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1.
1837年甘肃岷县北6级地震考证与发震构造分析 总被引：8，自引：0，他引：8
通过对1837年甘肃岷县北6级地震的历史资料考证、发震构造的综合研究表明:在1837年地震中遭破坏最为严重的地区位于今岷县堡子乡武旗及临潭县陈旗一带(当时的洮州厅以东约15km)。由此确定1837年甘肃岷县地震极震区位于甘肃岷县-临潭-卓尼三县交界,极震区烈度为Ⅷ度,震中位于北纬34.7°,东经103.9°,误差在10km以内。该地区构造位于东昆仑断裂带和西秦岭北缘断裂带的应变传递和构造转换的中间过渡区,其中临潭-宕昌断裂带活动特性差异明显,只有部分地段表现出全新世活动特征,地震极震区一带分布有不同程度的滑坡和基岩崩塌等。综合分析认为,临潭-宕昌断裂带的岷县-宕昌段的前缘分支断裂是甘肃岷县1837年6级地震的发震构造。 相似文献
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使用甘东南地区三维速度模型,利用三维网格搜索法和双差地震定位法对2013年7月22日甘肃岷县漳县MS6.6地震及其震后三天的余震序列进行了精确定位,结合地质构造资料对本次地震的发震构造进行了初步研究。其结果显示:主震的震中位置为34.54°N,104.189°E,震源深度13.5km;余震震中呈NW或NWW方向分布,与临潭-宕昌断裂的走向基本吻合,主要分布于5～20km的深度,震中在深度剖面上呈SW向;发震断裂为倾向SW的隐伏断层,位于临潭-宕昌断裂NE方向,距临潭-宕昌断裂约20km。 相似文献
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西秦岭临潭-宕昌断裂第四纪最新活动特征 总被引：2，自引：0，他引：2
临潭-宕昌断裂是西秦岭造山带内一条重要的分支断裂,其最新活动特征是分析西秦岭构造变形的重要依据。临潭-宕昌断裂的新构造活动强烈,中强地震频繁,但目前对于断裂的新活动特征研究程度较低,未见有其全新世活动地质地貌证据的报道。文中基于遥感解译、宏观地貌分析研究断裂的长期活动表现和分段性;同时通过地质地貌考察、无人机摄影测量、差分GPS和放射性碳测年等方法定量研究断裂的新活动特征;最后基于研究结果探讨了断裂及附近区域的地震危险性和区域构造变形。结果表明:根据断层迹线收敛程度和宏观地貌差异,可将临潭-宕昌断裂分为西、中、东3段;断裂的运动性质以左旋走滑为主,兼具逆冲分量,左旋走滑使洮河及其支流、冲沟和山脊等发生同步左旋拐弯,最大左旋位移可达3km,逆冲分量使新近纪盆地边缘和内部形成300~500m的垂向位移;断裂的最新活动时代为全新世,限定了1次2 090~7 745a BP(置信度为2σ)的全新世古地震事件;全新世早期以来,临潭-宕昌断裂东段主干断裂的左旋走滑速率为0.86~1.65mm/a,垂直滑动速率为0.05~0.10mm/a。临潭-宕昌断裂分配了约2mm/a的左旋走滑分量,是东昆仑-西秦岭阶区变形分配的关键断裂之一。 相似文献
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2013年甘肃岷县漳县6.6级地震震害分布特征及发震构造分析 总被引：1，自引：0，他引：1
2013年7月22日,甘肃岷县漳县MS6.6地震发生在南北地震带的中北段,东昆仑断裂和西秦岭北缘断裂是该地区复杂多样的构造几何特征中2条主要的边界控制断裂.这次地震的震害分布与临潭-宕昌断裂的走向基本一致,为长轴走向NWW的椭圆,极震区内严重破坏范围也完全位于该断裂带内,这与临潭-宕昌断裂复杂的几何结构密切相关,也说明地震的发生是多条次级断裂共同作用的结果.综合分析认为,受西秦岭北缘断裂带向南侧的扩展和青藏高原向NE扩展过程中东昆仑断裂带的NE向挤压作用共同影响下的临潭-宕昌断裂是这次地震的发震构造. 相似文献
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2013年7月22日甘肃岷县-漳县Ms6.6地震发生在临潭-宕昌断裂的东段,遥感和DEM研究表明,该断裂东段在晚第四纪以来仍有活动,自岷县至宕昌,断裂由左旋走滑兼具逆冲性质转为以左旋走滑性质为主。现场烈度和灾害调查发现,Ⅶ度区内形成Ⅷ度的异常点,在Ⅵ度区内形成Ⅶ度的异常点,这些异常点分布在沿断裂带附近约2km的范围内,主要分布在断层的上盘。进一步研究表明,由于临潭-宕昌断裂在岷县以南以走滑运动为主,强震动主要沿断裂传播,同时由于断裂活动形成软弱地基,强震动引起地基失效造成灾害,形成了烈度异常点。 相似文献
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应用速度和Q值成像方法以及小震精定位方法获得了2013年岷县漳县6.6级地震震源区的深部结构和余震序列的空间分布图像。结果表明:发震断层为一隐伏断裂,走向NW,倾向SW,逆冲兼左旋走滑,在地表距临潭-宕昌断裂岷县段约20km,在深部可能与临潭-宕昌断裂交汇在一起,向南组成一条NW向的断裂带。2003年11月13日岷县MS5.2、2004年9月7日岷县-卓尼MS5.0和本次MS6.6地震的发震断层可能属同一发震断层,位于漳县南部块体的西南边缘;该块体为次级块体(三角形),近几年来块体西南边界强震活跃,其它两边平静。 相似文献
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1573年甘肃岷县地震史料考证与发震构造探讨 总被引：1，自引：0，他引：1
通过对1573年甘肃岷县地震的历史资料考证和发震构造的综合研究表明:在1573年岷县地震中遭受破坏最为严重的地区位于如今的岷县县城一带(当时为岷州府所在地)。综合各种资料确定1573年甘肃岷县地震震级为621,极震区烈度为Ⅷ~Ⅸ度,震中位于北纬34.4°,东经104.0°,震中精度为2类,震中位置偏差小于或等于25km。该地区构造上位于东昆仑断裂带和西秦岭北缘断裂带的应变传递和构造转换的中间过渡区,其中的临潭-宕昌断裂带活动特性差异明显,只有部分地段表现出全新世活动特征,地震极震区一带分布有不同程度的滑坡和基岩崩塌等。综合分析认为,临潭-宕昌断裂带的岷县-宕昌段是甘肃岷县1573年621级地震的发震构造。 相似文献
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2013年7月22日甘肃岷县漳县Ms6.6级地震发生在临潭—宕昌断裂的东段，遥感和DEM研究表明，该断裂东段在晚第四纪以来仍有活动，自岷县至宕昌，断裂由左旋走滑兼具有逆冲性质转变为以左旋走滑性质为主。现场烈度和灾害调查发现，Ⅶ度区内形成Ⅷ度的异常点，在Ⅵ度区内形成Ⅶ度的异常点，这些异常点沿断裂带附近约2km的范围展布，主要分布在断层的上盘。进一步的研究表明，由于临潭-宕昌断裂在岷县以南以走滑运动为主，强震动主要沿断裂传播，同时由于断裂活动形成软弱地基，强震动引起地基失效造成灾害，形成了烈度异常点。 相似文献
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利用甘肃"十五"数字地震台网的波形资料,采用CAP方法反演了2013年7月22日岷县漳县6.6级地震的震源机制解。结果显示:本次地震的震源性质为逆冲兼走滑型,矩震级MW6.1,震源矩心深度为7km。最佳双力偶节面Ⅱ走向304°,倾角64°,滑动角44°,其走向与附近的临潭-宕昌断裂的走向一致;倾角和滑动角,表现为左旋走滑的特性与临潭-宕昌断裂的性质相符合,判定该节面代表了主震的发震断层面。分析认为岷县漳县6.6级地震的发生与该断裂的活动密切相关。 相似文献
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地貌参数指示的临潭-宕昌断裂带最新构造隆升差异与地震活动 总被引：5，自引：3，他引：2
2013年7月22日,甘肃岷县漳县MS6.6地震发生在青藏高原东北缘的临潭-宕昌断裂带上。为了研究该断裂的最新构造隆升的差异性,基于ASTER GDEM数字高程模型数据提取了流域盆地及水系,并以此为基础,计算了面积高程积分及河道坡度指数。2个地貌参数的分析结果表明,临潭-宕昌断裂不同部位的最新隆升呈现不均匀性。其中,断裂的最新逆冲活动在临潭以西及以岷县附近明显强于其他各段。上述地貌参数所指示的断裂抬升强度还与历史及现今地震发震位置较好地匹配,体现了定量化地貌分析对断裂活动强弱的指示作用。临潭-宕昌断裂受区域NE-SW向挤压构造应力作用影响,其活动的差异可能与晚第四纪以来巴颜喀拉块体NE向扩展背景下的局部应力集中有关。 相似文献
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《国际泥沙研究》2014,(4)
正Director:Shangfu Kuang,China Vice-directors:Chunhong Hu,China Duihu Ning,China Guangquan Liu,China The International Research and Training Center on Erosion and Sedimentation(IRTCES)was jointly set up by the Government of China and UNESCO on July 21,1984.It aims at the promotion of international exchange of knowledge and cooperation in the studies of erosion and 相似文献
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《中国科学:地球科学(英文版)》2014,(3)
正SCIENCE CHINA Earth Sciences,an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press and Springer,is committed to publishing high-quality,original results in both basic and applied research. 相似文献
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Richard D. Hey 《地球表面变化过程与地形》1979,4(1):59-72
Feedback mechanisms, which operate upstream through drawdown and backwater effects and downstream through sediment discharge are responsible for channel evolution. By combining these mechanisms with channel processes it euables a dynamic process-response model to be developed to simulate the initial evolution of straight gravel-bed channels. When erosion commences on a land surface, sediment entrained in the headwater reach by hydraulic action is selectively transported, deposited and reworked. This produces a damped oscillation between degradation and aggradation as the channel and valley respond to spatial and temporal variations in sediment calibre and hydraulic conditions. The initial cut and fill phases are responsible for valley incision and floodplain development while secondary and subsequent activity can produce river terraces. Eventually sediment entrainment in the headwaters declines as slopes are reduced. Subsequent channel evolution is relatively insignificant because it is dependent on local weathering activity producing material that can be transported on declining slopes. Therefore landforms produced during the initial phase of development, when local weathering was non-limiting, dominate the landscape. 相似文献
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Based on relocating the Jiujiang-Ruichang earthquake sequence which occurred on November 26, 2005 in Jiangxi Province with the double-difference （DD） algorithm and master event technique, the paper discusses the focal mechanism of the main shock （MsS.7） and the probable seismo-tectonics. The precise relocation results indicate that the average horizontal error is 0.31kin in a EW direction and 0.40kin in a NS direction, and the average depth error is 0.48kin. The focal depths vary from 8kin to 14kin, with the predominant distribution at 10kin - 12kin. The epicenter of the main shock is relocated to be 29.69^oN, 115.74^oE and the focal depth is about 10.Skin. Combining the predominant distribution of the earthquake sequence, the focal mechanism of the main shock and the tectonic conditions of N-E- and NW-strike faults growth in the seismic region, we infer that the main shock of the earthquake sequence was caused by a NW striking buried fault in the Rnichang basin. The nature of seismic faults needs to be further explored. 相似文献
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《水文科学杂志》2013,58(6)
Abstract The western reservoirs represent the principal groundwater system in Morocco. Demographic, industrial and agricultural developments during the last decade have markedly altered groundwater quality. The Mamora coastal aquifer system is among the Atlantic systems which are most heavily threatened by pollution. Agricultural and industrial activities, and rapid urban growth contribute to the pollution of the groundwater. Contamination transport is facilitated by a high permeability of the aquifer formations. In order to assess the actual groundwater quality of the Mamora aquifer and to understand the influence of the factors generating the pollution, an extensive multidisciplinary research programme is in progress, with hydrochemistry and microbiology playing essential roles. The present paper concerns the spatial distribution of physico-chemical parameters in the groundwater, subjected to domestic, industrial and agricultural pollution. Fifty-seven samples were analysed for several parameters (Ca2+, Mg2+, Na+, K+, Cl?, SO4 2?, HCO3 ?, NO3 ?, pH, electrical conductivity and temperature). The microbiological analysis of 143 samples reveals the presence of four kinds of indicator bacteria in the groundwater resources: faecal Streptococci, faecal coliform, Escherichia coli and Clostridium. The physico-chemical results and bacteriological monitoring show that the nitrate and bacteria concentrations exceed the maximum admissible levels, notably around pumping stations in the sectors of Sidi Taibi, Sidi Ahmed Taleb and Aïn Sbaâ. Contamination is generated by uncontrolled anthropogenic activities and accentuated by the high intrinsic vulnerability of the aquifer system. Several parameters appeared to exceed admissibility standards. Measures are recommended to prevent groundwater pollution in the region. 相似文献
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K.-G. Malle 《洁净——土壤、空气、水》1992,20(4):196-204
Zinc in the Environment. In 1990 the world production of zinc ammounted to 7 Mio. metric tons. The main areas of application were: galvanization, alloys like brass and zinc metal. The content in the earth crust varies between 10–300 ppm zinc with a mean of 70 ppm. Uncontaminated surface waters contain less than 10 mg/m3 zinc. Apart from civilization air contains 1–10 ng zinc per m3. These background concentrations are exceeded by orders of magnitude in zinc deposit areas and where anthropogenic influences predominate. Accumulation can occur in sediments and sewage sludge. Molluscs and Algae also accumulate zinc. Zinc is essential for live. With normal food the zinc supply of man is just sufficient. Bioaccumulation of zinc towards man or chronic oversupply of man is not known. Zinc has no teratogenic or mutagenic effects, a suspicion on a carcinogenic effect proved wrong. In stockbreeding and plant cultivation a minimum supply of zinc is necessary. Plants are relatively less sensitive against higher soil contents of zinc. Considering the toxicological and ecotoxicological effects of zinc in the environment, the critical organismens are marine invertebratae like tubifex, daphnia, gammarus and algae. But normally only a minor part of the total zinc contest is biologically available, depending on salt content and pH of the waters. 相似文献