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近年来中国在前兆性地震现象的研究方面取得的主要进展可概述如下:1.地震空区和地震条带。在判定空区和条带时,除了震中分布以外,必须同时考虑区、带内外地震频度,能量释放率以及 b 值等的变化特征。2.地震的相关性。近期的研究表明,在中国某些特定地区间,地震的发生在时间上具有同步性,在空间距离上亦有优势分布,优势距离约为400—600公里。此外,还发现了一些地震“窗”或地震发生的“敏感”点。3.地震序列性质的判别。提出了描述地震序列能量分布均匀度的参数 U 值和 K 值,对华北地区地震序列应用的结果表明,高 U 值或高 K 值(归一化熵值),可作为判别前兆性地震序列的参考指标。如果将它们与 h 值联合使用,有可能提高判别地震序列的概率增益。4.介质参数。利用尾波和 P 波,都观测到大地震前后,震源及其周围地区介质 Q 值有不同程度的变化。文中还从统计的观点出发,对前兆性地震活动预测大地震的能力,作了估计,并提出了进一步研究的意见。
In recent years, major advances made by China in the study of precursory seismic phenomena can be summarized as follows: 1. Earthquake areas and seismic strips. In determining the empty zone and strip, in addition to the epicenter distribution, we must also consider the district, with the earthquake frequency, energy release rate and b value changes. Earthquake correlations. Recent studies have shown that the occurrence of earthquakes in China is synchronized in time and in the spatial distance, and the dominant distance is about 400-600 km. In addition, some “window” of earthquakes or “sensitive” points occurred during earthquakes. 3. The nature of the earthquake sequence discrimination. The parameters U and K for describing the energy distribution uniformity of seismic sequences are presented. The results of applying the seismic sequences to North China indicate that the high U or high K values (normalized entropy) can be used as the precursory seismic sequences reference indicator. If used in conjunction with the h value, it is possible to improve the probability gain of discriminating seismic sequences. 4. Media parameters. Both coda wave and P wave have been observed before and after the earthquake, the source and its surrounding media Q value varying degrees of change. The article also from the statistical point of view, the prediction of earthquake precursors earthquake ability, made an estimate, and put forward the views of further research.