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地下水位地震短临预报前兆标志体系研究 总被引:2,自引:0,他引:2
建立地下水位地震短临预报前兆标志体系的主要依据是:从以往的震例中总结、统计出的多种异常特征参量与地震三要素之间的定量关系。判定震级的异常标志有:异常分布范围、异常时空转换、异常数量、异常形态异常时间和异常幅度;判定发震时间的异常标志有:异常开始和转折时间、异常数量、异常形态异常时空转换和异常速率;判定发震地点的异常标志有:异常空间分布图象、异常数量 相似文献
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对1993年8月14日大姚Ms5.7地震震前的预测预报过程、各类异常在时空分布和发震构造、破裂机制等方面的综合特征进行了论述,探讨了各类异常特征的物理机制。认为异常与发震构造的关系明显,异常空间分布有集中性和不均匀性,震源区是相对“盲区”,异常时间有同步性和渐进性,部分异常特征与震源机制有一定关系。 相似文献
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新疆大震前b值时空动态变化特征 总被引:1,自引:0,他引:1
研究了1970年以来新疆及各地震在大震前b值时空扫描动态变化。根据异常分布特征,结合新疆近几年b值时空扫描图象分析,给出了未来几年新疆b值异常分布区。最后对b异常特征进行了可能的物理解释。 相似文献
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采用水位滑动变差方法,研究了唐山地震前后地下水位时空演化特征。研究结果表明,水位滑动变差方法是突出地下水位前兆场时空演化特征的良好方法。唐山地震前后地下水位动态图像正负区和异常特征区的时空演化具有明显的规律性和阶段性。负值区的演化具有“收缩-扩展-急速扩展-发震”的特征;异常特征区的演化显示“迁移-扩展-稳定-发震-消失”的特征;滑动变差显示“增大-减小-发震-急速减小”的变化过程。据此给出了地震 相似文献
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采用水位滑动变差方法,研究了唐山地震前后地下水位时空演化特征。研究结果表明,水位滑动变差方法是突出地下水位前兆场时空演化特征的良好方法。唐山地震前后地下水位动态图像正负区和异常特征区的时空演化具有明显的规律性和阶段性。负值区的演化具有“收缩—扩展—急速扩展—发震”的特征;异常特征区的演化显示“迁移—扩展—稳定—发震—消失”的特征;滑动变差显示”增大—减小—发震—急速减小”的变化过程。据此给出了地震中短期预报新标志。 相似文献
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M. N. French R. L. Bras W. F. Krajewski 《Stochastic Environmental Research and Risk Assessment (SERRA)》1992,6(1):27-45
A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities. 相似文献
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Gtz Schroth Luciana Ferreira Da Silva Marc‐Andree Wolf Wenceslau Geraldes Teixeira Wolfgang Zech 《水文研究》1999,13(10):1423-1436
The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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M. A. Kahn 《洁净——土壤、空气、水》2000,28(2):95-101
Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate. 相似文献