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利用青海玉树地震台记录的2006年和2010年玉树两次地震序列数字化波形资料,基于Sato的尾波单次散射模型,计算玉树地区尾波Q值,并拟合Q值对频率的依赖关系.总体上,该地区尾波Q值与地震构造活动呈一定相关性,前者平均拟合Q0值. 相似文献
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利用Sato模型研究宁夏及邻区尾波Q值分布特征 总被引：3，自引：3，他引：0
《地震地磁观测与研究》2016,(1)
利用Sato模型,选取2008年1月至2013年12月宁夏地震台网记录的波形清晰、噪声水平满足计算条件的ML≥2.0地震,计算宁夏及邻区各区域尾波Q值,与前人研究结果进行对比,得到研究区尾波Q值的分布特征。结果表明:宁夏及邻区尾波Q值整体呈北高南低分布;吴忠、灵武地区尾波Q值相对较高,与该区域存在高速区相对应;阿拉善左旗西南尾波Q值较低;盐池地区尾波Q值相对较高,对应该区稳定的地质构造;中卫、海原及附近地区尾波Q值相对较高,认为与该区域地壳深部的高温度与高热流值有关。 相似文献
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云南地区尾波衰减及其与地震前兆的关系 总被引：1，自引：1，他引：0
本文用38个遍布云南地区的短周期地震台站的地震仪器记录的160多个区域地震的尾波观测资料,详细研究了云南地区尾波衰减的某些特征,给出了全省地壳尾波Q分布图。在考虑Q值与频率相点的情况下,发现频率相关值η在地震活动频繁的地区比较高,而在相对平静的地区比较低。从尾波Q值的空间分布来看,滇西北地区最低,在70—180之间,东部地区最高,约300—400左右,云南地区总的趋势是自西向东Q值逐渐增高。根据这些研究结果,讨论了尾波衰减的某些特征与地震活动前兆关系的理论基础,把尾波Q值作为地震前兆的可能性研究是具有实际意义的。 相似文献
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五大连池火山区尾波Q值研究 总被引：1，自引：1，他引：0
选取五大连池火山地区2008年至2011年ML＞0.6火山地震事件39个,根据尾波散射理论,利用Sato模型计算其尾波Q值,获得整个火山区尾波Q与频率f关系Q(f)=(34.89±8.75)f1.0727±0.2253,表现为低Q高η值的火山构造活动活跃区域尾波特征,同时获得老黑山、火烧山附近区域尾波Q0值为20.60,与国内外火山区尾波Q值加以对比,对本区域地震活动性进行分析,并结合本区其他火山研究成果给予简单解释. 相似文献
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从2008年1月至2013年12月宁夏地震台网记录的665次ML≥2.0地震的数字地震波形资料中,选取波形记录清晰、噪声水平满足计算条件的数字地震波形记录,利用Aki模型,计算宁夏及邻区各区域尾波Q值,并与前人已有结果进行对比,得到该区尾波Q值的分布特征。结果表明:宁夏及邻区尾波Q值整体呈北高南低分布;吴忠、灵武地区该值相对较高,与该区域存在高速区相对应;阿拉善左旗西南该值较低;中卫、海原及附近地区该值相对较低,认为与该区域地壳深部的高温度与高热流值有关。 相似文献
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依据sato单次散射模型,对山西北部（北纬380-41^0）2001年至2011年13个数字遥测子台记录的地震波形资料进行计算和分析。拟合尾波窗长40S时尾波Q值对频率的依赖关系,得到山西北部地区Q值随频率的变化关系式。其中,阳原台Q。值最高,大同台Q0值最低。研究区多数台站都表现为低Q0值,高q值,符合Q值与频率的依赖关系,表明该地区地下介质非均匀程度高,构造活动强烈;另外,研究区大同台、右玉台和偏关台相对于本次研究的其他台站为低Q0值区,这一区域正好位于我省西北部NNE走向的口泉活动断裂处,中间以盆地为分割,与恒山、六棱山断裂分开,表明研究结果与研究区活动断裂和沉积厚度有一定的关系。 相似文献
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粤西地区的地震尾波Q值和尾波衰减特征 总被引：1，自引：0，他引：1
根据Aki的尾波理论,利用短周期仪器记录的地震资料,用两种方法估测了粤西地区的尾波Q值,得到了如下结果;Q_0值为260—370,频率相关系数η值为0.0—0.2。阳江地区的Q_0值较低,其它地区大致相同.Q_0值的分布与地质构造和地震活动有较好的相关性. 研究了粤西地区的尾波衰减特征,得到尾波衰减率K为1.88—3.18,K值与Q值的分布彼此有较好的对应性。以上结果可为地震烈度衰减和地震危险性分析等方面的研究提供参考。 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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