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文安地震前华北区域长波辐射场的异常特征分析 总被引:6,自引:1,他引:6
利用NOAA/IR极轨卫星所获取并发布的热红外长波辐射(OLR)月平均网格数据信息(空间分辨率为2.5°×2.5°),采用涡度处理方法,在对华北地区OLR多年背景场分布特征分析的基础上,详细研究了2006年7月4日河北文安5.1级地震前华北地区OLR的短期异常演化特征。结果显示,华北地区OLR正常背景场变化较为平稳,但在文安地震之前这种平稳均一的分布格局发生了变化,主要表现为在地震发生之前2个月,在震中附近出现了OLR的显著增强异常现象。结合以往开展的大量的震例分析结果,显示出这种震前的异常演化特征具有广泛的普适性。这一认识的取得对于开展华北地区地震短临预报应用研究具有一定的现实意义。 相似文献
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大华北地区十次中强地震前后区域地震时间分布结构信息维D1特征 总被引:1,自引:0,他引:1
本文用分形理论的信息维方法研究了大华北地区1976年以来十次中强地震区域地震时间分布信息维在主震前后随时间的变化。结果表明信息维的变化反映了地震时间分布结构自组织特征,在震前一、二年内无标度区及其上、下限值出现明显的下降异常变化,无标度区跨度由1个数量级变宽为3个数量级,震后恢复到一个数量级。震前无标度区跨度越宽,表明地震时间分布自相似结构自组织程度越高,大华北地区十次中强震无论其所在地区、震源深度、地震序列类型、发震构造不同、震前信息维都显示了明显的下降过程,并且临震前降到最低值,震后回升。信息维下降异常时间与主震震级无关,但信息维下降的最低值与主震震级有关。 相似文献
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川滇地区长波辐射场变化与地震活动关系研究 总被引:4,自引:0,他引:4
2007年6月3日宁洱6.3级地震发生之前, 在川滇地区(20°~35°N, 95°~110°E)出现了一次显著的OLR短期和临震的异常增强现象。 对该区多年来OLR场的连续变化分析表明, 这种增强现象在强震多发年与平静年有明显的差异, 其中在地震多发年OLR数值场不仅为正距平, 而且震前短期大多增强幅度大; 而在地震平静年OLR数值场变化则多为负距平且波动小。 上述结果对今后应用卫星遥感长波辐射信息跟踪监视和预测强震有启示性意义。 相似文献
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本文在广泛收集、整理华北地区地震目录资料的基础上,应用地震活动度S定量地描述地震活动性的方法,通过S值时空扫描,给出了华北地区地震活动性的时空分布图像及其特征。还重点分析了唐山地震前后S值的时空分布现象。我们认为,用地震活动度定量地描述某时空域上的地震活动性的方法是可行的。同时还应在实践中逐步完善。 相似文献
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利用天体引潮力周期变化模型和地面长波辐射(OLR)数据资料,分析2010~2011年云南、西藏地区的4次M5.0以上地震震前OLR异常,探讨了诱发地震的外部因素,即天体引潮力周期与红外异常发展的关联特征。结果显示:以临近发震时刻所在周期引潮力值最低点日期为OLR参照背景,获取的地震前后NOAA长波辐射OLR日增量分布图像显示:震中附近热异常明显,异常受构造控制,且其分布与断裂关系密切;异常演化经历起始-加强-高峰-衰减-再增强-发震-平静的过程,符合岩石因应力增加而破裂的规律。一方面表明地应力的临界状态演化过程可通过OLR辐射变化来反映。另一方面表明引潮力可以改变构造内部地应力的状态。 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