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１９９３年８─１１月，在马起乏与新测点上进行了较长时间的地磁场对比观测，获得了大量准确可靠的地磁资料。应用通化处理法、同步差值法、日变特征量比较法、快速谱分析法（ＦＦＴ）、幅比与位相差值法，分析研究了地磁对比观测资料。结果表明，在相同时间段内，各测点地磁变化形态相当一致，两个测点之间的同步差值平稳。由各测点地磁场总强度日变化的定量分析比较得出，其日变化是相当一致的。快速谱分析显示，在相同时间段内，各测点的幅度随周期的变化形态十分相似，总体上看，ＦＦＴ幅度随周期的减小呈下降趋势；从ＦＦＴ幅度Ａ，位相以及快谱幅比Ａ＿ｉ／Ａ与位相差的定量比较结果上看，各测点的ＦＦＴ有着良好的一致性。此外，还得到了新老测点之间的地磁数据的接点差。 相似文献
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燕郊等测点迁移优化与地磁观测研究 总被引：1，自引：2，他引：1
为优化地磁观测条件，开展了燕郊、夏垫等测点迁移工作；按照测眯迁移原则与实施技术方案，完整地收集并整理了地质构造与地球物理等方面的基本资料；进行了野外实地勘察，磁场梯度的测量，确定了新测点，在新老测点上进行了较长时间的地磁场对比观测；应用多种方法分析研究了地磁对比观测资料，结果表明，新老测点与有关测点的地磁变化具有良好的一致性，并得到了新老测点之间的地磁数据的按点差。 相似文献
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本文通过收集整理三河—平谷地震区的地震目录、GPS测量和周边台站的地电、地磁、地下水、水温及钻孔形变观测资料,绘制了相应的图件,对该区的地球物理特征进行了研究.结果表明,区内夏垫—三河附近小震活动频繁,震源深度较浅,地震活动明显受断裂构造控制;周边台站的电、磁、水、温和形变在地震发生前后大部分有前兆异常现象,且特征各异,其特征和异常与三河—平谷地震区的构造运动及该区的地震活动有着密切关系,这些地球物理场特征可为今后的台站观测提供基础,将各方面的特征综合考虑,会对地震前兆信息的观测和识别具有一定的意义,进而为该区的地质构造运动特征、地震监测预测和防灾减灾工作提供地质和地球物理方面的依据. 相似文献
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文中通过收集整理三河-平谷8级地震的历史记录、野外地质调查和区域地震等资料,建立了该地震的震源模型;以穿过研究区的12条测线和区域第四纪、新近纪、古近纪沉积等厚度图等资料为基础,建立了北京地区的传播介质模型;利用哈尔滨工程力学研究所的近断层强地震动有限元程序和40节点的高性能并行计算机计算了北京地区震后60s内地表各点的地震动速度时程和峰值速度。为检验模拟结果的质量,我们取2排测点的速度时程和水平向峰值速度等值线图进行了分析,发现计算结果与历史地震记录及实际地震观测资料吻合良好,说明了我们的模拟结果的可信性和模拟方法的客观性 相似文献
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大震前水氡同步异常变化及其预测意义探讨 总被引：2，自引：0，他引：2
分析了1990年4月26日青海共和7.0级地震、2000年9月12日青海兴海6.6级地震、2001年11月14日昆仑山口西8.0级地震和2008年5月12日四川汶川8.0级地震前青海、甘肃以及四川北部地区部分水氡观测点的资料变化情况,发现这些测点的观测资料存在同步或准同步的变化,而且变化时间早,持续时间长。共和地震前,距震中越近的测点,出现的趋势性异常所占的比例越高,异常时间越早。昆仑山口西地震的异常持续时间更长,多数异常点距震中更远。随着时间的推移,异常点从西北向东南迁移。兴海地震个别测点出现异常。汶川地震的异常的同步性更好,而且多数测点的同震效应非常明显。这些地震的异常的恢复时间均无明显的规律,有些是在地震前恢复,有些是在地震后恢复。 相似文献
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李献智 《地震地磁观测与研究》1995,16(1):15-19
应用一种新思路、新方法研究兴都库什－贝加尔地震带内的地震迁移，结果表明，地震沿地震带由南西西向北东东方向定向迁移，平均迁移速度为每年１２９ＫＭ量级与中国大陆西部地震带（区）的地震迁移速度相当，研究结果为地震动力学和地震预报提供了一定的依据。 相似文献
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利用河北怀来4井1990年至2002年的水汞观测资料，对怀来4井汞量异常进行了分析，分析结果显示，怀来4井水汞异常与地震的对应率较好，1990年以来，其异常对于测点监测范围的有感地震及中小地震和距离测点较远的范围内发生的5．0级以上地震有很高的对应率。 相似文献
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李献智 《地震地磁观测与研究》1995,(1)
应用一种新思路、新方法研究兴都库什－贝加尔地震带内的地震迁移，结果表明，地震沿地震带由南西西向北东东方向定向迁移，平均迁移速度为每年１２９ｋｍ，量级与中国大陆西部地震带（区）的地震迁移速度相当．研究结果为地震动力学和地震预报提供了一定的依据． 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