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华北地区地震异常前兆信息场演化特征及其与地震关系的研究 总被引：7，自引：1，他引：6
在对地震异常前兆信息量先前研究的基础上,进一步给出了描述各种地震异常前兆信息量的普适性综合数学表达式.从大量震例资料入手,再次研究了地震异常延续有效性的问题,进而建立了地震异常持续有效时间与延续有效时间的数学关系式.收集整理了1980～1997年华北地区水化、形变、地磁、应力、水位、地电等371个观测项目、上百万个前兆观测数据,对每一观测项目逐一计算了它们的地震异常前兆信息量.研究了华北地区近20年的地震异常前兆信息场的演化特征及其与地震的关系,建立了华北地区Ms≥5地震的中短期综合预报指标体系,经R值评分检验,表明该地震综合预报指标体系在中短期地震预测中具有一定效果. 相似文献
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华北地区地震异常前光信息场演化特征及其与地震关系的研究 总被引：1，自引：0，他引：1
在对地震异常光信息量先前研究的基础上,进一步给出了描述各种地震异常前光信息量的普适性综合数学表达式,从大量震例资料入手,再次研究了地震异常延续有效性的问题,进而建立了地震异常持续有效的有效时间与有延续有效时间的数学关系式。收储整理了１９８０～１９９７年华北地区水化、形主为、地磁、应力、水位、地电等３７１个观测项目、上百万个前兆观测数据,对每一项观测项目逐一计算了它们的地震异常前光信息量,研究了华北地区近２０年的地震异常前光信息场的演化特征及其与地震的关系,建立了华北地区Ｍｓ≥地震的中短期综合预报指标体系,经Ｒ值评分检验,表明该地震综合预报指标体系在中短期地震预测中具有一定效果。 相似文献
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大同－阳高２次中强地震前，长治电感地应力曾出现明显的趋势异常和短临异常。本文就长治地应力的观测条件以及地震前后的异常特征进行了分析研究，认为对于山西地震带北部地区的地震监测预报有参考价值。 相似文献
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本文以几年来对海城地震宏观前兆资料系统整理和重点现象现场查实为基础,进一步研究了地震宏观前兆场的时空演变特征,各种宏观异常发展时间上的相关性,宏观异常的空间分布与活动断裂的关系。阐述了在地震短临孕育过程中,震前宏观异常所呈现的起伏性,空间分布上出现的密集条带、不均一和迁移性。在地震孕育的短临阶段应力的积累和加强随时间演化表现出起伏叠加,在空间上表现出孕震场内多点应力集中。并用震前宏观异常高潮期的起落对比,探索预报大地震临震的时间指标。用震前宏观异常在空间上分布的条带交叉和从外围向震中迁移的特点,探索了预报发震地点的可能性。最后对某些主要宏观异常的形成机制进行了初步讨论 相似文献
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大同－阳高２次中强地震前，长治电感地应力曾出现明显的趋势异常和短临异常。本文就长治地应力的观测条件以及地震前后的异常特征进行了分析研究，认为对于山西地震带北部地区的地震监测预报有参考价值。 相似文献
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通过对甘肃省各种前兆资料的分析,发现玉门5．9级地震前地电、地磁、应力和应变、地下流体及水氡和气氡等多种测项都有异常显示。研究各个测项的异常时间、幅度和异常台项的分布后,得到此次地震的中期和短期异常特征,对中强震的短期预报有一定参考意义。 相似文献
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本文通过对天祝—景泰6.2级地震监测预报工作全过程的研究,展示了地电方法监测预报地震的新进展。另外,对如何运用地电场的分布变化规律及地电阻率异常时间、幅度的特征进行监测预报作了探讨。 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. 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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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
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