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使用中国数字地震台网记录的区域和远震宽频带波形,通过频率域和时间域多步反演,研究四川芦山 MS 7．0地震基于点源模型的震源机制解和有限断层模型。考虑到使用不同波形资料类型、盆地效应及简化的一维速度模型等给反演震源参数带来的影响,经测试比较,结果表明：使用区域波形和本区域简化一维速度模型,波形拟合误差最小。此次地震表现为高倾角纯逆冲型事件矩心在水平方向上位于震中偏南西向约4．5 km,最佳波形拟合矩心深度约17 km,矩震级 MW约6．6。推断此地震大多数能量主要在震源偏南西约4．5 km 处释放。 相似文献
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2014年云南鲁甸MS6.5地震震源运动学特征 总被引：2，自引：1，他引：1
使用中国数字地震台网记录的区域宽频带波形,通过频率域和时间域多步反演,研究了2014年云南鲁甸MS6.5地震震源运动学特征.基于点源的震源机制解揭示:地震发震断层面参数分别为走向342°/倾角83°/滑动角-34°,表现为一次左旋走滑型为主兼有少量正断倾滑分量的事件.质心在水平方向位于震中(103.354°E,27.109°N)东南约5.4km,最佳波形拟合的质心深度约4.4km,平均总标量地震矩M0为2.1×1018N·m,矩震级MW约6.1.破裂过程图像显示:此地震为一次不对称双侧破裂事件,破裂半径约10km,整个破裂面积为227.6km2,平均滑动量约0.16m.破裂在6s内释放了大多数能量,震后0～2s,破裂以孕震点为中心向NW和SE两侧同时扩展,2s后,破裂表现出明显的方向性,主要向SE(沿走向342°相反方向)扩展,故导致SE向多数台站视破裂持续时间总体偏小,最小值为2s.约6s后破裂基本趋于停止.推断鲁甸地震破裂在上地壳浅层集中释放了大多数能量是导致灾害严重的主要原因之一. 相似文献
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为了更好地确定2017年8月8日九寨沟M_(S )7.0地震震源深度其发震机理,利用四川、甘肃和青海区域地震台网的观测波形数据,采用多种方法研究了此次地震的震源深度。首先,采用gCAP方法反演了九寨沟M_(S )7.0地震的震源机制解和矩心深度,结果显示,节面Ⅰ走向243°/倾角87°/滑动角-158°,节面Ⅱ走向151°/倾角68°/滑动角-3°,矩震级为M_(W )6.5,矩心深度为8 km;然后,采用ISOLA近震全波形方法反演了此次地震的震源机制解,反演结果与gCAP方法结果相差不大,矩心深度为7 km;最后,通过sPn震相与Pn震相之间的走时差测定此次地震初始破裂震源深度,结果显示深度约为12 km。研究表明,九寨沟M_(S )7.0地震的矩心深度为7—8 km,初始破裂深度约为12 km。 相似文献
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2017年8月9日的新疆精河MS6.6地震是近年来天山北缘发生的最大地震,震中位于由多条逆冲断层组成的库松木契克断裂带内.由于震源较深、构造形变复杂、区域地震台站相对稀疏,仅根据震源机制解、余震分布和InSAR观测结果等难以直接判定发震构造.本文针对倾滑型地震发展了一种基于区域地震波形的破裂方向性测定方法,利用余震作为参考地震进行路径校正,根据主震和参考地震的波形时移差和Pn-Pg到时差分别确定主震在水平方向和深度方向的破裂尺度,进而推断同震破裂的延展方向和延伸尺度.本文在反演了主震的点源参数后,应用新发展的方法测定了地震的破裂方向性.点源反演结果显示,精河地震是一个发生在中地壳的高角度逆冲地震,矩震级约6.2,质心深度21km,震源持续时间5.5s,两个双力偶节面分别为102°/45°/106°(NP1)和259°/47°/74°(NP2).破裂方向性分析结果显示,地震的破裂面为南倾的NP1节面,地震沿着破裂起始点向西南方向、向下破裂,总破裂长度约11.5km,其中,沿深度的破裂范围约7km,沿水平的破裂范围约9km,平均破裂速度约2.1km·s-1.综合区域地质资料、卫星影像等判定本次地震的发震断层为精河南断层,地震可能只破裂了断层的下段(17~25km),并未破出地表. 相似文献
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根据中国和全球地震台网记录的波形记录，采用W震相矩张量反演、反投影分析及有限断层模型反演方法，研究了2016年3月2日印尼7.8级地震破裂过程，分析讨论印尼地震震源运动学特征.结果表明：此地震为一次对称的双侧破裂走滑型事件，北北东─南南西向的断层节面（走向5°/倾角85°）为发震断层面.标量地震矩约6.19×1020 Nm，矩震级为7.79，最大的滑动量约11 m，位于破裂起始点北东，沿着断层走向约30 km处.破裂平均速度2.0~2.2 km·s-1，破裂持续时间35 s，破裂在5~25 s内释放的能量，约占总能量的97%.最终形成了总长度90 km左右的断层.印尼地震具有破裂持续时间短、破裂速度慢、高滑动能量带相对集中等显著特点.本研究对进一步增进海洋岩石圈地震的震源特性认识有重要参考意义. 相似文献
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利用中小震作为经验格林函数,选取0.2~2.0 Hz频段的强震数据进行波形反演,获得了2021年福岛县冲地震的破裂过程。结果表明:该地震的破裂主要集中在断层面距离震源约25 km的区域内,沿震源向东北延伸约5 km,向西南延伸约20 km;在该区域内,识别出两个滑动量集中的区域,均分布在距离震源约15 km西南侧,主要滑动量集中区域最大滑动量约3.2 m,深度基本与震源一致;次要滑动量集中区域略比主要滑动量集中区域浅约18 km。该震源模型对应矩震级Mw7.3,破裂速度为2.4 km/s。通过选择不同的中小震组合进行波形反演,结果对该震源模型特性无显著影响,揭示了该震源模型的稳健性;基于该震源模型合成反演分析中未使用的强震观测台站强震动,获得的合成波形与观测波形有很好的相关性,充分证明了该震源模型时空特征的可靠性。 相似文献
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使用中国数字地震台网记录的区域宽频带波形,通过频率域和时间域多步反演,研究了2013年四川芦山“4·20”7.0级强烈地震的震源运动学特征.基于点源的震源机制解揭示：地震发震断层面参数分别为走向214°/倾角47°/滑动角96°,表现为一次高倾角的逆冲型事件.矩心在水平方向上位于震中（30.303°N/102.988°E）西南向约4.5 km,矩心深度约17 km.平均总标量地震矩M0为1.16×1019 N·m,矩震级Mw约6.6.进一步模拟高达0.5 Hz高频波形,获得了芦山地震破裂过程图像,结果显示：此地震为一次不对称双侧破裂事件.破裂半径约15 km,整个破裂面积为706.7 km2,平均滑动量约0.231 m.破裂在8 s内释放了大多数能量.震后0~3 s内,破裂以孕震点为中心向四周同时扩展,3 s后,破裂表现出明显的方向性,主要向北北东扩展,导致位于震中北东向多数台站视破裂持续时间总体偏小,最小值为4 s.破裂约8 s后基本停止. 相似文献
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为了深入认识2016年4月15日日本熊本地震破裂的复杂性，利用远场体波资料和同震InSAR资料联合反演了此次地震的震源破裂时空过程. 联合反演结果表明:熊本地震的震源破裂持续时间约为25 s，整个破裂过程释放的总标量矩为6.03×1019 N·m，对应于矩震级MW7.1；同震滑动主要集中分布于浅部，破裂以右旋走滑为主，但在沿倾向0—5 km范围内，破裂呈较强的正断特征；此次地震破裂的最大同震滑动量约为4.9 m，且最大同震位错区位于背离断层走向上、距离起始破裂点约5—10 km的区域；破裂前期（0—7 s），在倾向上向浅表发生破裂，在走向上向东北和西南两侧扩展；大约7 s后，破裂背离断层走向主要向东北方向扩展. 根据有限断层联合反演结果推测，此次熊本地震破裂可能出露至地表. 相似文献
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基于有限断层模型反演方法,利用区域宽频带数据反演了2022年1月青海门源MS6.9地震的震源破裂过程,并结合地质构造与地震重定位结果判断发震断层走向.综合反演结果表明:此次地震的发震断层走向为WNW向,主要以走滑为主;破裂主要发生在震源两侧,可能存在着双侧破裂,在震后2 s和9 s出现破裂极大值,最大错动量约为1.5 m,位于深度约6km处,发生明显破裂的深度约为16 km,地表破裂长度约20 km;此次地震释放的标量地震矩为1.23×1019N·m,相当于矩震级MW6.7,地震能量主要在前15 s释放;发震断层面的倾角为84.6°,接近于垂直,由于破裂范围较大,所以发生明显错动分布的地表投影也长达34 km. 相似文献
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《中国科学D辑》2008,(6)
通过反演全球范围内20个地震台的宽频带波形资料,获得了2007年6月3日在云南宁洱发生的MS6.4地震的矩张量解、震源时间函数和断层面上滑动随时间和空间的变化过程.根据反演结果,这次地震的标量地震矩为5.51×1018Nm,相当于矩震级MW6.4.震源机制解中,最佳双力偶对应的节面Ⅰ的走向、倾角和滑动角分别为152°,54°和166°,节面Ⅱ的走向、倾角和滑动角分别为250°,79°和37°.结合震后考察得到的烈度等震线分布特征以及当地的地质构造,可以判定这次地震的发震断层的走向为152°,倾角为54°,滑动角为166°,是一次以右旋走滑为主的地震.从震源时间函数的形态来看,震源破裂持续时间为14s,地震矩的释放主要集中在前11s,在11~14s之间释放的地震矩很少.震源的时空破裂过程图像表明,破裂过程分为3个阶段,在前4s的时间段内,破裂主要沿着走向方向和朝深处发展;在4~7s间,破裂呈扇形向着深处扩展;在7s之后的时间段,破裂点比较零散.地震破裂总体上表现为双侧破裂方式,但在走向方向和深度方向上的滑动略占优势.破裂较强的区域呈菱形,长约为19km.地震断层面上最大滑动量为1.2m,平均滑动量为0.1m,最大滑动速率为0.4m/s,平均滑动速率为0.1m/s.由反演得到的静态位错模型计算的震中区地表位移场的特征与地震的烈度分布特征具有很好的一致性. 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