantle wedge is extruded in the northeastern direction
to provide an additional stress at the Okhotsk Plate boundary. This process resulted in the formation of the Sakhalin high-seismicity
zone at the front of the mantle block. In its characteristics, the zone is similar to the convergence area between the Indian
and Eurasian plates. In both cases, the main deformation and seismicity features were caused by the horizontal pressure of
the tectonic block, the frontal part of which is marked by regularly alternating compression and extension zones. In Sakhalin,
strong earthquakes with M ≥ 6.0 are confined to the seismic suture 50 km wide with concentrated compression. This structure
is discordant relative to the main faults of the island, being parallel to the front of the mantle wedge. The two migration
cycles established for the Sakhalin earthquakes with M ≥ 6.0 correspond to periods of 1907–1971 and 1995–2007. During both
cycles, the first shocks occurred in the north and subsequently migrated in the southeastern direction simultaneously decreasing
in the depths of the earthquake foci. The systematic migration implies that asymmetrical compression is responsible for both
the extrusion of the mantle wedge and its southeastward clockwise rotation. The latter plays the decisive role in the initiation
of strong earthquakes on Sakhalin. 相似文献
15.
Abstract With increasing high-quality geological and geophysical data it becomes clear that seismicity of the continents is characterized by linear patterns which are closely associated with tectonic features. The aim of this paper is to give reasonable interpretation for the earthquake distribution in the contiguous continent of the United States. Seismic lines and earthquake concentrated zones are defined, which reflect the characteristics of the continental seismotectonics. Similarities and differences in seismotectonics between the continental part of China and the contiguous continent of US are analysed. It is demonstrated that the spatial distribution of earthquakes can provide the information of the active structures in the earth's crust. The authors consider that the patterns of continental seismotectonics are not only controlled by the pre—existing tectonic frameworks and the current boundary dynamic conditions, but also possibly affected by dynamic factors of global tectonics at a higher level. 相似文献
16.
I. El-Hussain Y. Al-Shijbi A. Deif A. M. E. Mohamed M. Ezzelarab 《Arabian Journal of Geosciences》2018,11(15):435
A seismic source model is developed for the entire Arabian Plate, which has been affected by a number of earthquakes in the past and in recent times. Delineation and characterization of the sources responsible for these seismic activities are crucial inputs for any seismic hazard study. Available earthquake data and installation of local seismic networks in most of the Arabian Plate countries made it feasible to delineate the seismic sources that have a hazardous potential on the region. Boundaries of the seismic zones are essentially identified based upon the seismicity, available data on active faults and their potential to generate effective earthquakes, prevailing focal mechanism, available geophysical maps, and the volcanic activity in the Arabian Shield. Variations in the characteristics given by the above datasets provide the bases for delineating individual seismic zones. The present model consists of 57 seismic zones extending along the Makran Subduction Zone, Zagros Fold-Thrust Belt, Eastern Anatolian Fault, Aqaba-Dead Sea Fault, Red Sea, Gulf of Aden, Owen Fracture Zone, Arabian Intraplate, and a background seismic zone, which models the floating seismicity that is unrelated to any of the distinctly identified seismic zones. The features of the newly developed model make the seismic hazard results likely be more realistic. 相似文献
17.
The seismicity of Israel has been evaluated from documented earthquake records of the present century and two years of routine monitoring of microearthquake activity by means of eleven stations spreading from the Gulf of Elat to northern Galilee.
The Dead Sea rift asserts itself as the tectonic feature that accounts for the seismicity of our region. The activity peaks at zones where the fault branches sideways or at a junction with other fault systems. In particular, the crescent fault of Wadi Faria seems to be a zone of high strain accumulation. This is probably the site of many historical earthquakes which caused inland and coastal damage. It is thus found that the most active fault today which constitutes the greatest seismic risk to Israeli metropolitan areas extends along the Dead Sea rift from 31.2°N to 33.4°N.
The seismicity around the Dead Sea conforms with the proposed movement along en-echelon faults. While the southwest segment is presently inactive, most of the seismic activity there is limited to the neighbourhood of its eastern shore with extreme seismicity at its southern tip near the prehistorical site of Bab-a-Dara'a. The seismicity of the Arava is much lower than the Jordan-Dead Sea section. The seismicity of the Israeli coast was found to be somewhat higher than that of the Arava. 相似文献
18.
Earthquakes are one of the most important natural hazards to be evaluated carefully in engineering projects, due to the severely damaging effects on human-life and human-made structures. The hazard of an earthquake is defined by several approaches and consequently earthquake parameters such as peak ground acceleration occurring on the focused area can be determined. In an earthquake prone area, the identification of the seismicity patterns is an important task to assess the seismic activities and evaluate the risk of damage and loss along with an earthquake occurrence. As a powerful and flexible framework to characterize the temporal seismicity changes and reveal unexpected patterns, Poisson hidden Markov model provides a better understanding of the nature of earthquakes. In this paper, Poisson hidden Markov model is used to predict the earthquake hazard in Bilecik (NW Turkey) as a result of its important geographic location. Bilecik is in close proximity to the North Anatolian Fault Zone and situated between Ankara and Istanbul, the two biggest cites of Turkey. Consequently, there are major highways, railroads and many engineering structures are being constructed in this area. The annual frequencies of earthquakes occurred within a radius of 100 km area centered on Bilecik, from January 1900 to December 2012, with magnitudes (M) at least 4.0 are modeled by using Poisson-HMM. The hazards for the next 35 years from 2013 to 2047 around the area are obtained from the model by forecasting the annual frequencies of M ≥ 4 earthquakes. 相似文献
19.
Santi Pailoplee 《Natural Hazards》2014,74(3):1813-1827
In this study, the earthquake hazard was evaluated for all of 19 of the proposed or built dams along the Mekong River. All values representing a potential indication of hazardous earthquakes, such as the closest earthquake and seismogenic faults and including the seismic parameters required for a seismic safety evaluation, were clarified. The results will be useful in reviewing the safety of existing dams and for the design of suitable earthquake resistant specifications for any currently or future planned dam construction in this area. Seismotectonically, 14 of the 19 proposed Mekong River dams are located within an earthquake source zone. Most of faults are potentially still active, according to both seismicity and paleoseismological evidence. In addition, the maximum credible earthquakes were estimated to be in the range of 7–8 Mw for the closest fault zone of each dam. Previous isoseismal maps indicated a risk of shaking intensities of around scale III–IV (Modified Mercalli Intensity Scale) for the dams. According to the preliminary ranging of the International Commission on Large Dams, 9 of these 19 dams are classified as in an extreme hazard class and so need careful observation and monitoring of hazardous earthquakes. An effective mitigation plan should also be prepared for each operating dam. 相似文献
20.
从断层中心论向块体中心论转变--论活动块体在地震活动中的作用 总被引：37，自引：2，他引：35
讨论活动块体在地震活动中的作用。板缘地震在空间上呈线性分布,而中国大陆地震在空间上呈片状分布。大陆强震往往涉及两个以上方向断层的活动,且强震往往沿块体边界迁移或在其两侧断层上对迁。一些强震前后由中小地震震源机制解反映的Ｐ轴方向往往发生近９０°的转向,这种现象难以用区域应力方向变化来解释,但可从块体活动角度出发,用块体两个边界断层的先后错动来解释。地震前异常的远程效应、震后烈度异常分布图像以及地震序列特点等也显示了活动块体的作用。不同地区由地震活动性推测的块体活动方式有所差别,其原因可能和区域主压应力轴与块体两个边界断层走向的夹角不同有关。据此认为,在分析中国地震活动时要把视角从以活动断层为中心转变为以活动块体为中心 相似文献