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论述了珲春7．0级深源地震地下流体中期、短期、临震、震时、震后异常,分析了地下流体异常特征。认为其时间展布具有阶段性,配套性和集中性,异常出现的时间与震中距密切相关,其空间展布具有迁移性,中期异常由外围向震中收缩,其速率很小,进入短期阶段,速率迅速加大。临震异常由震中向外围发散,其速率加大到剧增。此即为我们捕捉岩石变形临失稳阶段提供信息,是经验性预报向物理预报过渡的一种尝试。本文尚对地下流体异常与地震构造的关系,地下流体异常的场兆、源兆特征进行了讨论。 相似文献
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论述了1999~2002年分别发生在吉林省汪清县、 珲春县的二次深源地震前, 地下流体异常的形态、 时间及空间演化特征。 研究结果认为, 其异常具有阶段性、 配套性及集中性, 异常分布不均一、 不连续, 与震中距、 井震距密切相关。 异常的时空演化具有迁移性, 中、 短期阶段异常由外围向震中方向迁移、 收缩; 临震阶段, 异常由震中向外围发散。 并对深、 浅源地震前地下流体异常的异同及异常机制进行了讨论, 认为单井的异常曲线、 频带、 变化速率、 重复性及多井群体异常的空间分布是相同的, 而异常变化方向、 幅度、 形式、 宏观现象、 异常阶段和多井群体异常的时间特性、 时空演化是不同的。 深震前地下流体异常是等效张应力、 含水层孔隙压变化、 水动力学三重机制共同作用的结果。 相似文献
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2003年云南大姚6.2级、6.1级地震中短期地震学异常演化特征 总被引：1，自引：0，他引：1
通过对2003年云南大姚6．2级、6．1级地震中短期地震学特征的分析和初步研究，认为大姚地震孕育过程中的短期阶段，震中附近的地震学异常以中小地震活动增强为主，表现为震区附近中小地震频度增加，4级震群活动、A值、GL值出现异常，同时震源深度加深等；在由中期向短期过渡的过程中，震源区异常消失相对平静，使多种地震学异常收缩至震源区附近；地震孕育进入短临阶段，震中附近地区再次出现了3～4级小震活动增强的特征，云南省地震活动出现向震中附近迁移的趋势。整个孕震过程，地震活动体现了活动-平静-活动的动态演化特征。 相似文献
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2016年9月10日河北唐山发生MS 4.2地震，以该震为例，研究河北省地下流体观测井水位震前异常变化特征。结果表明：①震中区域观测井水位异常变化形态一般为缓变型，震中外围观测井水位异常变化形态一般为骤变型；②距离震中越近，观测井水位异常出现越早，异常持续时间越长；③临近地震震中时，观测井水位异常有从震中向外围扩散的趋势；④观测井水位异常最大幅度与井震距关系不大。 相似文献
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苍山5.2级地震异常群体时空演化特征 总被引：1，自引：0，他引：1
在对 1 995年山东省苍山 5 2级地震异常筛选的基础上 ,分析了异常群体阶段性演化过程。结果表明 ,震前 1 0a左右震中周围出现小震小区域综合断层面解主压应力P轴偏转 (约 3 0°) ,震前 7a左右震中附近 3～ 4级地震增强集中及应变释放加速 ;震前 4a左右转为异常平静 ;震前 1a左右震中外围开始出现形变类前兆异常 ,前兆异常台站比和异常台项比约达 6%及 4%左右 ,异常比例偏少 ;震前约半年起 ,以震中附近地震波速比异常出现为起点 ,相继出现各类前兆异常 6条 ,短期前兆异常台站比和异常台项比分别约达 2 5 %和 1 7%左右 ,显示孕震进入短期阶段 ,但临震异常不明显。对由此获得的 5级地震预测启示进行了讨论。 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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《中国科学:地球科学(英文版)》2014,(12)
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