地震条带及其在地震预报中的作用

SEISMICITY BAND AND PRECEDING EARTHQUAKES AND ITS APPLICATION IN EARTHQUAKE PREDICTION

本文分析了1970—1984年间我国大陆及邻近地区22次5.5级以上的地震震例,结果表明:(1)地震条带与大范围平静伴生这一结论具有普遍意义,在上述研究基础上本文给出了条带判别标志。(2)条带形成于主震前几个月—2年的时间段内,主要就发生在条带上;不同地震前的条带特点有所差异,7级以上强震前的条带尺度和持续时间比较相近,而中强地震前条带的上述参量差异较大。(3)实际资料与机理分析表明:地震条带分为二种,一种与大震孕育直接有关,另一种则反映了构造活动异常。文中提出了识别这二种条带的途径并对条带的共性特征及其差异的物理意义进行了讨论。 随着地震前兆研究的不断深入,地震条带图象已成为地震预报中广泛使用的一种重要方法。本文的目的有两个:其一是通过较多震例的分析,寻求条带的识别标志,以减小条带划分的不确定性;其二是在研究条带的共性特征及其差异的基础上,探讨条带的形成机理和物理判别途径。

The spatial-temporal variations of seismicity based on the analysis of twentt two earthquakes with M≥5. 5 during 1970-1984 in the China Mainland and the vicinity,it is shown that during several months to two years prior to the events, regional seismic activity tended to concentrate on the band where the eventual main shock was located, while the seismicity in the wide area around the band became very calm at the same time. This pattern,seismicity band is accompanied by quiescence in the surrouding region,is easily identified and can be used as a indicator of a large earthquake.The band pattern before different earthquakes also characterized some differences, especially the length and duration of seimic bands before strong earthquakes with M≥7 are relatively approximate, and contrary to the bands prior to moderate events,these parameters are very different. Based on the analysis of the physical process,it shows that the band before strong earthquake is directly related to the earthquake preparetory process,and that prior to modereate event may refect anomalous tectonic activity to some extent.