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分析矿震破裂机制及微震的时空分布能够为矿区灾害评估提供更多的有效信息.本研究基于密集台阵观测对2019年11月12日辽宁抚顺2.4级矿震开展震源参数研究,震源机制解显示地震破裂包含明显的非双力偶分量,表现为体积压缩的塌陷机制,且震源深度较浅,最佳拟合矩心深度为0.6 km.同时,对11月3日—25日记录的连续地震波形开展微震扫描,新检测出324个微震事件(-0.5~2.0级),定位结果显示在M 2.4矿震发生前M>1.0级事件显著增多,且在矿震位置存在近南北向的微震条带分布,微震序列随时间向深部迁移(约1.5 km),暗示存在断层活化迹象.结合震源破裂机制,我们认为此次事件与矿区塌陷破裂密切相关,同时伴随先存断裂的剪切滑动.本研究表明,基于密集台阵观测的地震矩张量反演和微震检测研究,对判定矿震类型及防范矿区灾害具有重要的研究意义. 相似文献
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利用青海和周边87个地震台站于2022年1月8—13日记录的青海门源M6.9地震主震及680次余震资料,经双差地震定位重新进行震源位置的修定,获得633个地震重新定位后的震源信息。结果显示,此次地震的余震分布明显以昌马—俄博断裂南末梢端为界分为东、西两段,西段呈近EW向沿托勒山断裂东段分布,东段呈NWW向沿冷龙岭断裂西段分布。重新定位前余震初始震源深度集中分布在5~15 km,重新定位后变化为在0~20 km深度范围内偏正态分布。根据重新定位后余震分布特点并参考地表破裂带的展布,依据成丛地震发生在断层附近的原则,选取2个矩形区域,基于这2个区域内重新定位后的震源信息,利用模拟退火与高斯\|牛顿相结合的算法进行断层面拟合计算,完整地获得每一个拟合区域的断层面参数。结果表明托勒山断裂东段断层面与冷龙岭断裂西段断层面分别为长约15 km总体走向为近EW向的高倾角左旋走滑断裂与长约12 km总体走向为NWW向的高倾角大型左旋走滑断裂。此次青海门源地震可能是上述两断层面末端相互挤压共同破裂形成的。 相似文献
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山东及邻区地震的重新定位及其与活动构造的关系 总被引：5，自引：0，他引：5
对山东及其邻区1975～2010年发生的地震经震相到时数据校正后,用双差定位(Hypodd)和Hypoinverse 2000定位法对其进行重新定位,分析结果表明:重新定位的地震在空间分布上与区域构造结合更为紧密,震源深度的分布与人工地震勘探所推测的断裂相吻合;研究区地震多发生在5 ～25km深度范围内,分别在10km和16km左右存在两个明显的优势分布层,推断为这两个优势分布层分别位于上地壳底面和中地壳;地震活动图像表明中强震易发生在上下地壳交界的脆-韧转换带内,是区域应力作用下深部构造动力与浅层断裂运动变形的结果. 相似文献
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利用双差定位方法对瀑布沟水库区域内2006-10-13~2013-07-31之间发生的3 784个地震进行了重新定位,获得了3 601个地震的重新定位结果,到时残差平均为0.12 s,E-W、N-S和U-D三个方向上平均定位误差分别为0.15 km、0.17 km和1.10 km。重新定位结果显示,在研究区域内的西南方向和水库流域,地震分布密集,这个区域处于鲜水河断裂中南段、安宁河断裂北段和大凉山断裂北段的位置,此区域内地震震源深度主要分布在5~30km间,表明该区域的地震主要是构造活动引起的,而水库库区内地震震源深度主要分布在0~5 km区间,分布比较集中,该地区的地震为水库诱发和人工爆破引起的地震。 相似文献
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使用双差定位法对2017年11月18日米林6.9级地震和余震进行重新定位,得到691个地震定位结果,发现：①余震序列分布更加集中,地震序列震中呈NW-SE向分布,与雅鲁藏布江断裂在NE向构造转弯处的走向基本一致;②地震序列的震源深度主要分布在5-15 km,东南侧地震数量较少,震源深度相对较深,西北侧地震数量较多,震源深度较浅。 相似文献
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紫坪铺水库库区地震精定位研究及分析 总被引：10，自引：0，他引：10
利用双差定位法, 对紫坪铺水库台网8个地震台站记录到的2004年8月16日至2008年5月10日的1569个小震进行重新定位。 结果显示, 重新定位后的小震主要集中分布在龙门山推覆构造带的中央北川—映秀断裂、 前山灌县-江油断裂和后山汶川—茂汶断裂上, 其中大部分地震位于北川—映秀断裂并收敛于紫坪铺水库的两端, 走向NE向; 震源深度集中在5~15 km范围内, 平均深度为7.8 km, 15~30 km也有少量地震发生。 水库区域小震活动频度与水库水位存在一定的相关性。 精定位后, 到时残差的均方根平均值为0.048 s, 震源位置的估算误差在水平方向上平均为0.63 km, 在垂直方向上平均为0.51 km。 文中还讨论了紫坪铺水库区震源分布和地质构造的关系。 相似文献
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采用双差定位法对2013年7月22日甘肃岷县—漳县交界地区M 6.6地震及主震后48小时内388次余震序列进行重新定位,得到350个精定位地震数据。结果表明,余震优势展布以北东向较大倾角的铲状结构为特征,长约12 km,以主震为中心两侧对称分布;震源深度主要集中在4—10 km范围内,但余震震级由10 km左右深度的3—4级向3 km深度之上近地表的2—3级迁移变化;余震分布清晰呈现双层结构,较深层分布在4—10 km深度,而较浅层分布3 km深度之上,2层之间地震分布较少。分析认为,浅层地震可能为本次地震地表破坏较强原因之一。震源深度剖面显示,破裂面向NE倾斜,推测此次地震的发震断裂为临潭—宕昌断裂。 相似文献
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文中基于青海和周边地震台网72个台站以及震后布设的12个流动观测台站于2021年5月22—27日记录的青海玛多M7.4地震主震及1 357次余震资料,使用双差地震定位法重新对余震位置进行了修定,获得了1 289次余震修定后的震源位置。重新定位后,余震基本沿昆仑山口-江错断裂呈NWW向线性分布,震源深度由重新定位前主要集中于5～10km变为在5～15km深度范围内相对均匀地分布。根据重新定位后的余震分布特点并参考地质断层及现场考察的地震破裂带展布情况,依据成丛地震发生在断层附近的原则,选取了6个矩形区域内重新定位后的震源信息,联合采用模拟退火与高斯-牛顿算法反演获得了每个区域断层面的详细参数。结果表明,主干断裂为长约146km、总体走向为285°～290°的高倾角大型左旋走滑兼逆冲断裂。重新定位还显示,主干断裂东、西两侧有分叉现象,可能是大地震发生时期由于复杂的应力分配导致触发并新产生2条分支断裂,断裂整体显示为树形。西侧分支走向为306°,与主干断裂相交,夹角为21°。东侧分支走向近EW,与主干断裂的东段相连。 相似文献
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用双差地震定位法对2005年9月23日克孜尔震群进行重新定位。 从平面上, 重新定位地震集中分布在一个长约14.5 km, 宽约 9.0 km的长方形内, 其长轴为N30°W向, 与克孜尔断裂近乎垂直。 从震源深度来看, 重新定位地震的震源深度全部分布在21 km以内, 集中分布在10~19 km, 平均深度为13.6 km; 震群中绝大部分小震发生在沉积层内, 而震级较大地震基本发生在结晶地壳的上地壳内。 其剖面图显示, 这次震群是从结晶地壳开始沿着N30°W方向向上破裂至沉积层。 根据震区附近断裂性质和该区历史小震震中分布分析认为, 克孜尔水库库区附近可能存在两条共轭断裂, 右翼断裂可能是这次震群的发震构造。 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