地震前兆综合追踪预报方法的研究

地震前兆综合追踪预报方法的研究１地震前兆综合追踪预报方法的提出地震三要素的预报是一个难题，关于时间的预报更难。近几年来推出的实用化攻关及多种研究成果，使预报规范化了，但预报的准确率仍然很低，这就需要科技工作者进行多种学科和多种方法的研究和探索。关于地...     

用H∞控制论方法识别地震前兆异常的初步探讨

本文利用控制论方法，给出由地震引起的井水水位变化和地形变变化的数学模型，并设计反馈控制器使用干扰在Ｈ∞的范数意义下达到最小或者使该系统稳定，由此所得到的输出反映了由地震引起的异常。作为例子，文中给出了用此方法得到的１９７６年７月２８唐山７．８级地震前大灰厂短水准和汉沽双桥１号井水位短期前兆异常变化的清晰识别结果。     

地震的短期前兆

当前在有关前兆及地震预报的研究中,短期前兆问题几乎是最重要的,要求人们予以充分关注。在转入研究不同地球物理场短期前兆异常问题之前,我们试图给出地震前兆的总体定义。在文献[1]中给出了这样的定义:地震孕育过程引起的,伴随并反映这一过程的地球物理场的变化称之为地震前兆。因而我们将可能解决(尽管仅在原则上)预报三要素,即地震的震中位置,震级     

Reverse tracing of precursors and earthquake precursors in Taiwan

In this paper, we investigate the precursors of large earthquakes in the eastern region of Taiwan by means of the reverse tracing of precursors. We discuss the parameters which are suitable for the seismic chains and intermedi- ate-term patterns in this region and obtain the threshold of the patterns. Applying the linear discriminate method to the intermediate-term patterns of seismic chains, we present an approach for exploring the precursors of large earthquakes. The results show that this method can reduce the false alarm rate for large earthquakes in this region, and the reverse tracing of precursors can be applied to the eastern region of Taiwan.     

Two categories of earthquake precursors,physical and tectonic,and their roles in intermediate-term earthquake prediction

I suggest that earthquake precursors can be divided into two major categories, physical and tectonic. I define physical precursor to be a direct or indirect indication of initiation or progression of an irreversible rupture-generating physical process within the preparation zone of a forthcoming earthquake. Tectonic precursor is defined as a manifestation of tectonic movement which takes place outside the preparation zone of an impending earthquake as a link in a chain of particular local tectonism in each individual area preceding the earthquake.Most intermediate-term, short-term and immediate precursors of various disciplines within the source regions of main shocks are considered physical ones. Some precursory crustal deformations around the source regions are, however, possibly tectonic precursors, because they may be caused by episodic plate motions or resultant block movements in the neighboring regions of the fault segments that will break. A possible example of this phenomena is the anomalous crustal uplift in the Izu Peninsula, Japan, before the 1978 Izu-Oshima earthquake ofM _s 6.8. Some precursory changes in seismicity patterns in wide areas surrounding source regions also seem to be tectonic precursors, because they were probably caused by the particular tectonic setting of each region. A typical example is a so-called doughnut pattern before the 1923 Kanto, Japan, earthquake ofM _s 8.2.Although most studies on earthquake precursors so far seem to regard implicitly all precursory phenomena observed as physical ones, the two categories should be distinguished carefully when statistical analysis or physical modeling is carried out based on reported precursory phenomena. In active plate boundary zones, where a practical strategy for earthquake prediction may well be different from that in intraplate regions, tectonic precursors can be powerful additional tools for intermediate-term earthquake prediction.     

深孔钻井地震前兆综合观测的研究与实践

广州市地震办公室于2002年4月完成了深孔钻井地震前兆综合观测研究课题，并建成了增城前兆综合观测试验系统，实现了利用单井进行多学科地震前兆的数字化综合观测。本文说明了该课题的来源，分析了研究过程中的一些关键问题，简要介绍了增城试验系统的结构及功能，并对实践过程的一些创新及不足进行了总结。     

礼县震群与岷县-临潭-卓尼县5.2级地震

对1970年以来甘肃地区发生的13次小震群进行分析研究,发现它们均不同程度的表现出前兆性震群特征,其中10次震群之后在震中或其附近地区发生了中强以上地震。在深入研究这些震群的时、空、强特征和性质的基础上,对甘肃礼县震群进行了重点研究,该震群的h、k、μ、ρ值均为异常,在震群结束2月后就发生了岷县-临潭-卓尼县5．2级地震。     

Statistical property of candidate earthquake precursors and its apparent focal mecha- nism dependence

Introduction Increasing evidences show that the properties of candidate earthquake precursors seem to befocal mechanism dependent (Tsuruoka, et al, 1995; Reasenberg, 1999; Wan, et al, 2002). Test ofearthquake precursors without the classification of earthquakes could be misleading (Wu, 1999,Nature debates, http://helix.nature.com/debates/). In this paper we use the reported earthquakeprecursors for some earthquakes in China (ZHANG, 1988; 1990a, b; 1999; 2000; CHEN, 2002a, b;2003) to…     

Statistical property of candidate earthquake precursors and its apparent focal mechanism dependence

Statistical properties of reported earthquake precursors show apparent focal mechanism dependence. Intensity of anomaly is described by the ‘anomaly ratio’ as defined by the number of stations/items reporting anomalies before the target earthquake over the number of stations/items in operation around the target earthquake. Variation of the ‘anomaly ratio’ with the magnitude of the target earthquake was studied for dip-slip earthquakes all over China, strike-slip earthquakes in eastern China, and strike-slip earthquakes in western China, respectively. It is observed that for strike-slip earthquakes, the ‘anomaly ratio’ increases linearly with the magnitude of the target earthquake, while earthquakes in eastern China and western China have different slopes. For dip-slip earthquakes, however, the ‘anomaly ratio’ has no statistically significant change with the magnitude of the target earthquake. Limited data imply that the ‘anomaly ratio’ seems proportional to the apparent stress of the target earthquake. The result might be heuristic for the analysis of candidate earthquake precursors. Foundation item: National Natural Science Foundation of China (40274013) and MOST Project (2001BA601B02). Contribution No.04FE1020, Institute of Geophysics, China Earthquake Administration.     

应用小波变换提取张北地震的震磁效应

以1998年1月10日的张北地震为例,应用小波变换及傅里叶分析,分析震中附近的6个地磁台站在地震前后共6个月的地磁场三分量分钟值采样数据.发现各个地磁台站记录的地磁场Z分量在张北地震前三个月内出现不同程度的异常现象,这种现象的出现频率随着离发震时间越近而越来越高,出现的地点由南向北迁移.地磁场H和D分量没有此类异常出现.用这6个地磁台出现异常时同一频率所对应的振幅值绘出等值曲线,得到的图形是稳定的四象限分布,震中基本上位于0～3nT的等值线上.结果表明小波分析是提取地震磁效应的有效工具,同时也证实了地震磁效应的客观存在.     

张北MS 6.2级地震前兆综合加权信息量的变化

地震前兆综合加权信息量是在地震综合息量的基础上,改进了地震前兆异常出现概率的计算方法后得出的一种综合预报新方法。利用“地震预报专家系统”的思想对每一异事件进行综合评估,考虑到异常的可靠性、有效性、显著性及相互关联性给予不同的权重,以每异常事件的最可能发震时间来估算异常出现的概率,计算了华北地区１９９０年以来的地震前兆综合加权信息量,分析了１９９８年１月１０日张北Ｍｓ６．２级地震前这种信息量变化的特     

西南地区前兆观测异常特征和地震短期预测方法研究

通过对西南地区1970～2001年39组52次6级以上地震及四川部分5级以上地震震例资料的剖析,进一步研究西南地区各类前兆中、短期异常判据和指标;研究西南地区强震孕育前兆异常由中期向短期(临震)过渡、演化的标志和判据并作物理解释;并进行了西南地区前兆短期预测方法及强震短期预测时、空、强指标和判据的研究和西南地区地下流体新观测方法及灵敏测项的研究。     

Experimental examination on the heterogeneity parameter C_v of earthquake precursors

Introduction Many earthquake cases indicate that there exists obvious heterogeneity in temporal-spatial distribution of earthquake precursors (FENG, 1983; MEI, et al, 1993). Therefore, it is very crucial for the study of earthquake prediction to describe the heterogeneity in temporal-spatial distribution of earthquake precursors and to understand its physical mechanism. Up to now, a lot of useful researches have been done in this field. Recently, WANG, et al (1999) and CHEN, et al (2000)…