参窝地震对海城大震的预报意义

1974年12月22日辽宁参窝水库区发生5.2级(M_L)地震,本文通过分析5.2级地震在海城7.3级地震前区域地震活动中的地位、测定地震序列在各台的P、S波振幅此以及P波初动半周期等地震学参量,认为该地震序列中最大地震发生前后,参窝地区构造应力作用形式及应力集中程度基本上没有变化,只在海城大震后才发生显著改变。作者认为,在监视大范围地震活动时空变化的同时,如果一次中等地震序列中的最大地震发生前后,某些诸如振幅比(反映构造应力作用形式)和P波初动半周期(反映地震应力降及应力集中程度)等地震学参量没有发生显著变化,则可能表明,不久将在附近地区发生更大地震。

PREDICTIVE IMPORTANCE OF THE SHENWO EARTHQUAKE TO THE HAICHENE GREAT EARTHQUAKE

The earthquake (m=5.2)occurred in Shenwo reservoir region in Liaoning Province on Dec.22, 1974. In this paper by analysing its status of the event in the regional seismicity before and after the Haicheng earthpuake (m=7.3), measuring amplitude ratio of P, S waves and half of the period of first p arrivals, it has shown that the action form of tectonic stress and its concentrative level in Shenwo region were unchanged before and after the largest earthpuakes among this seismic sequence and it was after the Haicheng earthquake that great change took place to them.The authors believe while monitoring the temporal spatial variation of seismicity in the extensive area, we should notice that a larger earthquake could occur in the vicinity if the seismological parameters such as amplitude ratio(the action form of tectonic stress)and half of the period of first p arrivals(seismic stress drop and concentrative level of tectonic stress) were unchanged before and after the largest earthquake in a moderate seismic sequence.