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71.
通过对测震学各单项指标的预测效能调研,为进一步提取前兆信息,选择了7项测震学指标:频次、地震蠕变、6值、缺震、η值、GL值和调制比,进行综合概率分析。7项指标对关注地区的全时空扫描并考虑了空间单元异常与中强震地点对应的模糊关系,得到指标在各空间单元异常后发生中强震的条件概率。根据历史上每个单项指标的预报效能求计算综合概率时的指标权重,按贝叶斯定律得到相应不同指标在不同时间窗和不同空间单元时中强震发生的加权综合概率。计算结果(1970年以来)表明,对华北地区和川滇地区这一综合概率方法预测效能的R值评估超过0.5。 相似文献
72.
南京地区中暑天气条件指数研究预报 总被引:4,自引:1,他引:4
本文采用南京地区1988-1997年每年夏季逐日各项气象要素及全市各医院同期重症中暑人数进行统计筛选出热夏年:1988年、1994年、1995年,对这三年中暑期重症中暑病例资料与气象资料进行相关统计分析,找出相关性较好的气象因子,经过方程化筛选,得出气温、湿度、气压、对中暑影响较大。三日滑动平均值为主要预报因子。设计中暑指数数学模式。根据中暑病病理、程度将中暑天气条件分三个等级,给出三个不同的中暑天气条件指数临界值,经过1998年、1999年试报验证,准确率较高,社会效益较好。该指数预测模式基本可行。 相似文献
73.
地震勘探在山东蓬家夼金矿深部预测中的应用 总被引:2,自引:0,他引:2
在分析了石油地震与金属矿地震不同点的基础上,简介了地震勘探方法的基本原理,并通过在山东蓬家夼金矿的实际应用,得到了理想的效果,为隐伏矿床的精确定位预测提供了十分重要的地球物理资料。 相似文献
74.
Rainfall-induced landslides constitute a major public concern in Hong Kong. This paper investigates two aspects of critical importance to landslide hazard and risk assessment and management: magnitude–cumulative frequency relationship for landslides, and relationship between rainfall and the occurrence of landslides. The results indicated that landslides with a failure volume of not less than 4 m3 have a cumulative frequency–size distribution with a power-law dependence on volume of failure. Analysis of rainfall/landslides showed that the 12-hour rolling rainfall is most important in predicting the number of landslides. Failure volume dependency in the relationships between rainfall and the number of landslides is also presented. However, with an increase in failure volume of landslides, the most important rainfall variable may vary from rainfall of short duration (12-h rolling rainfall) to that of relatively long duration (24-h rolling rainfall). 相似文献
75.
The brightness temperatures of the Microwave sensor MSMR (Multichannel Scanning Microwave Radiometer) launched in May 1999
onboard Indian Oceansat-1 IRS-P4 are used to develop a direct retrieval method for latent heat flux by multivariate regression
technique. The MSMR measures the microwave radiances at 8 channels at frequencies of 6.6, 10.7, 18 and 21 GHz at both vertical
and horizontal polarizations. It is found that the surface LHF (Latent Heat Flux) is sensitive to all the channels. The coefficients
were derived using the National Centre for Environmental Prediction (NCEP) reanalysis data of three months: July, September,
November of 1999. The NCEP daily analyzed latent heat fluxes and brightness temperatures observed by MSMR were used to derive
the coefficients. Validity of the derived coefficients was checked within situ observations over the Indian Ocean and with NCEP analyzed LHF for global points. The LHF derived directly from the MSMR brightness
temperature (Tb) yielded an accuracy of 35 watt/m2. LHF was also computed by applying bulk formula using the geophysical parameters extracted from MSMR. In this case the errors
were higher apparently due to the errors involved in derivation of the geophysical parameters. 相似文献
76.
本文研究了建立设计地震震源模型和用理论地震学方法预测基岩场地震震加速度的技术途径,预测了四相设计地震事件在秦山核电站厂址的加速度时程和反应谱,文中根据对地质和历史地震资料的研究,确定不同性质的设计地震事件,建立设计地震震源和工作区介质的确定性模型,针对未来地震的不可完全预见性,以及对地球介质和震源性质现有认识的局限性,文中发展了确定性和随机性组合的综合分析方法,在用确定的介质模型和设计震源计算地震 相似文献
77.
Wang Xiaoqing Gao MengtanCenter for Analysis Prediction SSB Beijing China Institute of Geophysics SSB Beijing China 《中国地震研究》1996,(2)
This paper offers an approach to the relative confidence level of medium- and long-term earthquake prediction methods by use of the analytical hierarchy process (AHP). We construct the criterion judgment matrices according to the results of an expert questionnaire known as the Delphi scheme. From the matrices we can obtain a scale for the relative preference or priority weight of each factor. The quantitative weights might be applied to make synthetic prediction of earthquake risk areas in the northern part of the North China seismic region. 相似文献
78.
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80.
In this paper the researches made in 1981-1990 have identified that the annual soil loss in the Three Gorges region is 157 million t. and the annual incoming sediment load of the Three Gorges reservoir is 40 million t. Soil erosion increases with the destruction of vegetative cover and its subsequent evolution. The annual amounts of sediment erosion for forest land, shrub land, grassland and farmland make up respectively 6.19%, 10.76%, 23.05% and 60% of the total erosion of the Three Gorges region; the quantities of incoming sediment load to the Yangtze River from the above four types of land account for 5.95%, 12.42%, 35.46% and 46.1 % of the total amount of sediment transported to the reservoir. The farmland of offers the main source of sediment. Gravitational erosion produces more bed loads, which will present serious threat to the Three Gorges Project if entering the reservoir. Resettlement of people to the upper parts of the mountainous areas for agricultural production will increase the sediment yield of the Three Gorges region by 10-20 million t and increase the incoming sediment of the Yangtze River by 50-60 million t. Consequently, it is necessary to make a realistic assessment of the soil erosion in the Three Gorges region. 相似文献