地震前兆含义、科学问题与研究途径的研讨

DISCUSSION ON THE IMPLICATIONS,SCIENTIFIC PROBLEMS AND RESEARCH APPROACHES OF EARTHQUAKE PRECURSORS

地震前兆的研究已经取得了很大的进展，地震前兆的复杂性引起了广泛的关注，对地震预报、有关科学问题和探索途径的研究现状及其前景有各种评价。文章认为由于一些科学问题没有解决，尽管对中缅边境1995年7月孟连7.3级地震作出了成功预报，经验性预报有一定的局限性。文中讨论了广义地震前兆和狭义地震前兆。广义地震前兆包含二类前兆：场兆（“构造前兆”）和源兆（“震源前兆”）；而狭义前兆仅指后者。中国大陆展例前兆的系统研究证实了广义地震前兆的存在，然而很难区别构造前兆和震源前兆。因此，作者认为地震前兆研究至今还没有新的突破。须要解决的关键问题之一是，经验性预报应向物理预报发展。这里应该进一步研究一些重要的科学问题，例如地震前兆的研究需要从单个震例前兆的研究过渡到成组地震前兆的研究，从点的时间序列的分析转为前兆场时空动态的研究。笔者选择了华北地区进行试验研究，取得了初步成果。

Great progress has been achieved in research on earthquake precursors, among which the complication of the earthquake precursors has been widely noticed. Various assessments on the present situation of research on earthquake prediction, relevant scientific problems,approaches and their prospect in the future have been discussed. Although asuccessful prediction has been made for Menglian M=7. 3 earthquake,which occurred in July 1995 in the border area between China and Bynmar,this paper considered that the empirical prediction has certain limitations due to some unsolved scientific problems. The socalled narrow sense precursors and broad sense precursors of earthquakes have been also discussed in this paper. The broad sense precursors include two kinds of precursors: one from tectonic stress field (i. e. 'tectonic precursors' ) and the other from focus (i. e. 'focal precursors') while the narrow sense precursors only mean the latter one. The systematic research on precursors in earthquake cases in China's continent confirmed indeed the existence of the broad sense precursors,however,it would be very difficult to distinguish each another between the tectonic one and the focal one. Therefore it seems to the authors that there has been no breakthrough in the research on earthquake precursors up to now. One of the key problems to be solved is that the empirical prediction should be put forward to the physical prediction, in which some important scientific problems should be further studied, e. g. conducting research on precursors associated with group of earthquakes instead of single one,and conducting analysis in the spatial-temporal evaluations of precursory fields instead of time series on single station. Authors of this paper selected North China for a special region to test this idea,and achieved a preliminary but new progress in this aspect.