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排序方式: 共有373条查询结果,搜索用时 11 毫秒
311.
地下水动态的超远强震异常问题 总被引:5,自引:0,他引:5
自20世纪80年代以来,在我国地震地下水动态观测网中陆续发现井水位在超远距离强震前的异常现象。这种异常表现为井水位的振荡与阶变,多出现在震前几小时至几天内,有一定的重现性。对这种异常的形成机制有多种不同观点,其中具有代表性的有强震的前驱波作用观点与强震孕育的林构造牵动观点等。 相似文献
312.
测定震源深度的意义的初步讨论 总被引:32,自引:5,他引:32
在地震目录中,震源深度是地震学最基本的参数之一,然而它也是一个最不易测准的参数,PDE报告中的震源深度以及USGS和Harvard大学的CMT反演的矩心深度和利用宽频带波形的深度震相资料获得的震源深度各不相同,其含义也不同,而宽频带波形模拟得到又是一种破裂“核心”的深度。本文对不同测量手段的震源深度的不同物理意义做了初步的探讨。 相似文献
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在北京太平庄井详细观察观测与研究了井水位、水温、流量、水化学离子、溶解气与逸出气及井区土壤气与气象因素等37项地下流体及其影响因素的短期动态。根据试验观察结果,本文初步解释出以地固体潮、大气大无畏民不动力条件的变动为共同基础的该井各测项短期-动态的内在联系,文中还对比分析了溶解气-逸出气-土壤气,水温-地温-气温等同类测项动态间的联系。 相似文献
316.
Liu Pu-xiong Zheng Da-lin Che Shi Pan Huai-wen Liu Gui-ping Yang Li-ming 《地震科学(英文版)》2003,16(2):219-225
A great earthquake of M S=8.1 took place in the west of Kunlun Pass on November 14, 2001. The epicenter is located at 36.2°N and 90.9°E. The analysis shows that some main precursory seismic patterns appear before the great earthquake, e.g., seismic gap, seismic band, increased activity, seismicity quiet and swarm activity. The evolution of the seismic patterns before the earthquake of M S=8.1 exhibits a course very similar to that found for earthquake cases with M S≥7. The difference is that anomalous seismicity before the earthquake of M S=8.1 involves in the larger area coverage and higher seismic magnitude. This provides an evidence for recognizing precursor and forecasting of very large earthquake. Finally, we review the rough prediction of the great earthquake and discuss some problems related to the prediction of great earthquakes. 相似文献
317.
The distributions of particulate heavy metals and its indication to the transfer of sediments in the Changjiang Estuary and Hangzhou Bay,China 总被引:7,自引:0,他引:7
Particulate heavy metals (Cu, Pb, Cd) were measured following intensive sampling in June and October 1994 at 70 stations in the Changjiang Estuary and Hangzhou Bay, China. In the study area, particulate Cu and Pb have a similar level that is higher than the concentration of particulate Cd. Cu, Pb and Cd concentrations in suspended sediments are higher than those in bed load. In the middle of Hangzhou Bay, heavy metal concentrations in suspended sediments and bed load are similar. This may be the result of the frequent exchange between them, which is due to the strong dynamic condition. A negative relationship was observed between concentrations of heavy metals in bed load and bulk density. Fine-grained sediments were the main carriers of heavy metals. Sedimentary dynamics dominate the fate of heavy metals in these sites. The distributions of metals (especially Cu) in suspended sediments can indicate the transfer of sediments in this area. 相似文献
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319.
地下水动态映震机制的试验与观测研究 总被引:3,自引:1,他引:3
本文根据一系列室内外试验与观测研究结果,论述了震前地下水位动态异常信息形成的四个基本环节:①地壳应力活动与含水层应力状态的变化,②含水层变形破坏与孔隙压力的变化;③孔压变化信息在井—含水层系统中的传递;④孔压变化信息在井孔地下水动态中的表现。在此基础上,提出了地下水动态映震特性的若干观点。 相似文献
320.
Lu Xiang Rucheng Wang Rolf L. Romer Xudong Che Huan Hu Zhimin Tang 《Geostandards and Geoanalytical Research》2023,47(3):609-628
Columbite-tantalite LA-ICP-MS U-Pb dating is a fast and useful method to determine the age of rare-metal deposits and fingerprint the provenance of columbite-tantalite ore concentrates. Accurate LA-ICP-MS U-Pb dating requires matrix-matched reference materials. We analysed three columbite-tantalite samples (SN3, HND and RL2) from China using ID-TIMS and LA-ICP-MS to assess their potential as reference materials for in situ U-Pb dating. Coltan 139 and these three columbite-tantalite samples with variable compositions yielded internally consistent LA-ICP-MS U-Pb ages when using each other for calibration and the weighted mean 206Pb/238U ages are comparable to respective ID-TIMS ages. Composition-dependent U-Pb fractionation seems to be insignificant under the LA-ICP-MS conditions used. Sample SN3 has a low percentage of heterogeneity for 206Pb/238U ages (4%) with low common Pb contributions (f206 < 1%) and shows a good potential in calibrating unknown samples as primary reference material for LA-ICP-MS analysis. Samples RL2 and HND have altered sections characterised by high LREE contents, flat LREE patterns and old 206Pb/238U apparent ages, and are not suited as reference materials. The low 207Pb/206Pb intercepts for samples RL2 and HND lack geological meaning but provide strong evidence that the disturbed U-Pb systematics with anomalous apparent 206Pb/238U ages is a secondary feature. 相似文献