共查询到20条相似文献，搜索用时 62 毫秒
1.
利用主成分分析法研究东北地震活动异常 总被引：5，自引：1，他引：4
选择与地震强度有关的地震频次N(ML≥3.0)、b值、η值、Mf值、A(b)值和AC值共6个参量进行主成分分析,实现对上述参量的有效约简。这6个参量之间有一定的相关性,在不同时段各参量的变化各有所异。根据主成分分析可以得到反应地震强度特征的综合指标W。1970年以来东北14次5级以上浅源地震前W都出现明显的异常变化,震后恢复。这表明综合指标W可以较好地反映地震活动的异常特征。 相似文献
2.
主成分分析法在汶川地震预测中的应用 总被引：4，自引：0，他引：4
选择与地震强度有关的3级以上地震频次N（ML≥3．0）、b值、η值、Mf值、C值和A。值等6个参量进行主成分分析，实现对上述参量的有效约简。这6个参量之间有一定的相关性，各参量在不同时段的变化各有所异，但是根据主成分分析可以得到映应地震强度特征的综合指标W，发现该指标W在汶川8．0级大地震前出现明显的异常变化。这表明综合指标可可以较好的反映地震活动的异常特征。 相似文献
3.
4.
目前地震活动性分析有许多指标参量,各参量在不同时段变化各异,预报效果不理想。由于各参量之间通常具有一定的相关性,本文选择地震频次N(ML≥3.0)、b值、η值、A(b)值、Mf值、Ac值、C值和D值8个参量进行因子分析,得到的反映地震活动时、空、强异常特征的综合指标Wfa。结果表明Wfa在2005年江西九江5.7级地震和华北14次5.7级以上地震前出现明显的异常变化,可以较好地反映地震活动时、空、强异常特征。还对因子分析的有关问题进行了讨论。 相似文献
5.
采用多因子分析的主成分分析法,选择与地震活动强度有关的地震频次N(ML≥3.0)、b值、η值、Mf值、A(b)值和Ac值等6个参量进行分析,实现对上述参量的有效约简,得到反映地震强度特征的综合指标W.发现指标W在辽宁海城7.3级、岫岩5.4级地震前出现明显的异常变化,震后恢复.表明综合指标W可以较好的反映地震活动的异常特征. 相似文献
6.
本文根据多因子分析的主成分分析法,选择与地震强度有关的3级以上地震频次N（ML≥3.0）、b值、η值、Mf值、C值和Ac值等6个参量进行主成分分析,实现对上述参量的有效约简。这6个参量之间有一定的相关性,各参量在不同时段的变化各有所异,但是采用主成分分析法可以得到反应地震强度特征的综合指标W,发现该指标W,在辽宁海城7.3级、岫岩5.4级地震前出现明显的异常变化,震后恢复。这表明综合指标W可以较好的反映地震活动的异常特征。 相似文献
7.
主成分分析法在林甸Ms5．1地震回顾性预测中的应用 总被引：3，自引：1，他引：2
用2005年林甸Ms5．1级地震前后震中附近的地震资料，选择与地震强度有关的3级以上地震频次N、b值、Mf值、C值、和Ac值等6个参量进行主成分分析，实现对上述参量的有效约简。这6个参量之间有一定的相关性，各参量在不同时段的变化各有所异，预报效果并不理想。但是根据主成分分析可以得到反映地震强度的综合指标W，发现该指标在震源区附近出现明显的异常变化，震后异常恢复。表明综合指标W可以较好的反映地震活动的异常特征。 相似文献
8.
使用2005年11月26日江西九江5.7级地震前震中附近地区的地震资料,选择反映地震活动时、空、强特征的地震频次N(ML≥3.0)、b值、η值、A(b)值、Mf值、Ac值、C值和D值参量进行因子分析。这些参量之间具有一定的相关性,各参量在不同时段的变化各有所异,预报效果并不理想。但是根据因子分析可以得到反映地震活动时、空、强特征的综合指标Wfa值,该指标在九江5.7级地震前出现明显的异常变化。表明综合指标Wfa值可以较好地反映地震活动的异常特征。文中还对与因子分析结果的有关问题进行了讨论。 相似文献
9.
主成分分析法在地震预测中的应用研究 总被引：10，自引：0，他引：10
用1979年7月9日江苏溧阳6．0级地震前后震中附近地区的地震资料，选择与地震活动强度有关的3级以上地震的频次N、b值、η值、A（b）值、Mf值和Ac值等6个参量进行主成分分析，实现对上述参量的有效约减。这6个参量之间具有一定的相关性，各参量在不同时段的变化各有所异，预报效果并不理想。但是根据主成分分析可以得到反应地震强度异常特征的综合指标形，发现该指标在2次溧阳地震前出现明显的异常变化，震后异常恢复。表明综合指标形可以较好地反映地震活动异常增强的特征。文章还对与主成分分析所得结论的有关问题进行了讨论。 相似文献
10.
基于因子分析的地震综合指数在辽宁地区地震预测中的应用 总被引：1，自引：0，他引：1
将辽宁地区按照地震活动特点划分为辽北、辽南、辽西三个主要区域,应用因子分析的方法,选取地震活动性参量中的11个参量(地震频次N、b值、η值、A(b)值、Mf值、Ac值、C值、D值、Rm值、能量E、响应比),进行数据的综合和再次挖掘,得到包含地震时、空、强及地下介质信息的综合指数。综合指数Wfa中涵盖了众多参量中80~90%的信息,并有效规避了各参量在地震预测中的不一致性。结果显示,在研究区域影响范围内发生较大地震前的1~2年时间内,综合指数Wfa都有明显的异常变化,说明综合指数可以较好反映地震活动异常特征。 相似文献
11.
12.
《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
13.
《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
14.
15.
16.
17.
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
18.
19.
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
20.
《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