共查询到20条相似文献，搜索用时 60 毫秒
1.
2.
简要回顾了我国地震预报的发展过程，并着重对最近10年（尤其是90年代以来）的地震预报研究进展作了较系统的阐述．主要分为：（1）大地震震源区地壳细结构和介质物性的探测研究；（2）地震和前兆数字化观测技术的研制；（3）地震短临预报方法及其判据、指标的研究；（4）地震序列类型和震后趋势早期应用判断方法及其指标的研究；（5）华北北部地震短临预报方法、前兆综合解释模型与短临预报综合判别系统的研究；（6）地震预报新技术、新方法的探索；（7）地震中长期预报研究及我国近期（10年左右尺度）地震重点监视防御区的确定；（8）板内地震孕育发生的物理模型及前兆场物理解释的探索研究．最后还对我国地震预报的未来发展进行了展望． 相似文献
3.
为了合理、有效地使用各种地震综合预报方法来加强地震预报工作，本文在检验多个单项测震学指标预报效能的基础上，根据“九五”攻关的思路，采用R值评分方法，在华东地区分区域对综合概率，图像识别，模糊聚类3种地震综合预报方法的预报效能进行了全时空分析和评估。结果认为：（1）3种综合预报方法在华东地区各区域的R评分值普遍较高，但预报效能各区域仍有差别；（2）每种预报方法在华东地区多个区域及全区均能通过97．5％置信水平下的R0值检验，且较4个单项指标的预报效能有明显提高，可用于实际预报。 相似文献
4.
5.
在分析了首都圈地区（３８．５°～４１°Ｎ，１１３°～１２０°Ｅ）中强以上地震前地震活动特征的基础上，总结出了本区中强以上地震前地震活动的普遍性特征，应用孕震模型对地震活动异常进行综合分析，给出了应用地震活动异常进行地震预报的物理基础。文中还提出了应用中期地震活动异常进行预报的综合判别指标，当其达到给定阈值时，再考虑地质构造、中强以上地震发生的自然概率、大震后的减震作用、中期地震活动异常的分布及其预报效能等因素，给出二维的综合概率分布图，把概率值较高的地区作为未来一、二年中强以上地震的危险区。此外还进行了震级、时间预测方面的研究。 相似文献
6.
江宁台地电阻率异常震例的数学模型建立 总被引：3，自引：2，他引：1
１９８３年以来的十多年时间内发生的８次地震前，江宁台地电阻率均显示了重复形态较好且规律性较强的前兆异常。本文分析总结了江宁台地电阻率震例异常的规律，建立了起了异常震例的灰色模型ＧＭ和多元线性回归方程。两种方法检验结果表明，多元线性回归方程预测结果更接近实际震级。同时，充分研究单一台站的震例异常规律，有利于地震预报研究的深，可从特性的研究中找到共同性，促进地震综合预报的发展。 相似文献
7.
依据新疆南北天山带地震预报实践中b值和η值的异常判据,对运用于地震预报专家系统（ＥＳＣＥＰ）测震学方法的主要异常判别指标进行了个性,并对个性前后的计算结果进行了对比分析,对预报效能进行了评价。结果表明,个性后的专家系统知识库预报效能明显提高,虚报和漏报率明显下降,预报效能明显提高,虚报和漏报率明显下降,预报效能通过检验,说明修改后了专场主家系统知识库更适合新疆地区中短期地震预报。 相似文献
8.
地震频次的Hurst指数在地震预报中的应用 总被引：1，自引：0，他引：1
引用Hurst指数，对华北地区18次中强地震前地震活动频次的Hurst指数进行了分析和研究，总结出了中强地震前地震活动频次的Hurst指数H值的异常主化特征，同时，把该方法应用到了河南及邻区中等地震预报研究中，制定了预报规则，进行了预测内符检验和预报评分，结果表明，该方法是一种有效的中短期地震预报方法，具有推广应用价值。 相似文献
9.
本文在短临预报指标研究的基础上，综合考虑各指标在综合预报中的作用，并用层次分析法计算出了参与滇西地震综合预测的各指标的综合权重值，最后进行系统合成，从而对滇西地区的地震的发震时间、地点进行定量化的预测，而对强度预测，而在发震时间预测的前提下，综合考虑指标异常出现的项次及持继时间长短（孕报期的长短），来综合判定预测强度。所得结果，通过１９７５年以来滇西地区２３次Ｍｓ≥５．０级地震检验，时间预测对应率 相似文献
10.
11.
Fragility curves constitute the cornerstone in seismic risk evaluations and performance-based earthquake engineering. They describe the probability of a structure to experience a certain damage level for a given earthquake intensity measure, providing a relationship between seismic hazard and vulnerability. In this paper a numerical approach is applied to derive fragility curves for tunnel shafts built in clays, a component that is found in several critical infrastructure such as urban metro networks, airport facilities or water and waste water projects. The seismic response of a representative tunnel shaft is assessed using tridimensional finite difference non-linear analyses carried out with the program FLAC3D, under increasing levels of seismic intensity. A hysteretic model is used to simulate the soil non-linear behavior during the seismic event. The effect of soil conditions and ground motion characteristics on the soil-structure system response is accounted for in the analyses. The damage is defined based on the exceedance of the concrete wall shaft capacity due to the developed seismic forces. The fragility curves are estimated in terms of peak ground acceleration at a rock or stiff soil outcrop, based on the evolution of damage with increasing earthquake intensity. The proposed fragility models allows the characterization of the seismic risk of a representative tunnel shaft typology and soil conditions considering the associated uncertainties, and partially fill the gap of data required in performing a risk analysis assessment of tunnels shafts. 相似文献
12.
13.
How to improve the representation of hydrological processes in SWAT for a lowland catchment – temporal analysis of parameter sensitivity and model performance 
下载免费PDF全文
下载免费PDF全文 Model diagnostic analyses help to improve the understanding of hydrological processes and their representation in hydrological models. A detailed temporal analysis detects periods of poor model performance and model components with potential for model improvements, which cannot be found by analysing the whole discharge time series. In this study, we aim to improve the understanding of hydrological processes by investigating the temporal dynamics of parameter sensitivity and of model performance for the Soil and Water Assessment Tool model applied to the Treene lowland catchment in Northern Germany. The temporal analysis shows that the parameter sensitivity varies temporally with high sensitivity for three groundwater parameters (groundwater time delay, baseflow recession constant and aquifer fraction coefficient) and one evaporation parameter (soil evaporation compensation factor). Whereas the soil evaporation compensation factor dominates in baseflow and resaturation periods, groundwater time delay, baseflow recession constant and aquifer fraction coefficient are dominant in the peak and recession phases. The temporal analysis of model performance identifies three clusters with different model performances, which can be related to different phases of the hydrograph. The lowest performance, when comparing six performance measures, is detected for the baseflow cluster. A spatially distributed analysis for six hydrological stations within the Treene catchment shows similar results for all stations. The linkage of periods with poor model performance to the dominant model components in these phases and with the related hydrological processes shows that the groundwater module has the highest potential for improvement. This temporal diagnostic analysis enhances the understanding of the Soil and Water Assessment Tool model and of the dominant hydrological processes in the lowland catchment. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
14.
高精度频率衰减分析技术及其应用(英文) 总被引：3，自引：1，他引：2
本文从含流体孔隙介质中的地震波场的衰减理论出发,对常规的频率衰减分析技术中的"低频阴影"和"频率衰减梯度"分析方法进行了改进,提出了一种高精度的频率衰减分析技术。首先,通过引入三参数小波变换和时频聚焦准则,发展了一种基于自适应三参数小波变换的高精度时频分析方法,其不仅具有很高的时—频分辨率(有利于"低频阴影"分析),而且其频谱只有一个峰,旁瓣比较小(有利于"频率衰减梯度"分析)。其次,采用基于最小二乘法的Nelder-Mead非线性算法对频谱的衰减部分进行拟合计算,可以准确地计算衰减系数,提高了"频率衰减梯度"的计算精度。实际资料的计算结果表明,本文提出的综合"低频阴影"和"频率衰减梯度"方法的频率衰减分析技术能够有效地圈定碳酸盐岩鲕滩储层的发育区域,且两种方法具有很好的一致性,有效地提高了储层预测的可靠性,从而降低了勘探风险。 相似文献
15.
ABSTRACTAn adaptive multilevel correlation analysis, a kind of data-driven methodology, is proposed. The analysis is done by subdividing the time series into segments such that adjacent segments have significantly different mean values. It is shown that the proposed methodology can provide multilevel information about the correlation between two variables. An integrated coefficient with its significance testing is also proposed to summarize the correlation at each level. Using the adaptive multilevel correlation analysis methodology, the correlation between streamflow and water level is investigated for a case study, and the results indicate that real correlation might be far more complicated than the empirically constructed picture.
EDITOR D. Koutsoyiannis ASSOCIATE EDITOR E. Volpi 相似文献
16.
对白银形变观测站2008年以来观测资料的运行、变化和噪声水平做初步分析,结果表明：DSQ 型水管倾斜仪观测资料连续、稳定、可靠具有明确的正常背景---夏高冬低,为今后地震前兆异常的判断打下基础;水管倾斜仪 EW 分量在2013年7月22日 MS 6．6地震前出现破年变变化,说明白银地震台水管倾斜仪具有一定的地震前兆异常监测能力。 相似文献
17.
Analysis of data characterizing the chemical composition of atmospheric precipitation was presented, with an emphasis on components responsible for neutralization of rain acidity. For this purpose, chemometric methods were applied. Based on a principal component analysis (PCA) a strong correlation between precipitation pH and potassium and ammonium ions in the heating period (October–March) and potassium and sodium ions in the non‐heating period (April–September) was observed. Additionally, a classification of eight variables, i.e., Na+, K+, Mg2+, Ca2+, , , Cl?, and according to their similarities was made using a cluster analysis. Based on this study, two ions, potassium and ammonium, together with the pH value were classified into one group (cluster) in the heating period while in the non‐heating period ions of potassium and sodium were clustered together with the pH. The results of the cluster analysis indicated that the selected ions contributed the most to the neutralization of the atmospheric precipitation acidity. This relationship was confirmed by a discriminant analysis in which potassium and ammonium ions were selected as components of the highest potential for precipitation classification according to its acidity degree. The relationship between the precipitation pH and the number of non‐precipitation days preceding the precipitation was also analyzed. It was found that although the observed an increase of the pH value was not very high, nevertheless, the effect of the duration of the period preceding the precipitation on the pH value recorded on the day of the precipitation occurrence was quite evident. 相似文献
18.
19.
概述四川7.0级以上大震前观测场地的异常情况。在核实2个大震震前异常的基础上,将传统异常判别方法进行汇总。总结近年来针对跨断层监测数据进行分析进而识别异常的方法:原始数据反映的断层活动速率异常以及转折异常。在此基础上,引入小波分析的方法对大震前的异常进行判别。对小波分解得到的两个趋势项进行分析,发现了大震与小波分解项异常的对应性。最后,基于对原始数据和小波分解项的分析,提出利用跨断层数据分析大震前兆的参考意见,为以后的震前异常研究工作提供了基础。 相似文献
20.
Because it can be carried by flowing water, a sand/gravel pit on the river bed could migrate downstream. Consequently, the presence of pits on river beds could pose a safety threat to in-stream hydraulic structures such as bridge piers. A pit migration model can be used to predict progressive changes of pit geometry as it migrates downstream. However, due to the existence of many uncertainties, the maximum pit depth cannot be predicted with certainty. This paper adopted a simple pit migration model and evaluated the uncertainty associated with the calculated maximum pit depth. Such information is essential for evaluating the probability that a migrating pit could pose a safety threat to a downstream hydraulic structure. Three reliability analysis techniques were applied and their performances were compared. 相似文献